# class Socket

`Class` `Socket` provides access to the underlying operating system socket implementations. It can be used to provide more operating system specific functionality than the protocol-specific socket classes.

The constants defined under Socket::Constants are also defined under `Socket`. For example, Socket::AF_INET is usable as well as Socket::Constants::AF_INET. See Socket::Constants for the list of constants.

### What's a socket?¶ ↑

Sockets are endpoints of a bidirectional communication channel. Sockets can communicate within a process, between processes on the same machine or between different machines. There are many types of socket: `TCPSocket`, `UDPSocket` or `UNIXSocket` for example.

Sockets have their own vocabulary:

domain: The family of protocols:

- Socket::PF_INET

- Socket::PF_INET6

- Socket::PF_UNIX

- etc.

type: The type of communications between the two endpoints, typically

- Socket::SOCK_STREAM

- Socket::SOCK_DGRAM.

protocol: Typically zero. This may be used to identify a variant of a protocol.

hostname: The identifier of a network interface:

- a string (hostname, IPv4 or IPv6 address or `broadcast` which specifies a broadcast address)

- a zero-length string which specifies INADDR_ANY

- an integer (interpreted as binary address in host byte order).

### Quick start¶ ↑

Many of the classes, such as `TCPSocket`, `UDPSocket` or `UNIXSocket`, ease the use of sockets comparatively to the equivalent C programming interface.

Let's create an internet socket using the IPv4 protocol in a C-like manner:

    require 'socket'

    s = Socket.new Socket::AF_INET, Socket::SOCK_STREAM
    s.connect Socket.pack_sockaddr_in(80, 'example.com')

You could also use the `TCPSocket` class:

    s = TCPSocket.new 'example.com', 80

A simple server might look like this:

    require 'socket'

    server = TCPServer.new 2000 # Server bound to port 2000

    loop do
      client = server.accept    # Wait for a client to connect
      client.puts "Hello !"
      client.puts "Time is #{Time.now}"
      client.close
    end

A simple client may look like this:

    require 'socket'

    s = TCPSocket.new 'localhost', 2000

    while line = s.gets # Read lines from socket
      puts line         # and print them
    end

    s.close             # close socket when done

### `Exception` Handling¶ ↑

Ruby's `Socket` implementation raises exceptions based on the error generated by the system dependent implementation. This is why the methods are documented in a way that isolate Unix-based system exceptions from Windows based exceptions. If more information on a particular exception is needed, please refer to the Unix manual pages or the Windows WinSock reference.

### Convenience methods¶ ↑

Although the general way to create socket is `Socket.new`, there are several methods of socket creation for most cases.

TCP client socket

  `Socket.tcp`, `TCPSocket.open`

TCP server socket

  `Socket.tcp_server_loop`, `TCPServer.open`

UNIX client socket

  `Socket.unix`, `UNIXSocket.open`

UNIX server socket

  `Socket.unix_server_loop`, `UNIXServer.open`

### Documentation by¶ ↑

- Zach Dennis

- Sam Roberts

- Programming Ruby from The Pragmatic Bookshelf.

Much material in this documentation is taken with permission from Programming Ruby from The Pragmatic Bookshelf.

### Constants

AF_INET6

  IPv6 protocol family

### Public Class Methods

accept_loop(*sockets) { |socket, client_addrinfo| ... } click to toggle source

yield socket and client address for each a connection accepted via given sockets.

The arguments are a list of sockets. The individual argument should be a socket or an array of sockets.

This method yields the block sequentially. It means that the next connection is not accepted until the block returns. So concurrent mechanism, thread for example, should be used to service multiple clients at a time.

    # File ext/socket/lib/socket.rb, line 785
    def self.accept_loop(*sockets) # :yield: socket, client_addrinfo
      sockets.flatten!(1)
      if sockets.empty?
        raise ArgumentError, "no sockets"
      end
      loop {
        readable, _, _ = IO.select(sockets)
        readable.each {|r|
          sock, addr = r.accept_nonblock(exception: false)
          next if sock == :wait_readable
          yield sock, addr
        }
      }
    end

getaddrinfo(nodename, servname[, family[, socktype[, protocol[, flags[, reverse_lookup]]]]]) → array click to toggle source

Obtains address information for nodename:servname.

family should be an address family such as: :INET, :INET6, etc.

socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.

protocol should be a protocol defined in the family, and defaults to 0 for the family.

flags should be bitwise OR of Socket::AI_* constants.

    Socket.getaddrinfo("www.ruby-lang.org", "http", nil, :STREAM)
    #=> [["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68", 2, 1, 6]] # PF_INET/SOCK_STREAM/IPPROTO_TCP

    Socket.getaddrinfo("localhost", nil)
    #=> [["AF_INET", 0, "localhost", "127.0.0.1", 2, 1, 6],  # PF_INET/SOCK_STREAM/IPPROTO_TCP
    #    ["AF_INET", 0, "localhost", "127.0.0.1", 2, 2, 17], # PF_INET/SOCK_DGRAM/IPPROTO_UDP
    #    ["AF_INET", 0, "localhost", "127.0.0.1", 2, 3, 0]]  # PF_INET/SOCK_RAW/IPPROTO_IP

reverse_lookup directs the form of the third element, and has to be one of below. If reverse_lookup is omitted, the default value is `nil`.

    +true+, +:hostname+:  hostname is obtained from numeric address using reverse lookup, which may take a time.
    +false+, +:numeric+:  hostname is same as numeric address.
    +nil+:              obey to the current +do_not_reverse_lookup+ flag.

If `Addrinfo` object is preferred, use `Addrinfo.getaddrinfo`.

    static VALUE
    sock_s_getaddrinfo(int argc, VALUE *argv)
    {
        VALUE host, port, family, socktype, protocol, flags, ret, revlookup;
        struct addrinfo hints;
        struct rb_addrinfo *res;
        int norevlookup;

        rb_scan_args(argc, argv, "25", &host, &port, &family, &socktype, &protocol, &flags, &revlookup);

        MEMZERO(&hints, struct addrinfo, 1);
        hints.ai_family = NIL_P(family) ? PF_UNSPEC : rsock_family_arg(family);

        if (!NIL_P(socktype)) {
            hints.ai_socktype = rsock_socktype_arg(socktype);
        }
        if (!NIL_P(protocol)) {
            hints.ai_protocol = NUM2INT(protocol);
        }
        if (!NIL_P(flags)) {
            hints.ai_flags = NUM2INT(flags);
        }
        if (NIL_P(revlookup) || !rsock_revlookup_flag(revlookup, &norevlookup)) {
            norevlookup = rsock_do_not_reverse_lookup;
        }
        res = rsock_getaddrinfo(host, port, &hints, 0);

        ret = make_addrinfo(res, norevlookup);
        rb_freeaddrinfo(res);
        return ret;
    }

gethostbyaddr(address_string [, address_family]) → hostent click to toggle source

Obtains the host information for address.

    p Socket.gethostbyaddr([221,186,184,68].pack("CCCC"))
    #=> ["carbon.ruby-lang.org", [], 2, "\xDD\xBA\xB8D"]

    static VALUE
    sock_s_gethostbyaddr(int argc, VALUE *argv)
    {
        VALUE addr, family;
        struct hostent *h;
        char **pch;
        VALUE ary, names;
        int t = AF_INET;

        rb_scan_args(argc, argv, "11", &addr, &family);
        StringValue(addr);
        if (!NIL_P(family)) {
            t = rsock_family_arg(family);
        }
    #ifdef AF_INET6
        else if (RSTRING_LEN(addr) == 16) {
            t = AF_INET6;
        }
    #endif
        h = gethostbyaddr(RSTRING_PTR(addr), RSTRING_SOCKLEN(addr), t);
        if (h == NULL) {
    #ifdef HAVE_HSTRERROR
            extern int h_errno;
            rb_raise(rb_eSocket, "%s", (char*)hstrerror(h_errno));
    #else
            rb_raise(rb_eSocket, "host not found");
    #endif
        }
        ary = rb_ary_new();
        rb_ary_push(ary, rb_str_new2(h->h_name));
        names = rb_ary_new();
        rb_ary_push(ary, names);
        if (h->h_aliases != NULL) {
            for (pch = h->h_aliases; *pch; pch++) {
                rb_ary_push(names, rb_str_new2(*pch));
            }
        }
        rb_ary_push(ary, INT2NUM(h->h_addrtype));
    #ifdef h_addr
        for (pch = h->h_addr_list; *pch; pch++) {
            rb_ary_push(ary, rb_str_new(*pch, h->h_length));
        }
    #else
        rb_ary_push(ary, rb_str_new(h->h_addr, h->h_length));
    #endif

        return ary;
    }

gethostbyname(hostname) → [official_hostname, alias_hostnames, address_family, *address_list] click to toggle source

Obtains the host information for hostname.

    p Socket.gethostbyname("hal") #=> ["localhost", ["hal"], 2, "\x7F\x00\x00\x01"]

    static VALUE
    sock_s_gethostbyname(VALUE obj, VALUE host)
    {
        struct rb_addrinfo *res =
            rsock_addrinfo(host, Qnil, AF_UNSPEC, SOCK_STREAM, AI_CANONNAME);
        return rsock_make_hostent(host, res, sock_sockaddr);
    }

gethostname → hostname click to toggle source

Returns the hostname.

    p Socket.gethostname #=> "hal"

Note that it is not guaranteed to be able to convert to IP address using gethostbyname, getaddrinfo, etc. If you need local IP address, use `Socket.ip_address_list`.

    static VALUE
    sock_gethostname(VALUE obj)
    {
    #if defined(NI_MAXHOST)
    #  define RUBY_MAX_HOST_NAME_LEN NI_MAXHOST
    #elif defined(HOST_NAME_MAX)
    #  define RUBY_MAX_HOST_NAME_LEN HOST_NAME_MAX
    #else
    #  define RUBY_MAX_HOST_NAME_LEN 1024
    #endif

        long len = RUBY_MAX_HOST_NAME_LEN;
        VALUE name;

        name = rb_str_new(0, len);
        while (gethostname(RSTRING_PTR(name), len) < 0) {
            int e = errno;
            switch (e) {
              case ENAMETOOLONG:
    #ifdef __linux__
              case EINVAL:
                /* glibc before version 2.1 uses EINVAL instead of ENAMETOOLONG */
    #endif
                break;
              default:
                rb_syserr_fail(e, "gethostname(3)");
            }
            rb_str_modify_expand(name, len);
            len += len;
        }
        rb_str_resize(name, strlen(RSTRING_PTR(name)));
        return name;
    }

getifaddrs → [ifaddr1, ...] click to toggle source

Returns an array of interface addresses. An element of the array is an instance of `Socket::Ifaddr`.

This method can be used to find multicast-enabled interfaces:

    pp Socket.getifaddrs.reject {|ifaddr|
      !ifaddr.addr.ip? || (ifaddr.flags & Socket::IFF_MULTICAST == 0)
    }.map {|ifaddr| [ifaddr.name, ifaddr.ifindex, ifaddr.addr] }
    #=> [["eth0", 2, #<Addrinfo: 221.186.184.67>],
    #    ["eth0", 2, #<Addrinfo: fe80::216:3eff:fe95:88bb%eth0>]]

Example result on GNU/Linux:

    pp Socket.getifaddrs
    #=> [#<Socket::Ifaddr lo UP,LOOPBACK,RUNNING,0x10000 PACKET[protocol=0 lo hatype=772 HOST hwaddr=00:00:00:00:00:00]>,
    #    #<Socket::Ifaddr eth0 UP,BROADCAST,RUNNING,MULTICAST,0x10000 PACKET[protocol=0 eth0 hatype=1 HOST hwaddr=00:16:3e:95:88:bb] broadcast=PACKET[protocol=0 eth0 hatype=1 HOST hwaddr=ff:ff:ff:ff:ff:ff]>,
    #    #<Socket::Ifaddr sit0 NOARP PACKET[protocol=0 sit0 hatype=776 HOST hwaddr=00:00:00:00]>,
    #    #<Socket::Ifaddr lo UP,LOOPBACK,RUNNING,0x10000 127.0.0.1 netmask=255.0.0.0>,
    #    #<Socket::Ifaddr eth0 UP,BROADCAST,RUNNING,MULTICAST,0x10000 221.186.184.67 netmask=255.255.255.240 broadcast=221.186.184.79>,
    #    #<Socket::Ifaddr lo UP,LOOPBACK,RUNNING,0x10000 ::1 netmask=ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>,
    #    #<Socket::Ifaddr eth0 UP,BROADCAST,RUNNING,MULTICAST,0x10000 fe80::216:3eff:fe95:88bb%eth0 netmask=ffff:ffff:ffff:ffff::>]

Example result on FreeBSD:

    pp Socket.getifaddrs
    #=> [#<Socket::Ifaddr usbus0 UP,0x10000 LINK[usbus0]>,
    #    #<Socket::Ifaddr re0 UP,BROADCAST,RUNNING,MULTICAST,0x800 LINK[re0 3a:d0:40:9a:fe:e8]>,
    #    #<Socket::Ifaddr re0 UP,BROADCAST,RUNNING,MULTICAST,0x800 10.250.10.18 netmask=255.255.255.? (7 bytes for 16 bytes sockaddr_in) broadcast=10.250.10.255>,
    #    #<Socket::Ifaddr re0 UP,BROADCAST,RUNNING,MULTICAST,0x800 fe80:2::38d0:40ff:fe9a:fee8 netmask=ffff:ffff:ffff:ffff::>,
    #    #<Socket::Ifaddr re0 UP,BROADCAST,RUNNING,MULTICAST,0x800 2001:2e8:408:10::12 netmask=UNSPEC>,
    #    #<Socket::Ifaddr plip0 POINTOPOINT,MULTICAST,0x800 LINK[plip0]>,
    #    #<Socket::Ifaddr lo0 UP,LOOPBACK,RUNNING,MULTICAST LINK[lo0]>,
    #    #<Socket::Ifaddr lo0 UP,LOOPBACK,RUNNING,MULTICAST ::1 netmask=ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff>,
    #    #<Socket::Ifaddr lo0 UP,LOOPBACK,RUNNING,MULTICAST fe80:4::1 netmask=ffff:ffff:ffff:ffff::>,
    #    #<Socket::Ifaddr lo0 UP,LOOPBACK,RUNNING,MULTICAST 127.0.0.1 netmask=255.?.?.? (5 bytes for 16 bytes sockaddr_in)>]

    static VALUE
    socket_s_getifaddrs(VALUE self)
    {
        return rsock_getifaddrs();
    }

getnameinfo(sockaddr [, flags]) → [hostname, servicename] click to toggle source

Obtains name information for sockaddr.

sockaddr should be one of follows.

- packed sockaddr string such as `Socket.sockaddr_in`(80, “127.0.0.1”)

- 3-elements array such as [“AF_INET”, 80, “127.0.0.1”]

- 4-elements array such as [“AF_INET”, 80, ignored, “127.0.0.1”]

flags should be bitwise OR of Socket::NI_* constants.

Note: The last form is compatible with `IPSocket#addr` and `IPSocket#peeraddr`.

    Socket.getnameinfo(Socket.sockaddr_in(80, "127.0.0.1"))       #=> ["localhost", "www"]
    Socket.getnameinfo(["AF_INET", 80, "127.0.0.1"])              #=> ["localhost", "www"]
    Socket.getnameinfo(["AF_INET", 80, "localhost", "127.0.0.1"]) #=> ["localhost", "www"]

If `Addrinfo` object is preferred, use `Addrinfo#getnameinfo`.

    static VALUE
    sock_s_getnameinfo(int argc, VALUE *argv)
    {
        VALUE sa, af = Qnil, host = Qnil, port = Qnil, flags, tmp;
        char *hptr, *pptr;
        char hbuf[1024], pbuf[1024];
        int fl;
        struct rb_addrinfo *res = NULL;
        struct addrinfo hints, *r;
        int error, saved_errno;
        union_sockaddr ss;
        struct sockaddr *sap;
        socklen_t salen;

        sa = flags = Qnil;
        rb_scan_args(argc, argv, "11", &sa, &flags);

        fl = 0;
        if (!NIL_P(flags)) {
            fl = NUM2INT(flags);
        }
        tmp = rb_check_sockaddr_string_type(sa);
        if (!NIL_P(tmp)) {
            sa = tmp;
            if (sizeof(ss) < (size_t)RSTRING_LEN(sa)) {
                rb_raise(rb_eTypeError, "sockaddr length too big");
            }
            memcpy(&ss, RSTRING_PTR(sa), RSTRING_LEN(sa));
            if (!VALIDATE_SOCKLEN(&ss.addr, RSTRING_LEN(sa))) {
                rb_raise(rb_eTypeError, "sockaddr size differs - should not happen");
            }
            sap = &ss.addr;
            salen = RSTRING_SOCKLEN(sa);
            goto call_nameinfo;
        }
        tmp = rb_check_array_type(sa);
        if (!NIL_P(tmp)) {
            sa = tmp;
            MEMZERO(&hints, struct addrinfo, 1);
            if (RARRAY_LEN(sa) == 3) {
                af = RARRAY_AREF(sa, 0);
                port = RARRAY_AREF(sa, 1);
                host = RARRAY_AREF(sa, 2);
            }
            else if (RARRAY_LEN(sa) >= 4) {
                af = RARRAY_AREF(sa, 0);
                port = RARRAY_AREF(sa, 1);
                host = RARRAY_AREF(sa, 3);
                if (NIL_P(host)) {
                    host = RARRAY_AREF(sa, 2);
                }
                else {
                    /*
                     * 4th element holds numeric form, don't resolve.
                     * see rsock_ipaddr().
                     */
    #ifdef AI_NUMERICHOST /* AIX 4.3.3 doesn't have AI_NUMERICHOST. */
                    hints.ai_flags |= AI_NUMERICHOST;
    #endif
                }
            }
            else {
                rb_raise(rb_eArgError, "array size should be 3 or 4, %ld given",
                         RARRAY_LEN(sa));
            }
            /* host */
            if (NIL_P(host)) {
                hptr = NULL;
            }
            else {
                strncpy(hbuf, StringValueCStr(host), sizeof(hbuf));
                hbuf[sizeof(hbuf) - 1] = '\0';
                hptr = hbuf;
            }
            /* port */
            if (NIL_P(port)) {
                strcpy(pbuf, "0");
                pptr = NULL;
            }
            else if (FIXNUM_P(port)) {
                snprintf(pbuf, sizeof(pbuf), "%ld", NUM2LONG(port));
                pptr = pbuf;
            }
            else {
                strncpy(pbuf, StringValueCStr(port), sizeof(pbuf));
                pbuf[sizeof(pbuf) - 1] = '\0';
                pptr = pbuf;
            }
            hints.ai_socktype = (fl & NI_DGRAM) ? SOCK_DGRAM : SOCK_STREAM;
            /* af */
            hints.ai_family = NIL_P(af) ? PF_UNSPEC : rsock_family_arg(af);
            error = rb_getaddrinfo(hptr, pptr, &hints, &res);
            if (error) goto error_exit_addr;
            sap = res->ai->ai_addr;
            salen = res->ai->ai_addrlen;
        }
        else {
            rb_raise(rb_eTypeError, "expecting String or Array");
        }

      call_nameinfo:
        error = rb_getnameinfo(sap, salen, hbuf, sizeof(hbuf),
                               pbuf, sizeof(pbuf), fl);
        if (error) goto error_exit_name;
        if (res) {
            for (r = res->ai->ai_next; r; r = r->ai_next) {
                char hbuf2[1024], pbuf2[1024];

                sap = r->ai_addr;
                salen = r->ai_addrlen;
                error = rb_getnameinfo(sap, salen, hbuf2, sizeof(hbuf2),
                                       pbuf2, sizeof(pbuf2), fl);
                if (error) goto error_exit_name;
                if (strcmp(hbuf, hbuf2) != 0|| strcmp(pbuf, pbuf2) != 0) {
                    rb_freeaddrinfo(res);
                    rb_raise(rb_eSocket, "sockaddr resolved to multiple nodename");
                }
            }
            rb_freeaddrinfo(res);
        }
        return rb_assoc_new(rb_str_new2(hbuf), rb_str_new2(pbuf));

      error_exit_addr:
        saved_errno = errno;
        if (res) rb_freeaddrinfo(res);
        errno = saved_errno;
        rsock_raise_socket_error("getaddrinfo", error);

      error_exit_name:
        saved_errno = errno;
        if (res) rb_freeaddrinfo(res);
        errno = saved_errno;
        rsock_raise_socket_error("getnameinfo", error);

        UNREACHABLE;
    }

getservbyname(service_name) → port_number click to toggle source
getservbyname(service_name, protocol_name) → port_number

Obtains the port number for service_name.

If protocol_name is not given, “tcp” is assumed.

    Socket.getservbyname("smtp")          #=> 25
    Socket.getservbyname("shell")         #=> 514
    Socket.getservbyname("syslog", "udp") #=> 514

    static VALUE
    sock_s_getservbyname(int argc, VALUE *argv)
    {
        VALUE service, proto;
        struct servent *sp;
        long port;
        const char *servicename, *protoname = "tcp";

        rb_scan_args(argc, argv, "11", &service, &proto);
        StringValue(service);
        if (!NIL_P(proto)) StringValue(proto);
        servicename = StringValueCStr(service);
        if (!NIL_P(proto)) protoname = StringValueCStr(proto);
        sp = getservbyname(servicename, protoname);
        if (sp) {
            port = ntohs(sp->s_port);
        }
        else {
            char *end;

            port = STRTOUL(servicename, &end, 0);
            if (*end != '\0') {
                rb_raise(rb_eSocket, "no such service %s/%s", servicename, protoname);
            }
        }
        return INT2FIX(port);
    }

getservbyport(port [, protocol_name]) → service click to toggle source

Obtains the port number for port.

If protocol_name is not given, “tcp” is assumed.

    Socket.getservbyport(80)         #=> "www"
    Socket.getservbyport(514, "tcp") #=> "shell"
    Socket.getservbyport(514, "udp") #=> "syslog"

    static VALUE
    sock_s_getservbyport(int argc, VALUE *argv)
    {
        VALUE port, proto;
        struct servent *sp;
        long portnum;
        const char *protoname = "tcp";

        rb_scan_args(argc, argv, "11", &port, &proto);
        portnum = NUM2LONG(port);
        if (portnum != (uint16_t)portnum) {
            const char *s = portnum > 0 ? "big" : "small";
            rb_raise(rb_eRangeError, "integer %ld too %s to convert into `int16_t'", portnum, s);
        }
        if (!NIL_P(proto)) protoname = StringValueCStr(proto);

        sp = getservbyport((int)htons((uint16_t)portnum), protoname);
        if (!sp) {
            rb_raise(rb_eSocket, "no such service for port %d/%s", (int)portnum, protoname);
        }
        return rb_tainted_str_new2(sp->s_name);
    }

ip_address_list → array click to toggle source

Returns local IP addresses as an array.

The array contains `Addrinfo` objects.

    pp Socket.ip_address_list
    #=> [#<Addrinfo: 127.0.0.1>,
         #<Addrinfo: 192.168.0.128>,
         #<Addrinfo: ::1>,
         ...]

    static VALUE
    socket_s_ip_address_list(VALUE self)
    {
    #if defined(HAVE_GETIFADDRS)
        struct ifaddrs *ifp = NULL;
        struct ifaddrs *p;
        int ret;
        VALUE list;

        ret = getifaddrs(&ifp);
        if (ret == -1) {
            rb_sys_fail("getifaddrs");
        }

        list = rb_ary_new();
        for (p = ifp; p; p = p->ifa_next) {
            if (p->ifa_addr != NULL && IS_IP_FAMILY(p->ifa_addr->sa_family)) {
                struct sockaddr *addr = p->ifa_addr;
    #if defined(AF_INET6) && defined(__sun)
                /*
                 * OpenIndiana SunOS 5.11 getifaddrs() returns IPv6 link local
                 * address with sin6_scope_id == 0.
                 * So fill it from the interface name (ifa_name).
                 */
                struct sockaddr_in6 addr6;
                if (addr->sa_family == AF_INET6) {
                    socklen_t len = (socklen_t)sizeof(struct sockaddr_in6);
                    memcpy(&addr6, addr, len);
                    addr = (struct sockaddr *)&addr6;
                    if (IN6_IS_ADDR_LINKLOCAL(&addr6.sin6_addr) &&
                        addr6.sin6_scope_id == 0) {
                        unsigned int ifindex = if_nametoindex(p->ifa_name);
                        if (ifindex != 0) {
                            addr6.sin6_scope_id = ifindex;
                        }
                    }
                }
    #endif
                rb_ary_push(list, sockaddr_obj(addr, sockaddr_len(addr)));
            }
        }

        freeifaddrs(ifp);

        return list;
    #elif defined(SIOCGLIFCONF) && defined(SIOCGLIFNUM) && !defined(__hpux)
        /* Solaris if_tcp(7P) */
        /* HP-UX has SIOCGLIFCONF too.  But it uses different struct */
        int fd = -1;
        int ret;
        struct lifnum ln;
        struct lifconf lc;
        const char *reason = NULL;
        int save_errno;
        int i;
        VALUE list = Qnil;

        lc.lifc_buf = NULL;

        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd == -1)
            rb_sys_fail("socket(2)");

        memset(&ln, 0, sizeof(ln));
        ln.lifn_family = AF_UNSPEC;

        ret = ioctl(fd, SIOCGLIFNUM, &ln);
        if (ret == -1) {
            reason = "SIOCGLIFNUM";
            goto finish;
        }

        memset(&lc, 0, sizeof(lc));
        lc.lifc_family = AF_UNSPEC;
        lc.lifc_flags = 0;
        lc.lifc_len = sizeof(struct lifreq) * ln.lifn_count;
        lc.lifc_req = xmalloc(lc.lifc_len);

        ret = ioctl(fd, SIOCGLIFCONF, &lc);
        if (ret == -1) {
            reason = "SIOCGLIFCONF";
            goto finish;
        }

        list = rb_ary_new();
        for (i = 0; i < ln.lifn_count; i++) {
            struct lifreq *req = &lc.lifc_req[i];
            if (IS_IP_FAMILY(req->lifr_addr.ss_family)) {
                if (req->lifr_addr.ss_family == AF_INET6 &&
                    IN6_IS_ADDR_LINKLOCAL(&((struct sockaddr_in6 *)(&req->lifr_addr))->sin6_addr) &&
                    ((struct sockaddr_in6 *)(&req->lifr_addr))->sin6_scope_id == 0) {
                    struct lifreq req2;
                    memcpy(req2.lifr_name, req->lifr_name, LIFNAMSIZ);
                    ret = ioctl(fd, SIOCGLIFINDEX, &req2);
                    if (ret == -1) {
                        reason = "SIOCGLIFINDEX";
                        goto finish;
                    }
                    ((struct sockaddr_in6 *)(&req->lifr_addr))->sin6_scope_id = req2.lifr_index;
                }
                rb_ary_push(list, sockaddr_obj((struct sockaddr *)&req->lifr_addr, req->lifr_addrlen));
            }
        }

      finish:
        save_errno = errno;
        if (lc.lifc_buf != NULL)
            xfree(lc.lifc_req);
        if (fd != -1)
            close(fd);
        errno = save_errno;

        if (reason)
            rb_syserr_fail(save_errno, reason);
        return list;

    #elif defined(SIOCGIFCONF)
        int fd = -1;
        int ret;
    #define EXTRA_SPACE ((int)(sizeof(struct ifconf) + sizeof(union_sockaddr)))
        char initbuf[4096+EXTRA_SPACE];
        char *buf = initbuf;
        int bufsize;
        struct ifconf conf;
        struct ifreq *req;
        VALUE list = Qnil;
        const char *reason = NULL;
        int save_errno;

        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd == -1)
            rb_sys_fail("socket(2)");

        bufsize = sizeof(initbuf);
        buf = initbuf;

      retry:
        conf.ifc_len = bufsize;
        conf.ifc_req = (struct ifreq *)buf;

        /* fprintf(stderr, "bufsize: %d\n", bufsize); */

        ret = ioctl(fd, SIOCGIFCONF, &conf);
        if (ret == -1) {
            reason = "SIOCGIFCONF";
            goto finish;
        }

        /* fprintf(stderr, "conf.ifc_len: %d\n", conf.ifc_len); */

        if (bufsize - EXTRA_SPACE < conf.ifc_len) {
            if (bufsize < conf.ifc_len) {
                /* NetBSD returns required size for all interfaces. */
                bufsize = conf.ifc_len + EXTRA_SPACE;
            }
            else {
                bufsize = bufsize << 1;
            }
            if (buf == initbuf)
                buf = NULL;
            buf = xrealloc(buf, bufsize);
            goto retry;
        }

        close(fd);
        fd = -1;

        list = rb_ary_new();
        req = conf.ifc_req;
        while ((char*)req < (char*)conf.ifc_req + conf.ifc_len) {
            struct sockaddr *addr = &req->ifr_addr;
            if (IS_IP_FAMILY(addr->sa_family)) {
                rb_ary_push(list, sockaddr_obj(addr, sockaddr_len(addr)));
            }
    #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
    # ifndef _SIZEOF_ADDR_IFREQ
    #  define _SIZEOF_ADDR_IFREQ(r) \
              (sizeof(struct ifreq) + \
               (sizeof(struct sockaddr) < (r).ifr_addr.sa_len ? \
                (r).ifr_addr.sa_len - sizeof(struct sockaddr) : \
                0))
    # endif
            req = (struct ifreq *)((char*)req + _SIZEOF_ADDR_IFREQ(*req));
    #else
            req = (struct ifreq *)((char*)req + sizeof(struct ifreq));
    #endif
        }

      finish:

        save_errno = errno;
        if (buf != initbuf)
            xfree(buf);
        if (fd != -1)
            close(fd);
        errno = save_errno;

        if (reason)
            rb_syserr_fail(save_errno, reason);
        return list;

    #undef EXTRA_SPACE
    #elif defined(_WIN32)
        typedef struct ip_adapter_unicast_address_st {
            unsigned LONG_LONG dummy0;
            struct ip_adapter_unicast_address_st *Next;
            struct {
                struct sockaddr *lpSockaddr;
                int iSockaddrLength;
            } Address;
            int dummy1;
            int dummy2;
            int dummy3;
            long dummy4;
            long dummy5;
            long dummy6;
        } ip_adapter_unicast_address_t;
        typedef struct ip_adapter_anycast_address_st {
            unsigned LONG_LONG dummy0;
            struct ip_adapter_anycast_address_st *Next;
            struct {
                struct sockaddr *lpSockaddr;
                int iSockaddrLength;
            } Address;
        } ip_adapter_anycast_address_t;
        typedef struct ip_adapter_addresses_st {
            unsigned LONG_LONG dummy0;
            struct ip_adapter_addresses_st *Next;
            void *dummy1;
            ip_adapter_unicast_address_t *FirstUnicastAddress;
            ip_adapter_anycast_address_t *FirstAnycastAddress;
            void *dummy2;
            void *dummy3;
            void *dummy4;
            void *dummy5;
            void *dummy6;
            BYTE dummy7[8];
            DWORD dummy8;
            DWORD dummy9;
            DWORD dummy10;
            DWORD IfType;
            int OperStatus;
            DWORD dummy12;
            DWORD dummy13[16];
            void *dummy14;
        } ip_adapter_addresses_t;
        typedef ULONG (WINAPI *GetAdaptersAddresses_t)(ULONG, ULONG, PVOID, ip_adapter_addresses_t *, PULONG);
        HMODULE h;
        GetAdaptersAddresses_t pGetAdaptersAddresses;
        ULONG len;
        DWORD ret;
        ip_adapter_addresses_t *adapters;
        VALUE list;

        h = LoadLibrary("iphlpapi.dll");
        if (!h)
            rb_notimplement();
        pGetAdaptersAddresses = (GetAdaptersAddresses_t)GetProcAddress(h, "GetAdaptersAddresses");
        if (!pGetAdaptersAddresses) {
            FreeLibrary(h);
            rb_notimplement();
        }

        ret = pGetAdaptersAddresses(AF_UNSPEC, 0, NULL, NULL, &len);
        if (ret != ERROR_SUCCESS && ret != ERROR_BUFFER_OVERFLOW) {
            errno = rb_w32_map_errno(ret);
            FreeLibrary(h);
            rb_sys_fail("GetAdaptersAddresses");
        }
        adapters = (ip_adapter_addresses_t *)ALLOCA_N(BYTE, len);
        ret = pGetAdaptersAddresses(AF_UNSPEC, 0, NULL, adapters, &len);
        if (ret != ERROR_SUCCESS) {
            errno = rb_w32_map_errno(ret);
            FreeLibrary(h);
            rb_sys_fail("GetAdaptersAddresses");
        }

        list = rb_ary_new();
        for (; adapters; adapters = adapters->Next) {
            ip_adapter_unicast_address_t *uni;
            ip_adapter_anycast_address_t *any;
            if (adapters->OperStatus != 1) /* 1 means IfOperStatusUp */
                continue;
            for (uni = adapters->FirstUnicastAddress; uni; uni = uni->Next) {
    #ifndef INET6
                if (uni->Address.lpSockaddr->sa_family == AF_INET)
    #else
                if (IS_IP_FAMILY(uni->Address.lpSockaddr->sa_family))
    #endif
                    rb_ary_push(list, sockaddr_obj(uni->Address.lpSockaddr, uni->Address.iSockaddrLength));
            }
            for (any = adapters->FirstAnycastAddress; any; any = any->Next) {
    #ifndef INET6
                if (any->Address.lpSockaddr->sa_family == AF_INET)
    #else
                if (IS_IP_FAMILY(any->Address.lpSockaddr->sa_family))
    #endif
                    rb_ary_push(list, sockaddr_obj(any->Address.lpSockaddr, any->Address.iSockaddrLength));
            }
        }

        FreeLibrary(h);
        return list;
    #endif
    }

new(domain, socktype [, protocol]) → socket click to toggle source

Creates a new socket object.

domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.

socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.

protocol is optional and should be a protocol defined in the domain. If protocol is not given, 0 is used internally.

    Socket.new(:INET, :STREAM) # TCP socket
    Socket.new(:INET, :DGRAM)  # UDP socket
    Socket.new(:UNIX, :STREAM) # UNIX stream socket
    Socket.new(:UNIX, :DGRAM)  # UNIX datagram socket

    static VALUE
    sock_initialize(int argc, VALUE *argv, VALUE sock)
    {
        VALUE domain, type, protocol;
        int fd;
        int d, t;

        rb_scan_args(argc, argv, "21", &domain, &type, &protocol);
        if (NIL_P(protocol))
            protocol = INT2FIX(0);

        setup_domain_and_type(domain, &d, type, &t);
        fd = rsock_socket(d, t, NUM2INT(protocol));
        if (fd < 0) rb_sys_fail("socket(2)");

        return rsock_init_sock(sock, fd);
    }

pack_sockaddr_in(port, host) → sockaddr click to toggle source

Packs port and host as an AF_INET/AF_INET6 sockaddr string.

    Socket.sockaddr_in(80, "127.0.0.1")
    #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"

    Socket.sockaddr_in(80, "::1")
    #=> "\n\x00\x00P\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00"

    static VALUE
    sock_s_pack_sockaddr_in(VALUE self, VALUE port, VALUE host)
    {
        struct rb_addrinfo *res = rsock_addrinfo(host, port, AF_UNSPEC, 0, 0);
        VALUE addr = rb_str_new((char*)res->ai->ai_addr, res->ai->ai_addrlen);

        rb_freeaddrinfo(res);
        OBJ_INFECT(addr, port);
        OBJ_INFECT(addr, host);

        return addr;
    }

pack_sockaddr_un(path) → sockaddr click to toggle source

Packs path as an AF_UNIX sockaddr string.

    Socket.sockaddr_un("/tmp/sock") #=> "\x01\x00/tmp/sock\x00\x00..."

    static VALUE
    sock_s_pack_sockaddr_un(VALUE self, VALUE path)
    {
        struct sockaddr_un sockaddr;
        VALUE addr;

        StringValue(path);
        INIT_SOCKADDR_UN(&sockaddr, sizeof(struct sockaddr_un));
        if (sizeof(sockaddr.sun_path) < (size_t)RSTRING_LEN(path)) {
            rb_raise(rb_eArgError, "too long unix socket path (%"PRIuSIZE" bytes given but %"PRIuSIZE" bytes max)",
                (size_t)RSTRING_LEN(path), sizeof(sockaddr.sun_path));
        }
        memcpy(sockaddr.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
        addr = rb_str_new((char*)&sockaddr, rsock_unix_sockaddr_len(path));
        OBJ_INFECT(addr, path);

        return addr;
    }

pair(domain, type, protocol) → [socket1, socket2] click to toggle source

Creates a pair of sockets connected each other.

domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.

socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.

protocol should be a protocol defined in the domain, defaults to 0 for the domain.

    s1, s2 = Socket.pair(:UNIX, :STREAM, 0)
    s1.send "a", 0
    s1.send "b", 0
    s1.close
    p s2.recv(10) #=> "ab"
    p s2.recv(10) #=> ""
    p s2.recv(10) #=> ""

    s1, s2 = Socket.pair(:UNIX, :DGRAM, 0)
    s1.send "a", 0
    s1.send "b", 0
    p s2.recv(10) #=> "a"
    p s2.recv(10) #=> "b"

    VALUE
    rsock_sock_s_socketpair(int argc, VALUE *argv, VALUE klass)
    {
        VALUE domain, type, protocol;
        int d, t, p, sp[2];
        int ret;
        VALUE s1, s2, r;

        rb_scan_args(argc, argv, "21", &domain, &type, &protocol);
        if (NIL_P(protocol))
            protocol = INT2FIX(0);

        setup_domain_and_type(domain, &d, type, &t);
        p = NUM2INT(protocol);
        ret = rsock_socketpair(d, t, p, sp);
        if (ret < 0) {
            rb_sys_fail("socketpair(2)");
        }

        s1 = rsock_init_sock(rb_obj_alloc(klass), sp[0]);
        s2 = rsock_init_sock(rb_obj_alloc(klass), sp[1]);
        r = rb_assoc_new(s1, s2);
        if (rb_block_given_p()) {
            return rb_ensure(pair_yield, r, io_close, s1);
        }
        return r;
    }

sockaddr_in(port, host) → sockaddr click to toggle source

Packs port and host as an AF_INET/AF_INET6 sockaddr string.

    Socket.sockaddr_in(80, "127.0.0.1")
    #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"

    Socket.sockaddr_in(80, "::1")
    #=> "\n\x00\x00P\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00"

    static VALUE
    sock_s_pack_sockaddr_in(VALUE self, VALUE port, VALUE host)
    {
        struct rb_addrinfo *res = rsock_addrinfo(host, port, AF_UNSPEC, 0, 0);
        VALUE addr = rb_str_new((char*)res->ai->ai_addr, res->ai->ai_addrlen);

        rb_freeaddrinfo(res);
        OBJ_INFECT(addr, port);
        OBJ_INFECT(addr, host);

        return addr;
    }

sockaddr_un(path) → sockaddr click to toggle source

Packs path as an AF_UNIX sockaddr string.

    Socket.sockaddr_un("/tmp/sock") #=> "\x01\x00/tmp/sock\x00\x00..."

    static VALUE
    sock_s_pack_sockaddr_un(VALUE self, VALUE path)
    {
        struct sockaddr_un sockaddr;
        VALUE addr;

        StringValue(path);
        INIT_SOCKADDR_UN(&sockaddr, sizeof(struct sockaddr_un));
        if (sizeof(sockaddr.sun_path) < (size_t)RSTRING_LEN(path)) {
            rb_raise(rb_eArgError, "too long unix socket path (%"PRIuSIZE" bytes given but %"PRIuSIZE" bytes max)",
                (size_t)RSTRING_LEN(path), sizeof(sockaddr.sun_path));
        }
        memcpy(sockaddr.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
        addr = rb_str_new((char*)&sockaddr, rsock_unix_sockaddr_len(path));
        OBJ_INFECT(addr, path);

        return addr;
    }

socketpair(domain, type, protocol) → [socket1, socket2] click to toggle source

Creates a pair of sockets connected each other.

domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.

socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.

protocol should be a protocol defined in the domain, defaults to 0 for the domain.

    s1, s2 = Socket.pair(:UNIX, :STREAM, 0)
    s1.send "a", 0
    s1.send "b", 0
    s1.close
    p s2.recv(10) #=> "ab"
    p s2.recv(10) #=> ""
    p s2.recv(10) #=> ""

    s1, s2 = Socket.pair(:UNIX, :DGRAM, 0)
    s1.send "a", 0
    s1.send "b", 0
    p s2.recv(10) #=> "a"
    p s2.recv(10) #=> "b"

    VALUE
    rsock_sock_s_socketpair(int argc, VALUE *argv, VALUE klass)
    {
        VALUE domain, type, protocol;
        int d, t, p, sp[2];
        int ret;
        VALUE s1, s2, r;

        rb_scan_args(argc, argv, "21", &domain, &type, &protocol);
        if (NIL_P(protocol))
            protocol = INT2FIX(0);

        setup_domain_and_type(domain, &d, type, &t);
        p = NUM2INT(protocol);
        ret = rsock_socketpair(d, t, p, sp);
        if (ret < 0) {
            rb_sys_fail("socketpair(2)");
        }

        s1 = rsock_init_sock(rb_obj_alloc(klass), sp[0]);
        s2 = rsock_init_sock(rb_obj_alloc(klass), sp[1]);
        r = rb_assoc_new(s1, s2);
        if (rb_block_given_p()) {
            return rb_ensure(pair_yield, r, io_close, s1);
        }
        return r;
    }

tcp(host, port, local_host=nil, local_port=nil, [opts]) {|socket| ... } click to toggle source
tcp(host, port, local_host=nil, local_port=nil, [opts])

creates a new socket object connected to host:port using TCP/IP.

If local_host:local_port is given, the socket is bound to it.

The optional last argument opts is options represented by a hash. opts may have following options:

:connect_timeout

  specify the timeout in seconds.

If a block is given, the block is called with the socket. The value of the block is returned. The socket is closed when this method returns.

If no block is given, the socket is returned.

    Socket.tcp("www.ruby-lang.org", 80) {|sock|
      sock.print "GET / HTTP/1.0\r\nHost: www.ruby-lang.org\r\n\r\n"
      sock.close_write
      puts sock.read
    }

    # File ext/socket/lib/socket.rb, line 608
    def self.tcp(host, port, local_host = nil, local_port = nil, connect_timeout: nil) # :yield: socket
      last_error = nil
      ret = nil

      local_addr_list = nil
      if local_host != nil || local_port != nil
        local_addr_list = Addrinfo.getaddrinfo(local_host, local_port, nil, :STREAM, nil)
      end

      Addrinfo.foreach(host, port, nil, :STREAM) {|ai|
        if local_addr_list
          local_addr = local_addr_list.find {|local_ai| local_ai.afamily == ai.afamily }
          next unless local_addr
        else
          local_addr = nil
        end
        begin
          sock = local_addr ?
            ai.connect_from(local_addr, timeout: connect_timeout) :
            ai.connect(timeout: connect_timeout)
        rescue SystemCallError
          last_error = $!
          next
        end
        ret = sock
        break
      }
      unless ret
        if last_error
          raise last_error
        else
          raise SocketError, "no appropriate local address"
        end
      end
      if block_given?
        begin
          yield ret
        ensure
          ret.close
        end
      else
        ret
      end
    end

tcp_server_loop(host=nil, port) { |socket, client_addrinfo| ... } click to toggle source

creates a TCP/IP server on port and calls the block for each connection accepted. The block is called with a socket and a client_address as an `Addrinfo` object.

If host is specified, it is used with port to determine the server addresses.

The socket is not closed when the block returns. So application should close it explicitly.

This method calls the block sequentially. It means that the next connection is not accepted until the block returns. So concurrent mechanism, thread for example, should be used to service multiple clients at a time.

Note that `Addrinfo.getaddrinfo` is used to determine the server socket addresses. When `Addrinfo.getaddrinfo` returns two or more addresses, IPv4 and IPv6 address for example, all of them are used. `Socket.tcp_server_loop` succeeds if one socket can be used at least.

    # Sequential echo server.
    # It services only one client at a time.
    Socket.tcp_server_loop(16807) {|sock, client_addrinfo|
      begin
        IO.copy_stream(sock, sock)
      ensure
        sock.close
      end
    }

    # Threaded echo server
    # It services multiple clients at a time.
    # Note that it may accept connections too much.
    Socket.tcp_server_loop(16807) {|sock, client_addrinfo|
      Thread.new {
        begin
          IO.copy_stream(sock, sock)
        ensure
          sock.close
        end
      }
    }

    # File ext/socket/lib/socket.rb, line 841
    def self.tcp_server_loop(host=nil, port, &b) # :yield: socket, client_addrinfo
      tcp_server_sockets(host, port) {|sockets|
        accept_loop(sockets, &b)
      }
    end

tcp_server_sockets(host=nil, port) { |sockets| ... } click to toggle source

creates TCP/IP server sockets for host and port. host is optional.

If no block given, it returns an array of listening sockets.

If a block is given, the block is called with the sockets. The value of the block is returned. The socket is closed when this method returns.

If port is 0, actual port number is chosen dynamically. However all sockets in the result has same port number.

    # tcp_server_sockets returns two sockets.
    sockets = Socket.tcp_server_sockets(1296)
    p sockets #=> [#<Socket:fd 3>, #<Socket:fd 4>]

    # The sockets contains IPv6 and IPv4 sockets.
    sockets.each {|s| p s.local_address }
    #=> #<Addrinfo: [::]:1296 TCP>
    #   #<Addrinfo: 0.0.0.0:1296 TCP>

    # IPv6 and IPv4 socket has same port number, 53114, even if it is chosen dynamically.
    sockets = Socket.tcp_server_sockets(0)
    sockets.each {|s| p s.local_address }
    #=> #<Addrinfo: [::]:53114 TCP>
    #   #<Addrinfo: 0.0.0.0:53114 TCP>

    # The block is called with the sockets.
    Socket.tcp_server_sockets(0) {|sockets|
      p sockets #=> [#<Socket:fd 3>, #<Socket:fd 4>]
    }

    # File ext/socket/lib/socket.rb, line 741
    def self.tcp_server_sockets(host=nil, port)
      if port == 0
        sockets = tcp_server_sockets_port0(host)
      else
        last_error = nil
        sockets = []
        begin
          Addrinfo.foreach(host, port, nil, :STREAM, nil, Socket::AI_PASSIVE) {|ai|
            begin
              s = ai.listen
            rescue SystemCallError
              last_error = $!
              next
            end
            sockets << s
          }
          if sockets.empty?
            raise last_error
          end
        rescue Exception
          sockets.each(&:close)
          raise
        end
      end
      if block_given?
        begin
          yield sockets
        ensure
          sockets.each(&:close)
        end
      else
        sockets
      end
    end

udp_server_loop(port) {|msg, msg_src| ... } click to toggle source
udp_server_loop(host, port) {|msg, msg_src| ... }

creates a UDP/IP server on port and calls the block for each message arrived. The block is called with the message and its source information.

This method allocates sockets internally using port. If host is specified, it is used conjunction with port to determine the server addresses.

The msg is a string.

The msg_src is a `Socket::UDPSource` object. It is used for reply.

    # UDP/IP echo server.
    Socket.udp_server_loop(9261) {|msg, msg_src|
      msg_src.reply msg
    }

    # File ext/socket/lib/socket.rb, line 1010
    def self.udp_server_loop(host=nil, port, &b) # :yield: message, message_source
      udp_server_sockets(host, port) {|sockets|
        udp_server_loop_on(sockets, &b)
      }
    end

udp_server_loop_on(sockets) {|msg, msg_src| ... } click to toggle source

Run UDP/IP server loop on the given sockets.

The return value of `Socket.udp_server_sockets` is appropriate for the argument.

It calls the block for each message received.

    # File ext/socket/lib/socket.rb, line 983
    def self.udp_server_loop_on(sockets, &b) # :yield: msg, msg_src
      loop {
        readable, _, _ = IO.select(sockets)
        udp_server_recv(readable, &b)
      }
    end

udp_server_recv(sockets) {|msg, msg_src| ... } click to toggle source

Receive UDP/IP packets from the given sockets. For each packet received, the block is called.

The block receives msg and msg_src. msg is a string which is the payload of the received packet. msg_src is a `Socket::UDPSource` object which is used for reply.

`Socket.udp_server_loop` can be implemented using this method as follows.

    udp_server_sockets(host, port) {|sockets|
      loop {
        readable, _, _ = IO.select(sockets)
        udp_server_recv(readable) {|msg, msg_src| ... }
      }
    }

    # File ext/socket/lib/socket.rb, line 956
    def self.udp_server_recv(sockets)
      sockets.each {|r|
        msg, sender_addrinfo, _, *controls = r.recvmsg_nonblock(exception: false)
        next if msg == :wait_readable
        ai = r.local_address
        if ai.ipv6? and pktinfo = controls.find {|c| c.cmsg_is?(:IPV6, :PKTINFO) }
          ai = Addrinfo.udp(pktinfo.ipv6_pktinfo_addr.ip_address, ai.ip_port)
          yield msg, UDPSource.new(sender_addrinfo, ai) {|reply_msg|
            r.sendmsg reply_msg, 0, sender_addrinfo, pktinfo
          }
        else
          yield msg, UDPSource.new(sender_addrinfo, ai) {|reply_msg|
            r.send reply_msg, 0, sender_addrinfo
          }
        end
      }
    end

udp_server_sockets([host, ] port) click to toggle source

Creates UDP/IP sockets for a UDP server.

If no block given, it returns an array of sockets.

If a block is given, the block is called with the sockets. The value of the block is returned. The sockets are closed when this method returns.

If port is zero, some port is chosen. But the chosen port is used for the all sockets.

    # UDP/IP echo server
    Socket.udp_server_sockets(0) {|sockets|
      p sockets.first.local_address.ip_port     #=> 32963
      Socket.udp_server_loop_on(sockets) {|msg, msg_src|
        msg_src.reply msg
      }
    }

    # File ext/socket/lib/socket.rb, line 869
    def self.udp_server_sockets(host=nil, port)
      last_error = nil
      sockets = []

      ipv6_recvpktinfo = nil
      if defined? Socket::AncillaryData
        if defined? Socket::IPV6_RECVPKTINFO # RFC 3542
          ipv6_recvpktinfo = Socket::IPV6_RECVPKTINFO
        elsif defined? Socket::IPV6_PKTINFO # RFC 2292
          ipv6_recvpktinfo = Socket::IPV6_PKTINFO
        end
      end

      local_addrs = Socket.ip_address_list

      ip_list = []
      Addrinfo.foreach(host, port, nil, :DGRAM, nil, Socket::AI_PASSIVE) {|ai|
        if ai.ipv4? && ai.ip_address == "0.0.0.0"
          local_addrs.each {|a|
            next unless a.ipv4?
            ip_list << Addrinfo.new(a.to_sockaddr, :INET, :DGRAM, 0);
          }
        elsif ai.ipv6? && ai.ip_address == "::" && !ipv6_recvpktinfo
          local_addrs.each {|a|
            next unless a.ipv6?
            ip_list << Addrinfo.new(a.to_sockaddr, :INET6, :DGRAM, 0);
          }
        else
          ip_list << ai
        end
      }

      if port == 0
        sockets = ip_sockets_port0(ip_list, false)
      else
        ip_list.each {|ip|
          ai = Addrinfo.udp(ip.ip_address, port)
          begin
            s = ai.bind
          rescue SystemCallError
            last_error = $!
            next
          end
          sockets << s
        }
        if sockets.empty?
          raise last_error
        end
      end

      sockets.each {|s|
        ai = s.local_address
        if ipv6_recvpktinfo && ai.ipv6? && ai.ip_address == "::"
          s.setsockopt(:IPV6, ipv6_recvpktinfo, 1)
        end
      }

      if block_given?
        begin
          yield sockets
        ensure
          sockets.each(&:close) if sockets
        end
      else
        sockets
      end
    end

unix(path) { |socket| ... } click to toggle source

creates a new socket connected to path using UNIX socket socket.

If a block is given, the block is called with the socket. The value of the block is returned. The socket is closed when this method returns.

If no block is given, the socket is returned.

    # talk to /tmp/sock socket.
    Socket.unix("/tmp/sock") {|sock|
      t = Thread.new { IO.copy_stream(sock, STDOUT) }
      IO.copy_stream(STDIN, sock)
      t.join
    }

    # File ext/socket/lib/socket.rb, line 1060
    def self.unix(path) # :yield: socket
      addr = Addrinfo.unix(path)
      sock = addr.connect
      if block_given?
        begin
          yield sock
        ensure
          sock.close
        end
      else
        sock
      end
    end

unix_server_loop(path) { |socket, client_addrinfo| ... } click to toggle source

creates a UNIX socket server on path. It calls the block for each socket accepted.

If host is specified, it is used with port to determine the server ports.

The socket is not closed when the block returns. So application should close it.

This method deletes the socket file pointed by path at first if the file is a socket file and it is owned by the user of the application. This is safe only if the directory of path is not changed by a malicious user. So don't use /tmp/malicious-users-directory/socket. Note that /tmp/socket and /tmp/your-private-directory/socket is safe assuming that /tmp has sticky bit.

    # Sequential echo server.
    # It services only one client at a time.
    Socket.unix_server_loop("/tmp/sock") {|sock, client_addrinfo|
      begin
        IO.copy_stream(sock, sock)
      ensure
        sock.close
      end
    }

    # File ext/socket/lib/socket.rb, line 1147
    def self.unix_server_loop(path, &b) # :yield: socket, client_addrinfo
      unix_server_socket(path) {|serv|
        accept_loop(serv, &b)
      }
    end

unix_server_socket(path) { |s| ... } click to toggle source

creates a UNIX server socket on path

If no block given, it returns a listening socket.

If a block is given, it is called with the socket and the block value is returned. When the block exits, the socket is closed and the socket file is removed.

    socket = Socket.unix_server_socket("/tmp/s")
    p socket                  #=> #<Socket:fd 3>
    p socket.local_address    #=> #<Addrinfo: /tmp/s SOCK_STREAM>

    Socket.unix_server_socket("/tmp/sock") {|s|
      p s                     #=> #<Socket:fd 3>
      p s.local_address       #=> # #<Addrinfo: /tmp/sock SOCK_STREAM>
    }

    # File ext/socket/lib/socket.rb, line 1090
    def self.unix_server_socket(path)
      unless unix_socket_abstract_name?(path)
        begin
          st = File.lstat(path)
        rescue Errno::ENOENT
        end
        if st&.socket? && st.owned?
          File.unlink path
        end
      end
      s = Addrinfo.unix(path).listen
      if block_given?
        begin
          yield s
        ensure
          s.close
          unless unix_socket_abstract_name?(path)
            File.unlink path
          end
        end
      else
        s
      end
    end

unpack_sockaddr_in(sockaddr) → [port, ip_address] click to toggle source

Unpacks sockaddr into port and ip_address.

sockaddr should be a string or an addrinfo for AF_INET/AF_INET6.

    sockaddr = Socket.sockaddr_in(80, "127.0.0.1")
    p sockaddr #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
    p Socket.unpack_sockaddr_in(sockaddr) #=> [80, "127.0.0.1"]

    static VALUE
    sock_s_unpack_sockaddr_in(VALUE self, VALUE addr)
    {
        struct sockaddr_in * sockaddr;
        VALUE host;

        sockaddr = (struct sockaddr_in*)SockAddrStringValuePtr(addr);
        if (RSTRING_LEN(addr) <
            (char*)&((struct sockaddr *)sockaddr)->sa_family +
            sizeof(((struct sockaddr *)sockaddr)->sa_family) -
            (char*)sockaddr)
            rb_raise(rb_eArgError, "too short sockaddr");
        if (((struct sockaddr *)sockaddr)->sa_family != AF_INET
    #ifdef INET6
            && ((struct sockaddr *)sockaddr)->sa_family != AF_INET6
    #endif
            ) {
    #ifdef INET6
            rb_raise(rb_eArgError, "not an AF_INET/AF_INET6 sockaddr");
    #else
            rb_raise(rb_eArgError, "not an AF_INET sockaddr");
    #endif
        }
        host = rsock_make_ipaddr((struct sockaddr*)sockaddr, RSTRING_SOCKLEN(addr));
        OBJ_INFECT(host, addr);
        return rb_assoc_new(INT2NUM(ntohs(sockaddr->sin_port)), host);
    }

unpack_sockaddr_un(sockaddr) → path click to toggle source

Unpacks sockaddr into path.

sockaddr should be a string or an addrinfo for AF_UNIX.

    sockaddr = Socket.sockaddr_un("/tmp/sock")
    p Socket.unpack_sockaddr_un(sockaddr) #=> "/tmp/sock"

    static VALUE
    sock_s_unpack_sockaddr_un(VALUE self, VALUE addr)
    {
        struct sockaddr_un * sockaddr;
        VALUE path;

        sockaddr = (struct sockaddr_un*)SockAddrStringValuePtr(addr);
        if (RSTRING_LEN(addr) <
            (char*)&((struct sockaddr *)sockaddr)->sa_family +
            sizeof(((struct sockaddr *)sockaddr)->sa_family) -
            (char*)sockaddr)
            rb_raise(rb_eArgError, "too short sockaddr");
        if (((struct sockaddr *)sockaddr)->sa_family != AF_UNIX) {
            rb_raise(rb_eArgError, "not an AF_UNIX sockaddr");
        }
        if (sizeof(struct sockaddr_un) < (size_t)RSTRING_LEN(addr)) {
            rb_raise(rb_eTypeError, "too long sockaddr_un - %ld longer than %d",
                     RSTRING_LEN(addr), (int)sizeof(struct sockaddr_un));
        }
        path = rsock_unixpath_str(sockaddr, RSTRING_SOCKLEN(addr));
        OBJ_INFECT(path, addr);
        return path;
    }

### Private Class Methods

unix_socket_abstract_name?(path) click to toggle source

    # File ext/socket/lib/socket.rb, line 1118
    def unix_socket_abstract_name?(path)
      /linux/ =~ RUBY_PLATFORM && /\A(\0|\z)/ =~ path
    end

### Public Instance Methods

accept → [client_socket, client_addrinfo] click to toggle source

Accepts a next connection. Returns a new `Socket` object and `Addrinfo` object.

    serv = Socket.new(:INET, :STREAM, 0)
    serv.listen(5)
    c = Socket.new(:INET, :STREAM, 0)
    c.connect(serv.connect_address)
    p serv.accept #=> [#<Socket:fd 6>, #<Addrinfo: 127.0.0.1:48555 TCP>]

    static VALUE
    sock_accept(VALUE sock)
    {
        rb_io_t *fptr;
        VALUE sock2;
        union_sockaddr buf;
        socklen_t len = (socklen_t)sizeof buf;

        GetOpenFile(sock, fptr);
        sock2 = rsock_s_accept(rb_cSocket,fptr->fd,&buf.addr,&len);

        return rb_assoc_new(sock2, rsock_io_socket_addrinfo(sock2, &buf.addr, len));
    }

accept_nonblock([options]) → [client_socket, client_addrinfo] click to toggle source

Accepts an incoming connection using accept(2) after O_NONBLOCK is set for the underlying file descriptor. It returns an array containing the accepted socket for the incoming connection, client_socket, and an `Addrinfo`, client_addrinfo.

### Example¶ ↑

    # In one script, start this first
    require 'socket'
    include Socket::Constants
    socket = Socket.new(AF_INET, SOCK_STREAM, 0)
    sockaddr = Socket.sockaddr_in(2200, 'localhost')
    socket.bind(sockaddr)
    socket.listen(5)
    begin # emulate blocking accept
      client_socket, client_addrinfo = socket.accept_nonblock
    rescue IO::WaitReadable, Errno::EINTR
      IO.select([socket])
      retry
    end
    puts "The client said, '#{client_socket.readline.chomp}'"
    client_socket.puts "Hello from script one!"
    socket.close

    # In another script, start this second
    require 'socket'
    include Socket::Constants
    socket = Socket.new(AF_INET, SOCK_STREAM, 0)
    sockaddr = Socket.sockaddr_in(2200, 'localhost')
    socket.connect(sockaddr)
    socket.puts "Hello from script 2."
    puts "The server said, '#{socket.readline.chomp}'"
    socket.close

Refer to `Socket#accept` for the exceptions that may be thrown if the call to accept_nonblock fails.

`Socket#accept_nonblock` may raise any error corresponding to accept(2) failure, including Errno::EWOULDBLOCK.

If the exception is Errno::EWOULDBLOCK, Errno::EAGAIN, `Errno::ECONNABORTED` or `Errno::EPROTO`, it is extended by `IO::WaitReadable`. So `IO::WaitReadable` can be used to rescue the exceptions for retrying accept_nonblock.

By specifying a keyword argument exception to `false`, you can indicate that `accept_nonblock` should not raise an `IO::WaitReadable` exception, but return the symbol `:wait_readable` instead.

### See¶ ↑

- `Socket#accept`

    # File ext/socket/lib/socket.rb, line 578
    def accept_nonblock(exception: true)
      __accept_nonblock(exception)
    end

bind(local_sockaddr) → 0 click to toggle source

Binds to the given local address.

### Parameter¶ ↑

- `local_sockaddr` - the `struct` sockaddr contained in a string or an `Addrinfo` object

### Example¶ ↑

    require 'socket'

    # use Addrinfo
    socket = Socket.new(:INET, :STREAM, 0)
    socket.bind(Addrinfo.tcp("127.0.0.1", 2222))
    p socket.local_address #=> #<Addrinfo: 127.0.0.1:2222 TCP>

    # use struct sockaddr
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.bind( sockaddr )

### Unix-based Exceptions¶ ↑

On unix-based based systems the following system exceptions may be raised if the call to bind fails:

- Errno::EACCES - the specified sockaddr is protected and the current user does not have permission to bind to it

- Errno::EADDRINUSE - the specified sockaddr is already in use

- Errno::EADDRNOTAVAIL - the specified sockaddr is not available from the local machine

- Errno::EAFNOSUPPORT - the specified sockaddr is not a valid address for the family of the calling `socket`

- Errno::EBADF - the sockaddr specified is not a valid file descriptor

- Errno::EFAULT - the sockaddr argument cannot be accessed

- Errno::EINVAL - the `socket` is already bound to an address, and the protocol does not support binding to the new sockaddr or the `socket` has been shut down.

- Errno::EINVAL - the address length is not a valid length for the address family

- Errno::ENAMETOOLONG - the pathname resolved had a length which exceeded PATH_MAX

- Errno::ENOBUFS - no buffer space is available

- Errno::ENOSR - there were insufficient STREAMS resources available to complete the operation

- Errno::ENOTSOCK - the `socket` does not refer to a socket

- Errno::EOPNOTSUPP - the socket type of the `socket` does not support binding to an address

On unix-based based systems if the address family of the calling `socket` is Socket::AF_UNIX the follow exceptions may be raised if the call to bind fails:

- Errno::EACCES - search permission is denied for a component of the prefix path or write access to the `socket` is denied

- Errno::EDESTADDRREQ - the sockaddr argument is a null pointer

- Errno::EISDIR - same as Errno::EDESTADDRREQ

- Errno::EIO - an i/o error occurred

- Errno::ELOOP - too many symbolic links were encountered in translating the pathname in sockaddr

- Errno::ENAMETOOLLONG - a component of a pathname exceeded NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters

- Errno::ENOENT - a component of the pathname does not name an existing file or the pathname is an empty string

- Errno::ENOTDIR - a component of the path prefix of the pathname in sockaddr is not a directory

- Errno::EROFS - the name would reside on a read only filesystem

### Windows Exceptions¶ ↑

On Windows systems the following system exceptions may be raised if the call to bind fails:

- Errno::ENETDOWN– the network is down

- Errno::EACCES - the attempt to connect the datagram socket to the broadcast address failed

- Errno::EADDRINUSE - the socket's local address is already in use

- Errno::EADDRNOTAVAIL - the specified address is not a valid address for this computer

- Errno::EFAULT - the socket's internal address or address length parameter is too small or is not a valid part of the user space addressed

- Errno::EINVAL - the `socket` is already bound to an address

- Errno::ENOBUFS - no buffer space is available

- Errno::ENOTSOCK - the `socket` argument does not refer to a socket

### See¶ ↑

- bind manual pages on unix-based systems

- bind function in Microsoft's Winsock functions reference

    static VALUE
    sock_bind(VALUE sock, VALUE addr)
    {
        VALUE rai;
        rb_io_t *fptr;

        SockAddrStringValueWithAddrinfo(addr, rai);
        GetOpenFile(sock, fptr);
        if (bind(fptr->fd, (struct sockaddr*)RSTRING_PTR(addr), RSTRING_SOCKLEN(addr)) < 0)
            rsock_sys_fail_raddrinfo_or_sockaddr("bind(2)", addr, rai);

        return INT2FIX(0);
    }

connect(remote_sockaddr) → 0 click to toggle source

Requests a connection to be made on the given `remote_sockaddr`. Returns 0 if successful, otherwise an exception is raised.

### Parameter¶ ↑

- `remote_sockaddr` - the `struct` sockaddr contained in a string or `Addrinfo` object

### Example:¶ ↑

    # Pull down Google's web page
    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 80, 'www.google.com' )
    socket.connect( sockaddr )
    socket.write( "GET / HTTP/1.0\r\n\r\n" )
    results = socket.read

### Unix-based Exceptions¶ ↑

On unix-based systems the following system exceptions may be raised if the call to connect fails:

- Errno::EACCES - search permission is denied for a component of the prefix path or write access to the `socket` is denied

- Errno::EADDRINUSE - the sockaddr is already in use

- Errno::EADDRNOTAVAIL - the specified sockaddr is not available from the local machine

- Errno::EAFNOSUPPORT - the specified sockaddr is not a valid address for the address family of the specified `socket`

- Errno::EALREADY - a connection is already in progress for the specified socket

- Errno::EBADF - the `socket` is not a valid file descriptor

- Errno::ECONNREFUSED - the target sockaddr was not listening for connections refused the connection request

- `Errno::ECONNRESET` - the remote host reset the connection request

- Errno::EFAULT - the sockaddr cannot be accessed

- Errno::EHOSTUNREACH - the destination host cannot be reached (probably because the host is down or a remote router cannot reach it)

- Errno::EINPROGRESS - the O_NONBLOCK is set for the `socket` and the connection cannot be immediately established; the connection will be established asynchronously

- Errno::EINTR - the attempt to establish the connection was interrupted by delivery of a signal that was caught; the connection will be established asynchronously

- Errno::EISCONN - the specified `socket` is already connected

- Errno::EINVAL - the address length used for the sockaddr is not a valid length for the address family or there is an invalid family in sockaddr

- Errno::ENAMETOOLONG - the pathname resolved had a length which exceeded PATH_MAX

- Errno::ENETDOWN - the local interface used to reach the destination is down

- Errno::ENETUNREACH - no route to the network is present

- Errno::ENOBUFS - no buffer space is available

- Errno::ENOSR - there were insufficient STREAMS resources available to complete the operation

- Errno::ENOTSOCK - the `socket` argument does not refer to a socket

- Errno::EOPNOTSUPP - the calling `socket` is listening and cannot be connected

- Errno::EPROTOTYPE - the sockaddr has a different type than the socket bound to the specified peer address

- Errno::ETIMEDOUT - the attempt to connect time out before a connection was made.

On unix-based systems if the address family of the calling `socket` is AF_UNIX the follow exceptions may be raised if the call to connect fails:

- Errno::EIO - an i/o error occurred while reading from or writing to the file system

- Errno::ELOOP - too many symbolic links were encountered in translating the pathname in sockaddr

- Errno::ENAMETOOLLONG - a component of a pathname exceeded NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters

- Errno::ENOENT - a component of the pathname does not name an existing file or the pathname is an empty string

- Errno::ENOTDIR - a component of the path prefix of the pathname in sockaddr is not a directory

### Windows Exceptions¶ ↑

On Windows systems the following system exceptions may be raised if the call to connect fails:

- Errno::ENETDOWN - the network is down

- Errno::EADDRINUSE - the socket's local address is already in use

- Errno::EINTR - the socket was cancelled

- Errno::EINPROGRESS - a blocking socket is in progress or the service provider is still processing a callback function. Or a nonblocking connect call is in progress on the `socket`.

- Errno::EALREADY - see Errno::EINVAL

- Errno::EADDRNOTAVAIL - the remote address is not a valid address, such as ADDR_ANY TODO check ADDRANY TO INADDR_ANY

- Errno::EAFNOSUPPORT - addresses in the specified family cannot be used with with this `socket`

- Errno::ECONNREFUSED - the target sockaddr was not listening for connections refused the connection request

- Errno::EFAULT - the socket's internal address or address length parameter is too small or is not a valid part of the user space address

- Errno::EINVAL - the `socket` is a listening socket

- Errno::EISCONN - the `socket` is already connected

- Errno::ENETUNREACH - the network cannot be reached from this host at this time

- Errno::EHOSTUNREACH - no route to the network is present

- Errno::ENOBUFS - no buffer space is available

- Errno::ENOTSOCK - the `socket` argument does not refer to a socket

- Errno::ETIMEDOUT - the attempt to connect time out before a connection was made.

- Errno::EWOULDBLOCK - the socket is marked as nonblocking and the connection cannot be completed immediately

- Errno::EACCES - the attempt to connect the datagram socket to the broadcast address failed

### See¶ ↑

- connect manual pages on unix-based systems

- connect function in Microsoft's Winsock functions reference

    static VALUE
    sock_connect(VALUE sock, VALUE addr)
    {
        VALUE rai;
        rb_io_t *fptr;
        int fd, n;

        SockAddrStringValueWithAddrinfo(addr, rai);
        addr = rb_str_new4(addr);
        GetOpenFile(sock, fptr);
        fd = fptr->fd;
        n = rsock_connect(fd, (struct sockaddr*)RSTRING_PTR(addr), RSTRING_SOCKLEN(addr), 0);
        if (n < 0) {
            rsock_sys_fail_raddrinfo_or_sockaddr("connect(2)", addr, rai);
        }

        return INT2FIX(n);
    }

connect_nonblock(remote_sockaddr, [options]) → 0 click to toggle source

Requests a connection to be made on the given `remote_sockaddr` after O_NONBLOCK is set for the underlying file descriptor. Returns 0 if successful, otherwise an exception is raised.

### Parameter¶ ↑

    # +remote_sockaddr+ - the +struct+ sockaddr contained in a string or Addrinfo object

### Example:¶ ↑

    # Pull down Google's web page
    require 'socket'
    include Socket::Constants
    socket = Socket.new(AF_INET, SOCK_STREAM, 0)
    sockaddr = Socket.sockaddr_in(80, 'www.google.com')
    begin # emulate blocking connect
      socket.connect_nonblock(sockaddr)
    rescue IO::WaitWritable
      IO.select(nil, [socket]) # wait 3-way handshake completion
      begin
        socket.connect_nonblock(sockaddr) # check connection failure
      rescue Errno::EISCONN
      end
    end
    socket.write("GET / HTTP/1.0\r\n\r\n")
    results = socket.read

Refer to `Socket#connect` for the exceptions that may be thrown if the call to connect_nonblock fails.

`Socket#connect_nonblock` may raise any error corresponding to connect(2) failure, including Errno::EINPROGRESS.

If the exception is Errno::EINPROGRESS, it is extended by `IO::WaitWritable`. So `IO::WaitWritable` can be used to rescue the exceptions for retrying connect_nonblock.

By specifying a keyword argument exception to `false`, you can indicate that `connect_nonblock` should not raise an `IO::WaitWritable` exception, but return the symbol `:wait_writable` instead.

### See¶ ↑

    # Socket#connect

    # File ext/socket/lib/socket.rb, line 1197
    def connect_nonblock(addr, exception: true)
      __connect_nonblock(addr, exception)
    end

ipv6only!() click to toggle source

enable the socket option IPV6_V6ONLY if IPV6_V6ONLY is available.

    # File ext/socket/lib/socket.rb, line 449
    def ipv6only!
      if defined? Socket::IPV6_V6ONLY
        self.setsockopt(:IPV6, :V6ONLY, 1)
      end
    end

listen( int ) → 0 click to toggle source

Listens for connections, using the specified `int` as the backlog. A call to listen only applies if the `socket` is of type SOCK_STREAM or SOCK_SEQPACKET.

### Parameter¶ ↑

- `backlog` - the maximum length of the queue for pending connections.

### Example 1¶ ↑

    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.bind( sockaddr )
    socket.listen( 5 )

### Example 2 (listening on an arbitrary port, unix-based systems only):¶ ↑

    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    socket.listen( 1 )

### Unix-based Exceptions¶ ↑

On unix based systems the above will work because a new `sockaddr` struct is created on the address ADDR_ANY, for an arbitrary port number as handed off by the kernel. It will not work on Windows, because Windows requires that the `socket` is bound by calling bind before it can listen.

If the backlog amount exceeds the implementation-dependent maximum queue length, the implementation's maximum queue length will be used.

On unix-based based systems the following system exceptions may be raised if the call to listen fails:

- Errno::EBADF - the socket argument is not a valid file descriptor

- Errno::EDESTADDRREQ - the socket is not bound to a local address, and the protocol does not support listening on an unbound socket

- Errno::EINVAL - the socket is already connected

- Errno::ENOTSOCK - the socket argument does not refer to a socket

- Errno::EOPNOTSUPP - the socket protocol does not support listen

- Errno::EACCES - the calling process does not have appropriate privileges

- Errno::EINVAL - the socket has been shut down

- Errno::ENOBUFS - insufficient resources are available in the system to complete the call

### Windows Exceptions¶ ↑

On Windows systems the following system exceptions may be raised if the call to listen fails:

- Errno::ENETDOWN - the network is down

- Errno::EADDRINUSE - the socket's local address is already in use. This usually occurs during the execution of bind but could be delayed if the call to bind was to a partially wildcard address (involving ADDR_ANY) and if a specific address needs to be committed at the time of the call to listen

- Errno::EINPROGRESS - a Windows Sockets 1.1 call is in progress or the service provider is still processing a callback function

- Errno::EINVAL - the `socket` has not been bound with a call to bind.

- Errno::EISCONN - the `socket` is already connected

- Errno::EMFILE - no more socket descriptors are available

- Errno::ENOBUFS - no buffer space is available

- Errno::ENOTSOC - `socket` is not a socket

- Errno::EOPNOTSUPP - the referenced `socket` is not a type that supports the listen method

### See¶ ↑

- listen manual pages on unix-based systems

- listen function in Microsoft's Winsock functions reference

    VALUE
    rsock_sock_listen(VALUE sock, VALUE log)
    {
        rb_io_t *fptr;
        int backlog;

        backlog = NUM2INT(log);
        GetOpenFile(sock, fptr);
        if (listen(fptr->fd, backlog) < 0)
            rb_sys_fail("listen(2)");

        return INT2FIX(0);
    }

recvfrom(maxlen) → [mesg, sender_addrinfo] click to toggle source
recvfrom(maxlen, flags) → [mesg, sender_addrinfo]

Receives up to maxlen bytes from `socket`. flags is zero or more of the `MSG_` options. The first element of the results, mesg, is the data received. The second element, sender_addrinfo, contains protocol-specific address information of the sender.

### Parameters¶ ↑

- `maxlen` - the maximum number of bytes to receive from the socket

- `flags` - zero or more of the `MSG_` options

### Example¶ ↑

    # In one file, start this first
    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.bind( sockaddr )
    socket.listen( 5 )
    client, client_addrinfo = socket.accept
    data = client.recvfrom( 20 )[0].chomp
    puts "I only received 20 bytes '#{data}'"
    sleep 1
    socket.close

    # In another file, start this second
    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.connect( sockaddr )
    socket.puts "Watch this get cut short!"
    socket.close

### Unix-based Exceptions¶ ↑

On unix-based based systems the following system exceptions may be raised if the call to recvfrom fails:

- Errno::EAGAIN - the `socket` file descriptor is marked as O_NONBLOCK and no data is waiting to be received; or MSG_OOB is set and no out-of-band data is available and either the `socket` file descriptor is marked as O_NONBLOCK or the `socket` does not support blocking to wait for out-of-band-data

- Errno::EWOULDBLOCK - see Errno::EAGAIN

- Errno::EBADF - the `socket` is not a valid file descriptor

- `Errno::ECONNRESET` - a connection was forcibly closed by a peer

- Errno::EFAULT - the socket's internal buffer, address or address length cannot be accessed or written

- Errno::EINTR - a signal interrupted recvfrom before any data was available

- Errno::EINVAL - the MSG_OOB flag is set and no out-of-band data is available

- Errno::EIO - an i/o error occurred while reading from or writing to the filesystem

- Errno::ENOBUFS - insufficient resources were available in the system to perform the operation

- Errno::ENOMEM - insufficient memory was available to fulfill the request

- Errno::ENOSR - there were insufficient STREAMS resources available to complete the operation

- Errno::ENOTCONN - a receive is attempted on a connection-mode socket that is not connected

- Errno::ENOTSOCK - the `socket` does not refer to a socket

- Errno::EOPNOTSUPP - the specified flags are not supported for this socket type

- Errno::ETIMEDOUT - the connection timed out during connection establishment or due to a transmission timeout on an active connection

### Windows Exceptions¶ ↑

On Windows systems the following system exceptions may be raised if the call to recvfrom fails:

- Errno::ENETDOWN - the network is down

- Errno::EFAULT - the internal buffer and from parameters on `socket` are not part of the user address space, or the internal fromlen parameter is too small to accommodate the peer address

- Errno::EINTR - the (blocking) call was cancelled by an internal call to the WinSock function WSACancelBlockingCall

- Errno::EINPROGRESS - a blocking Windows Sockets 1.1 call is in progress or the service provider is still processing a callback function

- Errno::EINVAL - `socket` has not been bound with a call to bind, or an unknown flag was specified, or MSG_OOB was specified for a socket with SO_OOBINLINE enabled, or (for byte stream-style sockets only) the internal len parameter on `socket` was zero or negative

- Errno::EISCONN - `socket` is already connected. The call to recvfrom is not permitted with a connected socket on a socket that is connection oriented or connectionless.

- Errno::ENETRESET - the connection has been broken due to the keep-alive activity detecting a failure while the operation was in progress.

- Errno::EOPNOTSUPP - MSG_OOB was specified, but `socket` is not stream-style such as type SOCK_STREAM. OOB data is not supported in the communication domain associated with `socket`, or `socket` is unidirectional and supports only send operations

- Errno::ESHUTDOWN - `socket` has been shutdown. It is not possible to call recvfrom on a socket after shutdown has been invoked.

- Errno::EWOULDBLOCK - `socket` is marked as nonblocking and a call to recvfrom would block.

- Errno::EMSGSIZE - the message was too large to fit into the specified buffer and was truncated.

- Errno::ETIMEDOUT - the connection has been dropped, because of a network failure or because the system on the other end went down without notice

- `Errno::ECONNRESET` - the virtual circuit was reset by the remote side executing a hard or abortive close. The application should close the socket; it is no longer usable. On a UDP-datagram socket this error indicates a previous send operation resulted in an ICMP Port Unreachable message.

    static VALUE
    sock_recvfrom(int argc, VALUE *argv, VALUE sock)
    {
        return rsock_s_recvfrom(sock, argc, argv, RECV_SOCKET);
    }

recvfrom_nonblock(maxlen[, flags[, outbuf[, opts]]]) → [mesg, sender_addrinfo] click to toggle source

Receives up to maxlen bytes from `socket` using recvfrom(2) after O_NONBLOCK is set for the underlying file descriptor. flags is zero or more of the `MSG_` options. The first element of the results, mesg, is the data received. The second element, sender_addrinfo, contains protocol-specific address information of the sender.

When recvfrom(2) returns 0, `Socket#recvfrom_nonblock` returns an empty string as data. The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.

### Parameters¶ ↑

- `maxlen` - the maximum number of bytes to receive from the socket

- `flags` - zero or more of the `MSG_` options

- `outbuf` - destination String buffer

- `opts` - keyword hash, supporting `exception: false`

### Example¶ ↑

    # In one file, start this first
    require 'socket'
    include Socket::Constants
    socket = Socket.new(AF_INET, SOCK_STREAM, 0)
    sockaddr = Socket.sockaddr_in(2200, 'localhost')
    socket.bind(sockaddr)
    socket.listen(5)
    client, client_addrinfo = socket.accept
    begin # emulate blocking recvfrom
      pair = client.recvfrom_nonblock(20)
    rescue IO::WaitReadable
      IO.select([client])
      retry
    end
    data = pair[0].chomp
    puts "I only received 20 bytes '#{data}'"
    sleep 1
    socket.close

    # In another file, start this second
    require 'socket'
    include Socket::Constants
    socket = Socket.new(AF_INET, SOCK_STREAM, 0)
    sockaddr = Socket.sockaddr_in(2200, 'localhost')
    socket.connect(sockaddr)
    socket.puts "Watch this get cut short!"
    socket.close

Refer to `Socket#recvfrom` for the exceptions that may be thrown if the call to recvfrom_nonblock fails.

`Socket#recvfrom_nonblock` may raise any error corresponding to recvfrom(2) failure, including Errno::EWOULDBLOCK.

If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by `IO::WaitReadable`. So `IO::WaitReadable` can be used to rescue the exceptions for retrying recvfrom_nonblock.

By specifying a keyword argument exception to `false`, you can indicate that `recvfrom_nonblock` should not raise an `IO::WaitReadable` exception, but return the symbol `:wait_readable` instead.

### See¶ ↑

- `Socket#recvfrom`

    # File ext/socket/lib/socket.rb, line 521
    def recvfrom_nonblock(len, flag = 0, str = nil, exception: true)
      __recvfrom_nonblock(len, flag, str, exception)
    end

sysaccept → [client_socket_fd, client_addrinfo] click to toggle source

Accepts an incoming connection returning an array containing the (integer) file descriptor for the incoming connection, client_socket_fd, and an `Addrinfo`, client_addrinfo.

### Example¶ ↑

    # In one script, start this first
    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.bind( sockaddr )
    socket.listen( 5 )
    client_fd, client_addrinfo = socket.sysaccept
    client_socket = Socket.for_fd( client_fd )
    puts "The client said, '#{client_socket.readline.chomp}'"
    client_socket.puts "Hello from script one!"
    socket.close

    # In another script, start this second
    require 'socket'
    include Socket::Constants
    socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
    sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
    socket.connect( sockaddr )
    socket.puts "Hello from script 2."
    puts "The server said, '#{socket.readline.chomp}'"
    socket.close

Refer to `Socket#accept` for the exceptions that may be thrown if the call to sysaccept fails.

### See¶ ↑

- `Socket#accept`

    static VALUE
    sock_sysaccept(VALUE sock)
    {
        rb_io_t *fptr;
        VALUE sock2;
        union_sockaddr buf;
        socklen_t len = (socklen_t)sizeof buf;

        GetOpenFile(sock, fptr);
        sock2 = rsock_s_accept(0,fptr->fd,&buf.addr,&len);

        return rb_assoc_new(sock2, rsock_io_socket_addrinfo(sock2, &buf.addr, len));
    }