Method: Socket.getservbyport

Defined in:

socket.c

.getservbyport(port[, protocol_name]) ⇒ Object

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"

# File 'socket.c', line 1102

static VALUE
sock_s_getservbyport(int argc, VALUE *argv, VALUE _)
{
    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_str_new2(sp->s_name);
}