1Socket(3pm) Perl Programmers Reference Guide Socket(3pm)
2
6 Socket, sockaddr_in, sockaddr_un, inet_aton, inet_ntoa - load the C
7 socket.h defines and structure manipulators
8
10 use Socket;
11 $proto = getprotobyname('udp');
13 socket(Socket_Handle, PF_INET, SOCK_DGRAM, $proto);
14 $iaddr = gethostbyname('hishost.com');
15 $port = getservbyname('time', 'udp');
16 $sin = sockaddr_in($port, $iaddr);
17 send(Socket_Handle, 0, 0, $sin);
18 $proto = getprotobyname('tcp');
20 socket(Socket_Handle, PF_INET, SOCK_STREAM, $proto);
21 $port = getservbyname('smtp', 'tcp');
22 $sin = sockaddr_in($port,inet_aton("127.1"));
23 $sin = sockaddr_in(7,inet_aton("localhost"));
24 $sin = sockaddr_in(7,INADDR_LOOPBACK);
25 connect(Socket_Handle,$sin);
26 ($port, $iaddr) = sockaddr_in(getpeername(Socket_Handle));
28 $peer_host = gethostbyaddr($iaddr, AF_INET);
29 $peer_addr = inet_ntoa($iaddr);
30 $proto = getprotobyname('tcp');
32 socket(Socket_Handle, PF_UNIX, SOCK_STREAM, $proto);
33 unlink('/var/run/usock');
34 $sun = sockaddr_un('/var/run/usock');
35 connect(Socket_Handle,$sun);
36
38 This module is just a translation of the C socket.h file. Unlike the
39 old mechanism of requiring a translated socket.ph file, this uses the
40 h2xs program (see the Perl source distribution) and your native C com‐
41 piler. This means that it has a far more likely chance of getting the
42 numbers right. This includes all of the commonly used pound-defines
43 like AF_INET, SOCK_STREAM, etc.
44 Also, some common socket "newline" constants are provided: the con‐
46 stants "CR", "LF", and "CRLF", as well as $CR, $LF, and $CRLF, which
47 map to "\015", "\012", and "\015\012". If you do not want to use the
48 literal characters in your programs, then use the constants provided
49 here. They are not exported by default, but can be imported individu‐
50 ally, and with the ":crlf" export tag:
51 use Socket qw(:DEFAULT :crlf);
53 In addition, some structure manipulation functions are available:
55 inet_aton HOSTNAME
57 Takes a string giving the name of a host, and translates that to an
58 opaque string (if programming in C, struct in_addr). Takes argu‐
59 ments of both the 'rtfm.mit.edu' type and '18.181.0.24'. If the
60 host name cannot be resolved, returns undef. For multi-homed hosts
61 (hosts with more than one address), the first address found is
62 returned.
63 For portability do not assume that the result of inet_aton() is 32
65 bits wide, in other words, that it would contain only the IPv4
66 address in network order.
67 inet_ntoa IP_ADDRESS
69 Takes a string (an opaque string as returned by inet_aton(), or a
70 v-string representing the four octets of the IPv4 address in net‐
71 work order) and translates it into a string of the form 'd.d.d.d'
72 where the 'd's are numbers less than 256 (the normal human-readable
73 four dotted number notation for Internet addresses).
74 INADDR_ANY
76 Note: does not return a number, but a packed string.
77 Returns the 4-byte wildcard ip address which specifies any of the
79 hosts ip addresses. (A particular machine can have more than one
80 ip address, each address corresponding to a particular network
81 interface. This wildcard address allows you to bind to all of them
82 simultaneously.) Normally equivalent to inet_aton('0.0.0.0').
83 INADDR_BROADCAST
85 Note: does not return a number, but a packed string.
86 Returns the 4-byte 'this-lan' ip broadcast address. This can be
88 useful for some protocols to solicit information from all servers
89 on the same LAN cable. Normally equivalent to
90 inet_aton('255.255.255.255').
91 INADDR_LOOPBACK
93 Note - does not return a number.
94 Returns the 4-byte loopback address. Normally equivalent to
96 inet_aton('localhost').
97 INADDR_NONE
99 Note - does not return a number.
100 Returns the 4-byte 'invalid' ip address. Normally equivalent to
102 inet_aton('255.255.255.255').
103 sockaddr_family SOCKADDR
105 Takes a sockaddr structure (as returned by pack_sockaddr_in(),
106 pack_sockaddr_un() or the perl builtin functions getsockname() and
107 getpeername()) and returns the address family tag. It will match
108 the constant AF_INET for a sockaddr_in and AF_UNIX for a sock‐
109 addr_un. It can be used to figure out what unpacker to use for a
110 sockaddr of unknown type.
111 sockaddr_in PORT, ADDRESS
113 sockaddr_in SOCKADDR_IN
114 In a list context, unpacks its SOCKADDR_IN argument and returns an
115 array consisting of (PORT, ADDRESS). In a scalar context, packs
116 its (PORT, ADDRESS) arguments as a SOCKADDR_IN and returns it. If
117 this is confusing, use pack_sockaddr_in() and unpack_sockaddr_in()
118 explicitly.
119 pack_sockaddr_in PORT, IP_ADDRESS
121 Takes two arguments, a port number and an opaque string, IP_ADDRESS
122 (as returned by inet_aton(), or a v-string). Returns the sock‐
123 addr_in structure with those arguments packed in with AF_INET
124 filled in. For Internet domain sockets, this structure is normally
125 what you need for the arguments in bind(), connect(), and send(),
126 and is also returned by getpeername(), getsockname() and recv().
127 unpack_sockaddr_in SOCKADDR_IN
129 Takes a sockaddr_in structure (as returned by pack_sockaddr_in())
130 and returns an array of two elements: the port and an opaque string
131 representing the IP address (you can use inet_ntoa() to convert the
132 address to the four-dotted numeric format). Will croak if the
133 structure does not have AF_INET in the right place.
134 sockaddr_un PATHNAME
136 sockaddr_un SOCKADDR_UN
137 In a list context, unpacks its SOCKADDR_UN argument and returns an
138 array consisting of (PATHNAME). In a scalar context, packs its
139 PATHNAME arguments as a SOCKADDR_UN and returns it. If this is
140 confusing, use pack_sockaddr_un() and unpack_sockaddr_un() explic‐
141 itly. These are only supported if your system has <sys/un.h>.
142 pack_sockaddr_un PATH
144 Takes one argument, a pathname. Returns the sockaddr_un structure
145 with that path packed in with AF_UNIX filled in. For unix domain
146 sockets, this structure is normally what you need for the arguments
147 in bind(), connect(), and send(), and is also returned by getpeer‐
148 name(), getsockname() and recv().
149 unpack_sockaddr_un SOCKADDR_UN
151 Takes a sockaddr_un structure (as returned by pack_sockaddr_un())
152 and returns the pathname. Will croak if the structure does not
153 have AF_UNIX in the right place.
154perl v5.8.8 2001-09-21 Socket(3pm)