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32 .\" From: @(#)send.2 8.2 (Berkeley) 2/21/94
33 .\" $FreeBSD: src/lib/libc/sys/send.2,v 1.10.2.6 2001/12/14 18:34:01 ru Exp $
34 .\" $DragonFly: src/lib/libc/sys/send.2,v 1.4 2004/08/27 21:23:32 asmodai Exp $
43 .Nd send a message from a socket
50 .Fn send "int s" "const void *msg" "size_t len" "int flags"
52 .Fn sendto "int s" "const void *msg" "size_t len" "int flags" "const struct sockaddr *to" "socklen_t tolen"
54 .Fn sendmsg "int s" "const struct msghdr *msg" "int flags"
60 are used to transmit a message to another socket.
62 may be used only when the socket is in a
68 may be used at any time.
70 The socket file descriptor is given by
77 points to a buffer containing the message.
81 points to a msghdr structure.
82 The address of the target is given by
87 The length of the message is given by
89 If the message is too long to pass atomically through the
90 underlying protocol, the error
93 the message is not transmitted.
95 No indication of failure to deliver is implicit in a
97 Locally detected errors are indicated by a return value of -1.
99 If no messages space is available at the socket to hold
100 the message to be transmitted, then
102 normally blocks, unless the socket has been placed in
103 non-blocking I/O mode.
106 call may be used to determine when it is possible to
111 parameter may include one or more of the following:
113 #define MSG_OOB 0x1 /* process out-of-band data */
114 #define MSG_PEEK 0x2 /* peek at incoming message */
115 #define MSG_DONTROUTE 0x4 /* bypass routing, use direct interface */
116 #define MSG_EOR 0x8 /* data completes record */
117 #define MSG_EOF 0x100 /* data completes transaction */
124 data on sockets that support this notion (e.g.\&
126 the underlying protocol must also support
130 is used to indicate a record mark for protocols which support the
133 requests that the sender side of a socket be shut down, and that an
134 appropriate indication be sent at the end of the specified data;
135 this flag is only implemented for
139 protocol family, and is used to implement Transaction
144 is usually used only by diagnostic or routing programs.
148 for a description of the
152 The call returns the number of characters sent, or -1
153 if an error occurred.
162 An invalid descriptor was specified.
164 The destination address is a broadcast address, and
166 has not been set on the socket.
172 An invalid user space address was specified for a parameter.
174 The socket requires that message be sent atomically,
175 and the size of the message to be sent made this impossible.
177 The socket is marked non-blocking and the requested operation
180 The system was unable to allocate an internal buffer.
181 The operation may succeed when buffers become available.
183 The output queue for a network interface was full.
184 This generally indicates that the interface has stopped sending,
185 but may be caused by transient congestion.
186 .It Bq Er EHOSTUNREACH
187 The remote host was unreachable.
188 .It Bq Er ECONNREFUSED
189 The socket received an ICMP destination unreachable message
190 from the last message sent. This typically means that the
191 receiver is not listening on the remote port.
193 The remote host was down.
195 The socket is unable to send anymore data (SS_CANTSENDMORE has
196 been set on the socket). This typically means that the socket
202 doesn't necessarily block until the data has been transferred, it
203 is possible to transfer an open file descriptor across an
210 it before it has actually been sent, the result being that the receiver
211 gets a closed file descriptor. It is left to the application to
212 implement an acknowlegment mechanism to prevent this from happening.
223 function call appeared in