SEND(2) | NetBSD System Calls Manual | SEND(2) |
ssize_t
send(int s, const void *msg, size_t len, int flags);
ssize_t
sendto(int s, const void *msg, size_t len, int flags, const struct sockaddr *to, socklen_t tolen);
ssize_t
sendmsg(int s, const struct msghdr *msg, int flags);
The address of the target is given by to with tolen specifying its size. The length of the message is given by len. If the message is too long to pass atomically through the underlying protocol, the error EMSGSIZE is returned, and the message is not transmitted.
No indication of failure to deliver is implicit in a send(). Locally detected errors are indicated by a return value of -1.
If no messages space is available at the socket to hold the message to be transmitted, then send() normally blocks, unless the socket has been placed in non-blocking I/O mode. The select(2) or poll(2) call may be used to determine when it is possible to send more data.
The flags parameter may include one or more of the following:
#define MSG_OOB 0x0001 /* process out-of-band data */ #define MSG_PEEK 0x0002 /* peek at incoming message */ #define MSG_DONTROUTE 0x0004 /* bypass routing, use direct interface */ #define MSG_EOR 0x0008 /* data completes record */ #define MSG_NOSIGNAL 0x0400 /* do not generate SIGPIPE on EOF */
The flag MSG_OOB is used to send “out-of-band” data on sockets that support this notion (e.g. SOCK_STREAM); the underlying protocol must also support “out-of-band” data. MSG_EOR is used to indicate a record mark for protocols which support the concept. MSG_DONTROUTE is usually used only by diagnostic or routing programs.
See recv(2) for a description of the msghdr structure. MSG_NOSIGNAL is used to prevent SIGPIPE generation when writing a socket that may be closed.
sendto() will also fail if:
sendmsg() will also fail if:
May 9, 2008 | NetBSD 5.99 |