ip.4p

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ip.4p	8.1	9/11/90
.TH ip 4p
.SH Name
ip \- Internet Protocol
.SH Syntax
.B #include <sys/socket.h>
.br
.B #include <netinet/in.h>
.PP
.B s = socket(AF_INET, SOCK_RAW, 0);
.SH Description
.NXR "IP transport protocol"
.NXS "network protocol" "IP transport protocol"
The IP is the transport layer protocol used
by the Internet protocol family.  It can be accessed
through a ``raw socket'' when developing new protocols or
special purpose applications.  IP sockets are connectionless
and are normally used with the
.PN sendto 
and
.PN recvfrom 
calls.  
The 
.MS connect 2
call, however, can also be used to fix the destination for future
packets, in which case the 
.MS read 2
or
.MS recv 2
and
.MS write 2
or
.MS send 2
system calls can be used.
.PP
Outgoing packets automatically have an IP header prepended to
them, based on the destination address and the protocol
number the socket is created with.
Incoming packets are received with their IP headers and
options intact.
.SH Diagnostics
On failure, a socket operation returns any of the following errors:
.TP 15
[EISCONN]
Tried to establish a connection on a socket that
already had one, or tried to send a datagram with the destination
address specified when the socket was already connected.
.TP 15
[ENOTCONN]
Tried to send a datagram, but
no destination address was specified and the socket was not
connected.
.TP 15
[ENOBUFS]
The system ran out of memory for
an internal data structure.
.TP 15
[EADDRNOTAVAIL]
Made an attempt to create a 
socket with a network address for which no network interface
existed.
.SH See Also
send(2), recv(2), inet(4f), intro(4n), packetfilter(4)