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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)idp.4 8.1 (Berkeley) 6/5/93 .\" .Dd June 5, 1993 .Dt IDP 4 .Os BSD 4.3 .Sh NAME .Nm idp .Nd Xerox Internet Datagram Protocol .Sh SYNOPSIS .Fd #include .Fd #include .Fd #include .Ft int .Fn socket AF_NS SOCK_DGRAM 0 .Sh DESCRIPTION .Tn IDP is a simple, unreliable datagram protocol which is used to support the .Dv SOCK_DGRAM abstraction for the Internet protocol family. .Tn IDP sockets are connectionless, and are normally used with the .Xr sendto and .Xr recvfrom calls, though the .Xr connect 2 call may also be used to fix the destination for future packets (in which case the .Xr recv 2 or .Xr read 2 and .Xr send 2 or .Xr write 2 system calls may be used). .Pp Xerox protocols are built vertically on top of .Tn IDP . Thus, .Tn IDP address formats are identical to those used by .Tn SPP . Note that the .Tn IDP port space is the same as the .Tn SPP port space (i.e. a .Tn IDP port may be .Dq connected to a .Tn SPP port, with certain options enabled below). In addition broadcast packets may be sent (assuming the underlying network supports this) by using a reserved .Dq broadcast address ; this address is network interface dependent. .Sh DIAGNOSTICS A socket operation may fail with one of the following errors returned: .Bl -tag -width [EADDRNOTAVAIL] .It Bq Er EISCONN when trying to establish a connection on a socket which already has one, or when trying to send a datagram with the destination address specified and the socket is already connected; .It Bq Er ENOTCONN when trying to send a datagram, but no destination address is specified, and the socket hasn't been connected; .It Bq Er ENOBUFS when the system runs out of memory for an internal data structure; .It Bq Er EADDRINUSE when an attempt is made to create a socket with a port which has already been allocated; .It Bq Er EADDRNOTAVAIL when an attempt is made to create a socket with a network address for which no network interface exists. .El .Sh SOCKET OPTIONS .Bl -tag -width [SO_HEADERS_ON_OUTPUT] .It Bq Dv SO_ALL_PACKETS When set, this option defeats automatic processing of Error packets, and Sequence Protocol packets. .It Bq Dv SO_DEFAULT_HEADERS The user provides the kernel an .Tn IDP header, from which it gleans the Packet Type. When requested, the kernel will provide an .Tn IDP header, showing the default packet type, and local and foreign addresses, if connected. .It Bq Dv SO_HEADERS_ON_INPUT When set, the first 30 bytes of any data returned from a read or recv from will be the initial 30 bytes of the .Tn IDP packet, as described by .Bd -literal -offset indent struct idp { u_short idp_sum; u_short idp_len; u_char idp_tc; u_char idp_pt; struct ns_addr idp_dna; struct ns_addr idp_sna; }; .Ed .Pp This allows the user to determine the packet type, and whether the packet was a multi-cast packet or directed specifically at the local host. When requested, gives the current state of the option, .Pf ( Dv NSP_RAWIN or 0). .It Bq Dv SO_HEADERS_ON_OUTPUT When set, the first 30 bytes of any data sent will be the initial 30 bytes of the .Tn IDP packet. This allows the user to determine the packet type, and whether the packet should be multi-cast packet or directed specifically at the local host. You can also misrepresent the sender of the packet. When requested, gives the current state of the option. .Pf ( Dv NSP_RAWOUT or 0). .It Bq Dv SO_SEQNO When requested, this returns a sequence number which is not likely to be repeated until the machine crashes or a very long time has passed. It is useful in constructing Packet Exchange Protocol packets. .El .Sh SEE ALSO .Xr send 2 , .Xr recv 2 , .Xr intro 4 , .Xr ns 4 .Sh HISTORY The .Nm protocol appeared in .Bx 4.3 .