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1 | .\" Copyright (c) 1985 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement | |
| 3 | .\" specifies the terms and conditions for redistribution. | |
| 4 | .\" | |
| 5 | .\" @(#)spp.4 1.1 (Berkeley) %G% | |
| 6 | .\" | |
| 7 | .TH SPP 4P "July 30, 1985" | |
| 8 | .UC 6 | |
| 9 | .SH NAME | |
| 10 | spp \- Xerox Sequenced Packet Protocol | |
| 11 | .SH SYNOPSIS | |
| 12 | .B #include <sys/socket.h> | |
| 13 | .br | |
| 14 | .B #include <netns/ns.h> | |
| 15 | .br | |
| 16 | .B s = socket(AF_NS, SOCK_STREAM, 0); | |
| 17 | .PP | |
| 18 | .B #include <netns/sp.h> | |
| 19 | .br | |
| 20 | .B s = socket(AF_NS, SOCK_SEQPACKET, 0); | |
| 21 | .SH DESCRIPTION | |
| 22 | The SPP protocol provides reliable, flow-controlled, two-way | |
| 23 | transmission of data. It is a byte-stream protocol used to | |
| 24 | support the SOCK_STREAM abstraction. SPP uses the standard | |
| 25 | NS(tm) address formats. | |
| 26 | .PP | |
| 27 | Sockets utilizing the SPP protocol are either \*(lqactive\*(rq or | |
| 28 | \*(lqpassive\*(rq. Active sockets initiate connections to passive | |
| 29 | sockets. By default SPP sockets are created active; to create a | |
| 30 | passive socket the | |
| 31 | .IR listen (2) | |
| 32 | system call must be used | |
| 33 | after binding the socket with the | |
| 34 | .IR bind (2) | |
| 35 | system call. Only | |
| 36 | passive sockets may use the | |
| 37 | .IR accept (2) | |
| 38 | call to accept incoming connections. Only active sockets may | |
| 39 | use the | |
| 40 | .IR connect (2) | |
| 41 | call to initiate connections. | |
| 42 | .PP | |
| 43 | Passive sockets may \*(lqunderspecify\*(rq their location to match | |
| 44 | incoming connection requests from multiple networks. This | |
| 45 | technique, termed \*(lqwildcard addressing\*(rq, allows a single | |
| 46 | server to provide service to clients on multiple networks. | |
| 47 | To create a socket which listens on all networks, the NS | |
| 48 | address of all zeroes must be bound. | |
| 49 | The SPP port may still be specified | |
| 50 | at this time; if the port is not specified the system will assign one. | |
| 51 | Once a connection has been established the socket's address is | |
| 52 | fixed by the peer entity's location. The address assigned the | |
| 53 | socket is the address associated with the network interface | |
| 54 | through which packets are being transmitted and received. Normally | |
| 55 | this address corresponds to the peer entity's network. | |
| 56 | .LP | |
| 57 | If the SOCK_SEQPACKET socket type is specified, | |
| 58 | each packet received has the actual 12 byte sequenced packet header | |
| 59 | left for the user to inspect: | |
| 60 | .nf | |
| 61 | struct sphdr { | |
| 62 | u_char sp_cc; /* \fIconnection control\fP */ | |
| 63 | #define SP_EM 0x10 /* \fIend of message\fP */ | |
| 64 | u_char sp_dt; /* \fIdatastream type\fP */ | |
| 65 | u_short sp_sid; | |
| 66 | u_short sp_did; | |
| 67 | u_short sp_seq; | |
| 68 | u_short sp_ack; | |
| 69 | u_short sp_alo; | |
| 70 | }; | |
| 71 | .fi | |
| 72 | This facilitates the implementation of higher level Xerox protocols | |
| 73 | which make use of the data stream type field and the end of message bit. | |
| 74 | Conversely, the user is required to supply a 12 byte header, | |
| 75 | the only part of which inspected is the data stream type and end of message | |
| 76 | fields. | |
| 77 | .LP | |
| 78 | For either socket type, | |
| 79 | packets received with the Attention bit sent are interpreted as | |
| 80 | out of band data. Data sent with send(..., ..., ..., MSG_OOB) | |
| 81 | cause the attention bit to be set. | |
| 82 | .SH DIAGNOSTICS | |
| 83 | A socket operation may fail with one of the following errors returned: | |
| 84 | .TP 20 | |
| 85 | [EISCONN] | |
| 86 | when trying to establish a connection on a socket which | |
| 87 | already has one; | |
| 88 | .TP 20 | |
| 89 | [ENOBUFS] | |
| 90 | when the system runs out of memory for | |
| 91 | an internal data structure; | |
| 92 | .TP 20 | |
| 93 | [ETIMEDOUT] | |
| 94 | when a connection was dropped | |
| 95 | due to excessive retransmissions; | |
| 96 | .TP 20 | |
| 97 | [ECONNRESET] | |
| 98 | when the remote peer | |
| 99 | forces the connection to be closed; | |
| 100 | .TP 20 | |
| 101 | [ECONNREFUSED] | |
| 102 | when the remote | |
| 103 | peer actively refuses connection establishment (usually because | |
| 104 | no process is listening to the port); | |
| 105 | .TP 20 | |
| 106 | [EADDRINUSE] | |
| 107 | when an attempt | |
| 108 | is made to create a socket with a port which has already been | |
| 109 | allocated; | |
| 110 | .TP 20 | |
| 111 | [EADDRNOTAVAIL] | |
| 112 | when an attempt is made to create a | |
| 113 | socket with a network address for which no network interface | |
| 114 | exists. | |
| 115 | .SH SOCKET OPTIONS | |
| 116 | .TP 20 | |
| 117 | SO_DEFAULT_HEADERS | |
| 118 | when set, this determines the data stream type and whether | |
| 119 | the end of message bit is to be set on every ensuing packet. | |
| 120 | .SH SEE ALSO | |
| 121 | intro(4N), ns(4F) | |
| 122 | .SH BUGS | |
| 123 | There should be a socket option to increase the nominal | |
| 124 | maximum SPP packet size. | |
| 125 | There should be some way to reflect record boundaries in | |
| 126 | a stream. | |
| 127 | For stream mode, there should be an option to get the data stream type of | |
| 128 | the record the user process is about to receive. |