| | 1 | .\" $NetBSD: udp.4,v 1.3 1994/11/30 16:22:41 jtc Exp $ |
| | 2 | .\" |
| | 3 | .\" Copyright (c) 1983, 1991, 1993 |
| | 4 | .\" The Regents of the University of California. All rights reserved. |
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| | 11 | .\" 2. Redistributions in binary form must reproduce the above copyright |
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| | 19 | .\" may be used to endorse or promote products derived from this software |
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| | 22 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| | 34 | .\" @(#)udp.4 8.1 (Berkeley) 6/5/93 |
| | 35 | .\" |
| | 36 | .Dd March 18, 2015 |
| | 37 | .Dt UDP 4 |
| | 38 | .Os BSD 4.2 |
| | 39 | .Sh NAME |
| | 40 | .Nm udp |
| | 41 | .Nd Internet User Datagram Protocol |
| | 42 | .Sh SYNOPSIS |
| | 43 | .Fd #include <sys/socket.h> |
| | 44 | .Fd #include <netinet/in.h> |
| | 45 | .Ft int |
| | 46 | .Fn socket AF_INET SOCK_DGRAM 0 |
| | 47 | .Sh DESCRIPTION |
| | 48 | .Tn UDP |
| | 49 | is a simple, unreliable datagram protocol which is used |
| | 50 | to support the |
| | 51 | .Dv SOCK_DGRAM |
| | 52 | abstraction for the Internet |
| | 53 | protocol family. |
| | 54 | .Tn UDP |
| | 55 | sockets are connectionless, and are |
| | 56 | normally used with the |
| | 57 | .Xr sendto |
| | 58 | and |
| | 59 | .Xr recvfrom |
| | 60 | calls, though the |
| | 61 | .Xr connect 2 |
| | 62 | or |
| | 63 | .Xr connectx 2 |
| | 64 | call may also be used to fix the destination for future |
| | 65 | packets (in which case the |
| | 66 | .Xr recv 2 |
| | 67 | or |
| | 68 | .Xr read 2 |
| | 69 | and |
| | 70 | .Xr send 2 |
| | 71 | or |
| | 72 | .Xr write 2 |
| | 73 | system calls may be used). |
| | 74 | .Pp |
| | 75 | .Tn UDP |
| | 76 | address formats are identical to those used by |
| | 77 | .Tn TCP . |
| | 78 | In particular |
| | 79 | .Tn UDP |
| | 80 | provides a port identifier in addition |
| | 81 | to the normal Internet address format. Note that the |
| | 82 | .Tn UDP |
| | 83 | port |
| | 84 | space is separate from the |
| | 85 | .Tn TCP |
| | 86 | port space (i.e. a |
| | 87 | .Tn UDP |
| | 88 | port |
| | 89 | may not be |
| | 90 | .Dq connected |
| | 91 | to a |
| | 92 | .Tn TCP |
| | 93 | port). In addition broadcast |
| | 94 | packets may be sent (assuming the underlying network supports |
| | 95 | this) by using a reserved |
| | 96 | .Dq broadcast address ; |
| | 97 | this address |
| | 98 | is network interface dependent. |
| | 99 | .Pp |
| | 100 | Options at the |
| | 101 | .Tn IP |
| | 102 | transport level may be used with |
| | 103 | .Tn UDP ; |
| | 104 | see |
| | 105 | .Xr ip 4 . |
| | 106 | .Sh DIAGNOSTICS |
| | 107 | A socket operation may fail with one of the following errors returned: |
| | 108 | .Bl -tag -width [EADDRNOTAVAIL] |
| | 109 | .It Bq Er EISCONN |
| | 110 | when trying to establish a connection on a socket which |
| | 111 | already has one, or when trying to send a datagram with the destination |
| | 112 | address specified and the socket is already connected; |
| | 113 | .It Bq Er ENOTCONN |
| | 114 | when trying to send a datagram, but |
| | 115 | no destination address is specified, and the socket hasn't been |
| | 116 | connected; |
| | 117 | .It Bq Er ENOBUFS |
| | 118 | when the system runs out of memory for |
| | 119 | an internal data structure; |
| | 120 | .It Bq Er EADDRINUSE |
| | 121 | when an attempt |
| | 122 | is made to create a socket with a port which has already been |
| | 123 | allocated; |
| | 124 | .It Bq Er EADDRNOTAVAIL |
| | 125 | when an attempt is made to create a |
| | 126 | socket with a network address for which no network interface |
| | 127 | exists. |
| | 128 | .El |
| | 129 | .Sh SEE ALSO |
| | 130 | .Xr connect 2 , |
| | 131 | .Xr connectx 2 , |
| | 132 | .Xr getsockopt 2 , |
| | 133 | .Xr recv 2 , |
| | 134 | .Xr send 2 , |
| | 135 | .Xr socket 2 , |
| | 136 | .Xr inet 4 , |
| | 137 | .Xr intro 4 , |
| | 138 | .Xr ip 4 |
| | 139 | .Sh HISTORY |
| | 140 | The |
| | 141 | .Nm |
| | 142 | protocol appeared in |
| | 143 | .Bx 4.2 . |
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