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Diffstat (limited to 'man/man7/udplite.7')
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diff --git a/man/man7/udplite.7 b/man/man7/udplite.7 new file mode 100644 index 0000000..eae059a --- /dev/null +++ b/man/man7/udplite.7 @@ -0,0 +1,137 @@ +.\" Copyright (c) 2008 by Gerrit Renker <gerrit@erg.abdn.ac.uk> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" $Id: udplite.7,v 1.12 2008/07/23 15:22:22 gerrit Exp gerrit $ +.\" +.TH udplite 7 2024-05-02 "Linux man-pages (unreleased)" +.SH NAME +udplite \- Lightweight User Datagram Protocol +.SH SYNOPSIS +.nf +.B #include <sys/socket.h> +.\" FIXME . see #defines under `BUGS', +.\" when glibc supports this, add +.\" #include <netinet/udplite.h> +.P +.B sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE); +.fi +.SH DESCRIPTION +This is an implementation of the Lightweight User Datagram Protocol +(UDP-Lite), as described in RFC\ 3828. +.P +UDP-Lite is an extension of UDP (RFC\ 768) to support variable-length +checksums. +This has advantages for some types of multimedia transport that +may be able to make use of slightly damaged datagrams, +rather than having them discarded by lower-layer protocols. +.P +The variable-length checksum coverage is set via a +.BR setsockopt (2) +option. +If this option is not set, the only difference from UDP is +in using a different IP protocol identifier (IANA number 136). +.P +The UDP-Lite implementation is a full extension of +.BR udp (7)\[em]that +is, it shares the same API and API behavior, and in addition +offers two socket options to control the checksum coverage. +.SS Address format +UDP-Litev4 uses the +.I sockaddr_in +address format described in +.BR ip (7). +UDP-Litev6 uses the +.I sockaddr_in6 +address format described in +.BR ipv6 (7). +.SS Socket options +To set or get a UDP-Lite socket option, call +.BR getsockopt (2) +to read or +.BR setsockopt (2) +to write the option with the option level argument set to +.BR IPPROTO_UDPLITE . +In addition, all +.B IPPROTO_UDP +socket options are valid on a UDP-Lite socket. +See +.BR udp (7) +for more information. +.P +The following two options are specific to UDP-Lite. +.TP +.B UDPLITE_SEND_CSCOV +This option sets the sender checksum coverage and takes an +.I int +as argument, with a checksum coverage value in the range 0..2\[ha]16-1. +.IP +A value of 0 means that the entire datagram is always covered. +Values from 1\-7 are illegal (RFC\ 3828, 3.1) and are rounded up to +the minimum coverage of 8. +.IP +With regard to IPv6 jumbograms (RFC\ 2675), the UDP-Litev6 checksum +coverage is limited to the first 2\[ha]16-1 octets, as per RFC\ 3828, 3.5. +Higher values are therefore silently truncated to 2\[ha]16-1. +If in doubt, the current coverage value can always be queried using +.BR getsockopt (2). +.TP +.B UDPLITE_RECV_CSCOV +This is the receiver-side analogue and uses the same argument format +and value range as +.BR UDPLITE_SEND_CSCOV . +This option is not required to enable traffic with partial checksum +coverage. +Its function is that of a traffic filter: when enabled, it +instructs the kernel to drop all packets which have a coverage +.I less +than the specified coverage value. +.IP +When the value of +.B UDPLITE_RECV_CSCOV +exceeds the actual packet coverage, incoming packets are silently dropped, +but may generate a warning message in the system log. +.\" SO_NO_CHECK exists and is supported by UDPv4, but is +.\" commented out in socket(7), hence also commented out here +.\".P +.\"Since UDP-Lite mandates checksums, checksumming can not be disabled +.\"via the +.\".B SO_NO_CHECK +.\"option from +.\".BR socket (7). +.SH ERRORS +All errors documented for +.BR udp (7) +may be returned. +UDP-Lite does not add further errors. +.SH FILES +.TP +.I /proc/net/snmp +Basic UDP-Litev4 statistics counters. +.TP +.I /proc/net/snmp6 +Basic UDP-Litev6 statistics counters. +.SH VERSIONS +UDP-Litev4/v6 first appeared in Linux 2.6.20. +.SH BUGS +.\" FIXME . remove this section once glibc supports UDP-Lite +Where glibc support is missing, the following definitions are needed: +.P +.in +4n +.EX +#define IPPROTO_UDPLITE 136 +.\" The following two are defined in the kernel in linux/net/udplite.h +#define UDPLITE_SEND_CSCOV 10 +#define UDPLITE_RECV_CSCOV 11 +.EE +.in +.SH SEE ALSO +.BR ip (7), +.BR ipv6 (7), +.BR socket (7), +.BR udp (7) +.P +RFC\ 3828 for the Lightweight User Datagram Protocol (UDP-Lite). +.P +.I Documentation/networking/udplite.txt +in the Linux kernel source tree |