| | The groff was fine. I made a few light edits to the page. I also | added some comments to the page with some "FIXME(gr)" pointing to | places where I think some work is needed. Thanks a lot for the review. It was particularly useful since it brought to light an unresolved issue: when the coverage > 65535, then unexpected things will happen since the internal fields are u16 and the setsockopt() argument is `int'. Will submit a bug-fix to netdev and resubmit the updated manpage when this issue has been resolved. Gerrit | | ============== | .\" FIXME(gr) we need a license for this page. | .\" The one I tend to favor is shown in the capabilities.7 page, | .\" but others are also used in man-pages (e.g., GPL, BSD). | .TH UDPLITE 7 2008-06-23 "Linux" "Linux Programmer's Manual" | .SH NAME | udplite \- Lightweight User Datagram Protocol | .SH SYNOPSIS | .B #include <sys/socket.h> | .br | .\" FIXME: see #defines under `BUGS', | .\" when glibc supports this, add | .\" #include <netinet/udplite.h> | .sp | .B s = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDPLITE); | .SH DESCRIPTION | This is an implementation of the Lightweight User Datagram Protocol | (UDP-Lite), as described in RFC\ 3828. | | UDP-Lite is an extension of UDP (RFC\ 768) to support variable-length | checksums. | This has advantages for some types of multimedia transport, | since it makes it possible to reuse partly damaged frames | (with few bit errors). | .\" FIXME(gr) is "reuse" the right word in the previous sentence? | .\" Reading the RFC suggests to me that a better wording might be: | .\" | .\" 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. | | The variable-length checksum coverage is set via a | .BR setsockopt (2) | option. | If this option is not set, the only difference to UDP is | in using a different IP protocol identifier (IANA number 136). | | The UDP-Lite implementation is a full extension of | .BR udp (7), | i.e., it shares the same API and API behaviour, 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. | | The following two options are specific to UDP-Lite. | .TP | .BR UDPLITE_SEND_CSCOV | This option sets the sender checksum coverage and takes an | .B int | as argument, with a checksum coverage value in the range 0..2^16-1. | | 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. | | With regard to IPv6 jumbograms (RFC\ 2675), the UDP-Litev6 checksum | coverage is limited to the first 2^16-1 octets, as per RFC\ 3828, 3.5. | Higher values are therefore not supported. | .\" FIXME(gr) If higher values are specified, what happens? | .\" If they are silently ignored, probably we should explicitly | .\" say so here. | .TP | .BR UDPLITE_RECV_CSCOV | This is the receiver-side analogue and uses 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. | .\" FIXME: SO_NO_CHECK exists and is supported by UDPv4, but is | .\" commented out in socket(7), hence also here ??? | .\".PP | .\"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. | When the value of | .B UDPLITE_RECV_CSCOV | exceeds the actual coverage, incoming packets are silently dropped, | but may generate a warning message in the system log. | .SH BUGS | .\" FIXME: remove this section once glibc supports UDP-Lite | Where glibc support is missing, the following definitions are needed: | .in +4n | .nf | | #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 | .fi | .in | .SH FILES | .I /proc/net/snmp | .br | .IR /proc/net/snmp6 | .\" FIXME(gr) | .\" Could you add some discussion of the UDPLITE-specific | .\" info in these files? | .SH VERSIONS | UDP-Litev4/v6 first appeared in Linux 2.6.20. | .SH "SEE ALSO" | .BR udp (7), | .BR ip (7), | .BR ipv6 (7), | .BR socket (7) | | RFC\ 3828 for the Lightweight User Datagram Protocol (UDP-Lite) | .br | .I Documentation/networking/udplite.txt | -- -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
