|| Linux Programmer's Manual
NAME udplite - Lightweight User Datagram Protocol
sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
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 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
(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
(7), i.e., it shares the same API and API behaviour, and in addition offers two socket options to control the checksum coverage.
Address format UDP-Litev4 uses the
sockaddr_in address format described in
ip(7). UDP-Litev6 uses the
sockaddr_in6 address format described in
To set or get a UDP-Lite socket option, call
(2) to read or
(2) to write the option with the option level argument set to
. In addition, all
socket options are valid on a UDP-Lite socket. See
(7) for more information.
The following two options are specific to UDP-Lite.
This option sets the sender checksum coverage and takes an
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 silently truncated to 2^16-1. If in doubt, the current coverage value can always be queried using
This is the receiver-side analogue and uses the same argument format and value range as
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
less than the specified coverage value.
When the value of
UDPLITE_RECV_CSCOV exceeds the actual packet coverage, incoming packets are silently dropped, but may generate a warning message in the system log.
ERRORS All errors documented for
udp(7) may be returned. UDP-Lite does not add further errors.
- basic UDP-Litev4 statistics counters.
- basic UDP-Litev6 statistics counters.
VERSIONS UDP-Litev4/v6 first appeared in Linux 2.6.20.
Where glibc support is missing, the following definitions are needed:
#define IPPROTO_UDPLITE 136
#define UDPLITE_SEND_CSCOV 10
#define UDPLITE_RECV_CSCOV 11
RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite).
in the Linux kernel source tree
COLOPHON This page is part of release 3.53 of the Linux
man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.