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 setsockopt
If this option is not set, the only difference from UDP is in using a
different IP protocol identifier (IANA number 136).
The UDP-Lite implementation is a full extension of udp
it shares the same API and API behavior, and in addition offers two socket
options to control the checksum coverage.
UDP-Litev4 uses the sockaddr_in
address format described in ip
UDP-Litev6 uses the sockaddr_in6
address format described in
To set or get a UDP-Lite socket option, call getsockopt
(2) to read or
(2) to write the option with the option level argument set to
. In addition, all IPPROTO_UDP
socket options are
valid on a UDP-Lite socket. See udp
(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.
All errors documented for udp
(7) may be returned. UDP-Lite does not add
- Basic UDP-Litev4 statistics counters.
- Basic UDP-Litev6 statistics counters.
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