udplite(7) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ERRORS | FILES | VERSIONS | BUGS | SEE ALSO | COLOPHON

UDPLITE(7)              Linux Programmer's Manual             UDPLITE(7)

NAME         top

       udplite - Lightweight User Datagram Protocol

SYNOPSIS         top

       #include <sys/socket.h>

       sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);

DESCRIPTION         top

       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(2)
       option.  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(7)—that
       is, it shares the same API and API behavior, 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 ipv6(7).

   Socket options
       To set or get a UDP-Lite socket option, call getsockopt(2) to
       read or setsockopt(2) to write the option with the option level
       argument set to IPPROTO_UDPLITE.  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.

       UDPLITE_SEND_CSCOV
              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 getsockopt(2).

       UDPLITE_RECV_CSCOV
              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         top

       All errors documented for udp(7) may be returned.  UDP-Lite does
       not add further errors.

FILES         top

       /proc/net/snmp
              Basic UDP-Litev4 statistics counters.

       /proc/net/snmp6
              Basic UDP-Litev6 statistics counters.

VERSIONS         top

       UDP-Litev4/v6 first appeared in Linux 2.6.20.

BUGS         top

       Where glibc support is missing, the following definitions are
       needed:

           #define IPPROTO_UDPLITE     136
           #define UDPLITE_SEND_CSCOV  10
           #define UDPLITE_RECV_CSCOV  11

SEE ALSO         top

       ip(7), ipv6(7), socket(7), udp(7)

       RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite).

       Documentation/networking/udplite.txt in the Linux kernel source
       tree

COLOPHON         top

       This page is part of release 5.12 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22                     UDPLITE(7)

Pages that refer to this page: ip(7)udp(7)