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 to 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 4.07 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                            2014-07-08                       UDPLITE(7)