man > udplite(7)

udplite(7)                        Miscellaneous Information Manual                        udplite(7)

NAME
       udplite - Lightweight User Datagram Protocol

SYNOPSIS
       #include <sys/socket.h>

       sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);

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 ad‐
       vantages for some types of multimedia transport that may be able to make use of slightly dam‐
       aged 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 sock‐
       addr_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 IP‐
       PROTO_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  in‐
              structs  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.

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

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

VERSIONS
       UDP-Litev4/v6 first appeared in Linux 2.6.20.

BUGS
       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
       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

Linux man-pages 6.7                          2023-10-31                                   udplite(7)