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udplite(7)

UDPLITE(7)                 Linux Programmer's 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 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)  op‐
       tion.   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 check‐
              sum  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  gener‐
              ate 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

COLOPHON
       This page is part of release 5.02 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                             2017-09-15                        UDPLITE(7)
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