udplite(7) - man - phpMan

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 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

COLOPHON
       This page is part of release 5.10 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)