udplite(7) - Linux manual page (original) (raw)

udplite(7) Miscellaneous Information 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)](../man2/setsockopt.2.html)
   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)](../man7/udp.7.html)—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 sockaddrin address format described in ip(7). UDP-Litev6 uses the sockaddrin6 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)](../man2/getsockopt.2.html).

   **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)](../man7/udp.7.html) 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

COLOPHON top

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Linux man-pages 6.10 2024-05-02 udplite(7)

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