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) option.  If this option is not set, the only difference from UDP is in using a different IP pro‐
       tocol 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
       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                                                                          2021-03-22                                                                     UDPLITE(7)