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X25 !!!X25 NAME SYNOPSIS DESCRIPTION SOCKET ADDRESSES SOCKET OPTIONS BUGS SEE ALSO VERSIONS ---- !!NAME x25, PF_X25 - ITU-T X.25 / ISO-8208 protocol interface. !!SYNOPSIS __#include __ #include __ __x25_socket = socket(PF_X25, SOCK_SEQPACKET, 0);__ !!DESCRIPTION X25 sockets provide an interface to the X.25 packet layer protocol. This allows applications to communicate over a public X.25 data network as standardised by International Telecommunication Union's recommendation X.25 (X.25 DTE-DCE mode). X25 sockets can also be used for communication without an intermediate X.25 network (X.25 DTE-DTE mode) as described in ISO-8208. Message boundaries are preserved - a read(2) from a socket will retrieve the same chunk of data as output with the corresponding __write(2)__ to the peer socket. When necessary, the kernel takes care of segmenting and re-assembling long messages by means of the X.25 M-bit. There is no hard-coded upper limit for the message size. However, re-assembling of a long message might fail if there is a temporary lack of system resources or when other constraints (such as socket memory or buffer size limits) become effective. If that occurs, the X.25 connection will be reset. !!SOCKET ADDRESSES The __AF_X25__ socket address family uses the __struct sockaddr_x25__ for representing network addresses as defined in ITU-T recommendation X.121. struct sockaddr_x25 { sa_family_t sx25_family; /* must be AF_X25 */ x25_address sx25_addr; /* X.121 Address */ }; ''sx25_addr'' contains a char array ''x25_addr[[]'' to be interpretated as a null-terminated string. ''sx25_addr.x25_addr[[]'' consists of up to 15 (not counting the terminating 0) ASCII characters forming the X.121 address. Only the decimal digit characters from `0' to `9' are allowed. !!SOCKET OPTIONS The following X.25 specific socket options can be set by using setsockopt(2) and read with getsockopt(2) with the level parameter set to __SOL_X25__. __X25_QBITINCL__ Controls whether the X.25 Q-bit (Qualified Data Bit) is accessible by the user. It expects an integer argument. If set to 0 (default), the Q-bit is never set for outgoing packets and the Q-bit of incoming packets is ignored. If set to 1, an additional first byte is prepended to each message read from or written to the socket. For data read from the socket, a 0 first byte indicates that the Q-bits of the corresponding incoming data packets were not set. A first byte with value 1 indicates that the Q-bit of the corresponding incoming data packets was set. If the first byte of the data written to the socket is 1 the Q-bit of the corresponding outgoing data packets will be set. If the first bit is 0 the Q-bit will not be set. !!BUGS Plenty, as the X.25 PLP implementation is __CONFIG_EXPERIMENTAL__. This man page is incomplete. There is no dedicated application programmer's header file yet; you need to include the kernel header file ____. __CONFIG_EXPERIMENTAL__ might also imply that future versions of the interface are not binary compatible. X.25 N-Reset events are not propagated to the user process yet. Thus, if a reset occurred, data might be lost without notice. !!SEE ALSO socket(7), socket(2) Jonathan Simon Naylor: ``The Re-Analysis and Re-Implementation of X.25.'' The URL is ''ftp://ftp.pspt.fi/pub/ham/linux/ax25/x25doc.tgz'' !!VERSIONS The PF_X25 protocol family is a new feature of Linux 2.2. ----
4 pages link to
x25(7)
:
AddressFamily
Man7x
bind(2)
socket(2)
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