oracular (2) msocket.2viewos.gz

Provided by: umview_0.8.2-4_amd64 bug

NAME

       msocket - create an endpoint for communication in a multi-stack environment

SYNOPSIS

       #include <sys/types.h>          /* See NOTES */
       #include <msocket.h>

       int msocket(char * path, int domain, int type, int protocol);

DESCRIPTION

       msocket()  creates an endpoint for communication and returns a descriptor in a multi-stack environment or
       defines the default stack.

       The path parameter selects the stack used for the call. The path must  refer  to  a  stack  special  file
       (S_IFSTACK).  When path is NULL, the default stack gets used. It is possible to specify a default network
       stack for each domain (see SOCK_DEFAULT below).

       The domain parameter specifies a communication domain; this selects the protocol  family  which  will  be
       used  for communication.  These families are defined in <sys/socket.h>.  The currently understood formats
       include:

       Name                Purpose                          Man page
       PF_UNIX, PF_LOCAL   Local communication              unix(7)
       PF_INET             IPv4 Internet protocols          ip(7)
       PF_INET6            IPv6 Internet protocols          ipv6(7)
       PF_IPX              IPX - Novell protocols
       PF_NETLINK          Kernel user interface device     netlink(7)
       PF_X25              ITU-T X.25 / ISO-8208 protocol   x25(7)
       PF_AX25             Amateur radio AX.25 protocol
       PF_ATMPVC           Access to raw ATM PVCs
       PF_APPLETALK        Appletalk                        ddp(7)
       PF_PACKET           Low level packet interface       packet(7)

       The socket has the indicated type, which specifies the communication semantics or SOCK_DEFAULT to  define
       the standard stack for the specified domain(s).  Currently defined types are:

       SOCK_STREAM
              Provides  sequenced,  reliable,  two-way,  connection-based  byte  streams.   An  out-of-band data
              transmission mechanism may be supported.

       SOCK_DGRAM
              Supports datagrams (connectionless, unreliable messages of a fixed maximum length).

       SOCK_SEQPACKET
              Provides a sequenced, reliable, two-way connection-based data transmission path for  datagrams  of
              fixed maximum length; a consumer is required to read an entire packet with each input system call.

       SOCK_RAW
              Provides raw network protocol access.

       SOCK_RDM
              Provides a reliable datagram layer that does not guarantee ordering.

       SOCK_PACKET
              Obsolete and should not be used in new programs; see packet(7).

       Some  socket  types  may  not be implemented by all protocol families; for example, SOCK_SEQPACKET is not
       implemented for AF_INET.

       When type is SOCK_DEFAULT msocket does not define any communication  endpoint,  instead  it  defines  the
       stack  that  will  be  used for the following msocket calls with NULL path, or for the following obsolete
       socket(2) calls.  Default stacks get inherited through process creation fork(2) and execution  execve(2).
       When  type  is SOCK_DEFAULT and domain is PF_UNSPEC the named stack becames the default stack for all the
       protocols it supports.

       The protocol specifies a particular protocol to be used with the socket.  Normally only a single protocol
       exists  to support a particular socket type within a given protocol family, in which case protocol can be
       specified as 0.  However, it is possible that many protocols  may  exist,  in  which  case  a  particular
       protocol  must be specified in this manner.  The protocol number to use is specific to the “communication
       domain” in which communication is to take place; see protocols(5).  See  getprotoent(3)  on  how  to  map
       protocol name strings to protocol numbers.

       Sockets  of type SOCK_STREAM are full-duplex byte streams, similar to pipes.  They do not preserve record
       boundaries.  A stream socket must be in a connected state before any data may be sent or received on  it.
       A  connection  to  another  socket  is  created  with  a  connect(2)  call.   Once connected, data may be
       transferred using read(2) and write(2) calls or some variant of the send(2) and recv(2)  calls.   When  a
       session  has  been  completed  a  close(2) may be performed.  Out-of-band data may also be transmitted as
       described in send(2) and received as described in recv(2).

       The communications protocols which implement a SOCK_STREAM ensure that data is not  lost  or  duplicated.
       If a piece of data for which the peer protocol has buffer space cannot be successfully transmitted within
       a reasonable length of time, then the connection is considered to be dead.  When SO_KEEPALIVE is  enabled
       on  the  socket  the  protocol  checks  in a protocol-specific manner if the other end is still alive.  A
       SIGPIPE signal is raised if a process sends or receives on a broken stream; this causes naive  processes,
       which  do  not  handle  the  signal,  to  exit.   SOCK_SEQPACKET  sockets employ the same system calls as
       SOCK_STREAM sockets.  The only difference is that read(2) calls will  return  only  the  amount  of  data
       requested,  and any data remaining in the arriving packet will be discarded.  Also all message boundaries
       in incoming datagrams are preserved.

       SOCK_DGRAM and SOCK_RAW sockets allow sending of datagrams to correspondents named  in  sendto(2)  calls.
       Datagrams are generally received with recvfrom(2), which returns the next datagram along with the address
       of its sender.

       SOCK_PACKET is an obsolete socket type to receive raw packets  directly  from  the  device  driver.   Use
       packet(7) instead.

       An  fcntl(2)  F_SETOWN  operation  can  be used to specify a process or process group to receive a SIGURG
       signal when the out-of-band  data  arrives  or  SIGPIPE  signal  when  a  SOCK_STREAM  connection  breaks
       unexpectedly.   This operation may also be used to set the process or process group that receives the I/O
       and asynchronous notification of I/O events via SIGIO.  Using F_SETOWN is equivalent to an ioctl(2)  call
       with the FIOSETOWN or SIOCSPGRP argument.

       When  the  network  signals an error condition to the protocol module (e.g., using a ICMP message for IP)
       the pending error flag is set for the socket.  The next operation on this socket will  return  the  error
       code  of  the  pending  error.   For  some protocols it is possible to enable a per-socket error queue to
       retrieve detailed information about the error; see IP_RECVERR in ip(7).

       The operation of  sockets  is  controlled  by  socket  level  options.   These  options  are  defined  in
       <sys/socket.h>.   The  functions  setsockopt(2)  and  getsockopt(2)  are  used  to  set  and get options,
       respectively.

RETURN VALUE

       On success, a file descriptor for the new socket is returned except when type is SOCK_DEFAULT.   In  this
       latter case 0 is returned on success.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       EACCES Permission to create a socket of the specified type and/or protocol is denied.

       EAFNOSUPPORT
              The implementation does not support the specified address family.

       EINVAL Unknown protocol, or protocol family not available.

       EMFILE Process file table overflow.

       ENFILE The system limit on the total number of open files has been reached.

       ENOBUFS or ENOMEM
              Insufficient  memory  is  available.   The socket cannot be created until sufficient resources are
              freed.

       EPROTONOSUPPORT
              The protocol type or the specified protocol is not supported within this domain.

       Other errors may be generated by the underlying protocol modules.

CONFORMING TO

       This is a system call defined for View-OS. It extends socket(), appeared  in  4.2BSD  and  conforming  to
       4.4BSD,  POSIX.1-2001.   System  providing  msocket()  do  provide  also  a  socket()  call  for backward
       compatibility.  In fact: socket(domain,type,protocol) is equivalent to msocket(NULL,domain,type,protocol)

       In this way it is generally portable to/from non-BSD systems supporting clones of the  BSD  socket  layer
       (including System V variants).

NOTES

       POSIX.1-2001  does  not  require  the inclusion of <sys/types.h>, and this header file is not required on
       Linux.   However,  some  historical  (BSD)  implementations  required  this  header  file,  and  portable
       applications are probably wise to include it.

       The manifest constants used under 4.x BSD for protocol families are PF_UNIX, PF_INET, etc., while AF_UNIX
       etc. are used for address families.  However, already the BSD man page  promises:  "The  protocol  family
       generally is the same as the address family", and subsequent standards use AF_* everywhere.

       The  header  file  <sys/types.h>  is only required for libc4 or earlier.  Some packages, like util-linux,
       claim portability to all Linux versions and libraries.  They certainly need this header file.

BUGS

       SOCK_UUCP is not implemented yet.

SEE ALSO

       socket(2), accept(2),  bind(2),  connect(2),  fcntl(2),  getpeername(2),  getsockname(2),  getsockopt(2),
       ioctl(2),   listen(2),  read(2),  recv(2),  select(2),  send(2),  shutdown(2),  socketpair(2),  write(2),
       getprotoent(3), ip(7), socket(7), tcp(7), udp(7), unix(7)

COLOPHON

       This page has been modified from socket(2) page of release 2.79 of the Linux. In fact  msocket(2)  is  an
       extension  of  this  call.   man-pages  project.   A  description  of  the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

       View-OS is a project of the Computer Science Department, University of  Bologna.  Project  Leader:  Renzo
       Davoli.
       <http://www.sourceforge.net/projects/view-os>

       Howto's and further information can be found on the project wiki
       <wiki.virtualsquare.org>.