328 lines
6.4 KiB
Text
328 lines
6.4 KiB
Text
.TH DIAL 2
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.SH NAME
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dial, hangup, announce, listen, accept, reject, netmkaddr, setnetmtpt, getnetconninfo, freenetconninfo \- make and break network connections
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.B
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int dial(char *addr, char *local, char *dir, int *cfdp)
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.PP
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.B
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int hangup(int ctl)
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.PP
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.B
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int announce(char *addr, char *dir)
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.PP
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.B
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int listen(char *dir, char *newdir)
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.PP
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.B
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int accept(int ctl, char *dir)
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.PP
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.B
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int reject(int ctl, char *dir, char *cause)
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.PP
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.B
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char* netmkaddr(char *addr, char *defnet, char *defservice)
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.PP
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.B
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void setnetmtpt(char *to, int tolen, char *from)
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.PP
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.B
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NetConnInfo* getnetconninfo(char *conndir, int fd)
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.PP
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.B
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void freenetconninfo(NetConnInfo*)
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.SH DESCRIPTION
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For these routines,
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.I addr
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is a network address of the form
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.IB network ! netaddr ! service\f1,
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.IB network ! netaddr\f1,
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or simply
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.IR netaddr .
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.I Network
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is any directory listed in
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.B /net
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or the special token,
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.BR net .
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.B Net
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is a free variable that stands for any network in common
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between the source and the host
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.IR netaddr .
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.I Netaddr
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can be a host name, a domain name, a network address,
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or a meta-name of the form
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.BI $ attribute\f1,
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which
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is replaced by
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.I value
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from the value-attribute pair
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.IB attribute = value
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most closely associated with the source host in the
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network data base (see
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.IR ndb (6)).
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.PP
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If a connection attempt is successful and
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.I dir
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is non-zero,
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the path name of a
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.I line directory
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that has files for accessing the connection
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is copied into
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.IR dir .
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The path name is guaranteed to be less than 40
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bytes long.
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One line directory exists for each possible connection.
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The
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.B data
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file in the line directory should be used to communicate with the destination.
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The
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.B ctl
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file in the line directory can be used to send commands to the line.
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See
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.IR ip (3)
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for messages that can be written to the
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.B ctl
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file.
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The last close of the
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.B data
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or
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.B ctl
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file will close the connection.
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.PP
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.I Dial
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makes a call to destination
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.I addr
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on a multiplexed network.
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If the network in
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.I addr
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is
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.BR net ,
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.I dial
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will try all addresses on networks in common between source
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and destination until a call succeeds.
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It returns a file descriptor open for reading and writing the
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.B data
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file in the line directory.
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The
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.B addr
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file in the line directory contains the address called.
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If the network allows the local address to be set,
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as is the case with UDP and TCP port numbers, and
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.IR local
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is non-zero, the local address will be set to
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.IR local .
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If
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.I cfdp
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is non-zero,
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.BI * cfdp
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is set to a file descriptor open for reading and
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writing the control file.
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.PP
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.I Hangup
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is a means of forcing a connection to hang up without
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closing the
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.B ctl
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and
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.B data
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files.
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.P
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.I Announce
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and
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.I listen
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are the complements of
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.IR dial .
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.I Announce
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establishes a network
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name to which calls can be made, and returns an open
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.B ctl
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file.
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The
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.I netaddr
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used in announce may be a local address or an asterisk,
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to indicate all local addresses, e.g.
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.BR tcp!*!echo .
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The
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.I listen
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routine takes as its first argument the
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.I dir
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of a previous
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.IR announce .
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When a call is received,
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.I listen
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returns an open
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.B ctl
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file for the line the call was received on.
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It sets
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.I newdir
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to the path name of the new line directory.
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.I Accept
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accepts a call received by
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.IR listen ,
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while
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.I reject
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refuses the call because of
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.IR cause .
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.I Accept
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returns a file descriptor for the data file opened
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.BR ORDWR .
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.PP
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.I Netmkaddr
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makes an address suitable for dialing or announcing.
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It takes an address along with a default network and service to use
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if they are not specified in the address.
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It returns a pointer to static data holding the actual address to use.
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.PP
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.I Getnetconninfo
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returns a structure containing information about a
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network connection. The structure is:
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.EX
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typedef struct NetConnInfo NetConnInfo;
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struct NetConnInfo
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{
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char *dir; /* connection directory */
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char *root; /* network root */
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char *spec; /* binding spec */
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char *lsys; /* local system */
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char *lserv; /* local service */
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char *rsys; /* remote system */
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char *rserv; /* remote service */
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char *laddr; /* local address */
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char *raddr; /* remote address */
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};
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.EE
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.PP
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The information is obtained from the connection directory,
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.IR conndir .
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If
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.I conndir
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is nil, the directory is obtained by performing
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.IR fd2path (2)
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on
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.IR fd .
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.I Getnetconninfo
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returns either a completely specified structure, or
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nil if either the structure can't be allocated or the
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network directory can't be determined.
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The structure
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is freed using
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.IR freenetconninfo .
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.PP
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.I Setnetmtpt
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copies the name of the network mount point into
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the buffer
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.IR to ,
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whose length is
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.IR tolen .
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It exists to merge two pre-existing conventions for specifying
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the mount point.
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Commands that take a network mount point as a parameter
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(such as
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.BR dns ,
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.BR cs
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(see
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.IR ndb (8)),
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and
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.IR ipconfig (8))
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should now call
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.IR setnetmtpt .
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If
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.I from
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is
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.BR nil ,
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the mount point is set to the default,
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.BR /net .
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If
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.I from
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points to a string starting with a slash,
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the mount point is that path.
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Otherwise, the mount point is the string pointed to by
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.I from
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appended to the string
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.BR /net .
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The last form is obsolete and it should be avoided.
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It exists only to aid in conversion.
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.SH EXAMPLES
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Make a call and return an open file descriptor to
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use for communications:
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.IP
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.EX
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int callkremvax(void)
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{
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return dial("kremvax", nil, nil, nil);
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}
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.EE
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.PP
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Call the local authentication server:
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.IP
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.EX
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int dialauth(char *service)
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{
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return dial(netmkaddr("$auth", nil, service), nil, nil, nil);
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}
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.EE
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.PP
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Announce as
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.B kremvax
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on TCP/IP and
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loop forever receiving calls and echoing back
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to the caller anything sent:
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.IP
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.EX
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int
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bekremvax(void)
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{
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int dfd, acfd, lcfd;
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char adir[40], ldir[40];
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int n;
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char buf[256];
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acfd = announce("tcp!*!7", adir);
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if(acfd < 0)
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return -1;
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for(;;){
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/* listen for a call */
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lcfd = listen(adir, ldir);
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if(lcfd < 0)
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return -1;
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/* fork a process to echo */
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switch(fork()){
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case -1:
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perror("forking");
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close(lcfd);
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break;
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case 0:
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/* accept the call and open the data file */
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dfd = accept(lcfd, ldir);
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if(dfd < 0)
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return -1;
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/* echo until EOF */
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while((n = read(dfd, buf, sizeof(buf))) > 0)
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write(dfd, buf, n);
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exits(nil);
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default:
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close(lcfd);
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break;
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}
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}
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}
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.EE
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.SH SOURCE
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.BR /sys/src/libc/9sys ,
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.B /sys/src/libc/port
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.SH "SEE ALSO"
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.IR auth (2),
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.IR ip (3),
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.IR ndb (8)
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.SH DIAGNOSTICS
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.IR Dial ,
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.IR announce ,
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and
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.I listen
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return \-1 if they fail.
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.I Hangup
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returns nonzero if it fails.
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