LISTEN(1)LISTEN(1)NAME
listen, styxlisten, dial - network connections
SYNOPSISlisten [ -Ats ] [ -a alg ]... [ -k keyfile ] [ -i {initscript} ] addr
command [ arg... ]
styxlisten [ -Ats ] [ -a alg ]... [ -k keyfile ] addr command [ arg...
]
dial [ -A ] [ -a alg ] [ -k keyfile ] addr command [ arg... ]
DESCRIPTION
Listen waits for an incoming network connection on addr, (as accepted
by announce in dial(2)) and then invokes sh(1) to run the associated
command. If the -A option is specified, no authentication or encryp‐
tion will take place on the connection; otherwise listen will attempt
to authenticate the party at the other end of the connection, allowing
any given alg to be used to encrypt and/or digest the connection's
data. If neither -A or any -a option is given, then listen will allow
any algorithm allowed by the local ssl(3) device. If keyfile is speci‐
fied, then that will be used as the server's certificate; otherwise
/usr/user/keyring/default will be used.
If an initscript is provided, it is executed by each listener after
announcing its network connection, with the shell variable net set to
the name of the corresponding network directory (see dial(2)), before
listening for incoming calls. This can be used to change, or find out
the characteristics of an announced port (for instance to find out the
actual port number that has been announced).
By default, listen backgrounds itself (after checking that the port
announcement proceeded ok); giving it the -s option causes it to run
synchronously.
Listen currently makes available the whole of its current name space
visible to the command, which might be undesirable, and perhaps should
be optional, with a new name space constructed for an incoming call.
The -t option declares the command to be `trusted' giving it access to
elements of the current name space such as /mnt/keys on an authentica‐
tion server. By default it has not got that access.
Styxlisten is similar to listen, except that it multiplexes a single
styx (see intro(5)) server between multiple clients. Styxlisten starts
its cmd only once; it assumes it will serve styx messages through file
descriptor 0 when started. For each client that attaches to address,
the command will see a new attach(5) message indicating the new connec‐
tion. Unless the -A option has been given, the uname field in the
attach message will be the name of the authenticated user. When the
command exits, the process listening on address is stopped.
Dial is the complement of listen. It tries to make a connection to
addr. If the -A option is given, no authentication or encryption will
take place; otherwise Inferno authentication and encryption will be
performed as usual, using alg if given, or a default algorithm other‐
wise. Keyfile is used for the certificate if given, otherwise
/usr/user/keyring/addr, if it exists, and failing that,
/usr/user/keyring/default. Alg is used for the encryption/digest algo‐
rithm on the connection. When the connection is made, command is run
in the context of that connection, as described below.
For both dial and listen, when the command is run, $user is set to the
name of the authenticated user at the other end of the connection (if
authentication is being used), and $net is set to the /net directory
corresponding to the connection. The standard input and output of the
command is redirected to the network connection (standard error is
unaffected).
EXAMPLES
Run a custom login daemon and an echo server that logs incoming connec‐
tions:
listen 'tcp!*!echo' {
echo connection from `{cat $net/remote} >[1=2]
echo user is $user >[1=2]
cat &
}
Dial up the above echo server:
dial tcp!somehost!echo {
echo made connection >[1=2]; echo hello; cat >[1=2]
}
Make the current name-space available to all:
styxlisten 'tcp!*!styx' export /
SOURCE
/appl/cmd/dial.b
/appl/cmd/listen.b
BUGS
The way that styxlisten is implemented means that the aname from the
remote mount(2) request cannot be passed through to the attach message
seen by the command that has been started by styxlisten.
SEE ALSOdial(2), ssl(3), auth(6), svc(8)LISTEN(1)
