From e9be34c9b798141dd6c224cf33934904935c49b2 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Wed, 7 Jan 2015 19:01:26 +0000 Subject: Complete conversion of s6-ipcserver and s6-tcpserver (4 and 6) to socketbinder + d model. With documentation (!) --- doc/s6-ipcserverd.html | 131 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 doc/s6-ipcserverd.html (limited to 'doc/s6-ipcserverd.html') diff --git a/doc/s6-ipcserverd.html b/doc/s6-ipcserverd.html new file mode 100644 index 0000000..916de12 --- /dev/null +++ b/doc/s6-ipcserverd.html @@ -0,0 +1,131 @@ + + + + + s6-networking: the s6-ipcserverd program + + + + + + +

+ +

The `s6-ipcserverd` program

+ +

+s6-ipcserverd is the serving part of the +s6-ipcserver super-server. +It assumes that its stdin is a bound and listening Unix +domain socket, and +it accepts connections from clients connecting to it, forking a +program to handle each connection. +

+ +

Interface

+ +

+     s6-ipcserverd [ -1 ] [ -v verbosity ] [ -P | -p ] [ -c maxconn ] [ -C localmaxconn ] prog...
+

+ +

s6-ipcserverd accepts connections from clients to an already +bound and listening SOCK_STREAM Unix domain socket which is its +standard input.
For every client connection to this socket, it +forks. The child sets some environment variables, then +executes prog... with stdin reading from the socket and +stdout writing to it.
Depending on the verbosity level, it logs what it does to stderr.
It runs until killed by a signal. Depending on the received +signal, it may kill its children before exiting.

+ +

Environment variables

+ +

+ For each connection, an instance of prog... is spawned with +the following variables set: +

+ +

PROTO: always set to IPC
IPCREMOTEEUID: set to the effective UID of the client, +unless credentials lookups have been disabled
IPCREMOTEEGID: set to the effective GID of the client, +unless credentials lookups have been disabled
IPCREMOTEPATH: set to the path associated with the remote socket, +if any. Be aware that it may contain arbitrary characters.
IPCCONNNUM: set to the number of connections originating from +the same user (i.e. same uid)

+ +

+ If client credentials lookup has been disabled, IPCREMOTEEUID and +IPCREMOTEEUID will be set, but empty. +

+ + +

Options

+ +

-1 : write a newline to stdout, and close stdout, +right before entering the client-accepting loop. +If stdout is suitably redirected, this can be used by monitoring +programs to check when the server is accepting connections. +The s6-notifywhenup +program can be used before the s6-ipcserver +invocation to notify listeners when the server is ready.
-v verbosity : be more or less +verbose. verbosity can be 0 (quiet), 1 (normal), or 2 +(verbose).
-P : disable client credentials lookups. The +IPCREMOTEEUID and IPCREMOTEEGID environment variables will be unset +in every instance of prog.... This is the portable option, +because not every system supports credential lookup across Unix domain +sockets; but it is not as secure.
-p : enable client credentials lookups. This +is the default; it works at least on Linux, Solaris, and +*BSD systems. On systems that do not support it, every connection +attempt will fail with a warning message.
-c maxconn : accept at most +maxconn concurrent connections. Default is 40. It is +impossible to set it higher than 1000.
-C localmaxconn : accept at most +localmaxconn connections from the same user ID. +Default is 40. It is impossible to set it higher than maxconn.

+ +

Signals

+ +

SIGTERM: exit.
SIGHUP: send a SIGTERM and a SIGCONT to all children.
SIGQUIT: send a SIGTERM and a SIGCONT to all children, then exit.
SIGABRT: send a SIGKILL to all children, then exit.

+ +

Notes

+ +

Unlike his close cousin +ipcserver, +s6-ipcserverd does not perform operations such as access control. Those are +delegated to the +s6-ipcserver-access program.
s6-ipcserverd can be used to set up +local services.
s6-ipcserverd is meant to be execve'd into by a program that gets +the listening socket. That program is normally +s6-ipcserver-socketbinder, +which creates the socket itself; but it can be a different one if the +socket is to be retrieved by another means, for instance by fd-passing +from a fd-holding daemon (some people call this "socket activation").