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diff --git a/doc/s6-ipcserverd.html b/doc/s6-ipcserverd.html new file mode 100644 index 0000000..8bf5ea4 --- /dev/null +++ b/doc/s6-ipcserverd.html @@ -0,0 +1,131 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-ipcserverd program</title> + <meta name="Description" content="s6: the s6-ipcserverd program" /> + <meta name="Keywords" content="s6 s6-ipcserverd ipcserver ucspi unix server super-server" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>s6-ipcserverd</tt> program </h1> + +<p> +<tt>s6-ipcserverd</tt> is the serving part of the +<a href="s6-ipcserver.html">s6-ipcserver</a> 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. +</p> + +<h2> Interface </h2> + +<pre> + s6-ipcserverd [ -1 ] [ -v verbosity ] [ -P | -p ] [ -c <em>maxconn</em> ] [ -C <em>localmaxconn</em> ] <em>prog...</em> +</pre> + +<ul> + <li> s6-ipcserverd accepts connections from clients to an already +bound and listening SOCK_STREAM Unix domain socket which is its +standard input. </li> + <li> For every client connection to this socket, it +forks. The child sets some environment variables, then +executes <em>prog...</em> with stdin reading from the socket and +stdout writing to it. </li> + <li> Depending on the verbosity level, it logs what it does to stderr. </li> + <li> It runs until killed by a signal. Depending on the received +signal, it may kill its children before exiting. </li> +</ul> + +<h2> Environment variables </h2> + +<p> + For each connection, an instance of <em>prog...</em> is spawned with +the following variables set: +</p> + +<ul> + <li> PROTO: always set to IPC </li> + <li> IPCREMOTEEUID: set to the effective UID of the client, +unless credentials lookups have been disabled </li> + <li> IPCREMOTEEGID: set to the effective GID of the client, +unless credentials lookups have been disabled </li> + <li> IPCREMOTEPATH: set to the path associated with the remote socket, +if any. Be aware that it may contain arbitrary characters. </li> + <li> IPCCONNNUM: set to the number of connections originating from +the same user (i.e. same uid) </li> +</ul> + +<p> + If client credentials lookup has been disabled, IPCREMOTEEUID and +IPCREMOTEEUID will be set, but empty. +</p> + + +<h2> Options </h2> + +<ul> + <li> <tt>-1</tt> : 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 <a href="s6-notifywhenup.html">s6-notifywhenup</a> +program can be used before the s6-ipcserver +invocation to notify listeners when the server is ready. </li> + <li> <tt>-v <em>verbosity</em></tt> : be more or less +verbose. <em>verbosity</em> can be 0 (quiet), 1 (normal), or 2 +(verbose). </li> + <li> <tt>-P</tt> : disable client credentials lookups. The +IPCREMOTEEUID and IPCREMOTEEGID environment variables will be unset +in every instance of <em>prog...</em>. This is the portable option, +because not every system supports credential lookup across Unix domain +sockets; but it is not as secure. </li> + <li> <tt>-p</tt> : 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. </li> + <li> <tt>-c <em>maxconn</em></tt> : accept at most +<em>maxconn</em> concurrent connections. Default is 40. It is +impossible to set it higher than 1000. </li> + <li> <tt>-C <em>localmaxconn</em></tt> : accept at most +<em>localmaxconn</em> connections from the same user ID. +Default is 40. It is impossible to set it higher than <em>maxconn</em>. </li> +</ul> + +<h2> Signals </h2> + +<ul> + <li> SIGTERM: exit. </li> + <li> SIGHUP: send a SIGTERM and a SIGCONT to all children. </li> + <li> SIGQUIT: send a SIGTERM and a SIGCONT to all children, then exit. </li> + <li> SIGABRT: send a SIGKILL to all children, then exit. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> Unlike his close cousin +<a href="http://www.superscript.com/ucspi-ipc/ipcserver.html">ipcserver</a>, +s6-ipcserverd does not perform operations such as access control. Those are +delegated to the +<a href="s6-ipcserver-access.html">s6-ipcserver-access</a> program. </li> + <li> s6-ipcserverd can be used to set up +<a href="localservice.html">local services</a>. </li> + <li> s6-ipcserverd is meant to be execve'd into by a program that gets +the listening socket. That program is normally +<a href="s6-ipcserver-socketbinder.html">s6-ipcserver-socketbinder</a>, +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"). </li> +</ul> + +</body> +</html> |