From bef76b45f480aa41209efdec09fc6bb0bfde7cbe Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Sat, 30 Sep 2023 05:40:04 +0000 Subject: Great Tcpserver Unification. Prepare for 2.6.0.0. Signed-off-by: Laurent Bercot --- doc/s6-tcpserver4d.html | 113 ------------------------------------------------ 1 file changed, 113 deletions(-) delete mode 100644 doc/s6-tcpserver4d.html (limited to 'doc/s6-tcpserver4d.html') diff --git a/doc/s6-tcpserver4d.html b/doc/s6-tcpserver4d.html deleted file mode 100644 index a11bae1..0000000 --- a/doc/s6-tcpserver4d.html +++ /dev/null @@ -1,113 +0,0 @@ - - - - - - s6-networking: the s6-tcpserver4d program - - - - - - -

- -

The `s6-tcpserver4d` program

- -

-s6-tcpserver4d is the serving part of the -s6-tcpserver4 super-server. -It assumes that its stdin is a bound and listening TCP/IPv4 socket, -and it accepts connections from clients connecting to it, -forking a program to handle each connection. -

- -

Interface

- -

-     s6-tcpserver4d [ -1 ] [ -v verbosity ] [ -c maxconn ] [ -C localmaxconn ] prog...
-

- -

s6-tcpserver4d accepts connections from clients to an already -bound and listening TCP socket which is its standard input.
For every TCP connection to this socket, it -forks. The child sets some environment variables, then -executes prog... with stdin reading from the network -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 TCP
TCPREMOTEIP: set to the originating address
TCPREMOTEPORT: set to the originating port
TCPCONNNUM: set to the number of connections originating from -the same IP address

- -

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. This can be -used with s6's readiness -notification mechanism to make sure subsequent services do not start -before the server is ready.
-v verbosity : be more or less verbose. -By default, verbosity is 1: print warning messages to stderr. -0 means only print fatal error messages ; 2 means print status and -connection information for every client.
-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 IP address. -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 its ancestor -tcpserver, -s6-tcpserver4d performs just the bare minimum: the point is to have a -very small and very fast process to serve connections with the least -possible overhead. Features such as additional environment variables, -access control and DNS resolution are provided -via the s6-tcpserver-access -program.
s6-tcpserver4d is meant to be execve'd into by a program that gets -the listening socket. That program is normally -s6-tcpserver4-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").