| Net::Server(3) | User Contributed Perl Documentation | Net::Server(3) |
Net::Server - Extensible, general Perl server engine
#!/usr/bin/perl -w -T
package MyPackage;
use base qw(Net::Server);
sub process_request {
my $self = shift;
while (<STDIN>) {
s/[\r\n]+$//;
print "You said '$_'\015\012"; # basic echo
last if /quit/i;
}
}
MyPackage->run(port => 160, ipv => '*');
# one liner to get going quickly
perl -e 'use base qw(Net::Server); main->run(port => 20208)'
NOTE: beginning in Net::Server 2.005, the default value for
ipv is IPv* meaning that if no host is passed, or
a hostname is past, any available IPv4 and IPv6 sockets will be
bound. You can force IPv4 only by adding an ipv => 4
configuration in any of the half dozen ways we let you
specify it.
* Full IPv6 support
* Working SSL sockets and https (both with and without IO::Socket::SSL)
* Single Server Mode
* Inetd Server Mode
* Preforking Simple Mode (PreForkSimple)
* Preforking Managed Mode (PreFork)
* Forking Mode
* Multiplexing Mode using a single process
* Multi port accepts on Single, Preforking, and Forking modes
* Basic HTTP Daemon (supports IPv6, SSL, full apache style logs)
* Basic PSGI Daemon
* Simultaneous accept/recv on tcp/udp/unix, ssl/tcp, and IPv4/IPv6 sockets
* Safe signal handling in Fork/PreFork avoids perl signal trouble
* User customizable hooks
* Chroot ability after bind
* Change of user and group after bind
* Basic allow/deny access control
* Pluggable logging (Sys::Syslog, Log::Log4perl, log_file, STDERR, or your own)
* HUP able server (clean restarts via sig HUP)
* Graceful shutdowns (via sig QUIT)
* Hot deploy in Fork and PreFork modes (via sig TTIN and TTOU)
* Dequeue ability in all Fork and PreFork modes.
* Taint clean
* Written in Perl
* Protection against buffer overflow
* Clean process flow
* Extensibility
"Net::Server" is an extensible, generic Perl server engine.
"Net::Server" attempts to be a generic server as in "Net::Daemon" and "NetServer::Generic". It includes with it the ability to run as an inetd process ("Net::Server::INET"), a single connection server ("Net::Server" or "Net::Server::Single"), a forking server ("Net::Server::Fork"), a preforking server which maintains a constant number of preforked children ("Net::Server::PreForkSimple"), or as a managed preforking server which maintains the number of children based on server load ("Net::Server::PreFork"). In all but the inetd type, the server provides the ability to connect to one or to multiple server ports.
The additional server types are made possible via "personalities" or sub classes of the "Net::Server". By moving the multiple types of servers out of the main "Net::Server" class, the "Net::Server" concept is easily extended to other types (in the near future, we would like to add a "Thread" personality).
"Net::Server" borrows several concepts from the Apache Webserver. "Net::Server" uses "hooks" to allow custom servers such as SMTP, HTTP, POP3, etc. to be layered over the base "Net::Server" class. In addition the "Net::Server::PreFork" class borrows concepts of min_start_servers, max_servers, and min_waiting servers. "Net::Server::PreFork" also uses the concept of an flock serialized accept when accepting on multiple ports (PreFork can choose between flock, IPC::Semaphore, and pipe to control serialization).
"Net::Server" is built around a common class (Net::Server) and is extended using sub classes, or "personalities". Each personality inherits, overrides, or enhances the base methods of the base class.
Included with the Net::Server package are several basic personalities, each of which has their own use.
"Net::Server" was partially written to make it easy to add new personalities. Using separate modules built upon an open architecture allows for easy addition of new features, a separate development process, and reduced code bloat in the core module.
Once started, the Net::Server will take care of binding to port and waiting for connections. Once a connection is received, the Net::Server will accept on the socket and will store the result (the client connection) in $self->{server}->{client}. This property is a Socket blessed into the the IO::Socket classes. UDP servers are slightly different in that they will perform a recv instead of an accept.
To make programming easier, during the post_accept phase, STDIN and STDOUT are opened to the client connection. This allows for programs to be written using <STDIN> and print "out\n" to print to the client connection. UDP will require using a ->send call.
The following is a very simple server. The main functionality occurs in the process_request method call as shown below. Notice the use of timeouts to prevent Denial of Service while reading. (Other examples of using "Net::Server" can, or will, be included with this distribution).
#!/usr/bin/perl -w -T
package MyPackage;
use strict;
use base qw(Net::Server::PreFork); # any personality will do
MyPackage->run;
# over-ride the default echo handler
sub process_request {
my $self = shift;
eval {
local $SIG{'ALRM'} = sub { die "Timed Out!\n" };
my $timeout = 30; # give the user 30 seconds to type some lines
my $previous_alarm = alarm($timeout);
while (<STDIN>) {
s/\r?\n$//;
print "You said '$_'\r\n";
alarm($timeout);
}
alarm($previous_alarm);
};
if ($@ =~ /timed out/i) {
print STDOUT "Timed Out.\r\n";
return;
}
}
1;
Playing this file from the command line will invoke a Net::Server using the PreFork personality. When building a server layer over the Net::Server, it is important to use features such as timeouts to prevent Denial Of Service attacks.
Net::Server comes with a built in echo server by default. You can test it out by simply running the following from the commandline:
net-server
If you wanted to try another flavor you could try
net-server PreFork
If you wanted to try out a basic HTTP server you could use
net-server HTTP
Or if you wanted to test out a CGI you are writing you could use
net-server HTTP --app ../../mycgi.cgi
There are at least five possible ways to pass arguments to Net::Server. They are passing to the new method, passing on command line, passing parameters to run, using a conf file, returning values in the default_values method, or configuring the values in post_configure_hook.
The "options" method is used to determine which arguments the server will search for and can be used to extend the parsed parameters. Any arguments found from the command line, parameters passed to run, and arguments found in the conf_file will be matched against the keys of the options template. Any commandline parameters that do not match will be left in place and can be further processed by the server in the various hooks (by looking at @ARGV). Arguments passed to new will automatically win over any other options (this can be used if you would like to disallow a user passing in other arguments).
Arguments consist of key value pairs. On the commandline these pairs follow the POSIX fashion of "--key value" or "--key=value", and also "key=value". In the conf file the parameter passing can best be shown by the following regular expression: ($key,$val)=~/^(\w+)\s+(\S+?)\s+$/. Passing arguments to the run method is done as follows: "<Net::Server->run(key1 =" 'val1')>>. Passing arguments via a prebuilt object can best be shown in the following code:
#!/usr/bin/perl -w -T
package MyPackage;
use strict;
use base qw(Net::Server);
my $server = MyPackage->new({
key1 => 'val1',
});
$server->run;
All five methods for passing arguments may be used at the same time. Once an argument has been set, it is not over written if another method passes the same argument. "Net::Server" will look for arguments in the following order:
1) Arguments passed to the C<new> method.
2) Arguments passed on command line.
3) Arguments passed to the C<run> method.
4) Arguments passed via a conf file.
5) Arguments set in the C<default_values> method.
Additionally the following hooks are available:
1) Arguments set in the configure_hook (occurs after new
but before any of the other areas are checked).
2) Arguments set and validated in the post_configure_hook
(occurs after all of the other areas are checked).
Each of these levels will override parameters of the same name specified in subsequent levels. For example, specifying --setsid=0 on the command line will override a value of "setsid 1" in the conf file.
Note that the configure_hook method doesn't return values to set, but is there to allow for setting up configured values before the configure method is called.
Key/value pairs used by the server are removed by the configuration process so that server layers on top of "Net::Server" can pass and read their own parameters.
It is possible to add in your own custom parameters to those parsed by Net::Server. The following code shows how this is done:
sub options {
my $self = shift;
my $prop = $self->{'server'};
my $template = shift;
# setup options in the parent classes
$self->SUPER::options($template);
# add a single value option
$prop->{'my_option'} ||= undef;
$template->{'my_option'} = \ $prop->{'my_option'};
# add a multi value option
$prop->{'an_arrayref_item'} ||= [];
$template->{'an_arrayref_item'} = $prop->{'an_arrayref_item'};
}
Overriding the "options" method allows for adding your own custom fields. A template hashref is passed in, that should then be modified to contain an of your custom fields. Fields which are intended to receive a single scalar value should have a reference to the destination scalar given. Fields which are intended to receive multiple values should reference the corresponding destination arrayref.
You are responsible for validating your custom options once they have been parsed. The post_configure_hook is a good place to do your validation.
Some emails have asked why we use this "template" method. The idea is that you are creating the the data structure to store the values in, and you are also creating a way to get the values into the data structure. The template is the way to get the values to the servers data structure. One of the possibilities (that probably isn't used that much) is that by letting you specify the mapping, you could build a nested data structure - even though the passed in arguments are flat. It also allows you to setup aliases to your names.
For example, a basic structure might look like this:
$prop = $self->{'server'}
$prop->{'my_custom_option'} ||= undef;
$prop->{'my_custom_array'} ||= [];
$template = {
my_custom_option => \ $prop->{'my_custom_option'},
mco => \ $prop->{'my_custom_option'}, # alias
my_custom_array => $prop->{'my_custom_array'},
mca => $prop->{'my_custom_array'}, # an alias
};
$template->{'mco2'} = $template->{'mco'}; # another way to alias
But you could also have more complex data:
$prop = $self->{'server'};
$prop->{'one_layer'} = {
two_layer => [
undef,
undef,
],
};
$template = {
param1 => \ $prop->{'one_layer'}->{'two_layer'}->[0],
param2 => \ $prop->{'one_layer'}->{'two_layer'}->[1],
};
This is of course a contrived example - but it does show that you can get the data from the flat passed in arguments to whatever type of structure you need - with only a little bit of effort.
The following arguments are available in the default "Net::Server" or "Net::Server::Single" modules. (Other personalities may use additional parameters and may optionally not use parameters from the base class.)
Key Value Default
conf_file "filename" undef
log_level 0-4 2
log_file (filename|Sys::Syslog
|Log::Log4perl) undef
port \d+ 20203
host "host" "*"
ipv (4|6|*) *
proto (tcp|udp|unix) "tcp"
listen \d+ SOMAXCONN
## syslog parameters (if log_file eq Sys::Syslog)
syslog_logsock (native|unix|inet|udp
|tcp|stream|console) unix (on Sys::Syslog < 0.15)
syslog_ident "identity" "net_server"
syslog_logopt (cons|ndelay|nowait|pid) pid
syslog_facility \w+ daemon
reverse_lookups 1 undef
allow /regex/ none
deny /regex/ none
cidr_allow CIDR none
cidr_deny CIDR none
## daemonization parameters
pid_file "filename" undef
chroot "directory" undef
user (uid|username) "nobody"
group (gid|group) "nobody"
background 1 undef
setsid 1 undef
no_close_by_child (1|undef) undef
## See Net::Server::Proto::(TCP|UDP|UNIX|SSL|SSLeay|etc)
## for more sample parameters.
There are two ways that you can specify a default location for a conf_file. The first is to pass the default value to the run method as in:
MyServer->run({
conf_file => '/etc/my_server.conf',
});
If the end user passes in --conf_file=/etc/their_server.conf then the value will be overridden.
The second way to do this was added in the 0.96 version. It uses the default_values method as in:
sub default_values {
return {
conf_file => '/etc/my_server.conf',
}
}
This method has the advantage of also being able to be overridden in the run method.
If you do not want the user to be able to specify a conf_file at all, you can pass conf_file to the new method when creating your object:
MyServer->new({
conf_file => '/etc/my_server.conf',
})->run;
If passed this way, the value passed to new will "win" over any of the other passed in values.
The log_file may also be the name of a Net::Server pluggable logging class. Net::Server is packaged with Sys::Syslog and Log::Log4perl. If the log_file looks like a module name, it will have "Net::Server::Log::" added to the front and it will then be required. The package should provide an "initialize" class method that returns a single function which will be used for logging. This returned function will be passed log_level, and message.
If the magic name "Sys::Syslog" is used, all logging will take place via the Net::Server::Log::Sys::Syslog module. If syslog is used the parameters "syslog_logsock", "syslog_ident", and "syslog_logopt",and "syslog_facility" may also be defined. See Net::Server::Log::Sys::Syslog.
If the magic name "Log::Log4perl" is used, all logging will be directed to the Log4perl system. If used, the "log4perl_conf", "log4perl_poll", "log4perl_logger" may also be defined. See Net::Server::Log::Log::Log4per.
If a "log_file" is given or if "setsid" is set, STDIN and STDOUT will automatically be opened to /dev/null and STDERR will be opened to STDOUT. This will prevent any output from ending up at the terminal.
Local port/socket on which to bind. If it is a low port, the process must start as root. If multiple ports are given, all will be bound at server startup. May be of the form "host:port/proto", "host:port/proto/ipv", "host:port", "port/proto", or "port", where host represents a hostname residing on the local box, where port represents either the number of the port (eg. "80") or the service designation (eg. "http"), where ipv represents the IP protocol version (IPv4 or IPv6 or IPv*) and where proto represents the protocol to be used. See Net::Server::Proto. The following are some valid port strings:
20203 # port only
localhost:20203 # host and port
localhost:http # localhost bound to port 80
localhost:20203/tcp # host, port, protocol
localhost:20203/tcp/IPv* # host, port, protocol and family
localhost, 20203, tcp, IPv* # same
localhost | 20203 | tcp | IPv* # same
localhost:20203/IPv* # bind any configured interfaces for IPv4 or 6 (default)
localhost:20203/IPv4/IPv6 # bind localhost on IPv4 and 6 (fails if it cannot do both)
*:20203 # bind all local interfaces
Additionally, when passed in the code (non-commandline, and non-config), the port may be passed as a hashref or array hashrefs of information:
port => {
host => 'localhost',
port => '20203',
ipv => 6, # IPv6 only
proto => 'udp', # UDP protocol
}
port => [{
host => '*',
port => '20203',
ipv => 4, # IPv4 only
proto => 'tcp', # (default)
}, {
host => 'localhost',
port => '20204',
ipv => '*', # default - all IPv4 and IPv6 interfaces tied to localhost
proto => 'ssleay', # or ssl - Using SSL
}],
An explicit host given in a port specification overrides a default binding address (a "host" setting, see below). The host part may be enclosed in square brackets, but when it is a numerical IPv6 address it should be enclosed in square brackets to avoid ambiguity in parsing a port number, e.g.: "[::1]:80". However you could also use pipes, white space, or commas to separate these. Note that host and port number must come first.
If the protocol is not specified, proto will default to the "proto" specified in the arguments. If "proto" is not specified there it will default to "tcp". If host is not specified, host will default to "host" specified in the arguments. If "host" is not specified there it will default to "*". Default port is 20203. Configuration passed to new or run may be either a scalar containing a single port number or an arrayref of ports. If "ipv" is not specified it will default to "*" (Any resolved addresses under IPv4 or IPv6).
If you are working with unix sockets, you may also specify "socket_file|unix" or "socket_file|type|unix" where type is SOCK_DGRAM or SOCK_STREAM.
On systems that support it, a port value of 0 may be used to ask the OS to auto-assign a port. The value of the auto-assigned port will be stored in the NS_port property of the Net::Server::Proto::TCP object and is also available in the sockport method. When the server is processing a request, the $self->{server}->{sockport} property contains the port that was connected through.
If an IPv4 address is passed, an IPv4 socket will be created. If an IPv6 address is passed, an IPv6 socket will be created. If a hostname is given, Net::Server will look at the value of ipv (default IPv4) to determine which type of socket to create. Optionally the ipv specification can be passed as part of the hostname.
host => "127.0.0.1", # an IPv4 address
host => "::1", # an IPv6 address
host => 'localhost', # addresses matched by localhost (default any IPv4 and/or IPv6)
host => 'localhost/IPv*', # same
ipv => 6,
host => 'localhost', # addresses matched by localhost (IPv6)
ipv => 4,
host => 'localhost', # addresses matched by localhost (IPv4)
ipv => 'IPv4 IPv6',
host => 'localhost', # addresses matched by localhost (requires IPv6 and IPv4)
host => '*', # any local interfaces (any IPv6 or IPv4)
host => '*/IPv*', # same (any IPv6 or IPv4)
ipv => 4,
host => '*', # any local IPv4 interfaces interfaces
Additionally the proto may also contain the ipv specification.
IPv6 is now available under Net::Server. It will be used automatically if an IPv6 address is passed, or if the ipv is set explicitly to IPv6, or if ipv is left as the default value of IPv*. This is a significant change from version 2.004 and earlier where the default value was IPv4. However, the previous behavior led to confusion on IPv6 only hosts, and on hosts that only had IPv6 entries for a local hostname. Trying to pass an IPv4 address when ipv is set to 6 (only 6 - not * or 4) will result in an error.
localhost:20203 # will use IPv6 if there is a corresponding entry for localhost
# it will also use IPv4 if there is a corresponding v4 entry for localhost
localhost:20203:IPv* # same (default)
localhost:20203:IPv6 # will use IPv6
[::1]:20203 # will use IPv6 (IPv6 style address)
localhost:20203:IPv4 # will use IPv4
127.0.0.1:20203 # will use IPv4 (IPv4 style address
localhost:20203:IPv4:IPv6 # will bind to both v4 and v6 - fails otherwise
# or as a hashref as
port => {
host => "localhost",
ipv => 6, # only binds IPv6
}
port => {
host => "localhost",
ipv => 4, # only binds IPv4
}
port => {
host => "::1",
ipv => "IPv6", # same as passing "6"
}
port => {
host => "localhost/IPv*", # any IPv4 or IPv6
}
port => {
host => "localhost IPv4 IPv6", # must create both
}
In many proposed Net::Server solutions, IPv* was enabled by default. For versions 2.000 through 2.004, the previous default of IPv4 was used. We have attempted to make it easy to set IPv4, IPv6, or IPv*. If you do not want or need IPv6, simply set ipv to 4, pass IPv4 along in the port specification, set $ENV{'IPV'}=4; before running the server, or uninstall IO::Socket::INET6.
On my local box the following command results in the following output:
perl -e 'use base qw(Net::Server); main->run(host => "localhost")'
Resolved [localhost]:20203 to [::1]:20203, IPv6
Resolved [localhost]:20203 to [127.0.0.1]:20203, IPv4
Binding to TCP port 20203 on host ::1 with IPv6
Binding to TCP port 20203 on host 127.0.0.1 with IPv4
My local box has IPv6 enabled and there are entries for localhost on both IPv6 ::1 and IPv4 127.0.0.1. I could also choose to explicitly bind ports rather than depending upon ipv => "*" to resolve them for me as in the following:
perl -e 'use base qw(Net::Server); main->run(port => [20203,20203], host => "localhost", ipv => [4,6])'
Binding to TCP port 20203 on host localhost with IPv4
Binding to TCP port 20203 on host localhost with IPv6
There is a special case of using host => "*" as well as ipv => "*". The Net::Server::Proto::_bindv6only method is used to check the system setting for "sysctl -n net.ipv6.bindv6only" (or net.inet6.ip6.v6only). If this setting is false, then an IPv6 socket will listen for the corresponding IPv4 address. For example the address [::] (IPv6 equivalent of INADDR_ANY) will also listen for 0.0.0.0. The address ::FFFF:127.0.0.1 (IPv6) would also listen to 127.0.0.1 (IPv4). In this case, only one socket will be created because it will handle both cases (an error is returned if an attempt is made to listen to both addresses when bindv6only is false).
However, if net.ipv6.bindv6only (or equivalent) is true, then a hostname (such as *) resolving to both a IPv4 entry as well as an IPv6 will result in both an IPv4 socket as well as an IPv6 socket.
On my linux box which defaults to net.ipv6.bindv6only=0, the following is output.
perl -e 'use base qw(Net::Server); main->run(host => "*")'
Resolved [*]:8080 to [::]:8080, IPv6
Not including resolved host [0.0.0.0] IPv4 because it will be handled by [::] IPv6
Binding to TCP port 8080 on host :: with IPv6
If I issue a "sudo /sbin/sysctl -w net.ipv6.bindv6only=1", the following is output.
perl -e 'use base qw(Net::Server); main->run(host => "*")'
Resolved [*]:8080 to [0.0.0.0]:8080, IPv4
Resolved [*]:8080 to [::]:8080, IPv6
Binding to TCP port 8080 on host 0.0.0.0 with IPv4
Binding to TCP port 8080 on host :: with IPv6
BSD differs from linux and generally defaults to net.inet6.ip6.v6only=0. If it cannot be determined on your OS, it will default to false and the log message will change from "it will be handled" to "it should be handled" (if you have a non-resource intensive way to check on your platform, feel free to email me). Be sure to check the logs as you test your server to make sure you have bound the ports you desire. You can always pass in individual explicit IPv4 and IPv6 port specifications if you need. For example, if your system has both IPv4 and IPv6 interfaces but you'd only like to bind to IPv6 entries, then you should use a hostname of [::] instead of [*].
If bindv6only (or equivalent) is false, and you receive an IPv4 connection on a bound IPv6 port, the textual representation of the peer's IPv4 address will typically be in a form of an IPv4-mapped IPv6 addresses, e.g. "::FFFF:127.0.0.1" .
The ipv parameter was chosen because it does not conflict with any other existing usage, it is very similar to ipv4 or ipv6, it allows for user code to not need to know about Socket::AF_INET or Socket6::AF_INET6 or Socket::AF_UNSPEC, and it is short.
This option has no affect on STDIN and STDOUT which has a magic client property that is tied to the already open STDIN and STDOUT.
Children of a Fork server will exit after their current request. Children of a Prefork type server will finish the current request and then exit.
Note - the newly restarted parent will start up a fresh set of servers on fork servers. The new parent will attempt to keep track of the children from the former parent but custom communication channels (open pipes from the child to the old parent) will no longer be available to the old child processes. New child processes will still connect properly to the new parent.
All of the "ARGUMENTS" listed above become properties of the server object under the same name. These properties, as well as other internal properties, are available during hooks and other method calls.
The structure of a Net::Server object is shown below:
$self = bless({
server => {
key1 => 'val1',
# more key/vals
},
}, 'Net::Server');
This structure was chosen so that all server related properties are grouped under a single key of the object hashref. This is so that other objects could layer on top of the Net::Server object class and still have a fairly clean namespace in the hashref.
You may get and set properties in two ways. The suggested way is to access properties directly via
my $val = $self->{server}->{key1};
Accessing the properties directly will speed the server process - though some would deem this as bad style. A second way has been provided for object oriented types who believe in methods. The second way consists of the following methods:
my $val = $self->get_property( 'key1' );
my $self->set_property( key1 => 'val1' );
Properties are allowed to be changed at any time with caution (please do not undef the sock property or you will close the client connection).
"Net::Server" allows for the use of a configuration file to read in server parameters. The format of this conf file is simple key value pairs. Comments and blank lines are ignored.
#-------------- file test.conf --------------
### user and group to become
user somebody
group everybody
# logging ?
log_file /var/log/server.log
log_level 3
pid_file /tmp/server.pid
# optional syslog directive
# used in place of log_file above
#log_file Sys::Syslog
#syslog_logsock unix
#syslog_ident myserver
#syslog_logopt pid|cons
# access control
allow .+\.(net|com)
allow domain\.com
deny a.+
cidr_allow 127.0.0.0/8
cidr_allow 192.0.2.0/24
cidr_deny 192.0.2.4/30
# background the process?
background 1
# ports to bind (this should bind
# 127.0.0.1:20205 on IPv6 and
# localhost:20204 on IPv4)
# See Net::Server::Proto
host 127.0.0.1
ipv IPv6
port localhost:20204/IPv4
port 20205
# reverse lookups ?
# reverse_lookups on
#-------------- file test.conf --------------
The process flow is written in an open, easy to override, easy to hook, fashion. The basic flow is shown below. This is the flow of the "$self->run" method.
$self->configure_hook;
$self->configure(@_);
$self->post_configure;
$self->post_configure_hook;
$self->pre_bind;
$self->bind;
$self->post_bind_hook;
$self->post_bind;
$self->pre_loop_hook;
$self->loop;
### routines inside a standard $self->loop
# $self->accept;
# $self->run_client_connection;
# $self->done;
$self->pre_server_close_hook;
$self->server_close;
The server then exits.
During the client processing phase ("$self->run_client_connection"), the following represents the program flow:
$self->post_accept;
$self->get_client_info;
$self->post_accept_hook;
if ($self->allow_deny
&& $self->allow_deny_hook) {
$self->process_request;
} else {
$self->request_denied_hook;
}
$self->post_process_request_hook;
$self->post_process_request;
$self->post_client_connection_hook;
The process then loops and waits for the next connection. For a more in depth discussion, please read the code.
During the server shutdown phase ("$self->server_close"), the following represents the program flow:
$self->close_children; # if any
$self->post_child_cleanup_hook;
if (Restarting server) {
$self->restart_close_hook();
$self->hup_server;
}
$self->shutdown_sockets;
$self->server_exit;
The method run may be called in any of the following ways.
MyPackage->run(port => 20201);
MyPackage->new({port => 20201})->run;
my $obj = bless {server=>{port => 20201}}, 'MyPackage';
$obj->run;
The ->run method should typically be the last method called in a server start script (the server will exit at the end of the ->run method).
Under the Fork, PreFork, and PreFork simple personalities, these signals are registered using Net::Server::SIG to allow for safe signal handling.
Net::Server and Net::Server single accept only one connection at a time.
Net::Server::INET runs one connection and then exits (for use by inetd or xinetd daemons).
Net::Server::MultiPlex allows for one process to simultaneously handle multiple connections (but requires rewriting the process_request code to operate in a more "packet-like" manner).
Net::Server::Fork forks off a new child process for each incoming connection.
Net::Server::PreForkSimple starts up a fixed number of processes that all accept on incoming connections.
Net::Server::PreFork starts up a base number of child processes which all accept on incoming connections. The server throttles the number of processes running depending upon the number of requests coming in (similar to concept to how Apache controls its child processes in a PreFork server).
Read the documentation for each of the types for more information.
This method takes care of cleaning up any remaining child processes, setting appropriate flags on sockets (for HUPing), closing up logging, and then closing open sockets.
Can optionally be passed an exit value that will be passed to the server_exit call.
Can optionally be passed an exit value that will be passed to the exit call.
This is the main method to override.
The default method implements a simple echo server that will repeat whatever is sent. It will quit the child if "quit" is sent, and will exit the server if "exit" is sent.
As of version 2.000, the client handle is passed as an argument.
"Net::Server" provides a number of "hooks" allowing for servers layered on top of "Net::Server" to respond at different levels of execution without having to "SUPER" class the main built-in methods. The placement of the hooks can be seen in the PROCESS FLOW section.
Almost all of the default hook methods do nothing. To use a hook you simply need to override the method in your subclass. For example to add your own post_configure_hook you could do something like the following:
package MyServer;
sub post_configure_hook {
my $self = shift;
my $prop = $self->{'server'};
# do some validation here
}
The following describes the hooks available in the plain Net::Server class (other flavors such as Fork or PreFork have additional hooks).
It is generally suggested that other avenues be pursued for sending messages via sockets not created by the Net::Server.
As of version 2.000, the client connection is passed as an argument.
item "$self->other_child_died_hook($pid)"
Net::Server takes control of signal handling and child process cleanup; this makes it difficult to tell when a child process terminates if that child process was not started by Net::Server itself. If Net::Server notices another child process dying that it did not start, it will fire this hook with the PID of the terminated process.
If your child processes will be needing random numbers, this hook is a good location to initialize srand (forked processes maintain the same random seed unless changed).
sub child_init_hook {
# from perldoc -f srand
srand(time ^ $$ ^ unpack "%L*", `ps axww | gzip -f`);
}
Should return a hashref.
sub default_values {
return {
port => 20201,
};
}
If log_level is set to 'Sys::Syslog', the parameters may alternately be a log_level, a format string, and format string parameters. (The second parameter is assumed to be a format string if additional arguments are passed along). Passing arbitrary format strings to Sys::Syslog will allow the server to be vulnerable to exploit. The server maintainer should make sure that any string treated as a format string is controlled.
# assuming log_file = 'Sys::Syslog'
$self->log(1, "My Message with %s in it");
# sends "%s", "My Message with %s in it" to syslog
$self->log(1, "My Message with %s in it", "Foo");
# sends "My Message with %s in it", "Foo" to syslog
If log_file is set to a file (other than Sys::Syslog), the message will be appended to the log file by calling the write_to_log_hook.
If the log_file is Sys::Syslog and an error occurs during write, the handle_syslog_error method will be called and passed the error exception. The default option of handle_syslog_error is to die - but could easily be told to do nothing by using the following code in your subclassed server:
sub handle_syslog_error {}
It the log had been closed, you could attempt to reopen it in the error handler with the following code:
sub handle_syslog_error {
my $self = shift;
$self->open_syslog;
}
package MyPackage;
use base qw(Net::Server);
my $obj = MyPackage->new({port => 20201});
# same as
my $obj = bless {server => {port => 20201}}, 'MyPackage';
Each of the server personalities (except for INET), support restarting via a HUP signal (see "kill -l"). When a HUP is received, the server will close children (if any), make sure that sockets are left open, and re-exec using the same commandline parameters that initially started the server. (Note: for this reason it is important that @ARGV is not modified until "->run" is called).
The Net::Server will attempt to find out the commandline used for starting the program. The attempt is made before any configuration files or other arguments are processed. The outcome of this attempt is stored using the method "->commandline". The stored commandline may also be retrieved using the same method name. The stored contents will undoubtedly contain Tainted items that will cause the server to die during a restart when using the -T flag (Taint mode). As it is impossible to arbitrarily decide what is taint safe and what is not, the individual program must clean up the tainted items before doing a restart.
sub configure_hook{
my $self = shift;
### see the contents
my $ref = $self->commandline;
use Data::Dumper;
print Dumper $ref;
### arbitrary untainting - VERY dangerous
my @untainted = map {/(.+)/;$1} @$ref;
$self->commandline(\@untainted)
}
Each of the Fork and PreFork personalities support graceful shutdowns via the QUIT signal. When a QUIT is received, the parent will signal the children and then wait for them to exit.
All server personalities support the normal TERM and INT signal shutdowns.
Since version 2.000, the Fork and PreFork personalities have accepted the TTIN and TTOU signals. When a TTIN is received, the max_servers is increased by 1. If a TTOU signal is received the max_servers is decreased by 1. This allows for adjusting the number of handling processes without having to restart the server.
If the log_level is set to at 3, then the new value is displayed in the logs.
The following files are installed as part of this distribution.
Net/Server.pm
Net/Server/Fork.pm
Net/Server/INET.pm
Net/Server/MultiType.pm
Net/Server/PreForkSimple.pm
Net/Server/PreFork.pm
Net/Server/Single.pm
Net/Server/Daemonize.pm
Net/Server/SIG.pm
Net/Server/Proto.pm
Net/Server/Proto/*.pm
Download and extract tarball before running these commands in its base directory:
perl Makefile.PL
make
make test
make install
Paul Seamons <paul at seamons.com>
As we move to a github flow, please be sure to add yourself to the credits as patches are passed along (if you'd like to be mentioned).
Thanks to Rob Brown (bbb at cpan.org) for help with miscellaneous concepts such as tracking down the serialized select via flock ala Apache and the reference to IO::Select making multiport servers possible. And for researching into allowing sockets to remain open upon exec (making HUP possible).
Thanks to Jonathan J. Miner <miner at doit.wisc.edu> for patching a blatant problem in the reverse lookups.
Thanks to Bennett Todd <bet at rahul.net> for pointing out a problem in Solaris 2.5.1 which does not allow multiple children to accept on the same port at the same time. Also for showing some sample code from Viktor Duchovni which now represents the semaphore option of the serialize argument in the PreFork server.
Thanks to traveler and merlyn from http://perlmonks.org for pointing me in the right direction for determining the protocol used on a socket connection.
Thanks to Jeremy Howard <j+daemonize at howard.fm> for numerous suggestions and for work on Net::Server::Daemonize.
Thanks to Vadim <vadim at hardison.net> for patches to implement parent/child communication on PreFork.pm.
Thanks to Carl Lewis for suggesting "-" in user names.
Thanks to Slaven Rezic for suggesing Reuse => 1 in Proto::UDP.
Thanks to Tim Watt for adding udp_broadcast to Proto::UDP.
Thanks to Christopher A Bongaarts for pointing out problems with the Proto::SSL implementation that currently locks around the socket accept and the SSL negotiation. See Net::Server::Proto::SSL.
Thanks to Alessandro Zummo for pointing out various bugs including some in configuration, commandline args, and cidr_allow.
Thanks to various other people for bug fixes over the years. These and future thank-you's are available in the Changes file as well as CVS comments.
Thanks to Ben Cohen and tye (on Permonks) for finding and diagnosing more correct behavior for dealing with re-opening STDIN and STDOUT on the client handles.
Thanks to Mark Martinec for trouble shooting other problems with STDIN and STDOUT (he proposed having a flag that is now the no_client_stdout flag).
Thanks to David (DSCHWEI) on cpan for asking for the nofatal option with syslog.
Thanks to Andreas Kippnick and Peter Beckman for suggesting leaving open child connections open during a HUP (this is now available via the leave_children_open_on_hup flag).
Thanks to LUPE on cpan for helping patch HUP with taint on.
Thanks to Michael Virnstein for fixing a bug in the check_for_dead section of PreFork server.
Thanks to Rob Mueller for patching PreForkSimple to only open lock_file once during parent call. This patch should be portable on systems supporting flock. Rob also suggested not closing STDIN/STDOUT but instead reopening them to /dev/null to prevent spurious warnings. Also suggested short circuit in post_accept if in UDP. Also for cleaning up some of the child managment code of PreFork.
Thanks to Mark Martinec for suggesting additional log messages for failure during accept.
Thanks to Bill Nesbitt and Carlos Velasco for pointing out double decrement bug in PreFork.pm (rt #21271)
Thanks to John W. Krahn for pointing out glaring precended with non-parened open and ||.
Thanks to Ricardo Signes for pointing out setuid bug for perl 5.6.1 (rt #21262).
Thanks to Carlos Velasco for updating the Syslog options (rt #21265). And for additional fixes later.
Thanks to Steven Lembark for pointing out that no_client_stdout wasn't working with the Multiplex server.
Thanks to Peter Beckman for suggesting allowing Sys::SysLog keyworks be passed through the ->log method and for suggesting we allow more types of characters through in syslog_ident. Also to Peter Beckman for pointing out that a poorly setup localhost will cause tests to hang.
Thanks to Curtis Wilbar for pointing out that the Fork server called post_accept_hook twice. Changed to only let the child process call this, but added the pre_fork_hook method.
And just a general Thanks You to everybody who is using Net::Server or who has contributed fixes over the years.
Thanks to Paul Miller for some ->autoflush, FileHandle fixes.
Thanks to Patrik Wallstrom for suggesting handling syslog errors better.
Thanks again to Rob Mueller for more logic cleanup for child accounting in PreFork server.
Thanks to David Schweikert for suggesting handling setlogsock a little better on newer versions of Sys::Syslog (>= 0.15).
Thanks to Mihail Nasedkin for suggesting adding a hook that is now called post_client_connection_hook.
Thanks to Graham Barr for adding the ability to set the check_for_spawn and min_child_ttl settings of the PreFork server.
Thanks to Daniel Kahn Gillmor for adding the other_child_died_hook.
Thanks to Dominic Humphries for helping not kill pid files on HUP.
Thanks to Kristoffer Møllerhøj for fixing UDP on Multiplex.
Thanks to mishikal for patches for helping identify un-cleaned up children.
Thanks to rpkelly and tim@retout for pointing out error in header regex of HTTP.
Thanks to dmcbride for some basic HTTP parsing fixes, as well as for some broken tied handle fixes.
Thanks to Gareth for pointing out glaring bug issues with broken pipe and semaphore serialization.
Thanks to CATONE for sending the idea for arbitrary signal passing to children. (See the sig_passthrough option)
Thanks to intrigeri@boum for pointing out and giving code ideas for NS_port not functioning after a HUP.
Thanks to Sergey Zasenko for adding sysread/syswrite support to SSLEAY as well as the base test.
Thanks to mbarbon@users. for adding tally dequeue to prefork server.
Thanks to stefanos@cpan for fixes to PreFork under Win32
Thanks to Mark Martinec for much of the initial work towards getting IPv6 going.
Thanks to the munin developers and Nicolai Langfeldt for hosting the development verion of Net::Server for so long and for fixes to the allow_deny checking for IPv6 addresses.
Thanks to Tatsuhiko Miyagawa for feedback, and for suggesting adding graceful shutdowns and hot deploy (max_servers adjustment).
Thanks to TONVOON@cpan for submitting a patch adding Log4perl functionality.
Thanks to Miko O'Sullivan for fixes to HTTP to correct tainting issues and passing initial log fixes, and for patches to fix CLOSE on tied stdout and various other HTTP issues.
Please see also Net::Server::Fork, Net::Server::INET, Net::Server::PreForkSimple, Net::Server::PreFork, Net::Server::MultiType, Net::Server::Single Net::Server::HTTP
Improve test suite to fully cover code (using Devel::Cover). Anybody that wanted to send me patches to the t/*.t tests that improved coverage would earn a big thank you.
https://github.com/rhandom/perl-net-server
Paul Seamons <paul at seamons.com>
http://seamons.com/
Rob Brown <bbb at cpan.org>
This package may be distributed under the terms of either the
GNU General Public License
or the
Perl Artistic License
All rights reserved.
Hey! The above document had some coding errors, which are explained below:
| 2017-08-10 | perl v5.34.0 |