'\" t
.\"     Title: socket_wrapper
.\"    Author: Samba Team
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 2018-11-28
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "SOCKET_WRAPPER" "1" "2018\-11\-28" "\ \&" "\ \&"
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.SH "NAME"
socket_wrapper \- A library passing all socket communications through unix sockets\&.
.SH "SYNOPSIS"
.sp
LD_PRELOAD=libsocket_wrapper\&.so SOCKET_WRAPPER_DIR=/tmp/tmp\&.bQRELqDrhM SOCKET_WRAPPER_DEFAULT_IFACE=10 \fB\&./myapplication\fR
.SH "DESCRIPTION"
.sp
socket_wrapper aims to help client/server software development teams willing to gain full functional test coverage\&. It makes possible to run several instances of the full software stack on the same machine and perform locally functional testing of complex network configurations\&.
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Redirects all network communication to happen over Unix sockets\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Support for IPv4 and IPv6 socket and addressing emulation\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Ability to capture network traffic in pcap format\&.
.RE
.SH "ENVIRONMENT VARIABLES"
.PP
\fBSOCKET_WRAPPER_DIR\fR
.RS 4
The user defines a directory where to put all the unix sockets using the environment variable "SOCKET_WRAPPER_DIR=/path/to/socket_dir"\&. When a server opens a port or a client wants to connect, socket_wrapper will translate IP addresses to a special socket_wrapper name and look for the relevant Unix socket in the SOCKET_WRAPPER_DIR\&.
.RE
.PP
\fBSOCKET_WRAPPER_IPV4_NETWORK\fR
.RS 4
By default the loopback IPv4 network "127\&.0\&.0\&.0/8" and the "127\&.0\&.0\&.x" can be used\&. In order to make more realistic testing possible it is possible to use the "10\&.0\&.0\&.0/8" IPv4 network instead\&. But note within "10\&.0\&.0\&.0/8" only "10\&.53\&.57\&.<ID>" can be used, but the broadcast address is "10\&.255\&.255\&.255"\&. The following two value are allowed: SOCKET_WRAPPER_IPV4_NETWORK="127\&.0\&.0\&.0" (the default) and SOCKET_WRAPPER_IPV4_NETWORK="10\&.53\&.57\&.0"\&.
.RE
.PP
\fBSOCKET_WRAPPER_DEFAULT_IFACE\fR
.RS 4
Additionally, the default interface to be used by an application is defined with "SOCKET_WRAPPER_DEFAULT_IFACE=<ID>" where the valid range for <ID> starts with 1 (the default) and ends with 64\&. This is analogous to use the IPv4 addresses "127\&.0\&.0\&.<ID>"/"10\&.53\&.57\&.<ID>" or IPv6 addresses "fd00::5357:5f<IDx>" (where <IDx> is a hexadecimal presentation of <ID>)\&. You should always set the default interface\&. If you listen on INADDR_ANY then it will use the default interface to listen on\&.
.RE
.PP
\fBSOCKET_WRAPPER_PCAP_FILE\fR
.RS 4
When debugging, it is often interesting to investigate the network traffic between the client and server within your application\&. If you define SOCKET_WRAPPER_PCAP_FILE=/path/to/file\&.pcap, socket_wrapper will dump all your network traffic to the specified file\&. After the test has been finished you\(cqre able to open the file for example with Wireshark\&.
.RE
.PP
\fBSOCKET_WRAPPER_MTU\fR
.RS 4
With this variable you can change the MTU size\&. However we do not recomment to do that as the default size of 1500 byte is best for formatting PCAP files\&.
.RE
.sp
The minimum value you can set is 512 and the maximum 32768\&.
.PP
\fBSOCKET_WRAPPER_MAX_SOCKETS\fR
.RS 4
This variable can be used to set the maximum number of sockets to be used by an application\&.
.RE
.sp
The default value is set to 65535 and the maximum 256000\&.
.PP
\fBSOCKET_WRAPPER_DEBUGLEVEL\fR
.RS 4
If you need to see what is going on in socket_wrapper itself or try to find a bug, you can enable logging support in socket_wrapper if you built it with debug symbols\&.
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
0 = ERROR
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
1 = WARNING
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
2 = DEBUG
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
3 = TRACE
.RE
.RE
.PP
\fBSOCKET_WRAPPER_DISABLE_DEEPBIND\fR
.RS 4
This allows you to disable deep binding in socket_wrapper\&. This is useful for running valgrind tools or sanitizers like (address, undefined, thread)\&.
.RE
.PP
\fBSOCKET_WRAPPER_DIR_ALLOW_ORIG\fR
.RS 4
SOCKET_WRAPPER_DIR is resolved by socket_wrapper using realpath(3)\&. Given that Unix sockets are constructed relative to this directory, the resulting path can sometimes be too long to allow valid socket paths to be constructed due to length restrictions\&. Setting this variable (to any value) allows socket_wrapper to fall back to the original value of SOCKET_WRAPPER_DIR if realpath(3) makes it too long to be usable\&.
.RE
.SH "EXAMPLE"
.sp
.if n \{\
.RS 4
.\}
.nf
# Open a console and create a directory for the unix sockets\&.
$ mktemp \-d
/tmp/tmp\&.bQRELqDrhM
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
# Then start nc to listen for network traffic using the temporary directory\&.
$ LD_PRELOAD=libsocket_wrapper\&.so \e
  SOCKET_WRAPPER_DIR=/tmp/tmp\&.bQRELqDrhM \e
  SOCKET_WRAPPER_DEFAULT_IFACE=10 nc \-v \-l 127\&.0\&.0\&.10 7
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
# (If nc, listens on 0\&.0\&.0\&.0 then listener will be open on 127\&.0\&.0\&.10 because
#  it is the default interface)
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
# Now open another console and start \*(Aqnc\*(Aq as a client to connect to the server:
$ LD_PRELOAD=libsocket_wrapper\&.so \e
  SOCKET_WRAPPER_DIR=/tmp/tmp\&.bQRELqDrhM \e
  SOCKET_WRAPPER_DEFAULT_IFACE=100 nc \-v 127\&.0\&.0\&.10 7
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
# (The client will use the address 127\&.0\&.0\&.100 when connecting to the server)
# Now you can type \*(AqHello!\*(Aq which will be sent to the server and should appear
# in the console output of the server\&.
.fi
.if n \{\
.RE
.\}
.SH "AUTHOR"
.PP
\fBSamba Team\fR
.RS 4
Author.
.RE