NAME

       socket_wrapper - A library passing all socket communications through unix sockets.

SYNOPSIS

       LD_PRELOAD=libsocket_wrapper.so SOCKET_WRAPPER_DIR=/tmp/tmp.bQRELqDrhM
       SOCKET_WRAPPER_DEFAULT_IFACE=10 ./myapplication

DESCRIPTION

       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.

       •   Redirects all network communication to happen over Unix sockets.

       •   Support for IPv4 and IPv6 socket and addressing emulation.

       •   Ability to capture network traffic in pcap format.

ENVIRONMENT VARIABLES

       SOCKET_WRAPPER_DIR
           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.

       SOCKET_WRAPPER_IPV4_NETWORK
           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".

       SOCKET_WRAPPER_DEFAULT_IFACE
           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.

       SOCKET_WRAPPER_PCAP_FILE
           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’re able to open
           the file for example with Wireshark.

       SOCKET_WRAPPER_MTU
           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.

       The minimum value you can set is 512 and the maximum 32768.

       SOCKET_WRAPPER_MAX_SOCKETS
           This variable can be used to set the maximum number of sockets to be used by an
           application.

       The default value is set to 65535 and the maximum 256000.

       SOCKET_WRAPPER_DEBUGLEVEL
           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.

           •   0 = ERROR

           •   1 = WARNING

           •   2 = DEBUG

           •   3 = TRACE

       SOCKET_WRAPPER_DISABLE_DEEPBIND
           This allows you to disable deep binding in socket_wrapper. This is useful for running
           valgrind tools or sanitizers like (address, undefined, thread).

       SOCKET_WRAPPER_DIR_ALLOW_ORIG
           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.

EXAMPLE

           # Open a console and create a directory for the unix sockets.
           $ mktemp -d
           /tmp/tmp.bQRELqDrhM

           # Then start nc to listen for network traffic using the temporary directory.
           $ LD_PRELOAD=libsocket_wrapper.so \
             SOCKET_WRAPPER_DIR=/tmp/tmp.bQRELqDrhM \
             SOCKET_WRAPPER_DEFAULT_IFACE=10 nc -v -l 127.0.0.10 7

           # (If nc, listens on 0.0.0.0 then listener will be open on 127.0.0.10 because
           #  it is the default interface)

           # Now open another console and start 'nc' as a client to connect to the server:
           $ LD_PRELOAD=libsocket_wrapper.so \
             SOCKET_WRAPPER_DIR=/tmp/tmp.bQRELqDrhM \
             SOCKET_WRAPPER_DEFAULT_IFACE=100 nc -v 127.0.0.10 7

           # (The client will use the address 127.0.0.100 when connecting to the server)
           # Now you can type 'Hello!' which will be sent to the server and should appear
           # in the console output of the server.

AUTHOR

       Samba Team
           Author.

                                            2018-11-28                          SOCKET_WRAPPER(1)