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_DEFAULT_IFACE
Additionally, the default interface to be used by an
application is defined with
"SOCKET_WRAPPER_DEFAULT_IFACE=<ID>" where <ID> is
between 2 and 254. This is analogous to use the IPv4 addresses
"127.0.0.<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).
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.