README.build - platform/external/libwebsockets - Git at Google

 Introduction
 ------------
 Libwebsockets can be built using two different build systems
 autoconf or CMake. autoconf only works on Unix systems, or mingw/cygwin
 on Windows. CMake works differently and can generate platform specific
 project files for most popular IDEs and build systems.

 ################################### Autoconf ###################################

 Building the library and test apps
 ----------------------------------

 You need to regenerate the autotools and libtoolize stuff for your system

 $ ./autogen.sh

 Then,

 ------Fedora x86_64

  ./configure --prefix=/usr --libdir=/usr/lib64 --enable-openssl

 ------Apple

 Christopher Baker reported that this is needed

 ./configure CC="gcc -arch i386 -arch x86_64" CXX="g++ -arch i386 -arch
 x86_64" CPP="gcc -E" CXXCPP="g++ -E" --enable-nofork

 ------mingw

 I did the following to get working build, ping test is disabled when
 building this way

 1) install mingw64_w32 compiler packages from Fedora
 2) additionally install mingw64-zlib package
 3) ./configure --prefix=/usr --enable-mingw --host=x86_64-w64-mingw32
 4) make

 ------MIPS cross-build using OpenWRT

  ./configure --prefix=/usr --without-extensions --host mips-openwrt-linux

 I did not try building the extensions since they need cross-zlib, but it
 should also be workable.

 ------Other uClibc

 you may need --enable-builtin-getifaddrs if your toolchain
 doesn't have it - openWRT uclibc has it so you don't need this option.

 ------ARM cross-build

 ./configure --prefix=/usr --host=arm-linux-gnueabi --without-client --without-extensions

 you can build cross with client and extensions perfectly well, but
 apart from the size shrink this has the nice characteristic that no
 non-toolchain libraries are needed to build it.


 otherwise if /usr/local/... and /usr/local/lib are OK then...

 $ ./configure
 $ make clean
 $ make && sudo make install
 $ libwebsockets-test-server

 should be enough to get a test server listening on port 7861.


 Configure script options
 ------------------------

 There are several other possible configure options

 --enable-openssl	Builds in the SSL support

 --with-cyassl		Use cyassl instead of OpenSSL... you will need CyaSSL
 			to have been configured with --enable-opensslExtra
 \			when it was built.

 --enable-libcrypto	by default libwebsockets uses its own
 			built-in md5 and sha-1 implementation for
 			simplicity.  However the libcrypto ones
 			may be faster, and in a distro context it
 			may be highly desirable to use a common
 			library implementation for ease of security
 			upgrades.  Give this configure option
 			to disable the built-in ones and force use
 			of the libcrypto (part of openssl) ones.

 --with-client-cert-dir=dir   tells the client ssl support where to
 			     look for trust certificates to validate
 			     the remote certificate against.

 --enable-noping		Don't try to build the ping test app
 			It needs some unixy environment that
 			may choke in other build contexts, this
 			lets you cleanly stop it being built

 --enable-builtin-getifaddrs  if your libc lacks getifaddrs, you can build an
 			implementation into the library.  By default your libc
 			one is used.

 --without-testapps	Just build the library not the test apps

 --without-client	Don't build the client part of the library nor the
 			test apps that need the client part.  Useful to
 			minimize library footprint for embedded server-only
 			case

 --without-server	Don't build the server part of the library nor the
 			test apps that need the server part.  Useful to
 			minimize library footprint for embedded client-only
 			case

 --without-daemonize	Don't build daemonize.c / lws_daemonize

 --disable-debug		Remove all debug logging below lwsl_notice in severity
 			from the code -- it's not just defeated from logging
 			but removed from compilation

 --without-extensions	Remove all code and data around protocol extensions.
 			This reduces the code footprint considerably but
 			you will lose extension features like compression.
 			However that may be irrelevant for embedded use and
 			the code / data size / speed improvements may be
 			critical.

 --with-latency		Builds the latency-tracking code into the library...
 			this slows your library down a bit but is very useful
 			to find the cause of unexpected latencies occurring
 			inside the library.  See README.test-apps for more
 			info


 Externally configurable important constants
 -------------------------------------------

 You can control these from configure by just setting them as commandline
 args throgh CFLAGS, eg

 ./configure CFLAGS="-DLWS_MAX_ZLIB_CONN_BUFFER=8192"


 They all have reasonable defaults usable for all use-cases except resource-
 constrained, so you only need to take care about them if you want to tune them
 to the amount of memory available.

  - LWS_MAX_HEADER_LEN default 1024: allocated area to copy http headers that
 libwebsockets knows about into.  You only need to think about increasing this
 if your application might have monster length URLs for example, or some other
 header that lws cares about will be abnormally large (headers it does not
 know about are skipped).

  - LWS_MAX_PROTOCOLS default 5: largest amount of different protocols the
 server can serve

  - LWS_MAX_EXTENSIONS_ACTIVE default 3: largest amount of extensions we can
 choose to have active on one connection

  - SPEC_LATEST_SUPPORTED default 13: only change if you want to remove support
 for later protocol versions... unlikely

  - AWAITING_TIMEOUT default 5: after this many seconds without a response, the
 server will hang up on the client

  - SYSTEM_RANDOM_FILEPATH default "/dev/urandom": if your random device differs
 you can set it here

  - LWS_MAX_ZLIB_CONN_BUFFER  maximum size a compression buffer is allowed to
 grow to before closing the connection.  Some limit is needed or any connecton
 can exhaust all server memory by sending it 4G buffers full of zeros which the
 server is expect to expand atomically.  Default is 64KBytes.

  - LWS_SOMAXCONN  maximum number of pending connect requests the listening
 socket can cope with.  Default is SOMAXCONN.  If you need to use synthetic
 tests that just spam hundreds of connect requests at once without dropping
 any, you can try messing with these as well as ulimit (see later)
 (courtesy Edwin van der Oetelaar)

 echo "2048 64512" > /proc/sys/net/ipv4/ip_local_port_range
 echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle
 echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse
 echo "10" > /proc/sys/net/ipv4/tcp_fin_timeout
 echo "65536" > /proc/sys/net/core/somaxconn
 echo "65536" > /proc/sys/net/ipv4/tcp_max_syn_backlog
 echo "262144" > /proc/sys/net/netfilter/nf_conntrack_max


 Memory efficiency
 -----------------

 Embedded server-only configuration without extensions (ie, no compression
 on websocket connections), but with full v13 websocket features and http
 server, built on ARM Cortex-A9:

 Update at 8dac94d (2013-02-18)

 ./configure --without-client --without-extensions --disable-debug --without-daemonize

 Context Creation, 1024 fd limit[2]:   16720 (includes 12 bytes per fd)
 Per-connection [3]:                      72 bytes, +1328 during headers

 .text	.rodata	.data	.bss
 11512	2784	288	4

 This shows the impact of the major configuration with/without options at
 13ba5bbc633ea962d46d using Ubuntu ARM on a PandaBoard ES.

 These are accounting for static allocations from the library elf, there are
 additional dynamic allocations via malloc.  These are a bit old now but give
 the right idea for relative "expense" of features.

 Static allocations, ARM9
 				.text	.rodata	.data	.bss
  All (no without)		35024	9940	336	4104
  without client			25684	7144	336	4104
  without client, exts		21652	6288	288	4104
  without client, exts, debug[1]	19756	3768	288	4104
  without server			30304	8160	336	4104
  without server, exts		25382	7204	288	4104
  without server, exts, debug[1]	23712	4256	288	4104

 [1] --disable-debug only removes messages below lwsl_notice.  Since that is
 the default logging level the impact is not noticable, error, warn and notice
 logs are all still there.

 [2] 1024 fd per process is the default limit (set by ulimit) in at least Fedora
 and Ubuntu.  You can make significant savings tailoring this to actual expected
 peak fds, ie, at a limit of 20, context creation allocation reduces to 4432 +
 240 = 4672)

 [3] known header content is freed after connection establishment


 #################################### CMake ####################################

 CMake is a multi-platform build tool that can generate build files for many
 different target platforms. See more info at http://www.cmake.org

 CMake also allows/recommends you to do "out of source"-builds, that is,
 the build files are separated from your sources, so there is no need to
 create elaborate clean scripts to get a clean source tree, instead you
 simply remove your build directory.

 Libwebsockets has been tested to build successfully on the following platforms
 with SSL support (both OpenSSL/CyaSSL):

 - Windows
 - Linux (x86 and ARM)
 - OSX
 - NetBSD

 Building the library and test apps
 ----------------------------------

 The project settings used by CMake to generate the platform specific build
 files is called CMakeLists.txt. CMake then uses one of its "Generators" to
 output a Visual Studio project or Make file for instance. To see a list of
 the available generators for your platform, simply run the "cmake" command.

 Note that by default OpenSSL will be linked, if you don't want SSL support
 see below on how to toggle compile options.

 Building on Unix:
 -----------------

 1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html
    (Most Unix distributions comes with a packaged version also)

 2. Install OpenSSL.

 3. Generate the build files (default is Make files):

 	cd /path/to/src
 	mkdir build
 	cd build
 	cmake ..

 	(NOTE: The build/ directory can have any name and be located anywhere
 	 on your filesystem, and that the argument ".." given to cmake is simply
 	 the source directory of libwebsockets containing the CMakeLists.txt project
 	 file. All examples in this file assumes you use "..")

 	NOTE2
 	A common option you may want to give is to set the install path, same
 	as --prefix= with autotools.  It defaults to /usr/local.
 	You can do this by, eg

 	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr

 	NOTE3
 	On machines that want libraries in lib64, you can also add the
 	following to the cmake line

 		-DLIB_SUFFIX=64

 4. Finally you can build using the generated Makefile:

 	make

 Building on Windows (Visual Studio)
 -----------------------------------
 1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html

 2. Install OpenSSL binaries. http://www.openssl.org/related/binaries.html
    (Preferably in the default location to make it easier for CMake to find them)

 3. Generate the Visual studio project by opening the Visual Studio cmd prompt:

    cd <path to src>
    md build
    cd build
    cmake -G "Visual Studio 10" ..

    (NOTE: There is also a cmake-gui available on Windows if you prefer that)

 4. Now you should have a generated Visual Studio Solution in  your
    <path to src>/build directory, which can be used to build.

 Setting compile options
 -----------------------

 To set compile time flags you can either use one of the CMake gui applications
 or do it via command line.

 Command line
 ------------
 To list avaialable options (ommit the H if you don't want the help text):

 	cmake -LH ..

 Then to set an option and build (for example turn off SSL support):

 	cmake -DWITH_SSL=0 ..
 or
 	cmake -DWITH_SSL:BOOL=OFF ..

 Unix GUI
 --------
 If you have a curses enabled build you simply type:
 (not all packages include this, my debian install does not for example).

 	ccmake

 Windows GUI
 -----------
 On windows CMake comes with a gui application:
 	Start -> Programs -> CMake -> CMake (cmake-gui)

 CyaSSL replacement for OpenSSL
 ------------------------------
 CyaSSL is a lightweight SSL library targeted at embedded system:
 http://www.yassl.com/yaSSL/Products-cyassl.html

 It contains a OpenSSL compatability layer which makes it possible to pretty
 much link to it instead of OpenSSL, giving a much smaller footprint.

 NOTE: At the time of writing this the current release of CyaSSL contains a
 crash bug due to some APIs libwebsocket uses. To be able to use this you will
 need to use the current HEAD in their official repository:
 	https://github.com/cyassl/cyassl

 NOTE: cyassl needs to be compiled using the --enable-opensslExtra flag for
 this to work.

 Compiling libwebsockets with CyaSSL
 -----------------------------------

 cmake -DUSE_CYASSL=1
 	  -DCYASSL_INCLUDE_DIRS=/path/to/cyassl
 	  -DCYASSL_LIB=/path/to/cyassl/cyassl.a ..

 NOTE: On windows use the .lib file extension for CYASSL_LIB instead.

 Cross compiling
 ---------------
 To enable cross compiling libwebsockets using CMake you need to create
 a "Toolchain file" that you supply to CMake when generating your build files.
 CMake will then use the cross compilers and build paths specified in this file
 to look for dependencies and such.

 Below is an example of how one of these files might look like:

 	#
 	# CMake Toolchain file for crosscompiling on ARM.
 	#
 	# This can be used when running cmake in the following way:
 	#  cd build/
 	#  cmake .. -DCMAKE_TOOLCHAIN_FILE=/path/to/this/file/TC_arm-linux-gcc.cmake
 	#

 	set(CROSS_PATH /path/to/cross_environment/uClibc)

 	# Target operating system name.
 	set(CMAKE_SYSTEM_NAME Linux)

 	# Name of C compiler.
 	set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-uclibc-gcc")
 	set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-uclibc-g++")

 	# Where to look for the target environment. (More paths can be added here)
 	set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")

 	# Adjust the default behavior of the FIND_XXX() commands:
 	# search programs in the host environment only.
 	set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

 	# Search headers and libraries in the target environment only.
 	set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 	set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

 Additional information on cross compilation with CMake:
 	http://www.vtk.org/Wiki/CMake_Cross_Compiling
	Introduction
	------------
	Libwebsockets can be built using two different build systems
	autoconf or CMake. autoconf only works on Unix systems, or mingw/cygwin
	on Windows. CMake works differently and can generate platform specific
	project files for most popular IDEs and build systems.

	################################### Autoconf ###################################

	Building the library and test apps
	----------------------------------

	You need to regenerate the autotools and libtoolize stuff for your system

	$ ./autogen.sh

	Then,

	------Fedora x86_64

	./configure --prefix=/usr --libdir=/usr/lib64 --enable-openssl

	------Apple

	Christopher Baker reported that this is needed

	./configure CC="gcc -arch i386 -arch x86_64" CXX="g++ -arch i386 -arch
	x86_64" CPP="gcc -E" CXXCPP="g++ -E" --enable-nofork

	------mingw

	I did the following to get working build, ping test is disabled when
	building this way

	1) install mingw64_w32 compiler packages from Fedora
	2) additionally install mingw64-zlib package
	3) ./configure --prefix=/usr --enable-mingw --host=x86_64-w64-mingw32
	4) make

	------MIPS cross-build using OpenWRT

	./configure --prefix=/usr --without-extensions --host mips-openwrt-linux

	I did not try building the extensions since they need cross-zlib, but it
	should also be workable.

	------Other uClibc

	you may need --enable-builtin-getifaddrs if your toolchain
	doesn't have it - openWRT uclibc has it so you don't need this option.

	------ARM cross-build

	./configure --prefix=/usr --host=arm-linux-gnueabi --without-client --without-extensions

	you can build cross with client and extensions perfectly well, but
	apart from the size shrink this has the nice characteristic that no
	non-toolchain libraries are needed to build it.


	otherwise if /usr/local/... and /usr/local/lib are OK then...

	$ ./configure
	$ make clean
	$ make && sudo make install
	$ libwebsockets-test-server

	should be enough to get a test server listening on port 7861.


	Configure script options
	------------------------

	There are several other possible configure options

	--enable-openssl Builds in the SSL support

	--with-cyassl Use cyassl instead of OpenSSL... you will need CyaSSL
	to have been configured with --enable-opensslExtra
	\ when it was built.

	--enable-libcrypto by default libwebsockets uses its own
	built-in md5 and sha-1 implementation for
	simplicity. However the libcrypto ones
	may be faster, and in a distro context it
	may be highly desirable to use a common
	library implementation for ease of security
	upgrades. Give this configure option
	to disable the built-in ones and force use
	of the libcrypto (part of openssl) ones.

	--with-client-cert-dir=dir tells the client ssl support where to
	look for trust certificates to validate
	the remote certificate against.

	--enable-noping Don't try to build the ping test app
	It needs some unixy environment that
	may choke in other build contexts, this
	lets you cleanly stop it being built

	--enable-builtin-getifaddrs if your libc lacks getifaddrs, you can build an
	implementation into the library. By default your libc
	one is used.

	--without-testapps Just build the library not the test apps

	--without-client Don't build the client part of the library nor the
	test apps that need the client part. Useful to
	minimize library footprint for embedded server-only
	case

	--without-server Don't build the server part of the library nor the
	test apps that need the server part. Useful to
	minimize library footprint for embedded client-only
	case

	--without-daemonize Don't build daemonize.c / lws_daemonize

	--disable-debug Remove all debug logging below lwsl_notice in severity
	from the code -- it's not just defeated from logging
	but removed from compilation

	--without-extensions Remove all code and data around protocol extensions.
	This reduces the code footprint considerably but
	you will lose extension features like compression.
	However that may be irrelevant for embedded use and
	the code / data size / speed improvements may be
	critical.

	--with-latency Builds the latency-tracking code into the library...
	this slows your library down a bit but is very useful
	to find the cause of unexpected latencies occurring
	inside the library. See README.test-apps for more
	info


	Externally configurable important constants
	-------------------------------------------

	You can control these from configure by just setting them as commandline
	args throgh CFLAGS, eg

	./configure CFLAGS="-DLWS_MAX_ZLIB_CONN_BUFFER=8192"


	They all have reasonable defaults usable for all use-cases except resource-
	constrained, so you only need to take care about them if you want to tune them
	to the amount of memory available.

	- LWS_MAX_HEADER_LEN default 1024: allocated area to copy http headers that
	libwebsockets knows about into. You only need to think about increasing this
	if your application might have monster length URLs for example, or some other
	header that lws cares about will be abnormally large (headers it does not
	know about are skipped).

	- LWS_MAX_PROTOCOLS default 5: largest amount of different protocols the
	server can serve

	- LWS_MAX_EXTENSIONS_ACTIVE default 3: largest amount of extensions we can
	choose to have active on one connection

	- SPEC_LATEST_SUPPORTED default 13: only change if you want to remove support
	for later protocol versions... unlikely

	- AWAITING_TIMEOUT default 5: after this many seconds without a response, the
	server will hang up on the client

	- SYSTEM_RANDOM_FILEPATH default "/dev/urandom": if your random device differs
	you can set it here

	- LWS_MAX_ZLIB_CONN_BUFFER maximum size a compression buffer is allowed to
	grow to before closing the connection. Some limit is needed or any connecton
	can exhaust all server memory by sending it 4G buffers full of zeros which the
	server is expect to expand atomically. Default is 64KBytes.

	- LWS_SOMAXCONN maximum number of pending connect requests the listening
	socket can cope with. Default is SOMAXCONN. If you need to use synthetic
	tests that just spam hundreds of connect requests at once without dropping
	any, you can try messing with these as well as ulimit (see later)
	(courtesy Edwin van der Oetelaar)

	echo "2048 64512" > /proc/sys/net/ipv4/ip_local_port_range
	echo "1" > /proc/sys/net/ipv4/tcp_tw_recycle
	echo "1" > /proc/sys/net/ipv4/tcp_tw_reuse
	echo "10" > /proc/sys/net/ipv4/tcp_fin_timeout
	echo "65536" > /proc/sys/net/core/somaxconn
	echo "65536" > /proc/sys/net/ipv4/tcp_max_syn_backlog
	echo "262144" > /proc/sys/net/netfilter/nf_conntrack_max


	Memory efficiency
	-----------------

	Embedded server-only configuration without extensions (ie, no compression
	on websocket connections), but with full v13 websocket features and http
	server, built on ARM Cortex-A9:

	Update at 8dac94d (2013-02-18)

	./configure --without-client --without-extensions --disable-debug --without-daemonize

	Context Creation, 1024 fd limit[2]: 16720 (includes 12 bytes per fd)
	Per-connection [3]: 72 bytes, +1328 during headers

	.text .rodata .data .bss
	11512 2784 288 4

	This shows the impact of the major configuration with/without options at
	13ba5bbc633ea962d46d using Ubuntu ARM on a PandaBoard ES.

	These are accounting for static allocations from the library elf, there are
	additional dynamic allocations via malloc. These are a bit old now but give
	the right idea for relative "expense" of features.

	Static allocations, ARM9
	.text .rodata .data .bss
	All (no without) 35024 9940 336 4104
	without client 25684 7144 336 4104
	without client, exts 21652 6288 288 4104
	without client, exts, debug[1] 19756 3768 288 4104
	without server 30304 8160 336 4104
	without server, exts 25382 7204 288 4104
	without server, exts, debug[1] 23712 4256 288 4104

	[1] --disable-debug only removes messages below lwsl_notice. Since that is
	the default logging level the impact is not noticable, error, warn and notice
	logs are all still there.

	[2] 1024 fd per process is the default limit (set by ulimit) in at least Fedora
	and Ubuntu. You can make significant savings tailoring this to actual expected
	peak fds, ie, at a limit of 20, context creation allocation reduces to 4432 +
	240 = 4672)

	[3] known header content is freed after connection establishment


	#################################### CMake ####################################

	CMake is a multi-platform build tool that can generate build files for many
	different target platforms. See more info at http://www.cmake.org

	CMake also allows/recommends you to do "out of source"-builds, that is,
	the build files are separated from your sources, so there is no need to
	create elaborate clean scripts to get a clean source tree, instead you
	simply remove your build directory.

	Libwebsockets has been tested to build successfully on the following platforms
	with SSL support (both OpenSSL/CyaSSL):

	- Windows
	- Linux (x86 and ARM)
	- OSX
	- NetBSD

	Building the library and test apps
	----------------------------------

	The project settings used by CMake to generate the platform specific build
	files is called CMakeLists.txt. CMake then uses one of its "Generators" to
	output a Visual Studio project or Make file for instance. To see a list of
	the available generators for your platform, simply run the "cmake" command.

	Note that by default OpenSSL will be linked, if you don't want SSL support
	see below on how to toggle compile options.

	Building on Unix:
	-----------------

	1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html
	(Most Unix distributions comes with a packaged version also)

	2. Install OpenSSL.

	3. Generate the build files (default is Make files):

	cd /path/to/src
	mkdir build
	cd build
	cmake ..

	(NOTE: The build/ directory can have any name and be located anywhere
	on your filesystem, and that the argument ".." given to cmake is simply
	the source directory of libwebsockets containing the CMakeLists.txt project
	file. All examples in this file assumes you use "..")

	NOTE2
	A common option you may want to give is to set the install path, same
	as --prefix= with autotools. It defaults to /usr/local.
	You can do this by, eg

	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr

	NOTE3
	On machines that want libraries in lib64, you can also add the
	following to the cmake line

	-DLIB_SUFFIX=64

	4. Finally you can build using the generated Makefile:

	make

	Building on Windows (Visual Studio)
	-----------------------------------
	1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html

	2. Install OpenSSL binaries. http://www.openssl.org/related/binaries.html
	(Preferably in the default location to make it easier for CMake to find them)

	3. Generate the Visual studio project by opening the Visual Studio cmd prompt:

	cd <path to src>
	md build
	cd build
	cmake -G "Visual Studio 10" ..

	(NOTE: There is also a cmake-gui available on Windows if you prefer that)

	4. Now you should have a generated Visual Studio Solution in your
	<path to src>/build directory, which can be used to build.

	Setting compile options
	-----------------------

	To set compile time flags you can either use one of the CMake gui applications
	or do it via command line.

	Command line
	------------
	To list avaialable options (ommit the H if you don't want the help text):

	cmake -LH ..

	Then to set an option and build (for example turn off SSL support):

	cmake -DWITH_SSL=0 ..
	or
	cmake -DWITH_SSL:BOOL=OFF ..

	Unix GUI
	--------
	If you have a curses enabled build you simply type:
	(not all packages include this, my debian install does not for example).

	ccmake

	Windows GUI
	-----------
	On windows CMake comes with a gui application:
	Start -> Programs -> CMake -> CMake (cmake-gui)

	CyaSSL replacement for OpenSSL
	------------------------------
	CyaSSL is a lightweight SSL library targeted at embedded system:
	http://www.yassl.com/yaSSL/Products-cyassl.html

	It contains a OpenSSL compatability layer which makes it possible to pretty
	much link to it instead of OpenSSL, giving a much smaller footprint.

	NOTE: At the time of writing this the current release of CyaSSL contains a
	crash bug due to some APIs libwebsocket uses. To be able to use this you will
	need to use the current HEAD in their official repository:
	https://github.com/cyassl/cyassl

	NOTE: cyassl needs to be compiled using the --enable-opensslExtra flag for
	this to work.

	Compiling libwebsockets with CyaSSL
	-----------------------------------

	cmake -DUSE_CYASSL=1
	-DCYASSL_INCLUDE_DIRS=/path/to/cyassl
	-DCYASSL_LIB=/path/to/cyassl/cyassl.a ..

	NOTE: On windows use the .lib file extension for CYASSL_LIB instead.

	Cross compiling
	---------------
	To enable cross compiling libwebsockets using CMake you need to create
	a "Toolchain file" that you supply to CMake when generating your build files.
	CMake will then use the cross compilers and build paths specified in this file
	to look for dependencies and such.

	Below is an example of how one of these files might look like:

	#
	# CMake Toolchain file for crosscompiling on ARM.
	#
	# This can be used when running cmake in the following way:
	# cd build/
	# cmake .. -DCMAKE_TOOLCHAIN_FILE=/path/to/this/file/TC_arm-linux-gcc.cmake
	#

	set(CROSS_PATH /path/to/cross_environment/uClibc)

	# Target operating system name.
	set(CMAKE_SYSTEM_NAME Linux)

	# Name of C compiler.
	set(CMAKE_C_COMPILER "${CROSS_PATH}/bin/arm-linux-uclibc-gcc")
	set(CMAKE_CXX_COMPILER "${CROSS_PATH}/bin/arm-linux-uclibc-g++")

	# Where to look for the target environment. (More paths can be added here)
	set(CMAKE_FIND_ROOT_PATH "${CROSS_PATH}")

	# Adjust the default behavior of the FIND_XXX() commands:
	# search programs in the host environment only.
	set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

	# Search headers and libraries in the target environment only.
	set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
	set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

	Additional information on cross compilation with CMake:
	http://www.vtk.org/Wiki/CMake_Cross_Compiling