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Refer to [Networking API design](https://github.com/WebAssembly/WASI/issues/370) and [feat(socket): berkeley socket API v2](https://github.com/WebAssembly/WASI/pull/459): - Support the socket API of synchronous mode, including `socket/bind/listen/accept/send/recv/close/shutdown`, the asynchronous mode isn't supported yet. - Support adding `--addr-pool=<pool1,pool2,..>` argument for command line to identify the valid ip address range - Add socket-api sample and update the document
67 lines
2.2 KiB
Markdown
67 lines
2.2 KiB
Markdown
# How to use Berkeley/Posix Socket APIs in WebAssembly
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**_Berkeley sockets_** usually means an API for Internet sockets and Unix domain
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sockets. A socket is an abstract representation of the local endpoint of a
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network communication path.
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Currently, WAMR supports a limit set of all well-known functions:
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`accept()`, `bind()`, `connect()`, `listen()`, `recv()`, `send()`, `shutdown()`
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and `socket()`. Users can call those functions in WebAssembly code directly.
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Those WebAssembly socket calls will be dispatched to the imported
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functions and eventually will be implemented by host socket APIs.
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This document introduces a way to support _Berkeley/Posix Socket APIs_ in
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WebAssembly code.
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## Patch the native code
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The first step is to include a header file of the WAMR socket extension in the
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native source code.
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```c
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#ifdef __wasi__
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#include <wasi_socket_ext.h>
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#endif
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```
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`__wasi__` is a Marco defined by WASI. The host compiler will not enable it.
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## CMake files
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It is recommended that the project should use CMake as its build system. Use
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[_wasi-sdk_](https://github.com/WebAssembly/wasi-sdk)
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as a toolchain to compile C/C++ to WebAssembly
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```bash
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$ cmake -DWASI_SDK_PREFIX=${WASI_SDK_DIR}
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-DCMAKE_TOOLCHAIN_FILE=${WASI_TOOLCHAIN_FILE}
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-DCMAKE_SYSROOT=${WASI_SYS_ROOT}
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..
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```
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In the *CMakeLists.txt*, include an extension of socket support and link with it.
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```cmake
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include(${CMAKE_CURRENT_SOURCE_DIR}/../../../core/iwasm/libraries/lib-socket/lib_socket_wasi.cmake)
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add_executable(socket_example tcp_server.c)
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target_link_libraries(socket_example socket_wasi_ext)
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```
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Now, the native code with socket APIs is ready for compilation.
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## Run with iwasm
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If having the _.wasm_, the last step is to run it with _iwasm_.
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The _iwasm_ should be compiled with `WAMR_BUILD_LIBC_WASI=1`. By default, it is
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enabled.
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_iwasm_ accepts address ranges via an option, `--addr-pool`, to implement
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the capability control. All IP address the WebAssebmly application may need to `bind()` or `connect()` should be announced first. Every IP address should be in CIRD notation.
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```bash
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$ iwasm --addr-pool=1.2.3.4/15,2.3.4.6/16 socket_example.wasm
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```
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Refer to [socket api sample](../samples/socket-api) for more details.
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