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b090a3cb69
Adding a reverse dependency to lwip and define macros, which enable declarations of socketpair() and gai_strerror() in standard heders (sys/socket.h and netdb.h)
23 lines
2.4 KiB
Markdown
23 lines
2.4 KiB
Markdown
# Socket Utilities
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This component provides simplified implementations of common socket-related utilities using `lwIP` and `esp_netif`. It is especially useful for porting Linux-based libraries to ESP32 where performance and memory constraints are secondary considerations.
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## Supported Functions
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| API | Description | Limitations | Declared in |
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|--------------------|-------------------------------------------------------------|-------------------------------------------------------------------|----------------------------------------|
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| `ifaddrs()` | Retrieves interface addresses using `esp_netif` | IPv4 addresses only | `ifaddrs.h` |
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| `socketpair()` *) | Creates a pair of connected sockets using `lwIP` loopback stream sockets | IPv4 sockets only | `socketpair.h`, `sys/socket.h` **) |
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| `pipe()` *) | Wraps `socketpair()` to provide unidirectional pipe-like functionality | Uses bidirectional sockets in place of true pipes | `socketpair.h`, `unistd.h` ***) |
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| `getnameinfo()` | Converts IP addresses to human-readable form using `lwIP`'s `inet_ntop()` | IPv4 only; supports `NI_NUMERICHOST` and `NI_NUMERICSERV` flags only | `getnameinfo.h`, `netdb.h` in ESP-IDF |
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| `gai_strerror()` | Returns error code as a string | Simple numeric string representation only | `gai_strerror.h`, `netdb.h` **) |
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| `gethostname()` | Returns lwip netif hostname | Not a system-wide hostname, but interface specific hostname | `gethostname.h`, `unistd.h` in ESP-IDF |
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**Notes**:
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- **`*)`** `socketpair()` and `pipe()` are built on top of `lwIP` TCP sockets, inheriting the same characteristics. For instance, the maximum transmit buffer size is based on the `TCP_SND_BUF` setting.
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- **`**)`** `socketpair()` and `gai_strerror()` are declared in sock_utils header files, the declaration is propagated to ESP-IDF from v5.5 to the official header files. If you're using older IDF version, you need to manually pre-include related header files from the sock_utils public include directory.
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- **`***)`** `pipe()` is declared in compiler's `sys/unistd.h`.
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