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fix(sockutls): Explain declaration issues and suggestions
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david-cermak committed Dec 17, 2024
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22 changes: 13 additions & 9 deletions components/sock_utils/README.md
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Expand Up @@ -6,13 +6,17 @@ This component provides simplified implementations of common socket-related util
## Supported Functions


| API | Description | Limitations |
|------------------|-------------------------------------------------------------|-------------------------------------------------------------------|
| `ifaddrs()` | Retrieves interface addresses using `esp_netif` | IPv4 addresses only |
| `socketpair()` | Creates a pair of connected sockets using `lwIP` loopback stream sockets | IPv4 sockets only |
| `pipe()` | Wraps `socketpair()` to provide unidirectional pipe-like functionality | Uses bidirectional sockets in place of true pipes |
| `getnameinfo()` | Converts IP addresses to human-readable form using `lwIP`'s `inet_ntop()` | IPv4 only; supports `NI_NUMERICHOST` and `NI_NUMERICSERV` flags only |
| `gai_strerror()` | Returns error code as a string | Simple numeric string representation only |
| `gethostname()` | Returns lwip netif hostname | Not a system-wide hostname, but interface specific hostname |
| API | Description | Limitations | Declared in |
|--------------------|-------------------------------------------------------------|-------------------------------------------------------------------|----------------------------------------|
| `ifaddrs()` | Retrieves interface addresses using `esp_netif` | IPv4 addresses only | `ifaddrs.h` |
| `socketpair()` *) | Creates a pair of connected sockets using `lwIP` loopback stream sockets | IPv4 sockets only | `socketpair.h`, `sys/socket.h` **) |
| `pipe()` *) | Wraps `socketpair()` to provide unidirectional pipe-like functionality | Uses bidirectional sockets in place of true pipes | `socketpair.h`, `unistd.h` ***) |
| `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 |
| `gai_strerror()` | Returns error code as a string | Simple numeric string representation only | `gai_strerror.h`, `netdb.h` **) |
| `gethostname()` | Returns lwip netif hostname | Not a system-wide hostname, but interface specific hostname | `gethostname.h`, `unistd.h` in ESP-IDF |

**Note**: `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.
**Notes**:

- **`*)`** `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.
- **`**)`** `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.
- **`***)`** `pipe()` is declared in compiler's `sys/unistd.h`.

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