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doc: adjust examples with ELF metadata

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boreddevnl
2026-04-21 00:28:29 +02:00
parent d14000b7eb
commit 8d51238a3d
6 changed files with 32 additions and 18 deletions
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10
docs/appdev/examples/04_tcp_client.md
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@@ -12,12 +12,15 @@ This advanced example demonstrates the steps required to use the raw network sys
* Performing DNS lookups manually via `sys_dns_lookup`.
* Managing strict TCP flow logic (`sys_tcp_connect`, send, block for receive).
* Using the terminal `SYS_WRITE` output for debugging.
* Declaring app metadata via source annotations.
---
## 💻 The Code (`src/userland/cli/http_get.c`)
## The Code (`src/userland/cli/http_get.c`)
```c
// BOREDOS_APP_DESC: HTTP GET client — fetches a webpage over TCP.
// BOREDOS_APP_ICONS: /Library/images/icons/colloid/network-wired.png
#include <stdlib.h>
#include <string.h>
#include <syscall.h>
@@ -79,14 +82,15 @@ int main(void) {
}
```
## 🛠️ How it Works
## How it Works
1. **Network Setup**: First, we must ensure the host machine or QEMU environment gave BoredOS a valid IP address via DHCP. The `sys_network_has_ip()` check prevents our app from hanging trying to route data to nowhere.
2. **DNS (`sys_dns_lookup`)**: Since we want to connect to a domain name, not a raw IP, we query the DNS server configured by the OS (which it received via DHCP).
3. **Connection (`sys_tcp_connect`)**: We block the application thread while the OS performs the 3-way TCP handshake over port 80.
4. **Payload (`sys_tcp_send`)**: We format a compliant HTTP/1.1 payload representing a simple GET request for the root directory `/`.
5. **Chunked Receiving (`sys_tcp_recv`)**: The server's response might be larger than our `recv_buf` (512 bytes). Therefore, we loop. `sys_tcp_recv` blocks execution until data arrives. If it returns `0`, the remote server cleanly closed the connection (which happens automatically because we specified `Connection: close` in our request payload!).
6. **`BOREDOS_APP_DESC` / `BOREDOS_APP_ICONS`**: Embedded into the compiled `.elf` as a BoredOS NOTE section. The Desktop and File Explorer read this to display the app's icon. See [`elf_metadata.md`](../elf_metadata.md) for full details.
## 🚀 Running It
## Running It
Make sure QEMU is running with networking enabled. Launch the terminal and type `http_get`. You will see the raw headers and HTML source of the target webpage scroll down the CLI interface!