# net-tools

A collection of ICMPv4 network utilities as an alternative to standard
system commands (ping, ...).

## Code Style

- Allman braces: opening and closing braces each on their own line
- Yoda conditions: constant on the left (e.g. 0 == val, NULL != ptr)
- C99 compliant
- Tabs only, width 4
- snake_case for functions and variables, SCREAMING_SNAKE_CASE for macros
- System includes, then a blank line, then local includes
- Variable declarations aligned with tabs within the function body
- Static helper functions are forward-declared at the top of the file and
    defined after the main public function
- Function definitions (not forward declarations or prototypes) have a newline
    between the return type and the function name
- Line continuations are indented 2 tabs past the base scope indentation

## Dependencies

- clang (C99)
- make
- bash (configure script)
- POSIX-compliant OS
- libc

For tests only:
- criterion

## Binaries

### ft_ping

Alternative to inetutils ping. Sends ICMPv4 ECHO_REQUEST packets to network
hosts and reports RTT statistics. Requires root (raw socket).

```
ft_ping - Send ICMP ECHO_REQUEST to network hosts
Usage: ft_ping [options] <destination>

Options:
  -h, --help                Display this help and exit
  -V, --version             Display version information and exit
  -v, --verbose             Verbose output
  -q, --quiet               Quiet mode (only show summary)
  -c, --count      <NUM>    Stop after sending N packets
  -i, --interval   <SEC>    Wait N seconds between packets
  -t, --ttl        <TTL>    Set Time To Live
  -s, --size       <SIZE>   Packet size in bytes
  -W, --timeout    <SEC>    Timeout for replies in seconds
  -w, --deadline   <SEC>    Exit after N seconds regardless of packets sent/received
  -f, --flood               Flood mode
  -M, --dont-fragment       Set the Don't Fragment bit
```

## Modules

### libicmp
Handles everything ICMP at the socket level: open a raw socket, build and
send echo requests, receive and parse replies. No loop, no display. Just a
clean interface over the kernel socket.

### src/cli
Shared CLI parsing layer used by all binaries. Provides a generic getopt
wrapper and primitive parsers (int, float) that each binary plugs into.

### src/<binary>/cli
Per-binary argument parsing. Defines the accepted options, validates them,
and fills the binary-specific config struct.

### src/ping/core
Drives the ping session for one destination. ping_run() creates the socket
and calls ping_one() for each destination. ping_one() sets up state, runs
the loop, and prints the summary. ping_loop() uses select() to wait for
packets and reacts to send/stop flags. ping_send_one() builds the payload
and calls libicmp. ping_callback() handles incoming replies and errors.

### src/ping/scheduler
Manages timing and signals. Installs SIGALRM (triggers send) and SIGINT
(triggers stop). Arms a one-shot timer via setitimer() after each send.
Signal handlers only write a flag -- the loop does the actual work.

### src/ping/tracker
A 128-slot circular buffer indexed by (seq % 128). Records when each
packet was sent and marks it when a reply arrives. Used to compute RTT
and detect duplicates.

### src/ping/stats
Accumulates RTT samples (min, max, sum, sum of squares) in nanoseconds.
Computes min/avg/max/mdev in milliseconds on demand.

### src/ping/output
All user-facing output: the opening line, per-packet lines, ICMP error
messages, the final statistics summary, and flood mode dots.

## License

This project is licensed under the GNU General Public License v3.0 - see the [LICENSE](LICENSE) file for details.

## Authors

- **lohhiiccc** - [git](git.lohic.dev)

## See Also

- [RFC 792 - Internet Control Message Protocol](https://tools.ietf.org/html/rfc792)
- [RFX 1071 - Computing the Internet Checksum](https://datatracker.ietf.org/doc/html/rfc1071)
- [libicmp](https://github.com/lohhiiccc/icmp)
- [inetutils](https://www.gnu.org/software/inetutils/)