doc: update README and LICENSE

LICENSE

@@ -631,7 +631,7 @@ to attach them to the start of each source file to most effectively
 state the exclusion of warranty; and each file should have at least
 the "copyright" line and a pointer to where the full notice is found.
 
-    ft_ping - TODO
+    net-tools - ICMPv4 network utilities
     Copyright (C) 2026
 
     This program is free software: you can redistribute it and/or modify

README.md

@@ -1,10 +1,99 @@
-# ft_ping
+# net-tools
 
-TODO
+A collection of ICMPv4 network utilities as an alternative to standard
+system commands (ping, ...).
 
-### Code Style
+## Code Style
 
-TODO
+- 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