From 86b9051277849d5f9f2f1cb4afc00d4531dfa274 Mon Sep 17 00:00:00 2001
From: Stefan Friese <stefan.friese@t-systems.com>
Date: Fri, 15 May 2020 19:37:23 +0200
Subject: [PATCH] added arp packet handler

---
 src/parser/packet_handler.rs | 72 ++++++++++++++++++++++++++++++++++--
 1 file changed, 69 insertions(+), 3 deletions(-)

diff --git a/src/parser/packet_handler.rs b/src/parser/packet_handler.rs
index a115da1..4b0e72d 100644
--- a/src/parser/packet_handler.rs
+++ b/src/parser/packet_handler.rs
@@ -5,7 +5,7 @@ extern crate bitfield;
 use byteorder::{ByteOrder, LittleEndian};
 use eui48::{MacAddress, Eui48};
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
-use bitfield::bitfield;
+use bitfield::{bitfield, BitRange};
 
 
 /* ethernet */
@@ -199,7 +199,7 @@ pub struct TcpHeader {
 
 
 bitfield! {
-    struct BitfieldTcpHeader (MSB0 [u8]);
+    struct BitfieldTcpHeader ( MSB0 [u8] );
     u32;
     get_source_port, _:             15, 0;
     get_destination_port, _:        31,16;
@@ -252,10 +252,76 @@ pub fn tcp_handler ( ip_hlen: u32, packet_data: &[u8] ) ->TcpHeader {
 
 }
 
+/* arp */
+#[derive(Debug, Clone)]
+pub struct ArpHeader {
+    pub htype:  u32,
+    pub ptype:  u32,
+    pub hlen:   u32,
+    pub plen:   u32,
+    pub oper:   u32,
+    pub sha:    String,
+    pub spa:    IpAddr,
+    pub tha:    String,
+    pub tpa:    IpAddr,
+}
+   // u8, get_source_address, _: 103, 96, 4;
+   // u32, into Ipv4Addr, get_destination_address, _: 159, 128;
+
+bitfield!{
+    struct BitfieldArpHeader ( MSB0 [u8] );
+    impl Debug;
+    u32;
+    get_htype, _:       0, 1;
+    get_ptype, _:       2, 3;
+    get_hlen, _:        4;
+    get_plen, _:        5;
+    get_oper, _:        6, 7;
+    get_sha, _:         8,13;
+    get_tha, _:         18, 23; 
+    u8, get_spa, _:         17, 14, 4;
+    u32, into Ipv4Addr, get_tpa, _:         28, 24;
+}  
+
+impl<T: AsRef<[u8]> + AsMut<[u8]>> BitfieldArpHeader<T> {
+    fn get_spa_as_ip_addr(&self) -> Ipv4Addr{
+        let mut src = [0; 4];
+        for (i, src) in src.iter_mut().enumerate() {
+            *src = self.get_spa(i);
+        }
+        src.into()
+    }
+}
+
+pub fn arp_handler ( packet_data: &[u8] ) -> ArpHeader {
+    let (_head, tail) = packet_data.split_at(ETHER_HDRLEN);
+    let (raw_hdr, _) = tail.split_at(28);
+    let mut _tail: [u8; 28] = [0; 28];
+    _tail.copy_from_slice(raw_hdr);
+
+    let arp_header = BitfieldArpHeader(_tail); 
+    let _sha: [u8;6] = [0;6]; let _tha: [u8;6] = [0;6];
+    _tail[8..13].copy_from_slice(&_sha);
+    _tail[18..23].copy_from_slice(&_tha);
+
+
+    ArpHeader{
+        htype:      arp_header.get_htype(),
+        ptype:      arp_header.get_ptype(),
+        hlen:       arp_header.get_hlen().into(),
+        plen:       arp_header.get_plen().into(),
+        oper:       arp_header.get_oper(),
+        sha:        MacAddress::new(_sha as Eui48).to_hex_string(),
+        //MacAddress::new(arp_header.get_sha() as Eui48).to_hex_string(),
+        spa:        IpAddr::V4(arp_header.get_spa_as_ip_addr()),
+        tha:        MacAddress::new(_tha as Eui48).to_hex_string(),
+        tpa:        IpAddr::V4(arp_header.get_tpa()),
+    }
+}
+          
 /* payload */
 pub fn payload_handler ( ip_hlen: u32, data_offset: u32, packet_data : &[u8] ) -> Option<Vec<u8>> {
     let (_head, tail)= packet_data.split_at(ETHER_HDRLEN+ip_hlen as usize * 4+data_offset as usize * 4);
     Some(tail.to_vec())    
 }
 
-