networking abstractions & early parsing logic

src/sniffing/headers.rs

@@ -1,9 +1,67 @@
+use tun::Error;
+
 // Here we will recieve bytes and try to get their destanation & apply Rules for them.
 use crate::config::Config;
 
-struct PacketInfo;
+enum Protocol {
+    TCP,
+    UDP
+}
+type Ipv4 = [u8; 4];
+type Ipv6 = [u8; 16];
+type Port = u16;
+enum PacketInfo {
+    // <https://www.geeksforgeeks.org/computer-networks/what-is-ipv4/>
+    V4 {
+        src_ip: Ipv4,
+        src_port: Port,
+        dst_ip: Ipv4,
+        dst_port: Port,
+        protocol: Protocol
+    },
+    // <https://www.geeksforgeeks.org/computer-networks/internet-protocol-version-6-ipv6-header/>
+    V6 {
+        src_ip: Ipv6,
+        src_port: Port,
+        dst_ip: Ipv6,
+        dst_port: Port,
+        protocol: Protocol
+    }
+}
 pub fn sniff_raw_packets(packet: &[u8]) -> Result<PacketInfo, Box<dyn std::error::Error + Send + Sync + 'static>> {
-    todo!()
+    let ver = packet[0] >> 4;
+    match ver {
+        4 => {
+            PacketInfo::V4{
+                src_ip: packet[12..16],
+                src_port: u16::from_be_bytes([packet[20], packet[21]]),
+                dst_ip: packet[16..20],
+                dst_port: u16::from_be_bytes([packet[22], packet[23]]),
+                protocol: match packet[9] {
+                    6 => Protocol::TCP,
+                    4 => Protocol::UDP,
+                    _ => return Err(format!("unsuppiorted protocol: {p}").into())
+                }
+            }
+        },
+        6 => {
+            PacketInfo::V6{
+                src_ip: packet[8..24],
+                src_port: u16::from_be_bytes([packet[40], packet[41]]),
+                dst_ip: packet[24..40],
+                dst_port: u16::from_be_bytes([packet[42], packet[43]]),
+                protocol: match packet[6] {
+                    6 => Protocol::TCP,
+                    4 => Protocol::UDP,
+                    _ => return Err(format!("unsuppiorted protocol: {p}").into())
+                }
+            }
+        },
+        ver => {
+            panic!("unexpected packet ver: {ver}");
+            Error
+        }
+    }
 }
 
 pub fn apply_rules(config: Config, pinfo: PacketInfo) {