feat(payload): add support for arp

.changes/arp.md

@@ -0,0 +1,5 @@
+---
+"tyr": patch:feat
+---
+
+Add support for ARP payload.

src/error.rs

@@ -7,7 +7,7 @@ pub enum Error {
     #[error("Interface not found")]
     InterfaceNotFound,
     #[error("Buffer too small")]
-    BufferTooSmall,
+    InsufficientBuffer,
     #[error("Invalid interface: {0}")]
     InvalidInterface(String),
 }

src/payload/arp.rs

@@ -0,0 +1,50 @@
+use std::net::Ipv4Addr;
+
+use pnet::packet::{arp, ethernet};
+use pnet::{datalink, util::MacAddr};
+
+pub struct ArpPayload {
+    pub src_ip: Ipv4Addr,
+    pub dst_ip: Ipv4Addr,
+    pub interface: datalink::NetworkInterface,
+}
+
+impl super::Payload for ArpPayload {
+    fn build(&mut self, packet: &mut [u8]) -> crate::Result<()> {
+        {
+            let mut ethernet_header =
+                ethernet::MutableEthernetPacket::new(&mut packet[..super::PKT_ETH_SIZE])
+                    .ok_or(crate::error::Error::InsufficientBuffer)?;
+            ethernet_header.set_destination(MacAddr::broadcast());
+            ethernet_header.set_source(self.interface.mac.ok_or(
+                crate::error::Error::InvalidInterface(format!(
+                    "Failed to get MAC address for interface {}",
+                    self.interface.name,
+                )),
+            )?);
+            ethernet_header.set_ethertype(ethernet::EtherTypes::Arp);
+        }
+
+        {
+            let mut arp_header = arp::MutableArpPacket::new(&mut packet[super::PKT_ETH_SIZE..])
+                .ok_or(crate::error::Error::InsufficientBuffer)?;
+
+            arp_header.set_hardware_type(arp::ArpHardwareTypes::Ethernet);
+            arp_header.set_protocol_type(ethernet::EtherTypes::Ipv4);
+            arp_header.set_hw_addr_len(6);
+            arp_header.set_proto_addr_len(4);
+            arp_header.set_operation(arp::ArpOperations::Request);
+            arp_header.set_sender_hw_addr(self.interface.mac.ok_or(
+                crate::error::Error::InvalidInterface(format!(
+                    "Failed to get MAC address for interface {}",
+                    self.interface.name,
+                )),
+            )?);
+            arp_header.set_sender_proto_addr(self.src_ip);
+            arp_header.set_target_hw_addr(MacAddr::zero());
+            arp_header.set_target_proto_addr(self.dst_ip);
+        }
+
+        Ok(())
+    }
+}

src/payload/mod.rs

@@ -2,6 +2,7 @@ pub trait Payload {
     fn build(&mut self, packet: &mut [u8]) -> crate::Result<()>;
 }
 
+pub mod arp;
 pub mod syn;
 
 mod constant;

src/payload/syn.rs

@@ -63,7 +63,7 @@ impl super::Payload for SynPayload {
         {
             let mut ethernet_header =
                 ethernet::MutableEthernetPacket::new(&mut packet[..super::PKT_ETH_SIZE])
-                    .ok_or(crate::error::Error::BufferTooSmall)?;
+                    .ok_or(crate::error::Error::InsufficientBuffer)?;
             ethernet_header.set_destination(MacAddr::broadcast());
             ethernet_header.set_source(self.interface.mac.ok_or(
                 crate::error::Error::InvalidInterface(format!(
@@ -78,7 +78,7 @@ impl super::Payload for SynPayload {
             let mut ipv4_header = ipv4::MutableIpv4Packet::new(
                 &mut packet[super::PKT_ETH_SIZE..(super::PKT_ETH_SIZE + super::PKT_IPV4_SIZE)],
             )
-            .ok_or(crate::error::Error::BufferTooSmall)?;
+            .ok_or(crate::error::Error::InsufficientBuffer)?;
             ipv4_header.set_header_length(69);
             ipv4_header.set_total_length(52);
             ipv4_header.set_next_level_protocol(ip::IpNextHeaderProtocols::Tcp);
@@ -97,7 +97,8 @@ impl super::Payload for SynPayload {
             let mut tcp_header = tcp::MutableTcpPacket::new(
                 &mut packet[(super::PKT_ETH_SIZE + super::PKT_IPV4_SIZE)..],
             )
-            .ok_or(crate::error::Error::BufferTooSmall)?;
+            .ok_or(crate::error::Error::InsufficientBuffer)?;
+
             tcp_header.set_source(self.src_port);
             tcp_header.set_destination(self.dst_port);