fix tun mode

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Unreleased: mitmproxy_rs next
 
+- Assign a local IP address to our `tun` interface for Linux compatibility.
 
 ## 27 October 2024: mitmproxy_rs 0.10.0
 

src/messages.rs

@@ -1,4 +1,5 @@
 use std::fmt;
+use std::fmt::Formatter;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
 
 use anyhow::{anyhow, Result};
@@ -112,12 +113,22 @@ impl TransportCommand {
 }
 
 /// Generic IPv4/IPv6 packet type that wraps smoltcp's IPv4 and IPv6 packet buffers
-#[derive(Debug, Clone)]
+#[derive(Clone)]
 pub enum SmolPacket {
     V4(Ipv4Packet<Vec<u8>>),
     V6(Ipv6Packet<Vec<u8>>),
 }
 
+impl fmt::Debug for SmolPacket {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.debug_struct("SmolPacket")
+            .field("src_ip", &self.src_ip())
+            .field("dst_ip", &self.dst_ip())
+            .field("transport_protocol", &self.transport_protocol())
+            .finish()
+    }
+}
+
 impl From<Ipv4Packet<Vec<u8>>> for SmolPacket {
     fn from(packet: Ipv4Packet<Vec<u8>>) -> Self {
         SmolPacket::V4(packet)

src/packet_sources/tun.rs

@@ -29,6 +29,8 @@ impl PacketSourceConf for TunConf {
     ) -> Result<(Self::Task, Self::Data)> {
         let mut config = tun2::Configuration::default();
         config.mtu(MAX_PACKET_SIZE as u16);
+        // Setting a local address is required on Linux.
+        config.address("169.254.0.1");
         config.up();
         if let Some(tun_name) = self.tun_name {
             config.tun_name(&tun_name);