Add --network-parse-packet option

protocol/src/protocol/mod.rs

@@ -1308,6 +1308,44 @@ impl Conn {
     }
 }
 
+/// Parse a clientbound packet, for debugging packet parsing issues (Conn::read_packet)
+pub fn try_parse_packet(ibuf: Vec<u8>, protocol_version: i32) {
+    println!("trying to parse packet data {:?}", ibuf);
+
+    let mut buf = io::Cursor::new(ibuf);
+
+    let id = VarInt::read_from(&mut buf).unwrap().0;
+    let dir = Direction::Clientbound;
+    let state = State::Play; // TODO: allow parsing other states
+
+    println!(
+        "about to parse id={:x}, dir={:?} state={:?}",
+        id, dir, state
+    );
+
+    let packet = packet::packet_by_id(protocol_version, state, dir, id, &mut buf).unwrap();
+
+    println!("packet = {:?}", packet);
+
+    match packet {
+        Some(_val) => {
+            let pos = buf.position() as usize;
+            let ibuf = buf.into_inner();
+            if ibuf.len() != pos {
+                println!("pos = {:?}", pos);
+                println!("ibuf = {:?}", ibuf);
+                println!(
+                    "Failed to read all of packet 0x{:X}, \
+                                                       had {} bytes left",
+                    id,
+                    ibuf.len() - pos
+                )
+            }
+        }
+        None => println!("missing packet"),
+    }
+}
+
 #[derive(Debug)]
 pub struct Status {
     pub version: StatusVersion,

src/main.rs

@@ -18,6 +18,7 @@
 #![allow(clippy::float_cmp)] // float comparison used to check if changed
 
 use log::{error, info, warn};
+use std::fs;
 use std::time::{Duration, Instant};
 extern crate steven_shared as shared;
 
@@ -193,6 +194,10 @@ struct Opt {
     #[structopt(short = "n", long = "network-debug")]
     network_debug: bool,
 
+    /// Parse a network packet from a file
+    #[structopt(short = "N", long = "network-parse-packet")]
+    network_parse_packet: Option<String>,
+
     /// Protocol version to use in the autodetection ping
     #[structopt(short = "p", long = "default-protocol-version")]
     default_protocol_version: Option<String>,
@@ -328,6 +333,12 @@ fn main2() {
         protocol::enable_network_debug();
     }
 
+    if let Some(filename) = opt.network_parse_packet {
+        let data = fs::read(filename).unwrap();
+        protocol::try_parse_packet(data, default_protocol_version);
+        return;
+    }
+
     if opt.server.is_some() {
         game.connect_to(&opt.server.unwrap());
     }