From 1f235c90771e8f9a378f24f46c27bf0353c6cc23 Mon Sep 17 00:00:00 2001
From: Thibaut Vandervelden <thvdveld@vub.be>
Date: Tue, 17 Dec 2024 12:52:39 +0100
Subject: [PATCH] fix(issue-29): panic when different pan IDs

When the PAN IDs are equal, then PAN ID compression is used, removing
the source PAN ID from the frame. The same behaviour was observed when
the PAN IDs were different, which is incorrect. This commit fixes the
issue by only compressing the source PAN ID when the PAN IDs are equal.
---
 dot15d4-frame/src/repr/builder.rs |  6 ++++--
 dot15d4-frame/src/tests.rs        | 23 +++++++++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/dot15d4-frame/src/repr/builder.rs b/dot15d4-frame/src/repr/builder.rs
index 61c191d..75994b2 100644
--- a/dot15d4-frame/src/repr/builder.rs
+++ b/dot15d4-frame/src/repr/builder.rs
@@ -328,8 +328,10 @@ impl<'p, T> FrameBuilder<'p, T> {
                 addr.src_pan_id,
             ) {
                 (Some(_), Some(_), Some(dst_pan_id), Some(src_pan_id)) => {
-                    self.frame.frame_control.pan_id_compression = dst_pan_id == src_pan_id;
-                    addr.src_pan_id = None;
+                    if dst_pan_id == src_pan_id {
+                        self.frame.frame_control.pan_id_compression = true;
+                        addr.src_pan_id = None;
+                    }
                 }
                 (Some(_), None, Some(_), _) => {
                     self.frame.frame_control.pan_id_compression = false;
diff --git a/dot15d4-frame/src/tests.rs b/dot15d4-frame/src/tests.rs
index 6012534..fccdb43 100644
--- a/dot15d4-frame/src/tests.rs
+++ b/dot15d4-frame/src/tests.rs
@@ -339,3 +339,26 @@ fn emit_enhanced_beacon() {
         ],
     );
 }
+
+/// https://github.com/thvdveld/dot15d4/issues/29
+/// Setting `dst_pan_id` to a different value than `src_pan_id` made the `emit` function panic.
+#[test]
+fn issue29() {
+    let frame = FrameBuilder::new_data(&[0x2b, 0x00, 0x00, 0x00])
+        .set_sequence_number(1)
+        .set_dst_pan_id(0xabce)
+        .set_dst_address(Address::Short([0x02, 0x04]))
+        .set_src_pan_id(0xabcd)
+        .set_src_address(Address::Extended([
+            0x00, 0x12, 0x4b, 0x00, 0x14, 0xb5, 0xd9, 0xc7,
+        ]))
+        .finalize()
+        .unwrap();
+
+    let mut buffer = vec![0; frame.buffer_len()];
+
+    frame.emit(&mut Frame::new_unchecked(&mut buffer[..]));
+
+    println!("{:?}", frame);
+    println!("packet = {:#04X?}", buffer);
+}