From db37c7343017fed1e5ada6d7e820c507a937a3f8 Mon Sep 17 00:00:00 2001
From: Joseph Angelo <joseph.angelo@swift-nav.com>
Date: Fri, 1 May 2020 19:45:48 -0700
Subject: [PATCH] Improve how the parser handles errors, advancing the buffer
 in any error case.

Include a test of this behavior
---
 rust/sbp/src/lib.rs        | 30 ++++++++++++++++++++++++++++++
 rust/sbp/src/parser/mod.rs |  9 +++++++--
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/rust/sbp/src/lib.rs b/rust/sbp/src/lib.rs
index fd6f4db9d3..b57b57c5d1 100644
--- a/rust/sbp/src/lib.rs
+++ b/rust/sbp/src/lib.rs
@@ -189,6 +189,36 @@ mod tests {
         }
     }
 
+    #[test]
+    fn parser_crc_error() {
+        let packet = vec![
+            // Start with a mostly valid message, with a single byte error
+            0x55, 0x0c, // This byte should be 0x0b, changed to intentionally cause a CRC error
+            0x02, 0xd3, 0x88, 0x14, 0x28, 0xf4, 0x7a, 0x13, 0x96,
+            0x62, 0xee, 0xff, 0xbe, 0x40, 0x14, 0x00, 0xf6, 0xa3, 0x09, 0x00, 0x00, 0x00, 0x0e,
+            0x00, 0xdb, 0xbf, 0xde, 0xad, 0xbe, 0xef,
+            // Include another valid message to properly parse
+            0x55u8, 0x0b, 0x02, 0xd3, 0x88, 0x14, 0x28, 0xf4, 0x7a, 0x13, 0x96,
+            0x62, 0xee, 0xff, 0xbe, 0x40, 0x14, 0x00, 0xf6, 0xa3, 0x09, 0x00, 0x00, 0x00, 0x0e,
+            0x00, 0xdb, 0xbf, 0xde, 0xad, 0xbe, 0xef,
+        ];
+        let mut reader = std::io::Cursor::new(packet);
+        let mut parser = crate::parser::Parser::new();
+        // Iterate through the data until we hit something that is
+        // parsable
+        let sbp_result = parser.parse(&mut reader);
+        assert!(sbp_result.is_err());
+        match sbp_result.unwrap_err() {
+            crate::Error::CrcError => {},
+            e => {
+                assert!(false, "Unexpected error: {:?}", e);
+            }
+        };
+
+        let sbp_result = parser.parse(&mut reader);
+        assert!(sbp_result.is_ok());
+    }
+
     #[test]
     fn making_frame() {
         use crate::messages::SBPMessage;
diff --git a/rust/sbp/src/parser/mod.rs b/rust/sbp/src/parser/mod.rs
index bb8b241006..8b1a76fa5c 100644
--- a/rust/sbp/src/parser/mod.rs
+++ b/rust/sbp/src/parser/mod.rs
@@ -131,14 +131,19 @@ impl Parser {
                     self.buffer = self.buffer[bytes_read..].to_vec();
                     break Ok(msg);
                 }
-                (Err(crate::Error::ParseError), bytes_read) => {
+                (Err(e), bytes_read) => {
                     if bytes_read >= self.buffer.len() {
                         self.buffer.clear()
                     } else {
                         self.buffer = self.buffer[bytes_read..].to_vec();
                     }
+
+                    if let crate::Error::ParseError = e {
+                        // Continue parsing
+                    } else {
+                        break Err(e)
+                    }
                 }
-                (Err(e), _bytes_read) => break Err(e),
             }
 
             if self.buffer.is_empty() {