Fix OOB in DCS parser

This resolves an issue with parsing of DCS escapes, where it would try
to write parameters beyond the maximum parameter count limit.

Fixes #50.

2 files changed, 29 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b3e5dc..212b2ff 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 CHANGELOG
 =========
 
+## [Unreleased]
+
+- Out of bounds when parsing a DCS with more than 16 parameters
+
 ## 0.7.0
 
 - Fix params reset between escapes
diff --git a/src/lib.rs b/src/lib.rs
index af1682e..30708ca 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -202,8 +202,12 @@ impl Parser {
             Action::Print => performer.print(byte as char),
             Action::Execute => performer.execute(byte),
             Action::Hook => {
-                self.params[self.num_params] = self.param;
-                self.num_params += 1;
+                if self.num_params == MAX_PARAMS {
+                    self.ignoring = true;
+                } else {
+                    self.params[self.num_params] = self.param;
+                    self.num_params += 1;
+                }
 
                 performer.hook(self.params(), self.intermediates(), self.ignoring, byte as char);
             },
@@ -583,6 +587,25 @@ mod tests {
     }
 
     #[test]
+    fn parse_dcs_max_params() {
+        static INPUT: &[u8] = b"\x1bP1;1;1;1;1;1;1;1;1;1;1;1;1;1;1;1;1;p\x1b";
+        let mut dispatcher = DcsDispatcher::default();
+        let mut parser = Parser::new();
+
+        for byte in INPUT {
+            parser.advance(&mut dispatcher, *byte);
+        }
+
+        // Check that flag is set and thus osc_dispatch assertions ran.
+        assert!(dispatcher.ignore);
+        assert!(dispatcher.dispatched_dcs);
+        assert_eq!(dispatcher.params.len(), MAX_PARAMS);
+        for param in dispatcher.params.iter() {
+            assert_eq!(*param, 1);
+        }
+    }
+
+    #[test]
     fn osc_bell_terminated() {
         static INPUT: &[u8] = b"\x1b]11;ff/00/ff\x07";
         let mut dispatcher = OscDispatcher::default();