Merge #610: All peg-out related detection pushes should be <= OP_PUSH…

…DATA4

cff50f5 All peg-out related detection pushes should be <= OP_PUSHDATA4 (Gregory Sanders)

Pull request description:

  related to #598 , #596, #597

  This does not affect consensus, but affects consumers of these parsing rules such as rust-elements.

  cc @apoelstra @roconnor-blockstream

Tree-SHA512: 4ab6f0be52c3804b2af43c7b3eecbbe8f2868d3f33385dc54f3acb0e441188018a2b3df197801f2c20fa96e224b6acacb642ecf2f030227618e0aea1e2da44ea

src/primitives/pak.cpp

@@ -185,7 +185,7 @@ bool ScriptHasValidPAKProof(const CScript& script, const uint256& genesis_hash)
     std::vector<unsigned char> extracted_pubkey_hash;
 
     // Get full pubkey
-    if (!script.GetOp(pc, opcode, data) || opcode != 33 || data.size() != 33) {
+    if (!script.GetOp(pc, opcode, data) || data.size() != 33 || opcode > OP_PUSHDATA4) {
         return false;
     }
     CPubKey full_pubkey(data.begin(), data.end());

src/script/script.cpp

@@ -213,17 +213,24 @@ bool CScript::IsPegoutScript(uint256& genesis_hash, CScript& pegout_scriptpubkey
         return false;
     }
 
-    if (!GetOp(pc, opcode, data) || data.size() != 32 ) {
+    if (!GetOp(pc, opcode, data) || data.size() != 32 || opcode > OP_PUSHDATA4) {
         return false;
     }
     genesis_hash = uint256(data);
 
     // Read in parent chain destination scriptpubkey
-    if (!GetOp(pc, opcode, data) || data.size() == 0 ) {
+    if (!GetOp(pc, opcode, data) || opcode > OP_PUSHDATA4 ) {
         return false;
     }
     pegout_scriptpubkey = CScript(data.begin(), data.end());
 
+    // All extra opcodes must be pushes
+    while(GetOp(pc, opcode, data)) {
+        if (opcode > OP_PUSHDATA4) {
+            return false;
+        }
+    }
+
     return true;
 }