rest: Return error when header count is not integral

Author: MarcoFalke

src/rest.cpp

@@ -189,18 +189,19 @@ static bool rest_headers(const std::any& context,
     if (path.size() != 2)
         return RESTERR(req, HTTP_BAD_REQUEST, "No header count specified. Use /rest/headers/<count>/<hash>.<ext>.");
 
-    long count = strtol(path[0].c_str(), nullptr, 10);
-    if (count < 1 || count > 2000)
+    const auto parsed_count{ToIntegral<size_t>(path[0])};
+    if (!parsed_count.has_value() || *parsed_count < 1 || *parsed_count > 2000) {
         return RESTERR(req, HTTP_BAD_REQUEST, "Header count out of range: " + path[0]);
+    }
 
     std::string hashStr = path[1];
     uint256 hash;
     if (!ParseHashStr(hashStr, hash))
         return RESTERR(req, HTTP_BAD_REQUEST, "Invalid hash: " + hashStr);
 
     const CBlockIndex* tip = nullptr;
-    std::vector<const CBlockIndex *> headers;
-    headers.reserve(count);
+    std::vector<const CBlockIndex*> headers;
+    headers.reserve(*parsed_count);
     {
         ChainstateManager* maybe_chainman = GetChainman(context, req);
         if (!maybe_chainman) return false;
@@ -211,8 +212,9 @@ static bool rest_headers(const std::any& context,
         const CBlockIndex* pindex = chainman.m_blockman.LookupBlockIndex(hash);
         while (pindex != nullptr && active_chain.Contains(pindex)) {
             headers.push_back(pindex);
-            if (headers.size() == (unsigned long)count)
+            if (headers.size() == *parsed_count) {
                 break;
+            }
             pindex = active_chain.Next(pindex);
         }
     }

test/functional/interface_rest.py

@@ -279,6 +279,13 @@ def run_test(self):
         json_obj = self.test_rest_request(f"/headers/5/{bb_hash}")
         assert_equal(len(json_obj), 5)  # now we should have 5 header objects
 
+        # Test number parsing
+        for num in ['5a', '-5', '0', '2001', '99999999999999999999999999999999999']:
+            assert_equal(
+                bytes(f'Header count out of range: {num}\r\n', 'ascii'),
+                self.test_rest_request(f"/headers/{num}/{bb_hash}", ret_type=RetType.BYTES, status=400),
+            )
+
         self.log.info("Test tx inclusion in the /mempool and /block URIs")
 
         # Make 3 tx and mine them on node 1

test/lint/lint-locale-dependence.sh

@@ -43,7 +43,6 @@ export LC_ALL=C
 KNOWN_VIOLATIONS=(
     "src/bitcoin-tx.cpp.*stoul"
     "src/dbwrapper.cpp:.*vsnprintf"
-    "src/rest.cpp:.*strtol"
     "src/test/dbwrapper_tests.cpp:.*snprintf"
     "src/test/fuzz/locale.cpp"
     "src/test/fuzz/string.cpp"