crypto fix

tests/ShouldParseEurcChains/main.cpp

@@ -41,10 +41,18 @@ int main() {
           "eurc: €570.43 as 6-decimal base units, full 32-byte word");
     Check(ParseEthCallUint(R"({"result":"0xFF"})") == 255,
           "eurc: uppercase hex accepted");
-    // 2^63 does not fit; the decoder must saturate, never wrap to negative.
-    Check(ParseEthCallUint(R"({"result":"0x8000000000000000"})")
-              == std::numeric_limits<std::int64_t>::max(),
-          "eurc: overflow saturates");
+    // 2^63 does not fit. It must not wrap to negative, and it must not
+    // saturate to INT64_MAX either: a saturated maximum satisfies the covering
+    // comparison in CheckPaid, so a node answering 0xffff…ff would mark any
+    // order paid. int64 base units is already past EURC's entire supply, so an
+    // unrepresentable balance is a broken or lying node — "unknown", which
+    // neither settles nor lapses.
+    Check(!ParseEthCallUint(R"({"result":"0x8000000000000000"})").has_value(),
+          "eurc: an unrepresentable balance is unknown, not a covering maximum");
+    Check(!ParseEthCallUint(
+              R"({"result":"0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"})")
+               .has_value(),
+          "eurc: a lying node's 2^256-1 does not read as paid");
     Check(!ParseEthCallUint(
               R"({"jsonrpc":"2.0","id":1,"error":{"code":-32000,"message":"x"}})")
                .has_value(),
@@ -85,6 +93,47 @@ int main() {
     Check(!Server::ParseEurcChains("garbage").has_value(),
           "eurc: malformed chains file rejected");
 
+    // Two chains with one name would share a connection-map slot, so the
+    // second's requests would go to the first's host and one chain would never
+    // be watched at all.
+    Check(!Server::ParseEurcChains(R"({"chains":[
+        {"name":"base","rpc":"https://a.example",
+         "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"},
+        {"name":"base","rpc":"https://b.example",
+         "contract":"0x1aBaEA1f7C830bD89Acc67eC4af516284b1bC33c"}]})").has_value(),
+          "eurc: duplicate chain names reject the whole file");
+
+    // 18 decimals is legal ERC-20 but not representable here: cents × 10^16
+    // overflows int64 above €9.22, and the overflow answers "unknown", which
+    // neither settles nor lapses an order.
+    Check(!Server::ParseEurcChains(R"({"chains":[
+        {"name":"base","rpc":"https://a.example","decimals":18,
+         "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"}]})").has_value(),
+          "eurc: decimals beyond what the arithmetic carries is refused");
+
+    // block_tag reaches the eth_call params array. A quote in it closed the
+    // JSON string and appended another param; a typo silenced the chain.
+    Check(!Server::ParseEurcChains(R"({"chains":[
+        {"name":"base","rpc":"https://a.example","block_tag":"latest\",\"0xdead",
+         "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"}]})").has_value(),
+          "eurc: a block_tag that injects JSON is refused");
+    Check(!Server::ParseEurcChains(R"({"chains":[
+        {"name":"base","rpc":"https://a.example","block_tag":"finalised",
+         "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"}]})").has_value(),
+          "eurc: a misspelled block_tag is refused, not silently never-settling");
+    Check(!Server::ParseEurcChains(R"({"chains":[
+        {"name":"base","rpc":"https://a.example","block_tag":"",
+         "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"}]})").has_value(),
+          "eurc: an empty block_tag is refused");
+    {
+        // A specific block number stays legitimate.
+        const auto ok = Server::ParseEurcChains(R"({"chains":[
+            {"name":"base","rpc":"https://a.example","block_tag":"0x1b4",
+             "contract":"0x60a3E35Cc302bFA44Cb288Bc5a4F316Fdb1adb42"}]})");
+        Check(ok.has_value() && (*ok)[0].blockTag == "0x1b4",
+              "eurc: a hex block number is still accepted");
+    }
+
     if (failures != 0) {
         std::println(std::cerr, "{} check(s) failed", failures);
         return 1;