fix CTID in tx command returns invalidParams on lowercase hex (#5049)

* fix CTID in tx command returns invalidParams on lowercase hex

* test mixed case and change auto to explicit type

* add header cctype because std::tolower is called

* remove unused local variable

* change test case comment from 'lowercase' to 'mixed case'

---------

Co-authored-by: Zack Brunson <Zshooter@gmail.com>

src/test/rpc/Transaction_test.cpp

@@ -27,6 +27,7 @@
 #include <xrpl/protocol/jss.h>
 #include <xrpl/protocol/serialize.h>
 
+#include <cctype>
 #include <optional>
 #include <tuple>
 
@@ -671,6 +672,47 @@ class Transaction_test : public beast::unit_test::suite
             BEAST_EXPECT(jrr[jss::hash]);
         }
 
+        // test querying with mixed case ctid
+        {
+            Env env{*this, makeNetworkConfig(11111)};
+            std::uint32_t const netID = env.app().config().NETWORK_ID;
+
+            Account const alice = Account("alice");
+            Account const bob = Account("bob");
+
+            std::uint32_t const startLegSeq = env.current()->info().seq;
+            env.fund(XRP(10000), alice, bob);
+            env(pay(alice, bob, XRP(10)));
+            env.close();
+
+            std::string const ctid = *RPC::encodeCTID(startLegSeq, 0, netID);
+            auto isUpper = [](char c) { return std::isupper(c) != 0; };
+
+            // Verify that there are at least two upper case letters in ctid and
+            // test a mixed case
+            if (BEAST_EXPECT(
+                    std::count_if(ctid.begin(), ctid.end(), isUpper) > 1))
+            {
+                // Change the first upper case letter to lower case.
+                std::string mixedCase = ctid;
+                {
+                    auto const iter = std::find_if(
+                        mixedCase.begin(), mixedCase.end(), isUpper);
+                    *iter = std::tolower(*iter);
+                }
+                BEAST_EXPECT(ctid != mixedCase);
+
+                Json::Value jsonTx;
+                jsonTx[jss::binary] = false;
+                jsonTx[jss::ctid] = mixedCase;
+                jsonTx[jss::id] = 1;
+                Json::Value const jrr =
+                    env.rpc("json", "tx", to_string(jsonTx))[jss::result];
+                BEAST_EXPECT(jrr[jss::ctid] == ctid);
+                BEAST_EXPECT(jrr[jss::hash]);
+            }
+        }
+
         // test that if the network is 65535 the ctid is not in the response
         {
             Env env{*this, makeNetworkConfig(65535)};

src/xrpld/rpc/CTID.h

@@ -63,7 +63,7 @@ decodeCTID(const T ctid) noexcept
         if (ctidString.length() != 16)
             return {};
 
-        if (!boost::regex_match(ctidString, boost::regex("^[0-9A-F]+$")))
+        if (!boost::regex_match(ctidString, boost::regex("^[0-9A-Fa-f]+$")))
             return {};
 
         ctidValue = std::stoull(ctidString, nullptr, 16);