Fix the flag processing of NFTokenModify (#5246)

Adds checks for invalid flags.

include/xrpl/protocol/TxFlags.h

@@ -189,7 +189,7 @@ constexpr std::uint32_t const tfNFTokenCreateOfferMask =
     ~(tfUniversal | tfSellNFToken);
 
 // NFTokenCancelOffer flags:
-constexpr std::uint32_t const tfNFTokenCancelOfferMask     = ~(tfUniversal);
+constexpr std::uint32_t const tfNFTokenCancelOfferMask     = ~tfUniversal;
 
 // NFTokenAcceptOffer flags:
 constexpr std::uint32_t const tfNFTokenAcceptOfferMask     = ~tfUniversal;

src/test/app/NFToken_test.cpp

@@ -7799,6 +7799,11 @@ class NFTokenBaseUtil_test : public beast::unit_test::suite
                 ter(temBAD_FEE));
             env.close();
 
+            // Invalid Flags
+            env(token::modify(issuer, nftId),
+                txflags(0x00000001),
+                ter(temINVALID_FLAG));
+
             // Invalid Owner
             env(token::modify(issuer, nftId),
                 token::owner(issuer),
@@ -7868,6 +7873,19 @@ class NFTokenBaseUtil_test : public beast::unit_test::suite
             env.fund(XRP(10000), issuer, alice, bob);
             env.close();
 
+            // modify with tfFullyCanonicalSig should success
+            uint256 const nftId{token::getNextID(env, issuer, 0u, tfMutable)};
+            env(token::mint(issuer, 0u), txflags(tfMutable), token::uri("uri"));
+            env.close();
+
+            env(token::modify(issuer, nftId), txflags(tfFullyCanonicalSig));
+            env.close();
+        }
+        {
+            Env env{*this, features};
+            env.fund(XRP(10000), issuer, alice, bob);
+            env.close();
+
             // lambda that returns the JSON form of NFTokens held by acct
             auto accountNFTs = [&env](Account const& acct) {
                 Json::Value params;

src/xrpld/app/tx/detail/NFTokenModify.cpp

@@ -37,6 +37,9 @@ NFTokenModify::preflight(PreflightContext const& ctx)
     if (NotTEC const ret = preflight1(ctx); !isTesSuccess(ret))
         return ret;
 
+    if (ctx.tx.getFlags() & tfUniversalMask)
+        return temINVALID_FLAG;
+
     if (auto owner = ctx.tx[~sfOwner]; owner == ctx.tx[sfAccount])
         return temMALFORMED;