rpc: update getblocktemplate with signet rule, include signet_challenge

Author: ajtowns

src/rpc/mining.cpp

@@ -714,6 +714,13 @@ static RPCHelpMan getblocktemplate()
         // TODO: Maybe recheck connections/IBD and (if something wrong) send an expires-immediately template to stop miners?
     }
 
+    const Consensus::Params& consensusParams = Params().GetConsensus();
+
+    // GBT must be called with 'signet' set in the rules for signet chains
+    if (consensusParams.signet_blocks && setClientRules.count("signet") != 1) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "getblocktemplate must be called with the signet rule set (call with {\"rules\": [\"segwit\", \"signet\"]})");
+    }
+
     // GBT must be called with 'segwit' set in the rules
     if (setClientRules.count("segwit") != 1) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "getblocktemplate must be called with the segwit rule set (call with {\"rules\": [\"segwit\"]})");
@@ -745,7 +752,6 @@ static RPCHelpMan getblocktemplate()
     }
     CHECK_NONFATAL(pindexPrev);
     CBlock* pblock = &pblocktemplate->block; // pointer for convenience
-    const Consensus::Params& consensusParams = Params().GetConsensus();
 
     // Update nTime
     UpdateTime(pblock, consensusParams, pindexPrev);
@@ -809,6 +815,12 @@ static RPCHelpMan getblocktemplate()
     UniValue aRules(UniValue::VARR);
     aRules.push_back("csv");
     if (!fPreSegWit) aRules.push_back("!segwit");
+    if (consensusParams.signet_blocks) {
+        // indicate to miner that they must understand signet rules
+        // when attempting to mine with this template
+        aRules.push_back("!signet");
+    }
+
     UniValue vbavailable(UniValue::VOBJ);
     for (int j = 0; j < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; ++j) {
         Consensus::DeploymentPos pos = Consensus::DeploymentPos(j);
@@ -889,6 +901,10 @@ static RPCHelpMan getblocktemplate()
     result.pushKV("bits", strprintf("%08x", pblock->nBits));
     result.pushKV("height", (int64_t)(pindexPrev->nHeight+1));
 
+    if (consensusParams.signet_blocks) {
+        result.pushKV("signet_challenge", HexStr(consensusParams.signet_challenge));
+    }
+
     if (!pblocktemplate->vchCoinbaseCommitment.empty()) {
         result.pushKV("default_witness_commitment", HexStr(pblocktemplate->vchCoinbaseCommitment));
     }