Merge #19937: signet mining utility

595a34dbea01954cb0372b0210d2fd64357a1762 contrib/signet: Document miner script in README.md (Anthony Towns)
ff7dbdc08a11e999e7718b6ac7645ecceef81188 contrib/signet: Add script for generating a signet chain (Anthony Towns)
13762bcc9618138dd28b53c2031defdc9d762d26 Add bitcoin-util command line utility (Anthony Towns)
95d5d5e6257825bb385cee318d5681597f7f7646 rpc: allow getblocktemplate for test chains when unconnected or in IBD (Anthony Towns)
81c54dec20891f2627a49b2e3e785fdaf2a1e664 rpc: update getblocktemplate with signet rule, include signet_challenge (Anthony Towns)

Pull request description:

  Adds `contrib/signet/miner` for mining signet blocks.

  Adds `bitcoin-util` cli utility, with the idea being it can provide bitcoin related functionality that does not rely on the ability to access a running node. Only subcommand currently is "grind" which takes a hex-encoded header and grinds its nonce until its nBits is satisfied.

  Updates `getblocktemplate` to include `signet_challenge` field, and makes `getblocktemplate` require the signet rule when invoked on the signet change. Removes connectivity and IBD checks from `getblocktemplate` when applied to a test chain (regtest, testnet, signet).

ACKs for top commit:
  laanwj:
    code review ACK 595a34dbea01954cb0372b0210d2fd64357a1762

Tree-SHA512: 8d43297710fdc1edc58acd9b53e1bd1671e5724f7097b40ab73653715dc8becc70534c4496cbba9290f4dd6538a7a3d5830eb85f83391ea31a3bb5b9d3378cc3

1 files changed, 25 insertions, 5 deletions

diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 52e033d0cc..d99ba90308 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -658,11 +658,15 @@ static RPCHelpMan getblocktemplate()
     if(!node.connman)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
 
-    if (node.connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
-        throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
+    if (!Params().IsTestChain()) {
+        if (node.connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0) {
+            throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
+        }
 
-    if (::ChainstateActive().IsInitialBlockDownload())
-        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
+        if (::ChainstateActive().IsInitialBlockDownload()) {
+            throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
+        }
+    }
 
     static unsigned int nTransactionsUpdatedLast;
     const CTxMemPool& mempool = EnsureMemPool(request.context);
@@ -714,6 +718,13 @@ 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 +756,6 @@ 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 +819,12 @@ 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 +905,10 @@ 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));
     }