Add getspecialtxes rpc (#2668)

* Add getspecialtxes rpc

Returns an array of special transactions found in the specified block

* small help text tweak

* add comments

src/rpc/blockchain.cpp

@@ -9,6 +9,7 @@
 #include "chainparams.h"
 #include "checkpoints.h"
 #include "coins.h"
+#include "core_io.h"
 #include "consensus/validation.h"
 #include "instantx.h"
 #include "validation.h"
@@ -1633,6 +1634,113 @@ UniValue reconsiderblock(const JSONRPCRequest& request)
     return NullUniValue;
 }
 
+UniValue getspecialtxes(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 5)
+        throw std::runtime_error(
+            "getspecialtxes \"blockhash\" ( type count skip verbosity ) \n"
+            "Returns an array of special transactions found in the specified block\n"
+            "\nIf verbosity is 0, returns tx hash for each transaction.\n"
+            "If verbosity is 1, returns hex-encoded data for each transaction.\n"
+            "If verbosity is 2, returns an Object with information for each transaction.\n"
+            "\nArguments:\n"
+            "1. \"blockhash\"          (string, required) The block hash\n"
+            "2. type                 (numeric, optional, default=-1) Filter special txes by type, -1 means all types\n"
+            "3. count                (numeric, optional, default=10) The number of transactions to return\n"
+            "4. skip                 (numeric, optional, default=0) The number of transactions to skip\n"
+            "5. verbosity            (numeric, optional, default=0) 0 for hashes, 1 for hex-encoded data, and 2 for json object\n"
+            "\nResult (for verbosity = 0):\n"
+            "[\n"
+            "  \"txid\" : \"xxxx\",    (string) The transaction id\n"
+            "]\n"
+            "\nResult (for verbosity = 1):\n"
+            "[\n"
+            "  \"data\",               (string) A string that is serialized, hex-encoded data for the transaction\n"
+            "]\n"
+            "\nResult (for verbosity = 2):\n"
+            "[                       (array of Objects) The transactions in the format of the getrawtransaction RPC.\n"
+            "  ...,\n"
+            "]\n"
+            "\nExamples:\n"
+            + HelpExampleCli("getspecialtxes", "\"00000000000fd08c2fb661d2fcb0d49abb3a91e5f27082ce64feed3b4dede2e2\"")
+            + HelpExampleRpc("getspecialtxes", "\"00000000000fd08c2fb661d2fcb0d49abb3a91e5f27082ce64feed3b4dede2e2\"")
+        );
+
+    LOCK(cs_main);
+
+    std::string strHash = request.params[0].get_str();
+    uint256 hash(uint256S(strHash));
+
+    int nTxType = -1;
+    if (request.params.size() > 1) {
+        nTxType = request.params[1].get_int();
+    }
+
+    int nCount = 10;
+    if (request.params.size() > 2) {
+        nCount = request.params[2].get_int();
+        if (nCount < 0)
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Negative count");
+    }
+
+    int nSkip = 0;
+    if (request.params.size() > 3) {
+        nSkip = request.params[3].get_int();
+        if (nSkip < 0)
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Negative skip");
+    }
+
+    int nVerbosity = 0;
+    if (request.params.size() > 4) {
+        nVerbosity = request.params[4].get_int();
+        if (nVerbosity < 0 || nVerbosity > 2) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Verbosity must be in range 0..2");
+        }
+    }
+
+    if (mapBlockIndex.count(hash) == 0)
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
+
+    CBlock block;
+    CBlockIndex* pblockindex = mapBlockIndex[hash];
+
+    if (fHavePruned && !(pblockindex->nStatus & BLOCK_HAVE_DATA) && pblockindex->nTx > 0)
+        throw JSONRPCError(RPC_INTERNAL_ERROR, "Block not available (pruned data)");
+
+    if(!ReadBlockFromDisk(block, pblockindex, Params().GetConsensus()))
+        throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");
+
+    int nTxNum = 0;
+    UniValue result(UniValue::VARR);
+    for(const auto& tx : block.vtx)
+    {
+        if (tx->nVersion != 3 || tx->nType == TRANSACTION_NORMAL // ensure it's in fact a special tx
+            || (nTxType != -1 && tx->nType != nTxType)) { // ensure special tx type matches filter, if given
+                continue;
+        }
+
+        nTxNum++;
+        if (nTxNum <= nSkip) continue;
+        if (nTxNum > nSkip + nCount) break;
+
+        switch (nVerbosity)
+        {
+            case 0 : result.push_back(tx->GetHash().GetHex()); break;
+            case 1 : result.push_back(EncodeHexTx(*tx)); break;
+            case 2 :
+                {
+                    UniValue objTx(UniValue::VOBJ);
+                    TxToJSON(*tx, uint256(), objTx);
+                    result.push_back(objTx);
+                    break;
+                }
+            default : throw JSONRPCError(RPC_INTERNAL_ERROR, "Unsupported verbosity");
+        }
+    }
+
+    return result;
+}
+
 static const CRPCCommand commands[] =
 { //  category              name                      actor (function)         okSafe argNames
   //  --------------------- ------------------------  -----------------------  ------ ----------
@@ -1651,6 +1759,7 @@ static const CRPCCommand commands[] =
     { "blockchain",         "getmempoolentry",        &getmempoolentry,        true,  {"txid"} },
     { "blockchain",         "getmempoolinfo",         &getmempoolinfo,         true,  {} },
     { "blockchain",         "getrawmempool",          &getrawmempool,          true,  {"verbose"} },
+    { "blockchain",         "getspecialtxes",         &getspecialtxes,         true,  {"blockhash", "type", "count", "skip", "verbosity"} },
     { "blockchain",         "gettxout",               &gettxout,               true,  {"txid","n","include_mempool"} },
     { "blockchain",         "gettxoutsetinfo",        &gettxoutsetinfo,        true,  {} },
     { "blockchain",         "pruneblockchain",        &pruneblockchain,        true,  {"height"} },

src/rpc/client.cpp

@@ -154,6 +154,10 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "getaddressdeltas", 0, "addresses" },
     { "getaddressutxos", 0, "addresses" },
     { "getaddressmempool", 0, "addresses" },
+    { "getspecialtxes", 1, "type" },
+    { "getspecialtxes", 2, "count" },
+    { "getspecialtxes", 3, "skip" },
+    { "getspecialtxes", 4, "verbosity" },
     // Echo with conversion (For testing only)
     { "echojson", 0, "arg0" },
     { "echojson", 1, "arg1" },