From 11106a4722558765a44ae45c7892724a73ce514c Mon Sep 17 00:00:00 2001
From: Jim Posen <jim.posen@gmail.com>
Date: Sun, 30 Jun 2019 15:42:13 +0200
Subject: [PATCH] [net processing] Message handling for getcfilters.

Handle getcfilters request if -peercfilter is configured.
---
 src/net_processing.cpp | 50 ++++++++++++++++++++++++++++++++++++++++++
 src/protocol.cpp       |  4 ++++
 src/protocol.h         | 11 ++++++++++
 3 files changed, 65 insertions(+)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index cc5b4e43623..4536c737d1f 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -129,6 +129,8 @@ static constexpr unsigned int INVENTORY_BROADCAST_MAX = 7 * INVENTORY_BROADCAST_
 static constexpr unsigned int AVG_FEEFILTER_BROADCAST_INTERVAL = 10 * 60;
 /** Maximum feefilter broadcast delay after significant change. */
 static constexpr unsigned int MAX_FEEFILTER_CHANGE_DELAY = 5 * 60;
+/** Maximum number of compact filters that may be requested with one getcfilters. See BIP 157. */
+static constexpr uint32_t MAX_GETCFILTERS_SIZE = 1000;
 /** Maximum number of cf hashes that may be requested with one getcfheaders. See BIP 157. */
 static constexpr uint32_t MAX_GETCFHEADERS_SIZE = 2000;
 
@@ -2051,6 +2053,49 @@ static bool PrepareBlockFilterRequest(CNode& pfrom, const CChainParams& chain_pa
     return true;
 }
 
+/**
+ * Handle a cfilters request.
+ *
+ * May disconnect from the peer in the case of a bad request.
+ *
+ * @param[in]   pfrom           The peer that we received the request from
+ * @param[in]   vRecv           The raw message received
+ * @param[in]   chain_params    Chain parameters
+ * @param[in]   connman         Pointer to the connection manager
+ */
+static void ProcessGetCFilters(CNode& pfrom, CDataStream& vRecv, const CChainParams& chain_params,
+                               CConnman& connman)
+{
+    uint8_t filter_type_ser;
+    uint32_t start_height;
+    uint256 stop_hash;
+
+    vRecv >> filter_type_ser >> start_height >> stop_hash;
+
+    const BlockFilterType filter_type = static_cast<BlockFilterType>(filter_type_ser);
+
+    const CBlockIndex* stop_index;
+    BlockFilterIndex* filter_index;
+    if (!PrepareBlockFilterRequest(pfrom, chain_params, filter_type, start_height, stop_hash,
+                                   MAX_GETCFILTERS_SIZE, stop_index, filter_index)) {
+        return;
+    }
+
+    std::vector<BlockFilter> filters;
+
+    if (!filter_index->LookupFilterRange(start_height, stop_index, filters)) {
+        LogPrint(BCLog::NET, "Failed to find block filter in index: filter_type=%s, start_height=%d, stop_hash=%s\n",
+                     BlockFilterTypeName(filter_type), start_height, stop_hash.ToString());
+        return;
+    }
+
+    for (const auto& filter : filters) {
+        CSerializedNetMsg msg = CNetMsgMaker(pfrom.GetSendVersion())
+            .Make(NetMsgType::CFILTER, filter);
+        connman.PushMessage(&pfrom, std::move(msg));
+    }
+}
+
 /**
  * Handle a cfheaders request.
  *
@@ -3466,6 +3511,11 @@ bool ProcessMessage(CNode* pfrom, const std::string& msg_type, CDataStream& vRec
         return true;
     }
 
+    if (msg_type == NetMsgType::GETCFILTERS) {
+        ProcessGetCFilters(*pfrom, vRecv, chainparams, *connman);
+        return true;
+    }
+
     if (msg_type == NetMsgType::GETCFHEADERS) {
         ProcessGetCFHeaders(*pfrom, vRecv, chainparams, *connman);
         return true;
diff --git a/src/protocol.cpp b/src/protocol.cpp
index 243111c4491..947f33c3dfa 100644
--- a/src/protocol.cpp
+++ b/src/protocol.cpp
@@ -40,6 +40,8 @@ const char *SENDCMPCT="sendcmpct";
 const char *CMPCTBLOCK="cmpctblock";
 const char *GETBLOCKTXN="getblocktxn";
 const char *BLOCKTXN="blocktxn";
+const char *GETCFILTERS="getcfilters";
+const char *CFILTER="cfilter";
 const char *GETCFHEADERS="getcfheaders";
 const char *CFHEADERS="cfheaders";
 const char *GETCFCHECKPT="getcfcheckpt";
@@ -75,6 +77,8 @@ const static std::string allNetMessageTypes[] = {
     NetMsgType::CMPCTBLOCK,
     NetMsgType::GETBLOCKTXN,
     NetMsgType::BLOCKTXN,
+    NetMsgType::GETCFILTERS,
+    NetMsgType::CFILTER,
     NetMsgType::GETCFHEADERS,
     NetMsgType::CFHEADERS,
     NetMsgType::GETCFCHECKPT,
diff --git a/src/protocol.h b/src/protocol.h
index 9527dce9605..f61b724b742 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -225,6 +225,17 @@ extern const char* GETBLOCKTXN;
  * @since protocol version 70014 as described by BIP 152
  */
 extern const char* BLOCKTXN;
+/**
+ * getcfilters requests compact filters for a range of blocks.
+ * Only available with service bit NODE_COMPACT_FILTERS as described by
+ * BIP 157 & 158.
+ */
+extern const char* GETCFILTERS;
+/**
+ * cfilter is a response to a getcfilters request containing a single compact
+ * filter.
+ */
+extern const char* CFILTER;
 /**
  * getcfheaders requests a compact filter header and the filter hashes for a
  * range of blocks, which can then be used to reconstruct the filter headers