From 0b25a9fb42d5df54ea35ddb2bb4837e1e29355fd Mon Sep 17 00:00:00 2001
From: Jonas Schnelli <dev@jonasschnelli.ch>
Date: Tue, 29 Mar 2016 14:30:02 +0200
Subject: [ZMQ] append a message sequence number to every ZMQ notification

---
 src/zmq/zmqpublishnotifier.cpp | 29 +++++++++++++++++++++--------
 src/zmq/zmqpublishnotifier.h   | 12 ++++++++++++
 2 files changed, 33 insertions(+), 8 deletions(-)

(limited to 'src/zmq')

diff --git a/src/zmq/zmqpublishnotifier.cpp b/src/zmq/zmqpublishnotifier.cpp
index a9ce9c48c4..b6c907980f 100644
--- a/src/zmq/zmqpublishnotifier.cpp
+++ b/src/zmq/zmqpublishnotifier.cpp
@@ -123,6 +123,23 @@ void CZMQAbstractPublishNotifier::Shutdown()
     psocket = 0;
 }
 
+bool CZMQAbstractPublishNotifier::SendMessage(const char *command, const void* data, size_t size)
+{
+    assert(psocket);
+
+    /* send three parts, command & data & a LE 4byte sequence number */
+    unsigned char msgseq[sizeof(uint32_t)];
+    WriteLE32(&msgseq[0], nSequence);
+    int rc = zmq_send_multipart(psocket, command, strlen(command), data, size, msgseq, (size_t)sizeof(uint32_t), (void*)0);
+    if (rc == -1)
+        return false;
+
+    /* increment memory only sequence number after sending */
+    nSequence++;
+
+    return true;
+}
+
 bool CZMQPublishHashBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
 {
     uint256 hash = pindex->GetBlockHash();
@@ -130,8 +147,7 @@ bool CZMQPublishHashBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
     char data[32];
     for (unsigned int i = 0; i < 32; i++)
         data[31 - i] = hash.begin()[i];
-    int rc = zmq_send_multipart(psocket, MSG_HASHBLOCK, 9, data, 32, 0);
-    return rc == 0;
+    return SendMessage(MSG_HASHBLOCK, data, 32);
 }
 
 bool CZMQPublishHashTransactionNotifier::NotifyTransaction(const CTransaction &transaction)
@@ -141,8 +157,7 @@ bool CZMQPublishHashTransactionNotifier::NotifyTransaction(const CTransaction &t
     char data[32];
     for (unsigned int i = 0; i < 32; i++)
         data[31 - i] = hash.begin()[i];
-    int rc = zmq_send_multipart(psocket, MSG_HASHTX, 6, data, 32, 0);
-    return rc == 0;
+    return SendMessage(MSG_HASHTX, data, 32);
 }
 
 bool CZMQPublishRawBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
@@ -163,8 +178,7 @@ bool CZMQPublishRawBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
         ss << block;
     }
 
-    int rc = zmq_send_multipart(psocket, MSG_RAWBLOCK, 8, &(*ss.begin()), ss.size(), 0);
-    return rc == 0;
+    return SendMessage(MSG_RAWBLOCK, &(*ss.begin()), ss.size());
 }
 
 bool CZMQPublishRawTransactionNotifier::NotifyTransaction(const CTransaction &transaction)
@@ -173,6 +187,5 @@ bool CZMQPublishRawTransactionNotifier::NotifyTransaction(const CTransaction &tr
     LogPrint("zmq", "zmq: Publish rawtx %s\n", hash.GetHex());
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << transaction;
-    int rc = zmq_send_multipart(psocket, MSG_RAWTX, 5, &(*ss.begin()), ss.size(), 0);
-    return rc == 0;
+    return SendMessage(MSG_RAWTX, &(*ss.begin()), ss.size());
 }
diff --git a/src/zmq/zmqpublishnotifier.h b/src/zmq/zmqpublishnotifier.h
index 44d5cbea67..22f02a3d0d 100644
--- a/src/zmq/zmqpublishnotifier.h
+++ b/src/zmq/zmqpublishnotifier.h
@@ -11,7 +11,19 @@ class CBlockIndex;
 
 class CZMQAbstractPublishNotifier : public CZMQAbstractNotifier
 {
+private:
+    uint32_t nSequence; //! upcounting per message sequence number
+
 public:
+
+    /* send zmq multipart message
+       parts:
+          * command
+          * data
+          * message sequence number
+    */
+    bool SendMessage(const char *command, const void* data, size_t size);
+
     bool Initialize(void *pcontext);
     void Shutdown();
 };
-- 
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