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authorWladimir J. van der Laan <laanwj@gmail.com>2016-09-27 14:05:24 +0200
committerWladimir J. van der Laan <laanwj@gmail.com>2016-09-28 12:44:13 +0200
commit41e58faf043864a64a6db08a8df527fa5fd1ec5b (patch)
treedbe0c6c2dee6615abee3d97d6b8af98c66effc47
parent920ca1f0bf0b786250e3119a05984e0c2af1350a (diff)
net: Consistent checksum handling
In principle, the checksums of P2P packets are simply 4-byte blobs which are the first four bytes of SHA256(SHA256(payload)). Currently they are handled as little-endian 32-bit integers half of the time, as blobs the other half, sometimes copying the one to the other, resulting in somewhat confused code. This PR changes the handling to be consistent both at packet creation and receiving, making it (I think) easier to understand.
-rw-r--r--src/main.cpp9
-rw-r--r--src/net.cpp6
-rw-r--r--src/protocol.cpp4
-rw-r--r--src/protocol.h4
4 files changed, 11 insertions, 12 deletions
diff --git a/src/main.cpp b/src/main.cpp
index c33b41ac4e..ab67219714 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -6253,11 +6253,12 @@ bool ProcessMessages(CNode* pfrom, CConnman& connman)
// Checksum
CDataStream& vRecv = msg.vRecv;
uint256 hash = Hash(vRecv.begin(), vRecv.begin() + nMessageSize);
- unsigned int nChecksum = ReadLE32((unsigned char*)&hash);
- if (nChecksum != hdr.nChecksum)
+ if (memcmp(hash.begin(), hdr.pchChecksum, CMessageHeader::CHECKSUM_SIZE) != 0)
{
- LogPrintf("%s(%s, %u bytes): CHECKSUM ERROR nChecksum=%08x hdr.nChecksum=%08x\n", __func__,
- SanitizeString(strCommand), nMessageSize, nChecksum, hdr.nChecksum);
+ LogPrintf("%s(%s, %u bytes): CHECKSUM ERROR expected %s was %s\n", __func__,
+ SanitizeString(strCommand), nMessageSize,
+ HexStr(hash.begin(), hash.begin()+CMessageHeader::CHECKSUM_SIZE),
+ HexStr(hdr.pchChecksum, hdr.pchChecksum+CMessageHeader::CHECKSUM_SIZE));
continue;
}
diff --git a/src/net.cpp b/src/net.cpp
index cce06f2d64..770e2d2959 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2661,10 +2661,8 @@ void CNode::EndMessage(const char* pszCommand) UNLOCK_FUNCTION(cs_vSend)
// Set the checksum
uint256 hash = Hash(ssSend.begin() + CMessageHeader::HEADER_SIZE, ssSend.end());
- unsigned int nChecksum = 0;
- memcpy(&nChecksum, &hash, sizeof(nChecksum));
- assert(ssSend.size () >= CMessageHeader::CHECKSUM_OFFSET + sizeof(nChecksum));
- memcpy((char*)&ssSend[CMessageHeader::CHECKSUM_OFFSET], &nChecksum, sizeof(nChecksum));
+ assert(ssSend.size () >= CMessageHeader::CHECKSUM_OFFSET + CMessageHeader::CHECKSUM_SIZE);
+ memcpy((char*)&ssSend[CMessageHeader::CHECKSUM_OFFSET], hash.begin(), CMessageHeader::CHECKSUM_SIZE);
LogPrint("net", "(%d bytes) peer=%d\n", nSize, id);
diff --git a/src/protocol.cpp b/src/protocol.cpp
index 247c6c2120..54ad62b1a2 100644
--- a/src/protocol.cpp
+++ b/src/protocol.cpp
@@ -79,7 +79,7 @@ CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn)
memcpy(pchMessageStart, pchMessageStartIn, MESSAGE_START_SIZE);
memset(pchCommand, 0, sizeof(pchCommand));
nMessageSize = -1;
- nChecksum = 0;
+ memset(pchChecksum, 0, CHECKSUM_SIZE);
}
CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn, const char* pszCommand, unsigned int nMessageSizeIn)
@@ -88,7 +88,7 @@ CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn, const
memset(pchCommand, 0, sizeof(pchCommand));
strncpy(pchCommand, pszCommand, COMMAND_SIZE);
nMessageSize = nMessageSizeIn;
- nChecksum = 0;
+ memset(pchChecksum, 0, CHECKSUM_SIZE);
}
std::string CMessageHeader::GetCommand() const
diff --git a/src/protocol.h b/src/protocol.h
index 9b474ec79c..177d745308 100644
--- a/src/protocol.h
+++ b/src/protocol.h
@@ -45,7 +45,7 @@ public:
READWRITE(FLATDATA(pchMessageStart));
READWRITE(FLATDATA(pchCommand));
READWRITE(nMessageSize);
- READWRITE(nChecksum);
+ READWRITE(FLATDATA(pchChecksum));
}
// TODO: make private (improves encapsulation)
@@ -62,7 +62,7 @@ public:
char pchMessageStart[MESSAGE_START_SIZE];
char pchCommand[COMMAND_SIZE];
unsigned int nMessageSize;
- unsigned int nChecksum;
+ uint8_t pchChecksum[CHECKSUM_SIZE];
};
/**