From b837b334db5dd6232725fd2350928ff4fbd3feee Mon Sep 17 00:00:00 2001 From: "Wladimir J. van der Laan" Date: Mon, 30 Sep 2019 12:27:27 +0200 Subject: [PATCH] net: Fail instead of truncate command name in CMessageHeader Replace the memset/strncpy dance in `CMessageHeader::CMessageHeader` with explicit code that copies then name and asserts the length. This removes a warning in g++ 9.1.1 and IMO makes the code more readable by not relying on strncpy padding and silent truncation behavior. --- src/protocol.cpp | 9 +++++++-- src/protocol.h | 4 ++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/src/protocol.cpp b/src/protocol.cpp index e49e5523aca..bd3ed25a8af 100644 --- a/src/protocol.cpp +++ b/src/protocol.cpp @@ -85,8 +85,13 @@ CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn) CMessageHeader::CMessageHeader(const MessageStartChars& pchMessageStartIn, const char* pszCommand, unsigned int nMessageSizeIn) { memcpy(pchMessageStart, pchMessageStartIn, MESSAGE_START_SIZE); - memset(pchCommand, 0, sizeof(pchCommand)); - strncpy(pchCommand, pszCommand, COMMAND_SIZE); + + // Copy the command name, zero-padding to COMMAND_SIZE bytes + size_t i = 0; + for (; i < COMMAND_SIZE && pszCommand[i] != 0; ++i) pchCommand[i] = pszCommand[i]; + assert(pszCommand[i] == 0); // Assert that the command name passed in is not longer than COMMAND_SIZE + for (; i < COMMAND_SIZE; ++i) pchCommand[i] = 0; + nMessageSize = nMessageSizeIn; memset(pchChecksum, 0, CHECKSUM_SIZE); } diff --git a/src/protocol.h b/src/protocol.h index db07efb9f99..6639ae2aacf 100644 --- a/src/protocol.h +++ b/src/protocol.h @@ -37,6 +37,10 @@ public: typedef unsigned char MessageStartChars[MESSAGE_START_SIZE]; explicit CMessageHeader(const MessageStartChars& pchMessageStartIn); + + /** Construct a P2P message header from message-start characters, a command and the size of the message. + * @note Passing in a `pszCommand` longer than COMMAND_SIZE will result in a run-time assertion error. + */ CMessageHeader(const MessageStartChars& pchMessageStartIn, const char* pszCommand, unsigned int nMessageSizeIn); std::string GetCommand() const;