Fix SingleCommandTextProtocol parsing (#1259)

* fix SingleCommandTextProtocol * comment fix * fix space
seladb · Dec 8, 2023 · 4e848ce · 4e848ce
1 parent b31bdfa
commit 4e848ce
Showing 1 changed file with 33 additions and 24 deletions.
diff --git a/Packet++/src/SingleCommandTextProtocol.cpp b/Packet++/src/SingleCommandTextProtocol.cpp
@@ -5,29 +5,41 @@
 
 #define ASCII_HYPHEN 0x2d
 #define ASCII_SPACE 0x20
+#define MAX_COMMAND_LENGTH 9 // From SMTP command "STARTTLS" + 1 byte hyphen or space
+#define MIN_PACKET_LENGTH 2 // CRLF
 
 namespace pcpp
 {
 
 	size_t SingleCommandTextProtocol::getArgumentFieldOffset() const
 	{
 		size_t maxLen;
-		if (m_DataLen < 5)
+		if (m_DataLen < MAX_COMMAND_LENGTH)
 			maxLen = m_DataLen;
 		else
-			maxLen = 5;
+			maxLen = MAX_COMMAND_LENGTH;
 
-		// Find <SP> if exists
-		uint8_t *pos = (uint8_t *)memchr(m_Data, ASCII_SPACE, maxLen);
-		if (pos)
-			return pos - m_Data;
+		// To correctly detect multi-line packets with the option containing a space in
+		// the first MAX_CONTENT_LENGTH bytes, search the both of hyphen and space to take
+		// correct command delimiter
 
-		// Find Hyphen "-" if exists
-		pos = (uint8_t *)memchr(m_Data, ASCII_HYPHEN, maxLen);
-		if (pos)
-			return pos - m_Data;
+		std::string field(reinterpret_cast<char *>(m_Data), maxLen);
 
-		return m_DataLen - 1;
+		size_t posHyphen = field.find_first_of(ASCII_HYPHEN);
+		size_t posSpace = field.find_first_of(ASCII_SPACE);
+		size_t posCRLF = field.rfind("\r\n");
+
+		// No delimiter or packet end
+		if (posHyphen == std::string::npos && posSpace == std::string::npos && posCRLF == std::string::npos)
+			return 0;
+		// Both hyphen and space found
+		else if (posHyphen != std::string::npos || posSpace != std::string::npos)
+			return std::min(posSpace, posHyphen);
+		// If nothing found but there is a CRLF it is a only command packet
+		else if (posCRLF != std::string::npos)
+			return posCRLF;
+
+		return 0;
 	}
 
 	void SingleCommandTextProtocol::setDelimiter(bool hyphen)
@@ -38,17 +50,17 @@ namespace pcpp
 			memset(&m_Data[getArgumentFieldOffset()], ASCII_SPACE, 1);
 	}
 
-	bool SingleCommandTextProtocol::hyphenRequired(const std::string& value)
+	bool SingleCommandTextProtocol::hyphenRequired(const std::string &value)
 	{
-		size_t firstPos = value.find_first_of("\r\n");
-		size_t lastPos = value.find_last_of("\r\n");
-		return (firstPos != std::string::npos) && (lastPos != std::string::npos) && (firstPos != lastPos - 1);
+		size_t firstPos = value.find("\r\n");
+		size_t lastPos = value.rfind("\r\n");
+		return (firstPos != std::string::npos) && (lastPos != std::string::npos) && (firstPos != lastPos);
 	}
 
 	SingleCommandTextProtocol::SingleCommandTextProtocol(const std::string &command, const std::string &option)
 	{
-		m_Data = new uint8_t[6];
-		m_DataLen = 6;
+		m_Data = new uint8_t[MIN_PACKET_LENGTH];
+		m_DataLen = MIN_PACKET_LENGTH;
 		if (!command.empty())
 			setCommandInternal(command);
 		if (!option.empty())
@@ -80,7 +92,7 @@ namespace pcpp
 
 	bool SingleCommandTextProtocol::setCommandOptionInternal(std::string value)
 	{
-		size_t lastPos = value.find_last_of("\r\n");
+		size_t lastPos = value.rfind("\r\n");
 		if (lastPos == std::string::npos || lastPos != value.size() - 2)
 			value += "\r\n";
 
@@ -123,18 +135,15 @@ namespace pcpp
 		return "";
 	}
 
-	bool SingleCommandTextProtocol::isMultiLine() const
-	{
-		return m_Data[getArgumentFieldOffset()] == ASCII_HYPHEN;
-	}
+	bool SingleCommandTextProtocol::isMultiLine() const { return m_Data[getArgumentFieldOffset()] == ASCII_HYPHEN; }
 
 	bool SingleCommandTextProtocol::isDataValid(const uint8_t *data, size_t dataSize)
 	{
-		if (data == nullptr || dataSize < 6)
+		if (data == nullptr || dataSize < MIN_PACKET_LENGTH)
 			return false;
 
 		std::string payload = std::string((char *)data, dataSize);
-		return payload.find_last_of("\r\n") == dataSize - 1;
+		return payload.rfind("\r\n") == dataSize - 2;
 	}
 
 } // namespace pcpp