Which function in which file verifies that transactions are the right size Which file(s) are responsible for the procedure which confirms that transactions are well-formed, specifically that "Size in bytes &lt; MAX_BLOCK_SIZE" as described in the Protocol Rules article on the wiki: https://en.bitcoin.it/wiki/Protocol_rules?
The function, which is found in main.cpp is called CheckTransaction():
https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L526