does miner software need to check whether a transaction or a block is valid?

[ebyccc]

I am now reading the source code of cgminer, trying to figure out how it checks blocks and transactions, but still can't find the right place.
So is the software responsible for the checking?

[-ck]

No. That's all done at the pool level for pooled mining and at bitcoind level for solo mining.

[ebyccc]

No. That's all done at the pool level for pooled mining and at bitcoind level for solo mining.

So the miner is only responsible for finding a hash to meet the target? And, maybe this is a quite silly question, is the bitcoind sourced in the bitcoin-master project? I always assume that it is only a wallet program.