> Adding to David's response...
>
> MSG_PEEK is problematic on some systems. On Windows for example
> (maybe only
> the 9x series, but a problem none-the-less) using MSG_PEEK will
> effectively
> freeze the contents of the buffered data that can be seen with MSG_PEEK,
> meaning that any further peeks will not be able to see any subsequently
> received data. This means that if you need to peek at 4 bytes
> and only one
> has arrived when you perform the first peek you will never see
> the following
> three bytes and will therefore hang or need to abort.
Which could happen even without MSG_PEEK. TCP does not guarantee that it
can ever receive any particular number of bytes at one time. This is another
reason you will see such a violent knee-jerk reaction when you mention
MSG_PEEK -- it is usually used to try to force TCP to do something it cannot
do.
> The BIO support in OpenSSL can help you. By using a BIO to wrapper the
> socket and buffer data that you want to peek/push-back-on you can get a
> similar result. There has been plently of BIO discussion on this list
> recently and there are samples included with OpenSSL.
Right. This way you still receive the data from the TCP or SSL engine
immediately, allowing it to do its job.
DS
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