asked    Phoenix     2018-10-22       c       74 view        1 Answer

[SOLVED] C TCP cannot detect broken connection

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        answered    Joanne     2018-10-22      

If the peer of a TCP connection closes the connection, it will lead to a recv call on your end to return 0. That's the way to detect closed (but not broken) connections.

If you don't currently receive anything from the peer, you need to make up a protocol on top of TCP which includes receiving data.

Furthermore, sending might not detect broken connections (like missing cables etc.) directly, as there are a lot of retransmissions and timeouts. The best way is again to implement some kind of protocol overlaying TCP, one that for example contains a kind of "are you there" message which expects a reply. If a reply to the "are you there" message isn't received within some specific timeout, then consider the connection broken and disconnect.

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