Unix Socket Programming Question:
How can I put a timeout on connect()?
Answer:
First, create the socket and put it into non-blocking mode, then call connect(). There are three possibilities:
o connect succeeds: the connection has been successfully made (this usually only happens when connecting to the same machine)
o connect fails: obvious
o connect returns -1/EINPROGRESS. The connection attempt has begun, but not yet completed.
If the connection succeeds:
o the socket will select() as writable (and will also select as readable if data arrives)
If the connection fails:
o the socket will select as readable *and* writable, but either a read or write will return the error code from the connection attempt. Also, you can use getsockopt(SO_ERROR) to get the error status - but be careful; some systems return the error code in the result parameter of getsockopt(), but others (incorrectly) cause the getsockopt call itself to fail with the stored value as the error.
o connect succeeds: the connection has been successfully made (this usually only happens when connecting to the same machine)
o connect fails: obvious
o connect returns -1/EINPROGRESS. The connection attempt has begun, but not yet completed.
If the connection succeeds:
o the socket will select() as writable (and will also select as readable if data arrives)
If the connection fails:
o the socket will select as readable *and* writable, but either a read or write will return the error code from the connection attempt. Also, you can use getsockopt(SO_ERROR) to get the error status - but be careful; some systems return the error code in the result parameter of getsockopt(), but others (incorrectly) cause the getsockopt call itself to fail with the stored value as the error.
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