Hi Frank, Today I have modified SOCKET-SEND and SOCKET-RECEIVE for LispWorks, to be able to detect and report socket errors. I think in this way, these APIs on LispWorks could behavior closer to other platforms.
Now on Windows, your test code should return a USOCKET:CONNECTION-RESET-ERROR condition, which equals to WSA error ECONNRESET. However, when I test the same code on Mac OS X, it instead returns USOCKET:CONNECTION-REFUSED-ERROR, I think this is a behavior of BSD sockets. I hope you can try latest usocket code from Git [1], to see if it works better for your case now. My code changes commit can be seen here [2]. For wait-for-input, I can’t see what you see (the socket object remains in a :READ state), if you still think this is an issue, I hope you can create another test code to demonstrate this issue. Regards, Chun [1] https://github.com/usocket/usocket [2] https://github.com/usocket/usocket/commit/13386639889fa812540fc4f77824c47e7616db37 Il giorno 10/apr/2015, alle ore 23:00, Frank James <frank.a.ja...@gmail.com> ha scritto: > I've been testing some UDP codes on Lispworks (personal 32bit Windows > version) and have encountered some undocumented behaviour, I think it's a > matter of opinion whether it's a bug or not but it should probably have a > sentence or two documenting it somewhere. > > Basically I'm sending a UDP packet to a host and listening for a reply, using > socket-send and socket-receive. If the host in question is not listening for > UDP traffic on that particular port, the Windows socket API says it should > return an ECONNRESET error immediately on the socket-receive call, this is > indicated by a -1 return value from the underlying recvfrom call. > > When this happens the Lispworks backend code returns a length of -1 (and > buffer nil). This is perfectly acceptable behaviour I think (although it'd be > somewhat nicer to signal an error, but that's a matter of taste). But it > should be documented that checking the length here is the correct way to > detect an error occurred. > > Example code would be something like: > > (let ((sock (usocket:socket-connect "localhost" 1234 :protocol :datagram > :element-type '(unsigned-byte 8)))) > (unwind-protect > (progn > (usocket:socket-send sock (make-array 16 :element-type '(unsigned-byte > 8) :initial-element 0) 16) > (let ((buffer (make-array 16 :element-type '(unsigned-byte 8) > :initial-element 0))) > (usocket:socket-receive sock buffer 16))) > (usocket:socket-close sock))) > > > What is somewhat more annoying is that the socket object remains in a :READ > state. This means that a polling loop using wait-for-input spins > continuously, with each socket-receive returning -1 (as explained above). > Probably the socket state should be cleared if a socket-receive fails. > > Apologies if this is all well-known to those reading this list, but it caused > me 10 minutes of head scratching earlier today and thought it was worth > mentioning. > > Frank. >
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