Kieran Mansley <[email protected]> wrote: > > 1. ERR_WOULDBLOCK is treated as a FATAL error - it seems as if someone > > forgot to update the ERR_IS_FATAL macro when the error code was added. A > > non-blocking operation that sets the conn error to WOULDBLOCK (e.g > > send() and recv() ) renders the socket unusable. Our workaround was to > > use ERR_WOULDBLOCK in the ERR_IS_FATAL macro instead of ERR_VAL. > > I agree that looks wrong. I'm sure it was correct in the past. I'll make > sure this is fixed before 1.4.0 is released. If you could file a bug for > this on savannah it would help.
I've just fixed that in CVS, thanks for reporting. (I can still not add a new bug to savannah...) > > 2. As far as we know, EMSGSIZE is not a valid return code for send() on > > a STREAM socket. netconn_write does not return the number of bytes > > processed and cannot perform partial sends. This makes an application > > that uses select run in tight loops since select returns writable, but > > send [working on an all or nothing assumption] returns an error > > (EWOULDBLOCK) > > I'd like to see lwIP updated to support partial sends (which I think would > solve this problem) but it won't happen before 1.4.0. A task on savannah > would again be very helpful, if there's not one already - I think this > might have been discussed before. There's bug #31084 for that on savannah: https://savannah.nongnu.org/bugs/?31084 I've targeted it at 1.4.0 though. I think it's one of the main missing things for lwIP to support nonblocking sockets, so it might be worth including that to prevent having to launch 1.4.1 too soon... > > 3. connect has several problems: > > > > a. connect sets sock->err to EINPROGRESS. When select returns > > writable, getsockopt(SO_ERROR) will never let us know what happened [i.e > > no access to conn->err] since getsockopt(SO_ERROR) does not return the > > error value when sock->err is not 0 (it is set to EINPROGRESS). It seems > > to me the non-blocking path lacks the propagation of the connect result > > to sock->err (which does happen when using a blocking call). Could you try CVS HEAD? There was a bug there (http://savannah.nongnu.org/bugs/?31590) which should be fixed since a week or so now. > > b. getsockopt(SO_ERROR) - behaviour according to Posix is to return > > and clear the _pending_ error for the socket (if one exists). instead > > getsockopt returns the last socket call error once. If additional calls > > are made netconn's last error is returned repeatedly. That's a problem of the mixture of 3 APIs here: socket API is built on top of the netconn API which in turn is built on top of the raw API. In a fatal error state, the socket could have an error that cannot easily be removed, so not returning that first could be a problem. This code needs further thoughts, so it would be best to open a bug entry for discussion (as soon as savannah is fully back online again). > > c. if connect is called again while a previous non-blocking connect > > is being processed, ERR_ISCONN is assigned to conn->err [which by the > > way translates to an errno of -1]. Now, if the connection succeeds, > > do_connected will not be able to set conn->err to ERR_OK since it checks > > for ERR_INPROGRESS. To make things worse, ERR_ISCONN is treated as a > > FATAL error, and will therefore render the socket unusable. According to > > Posix, EALREADY should be returned while a connect is in progress, and > > EISCONN should be returned when a socket is connected. That's a good one. Again, please file a bug report to make sure this doesn't get lost! > > 4. lwip_select seems to be susceptible to race conditions and has issued > > many ASSERTs as well as crashed. > > These sounds like you're using a socket from two different threads (one > calling select(), the other calling close()). Unfortunately this style of > operation isn't supported in lwIP. Hmm, select() does use a global list to queue all threads waiting in a select (select_cb_list), but for me, that worked quite well, so any detailed bug report would be great. Thanks for the feedback, and please remember to open bug reports for the open issues: there are too many posts on this list to keep track of bugs without the bugtracker. Simon Simon -- GMX DSL Doppel-Flat ab 19,99 €/mtl.! Jetzt auch mit gratis Notebook-Flat! http://portal.gmx.net/de/go/dsl _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
