Il 03/08/2014 14:21, Mark Lvov ha scritto: > This is exactly what I've done, only I have a class, each instance of > which manages a connection to a particular endpoint (only, my "state" > enum has ACTIVE_CLOSE and PASSIVE_CLOSE instead of CLOSING, since > those are handled differently). The thing is, it does not really help > much with the problem I've outlined in the earlier message. Even > though I get the pointer to a particular instance of the class in the > "arg" argument to the err callback, it is still impossible to know if > it is the latest connection, that errored out, or if it is some other, > older connection, that was also opened to the same endpoint, but was > stuck in some "waiting" state, such as LAST_ACK. I hope, this makes sense. Yap, it makes sense but you should manage a little bit better your connection. You can't open a connection that is not close so... this event shouldn't be managed, in any case there are some timers in lwip to manage the timeouts, you should check in that area. > > Regards, > Mark > > > On Sun, Aug 3, 2014 at 12:25 AM, M. Manca > <m.ma...@micronengineering.it <mailto:m.ma...@micronengineering.it>> > wrote: > > Il 02/08/2014 20:52, Mark Lvov ha scritto: >> Hello, >> >> It seems, I still have some unanswered questions with regard to >> correct connection teardown. Let's consider the active close situation >> (we are closing the connection). We've just called tcp_closed and are >> waiting for the tcp_recv callback to be called with an empty pbuf. >> But, as I understand, if the remote side sends RST or does not send >> anything at all, the err handler will be called instead. The problem >> is, one does now know which particular connection (pcb) the callback >> is addressed to, because the callback function does not receive a pcb >> as an argument. > This is one of the reason I wrote an "upper layer" to the raw > functions to manage a tcp client connection. > The idea is simple: create a struct to embed every information > needed to manage a particular connection so I can pass it as the > void *arg > that is also present in the error callback. > I think you can understand my idea just reading the struct I made: > > typedef enum > { > STATE_NOT_CONNECTED = 0, > STATE_CONNECTING, > STATE_CONNECTED, > STATE_CLOSING, > } TTcpRawSktState_e; > > typedef struct > { > TTcpRawSktState_e eState; > err_t eError; > struct pbuf *pPbuf; > struct tcp_pcb *pPcb; > struct ip_addr tServerIpAddr; > uint16_t wServerPort; > uint16_t wBindPort; > char szDescription[8]; > } TTcpRawSkt; > > the description field isn't necessary, I used it to debug in the > simplest way my code. >> Consider the scenario, when one needs to keep a connection open by >> reconnecting to the remote side whenever the connection is closed >> (either by the remote or the local side). It is all fine when the >> remote side closes the connection - we just receive a NULL pbuf, after >> that we can just call tcp_close on the "current" pcb, then immediately >> ask for the new pcb and reconnect. If, on the other hand, *we* want to >> close the connection (to reopen if afterwards), and call tcp_close, we >> might have the err callback called and then we won't really know if it >> means, that the current connection was terminated or some older >> connection, that maybe stuck in LAST_ACK finally timed out. >> >> Does this mean, that in such a situation, one has to keep only one err >> callback active at a time? It seems, the best course of action is to >> zero out the err callback on a pcb after calling on it tcp_close >> successfully (actually, its more like this: zero out the callback, >> then call tcp_close and if it fails reattach the callback, because we >> will have to wait a bit before calling tcp_close again). But then, >> once we call tcp_close, we have to start a timer (for, say, 5 >> seconds?) and if it runs out we consider the connection closed, remove >> all callbacks from that pcb and ask for the new one. >> >> Hopefully, I've managed to explain the problem I am facing. Sorry, >> that it took such a long message. >> >> Thanks, >> Mark >> >> On Fri, Aug 1, 2014 at 9:01 AM, Mark Lvov <mark.l...@gmail.com> >> <mailto:mark.l...@gmail.com> wrote: >>> Well, shame on me! >>> >>> I was actually using >>> >>> http://git.savannah.gnu.org/cgit/lwip.git/tree/doc/rawapi.txt?id=5b8b5d459e7dd890724515bbfad86c705234f9ec >>> as a reference and it obviously lacks the details, that are present on >>> the page you've linked. All my questions are answered by that page, >>> thanks very much. >>> >>> Mark >>> >>> On Thu, Jul 31, 2014 at 10:01 PM, Sergio R. Caprile >>> <scapr...@gmail.com> <mailto:scapr...@gmail.com> wrote: >>>> Counter-proposal: >>>> Read the wiki, and if it is not clear enough, I will change it >>>> >>>> http://lwip.wikia.com/wiki/Raw/TCP >>>> >>>> Regards >>>> >>>> -- >>>> >>>> >>>> _______________________________________________ >>>> lwip-users mailing list >>>> lwip-users@nongnu.org <mailto:lwip-users@nongnu.org> >>>> https://lists.nongnu.org/mailman/listinfo/lwip-users >> _______________________________________________ lwip-users >> mailing list lwip-users@nongnu.org <mailto:lwip-users@nongnu.org> >> https://lists.nongnu.org/mailman/listinfo/lwip-users >> >> >> --- >> Questa e-mail è priva di virus e malware perché è attiva la protezione >> avast! Antivirus. >> http://www.avast.com >> >> > > > > logo > * > > Massimo Manca*/, Micron Engineering/ > via della Ferriera, 48 33170 Pordenone PN ITALIA > Tel: 39 0434 1856131| Mobile: 39 349 4504979 > www.micronengineering.it <http://www.micronengineering.it> > > Twitter > > <http://s.wisestamp.com/links?url=https%3A%2F%2Ftwitter.com%2Fmassimomanca> > LinkedIn > > <http://s.wisestamp.com/links?url=http%3A%2F%2Fit.linkedin.com%2Fpub%2Fmassimo-manca%2F7%2Fa15%2F479%2F> > SlideShare > > <http://s.wisestamp.com/links?url=http%3A%2F%2Fwww.slideshare.net%2Fmicronpn> > Contact me: Skype micron.engineering > Designed with WiseStamp - > > <http://s.wisestamp.com/links?url=http%3A%2F%2Fr1.wisestamp.com%2Fr%2Flanding%3Fu%3Daaa0e17b0c4ca423%26v%3D3.13.31%26t%3D1407010845407%26promo%3D10%26dest%3Dhttp%253A%252F%252Fwww.wisestamp.com%252Femail-install%253Futm_source%253Dextension%2526utm_medium%253Demail%2526utm_campaign%253Dpromo_10>Get > yours > > <http://s.wisestamp.com/links?url=http%3A%2F%2Fr1.wisestamp.com%2Fr%2Flanding%3Fu%3Daaa0e17b0c4ca423%26v%3D3.13.31%26t%3D1407010845407%26promo%3D10%26dest%3Dhttp%253A%252F%252Fwww.wisestamp.com%252Femail-install%253Futm_source%253Dextension%2526utm_medium%253Demail%2526utm_campaign%253Dpromo_10> > > > > ------------------------------------------------------------------------ > <http://www.avast.com/> > > Questa e-mail è priva di virus e malware perché è attiva la > protezione avast! 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