I was trying to pass custom non-global scoped data to my upgrade_cb for websockets (upgrade_cb is the name of the routine in test_upgrade.c). I noticed that the opaque MHD_UpgradeResponseHandle structure was passed as a pointer parameter to the callback, so I was trying to investigate its members to get some insight. That's when I realized that the members were not exported. Your answer provides the insight I needed regarding opacity, however I still need to pass in custom data to the upgrade callback.
The callback has the following parameters, and I'm guessing I'm supposed to be using extra_in to pass data into the callback: static void upgrade_cb ( void *cls, struct MHD_Connection *connection, void *con_cls, const char *extra_in, size_t extra_in_size, MHD_socket sock, struct MHD_UpgradeResponseHandle *urh ); However, the only time I see upgrade_cb referenced in test_upgrade.c is when it's used as follows: resp = MHD_create_response_for_upgrade (&upgrade_cb, NULL); Do I pass data in through the second parameter? Basically, my question boils down to: How do I attach my own data so that when the callback is triggered I can pass through my own pointers/structures to the callback without utilizing globally scoped variables? Thanks; ~JD On Thu, Mar 30, 2017 at 8:32 PM, Evgeny Grin <k...@yandex.ru> wrote: > Hi John, > > MHD_UpgradeResponseHandle is intentionally opaque. It's not designed for > direct usage of internal members. > If you define it locally, you'll almost likely to break compatibility > with future version. > MHD uses a lot of opaque structures which are internally changed from > version to version. But as long as application uses only public official > API, those changes don't break compatibility. > > Usually MHD has specific API to get information about opaque handle. > What do you want to get from internal members? > > -- > Best Wishes, > Evgeny Grin > > On 31.03.2017 0:58, John Duncan wrote: > > I noticed that microhttpd.h only contains only forward defintions of the > > MHD_UpgradeResponseHandle structure. The file internal.h contains the > > actual structure definition with all members. > > > > When I try to include the internal.h file directly, I get tons of > > compilation errors leading me to believe that I'm not supposed to be > > including it. > > > > My question is, when building my own applications, how am I supposed to > > access member portions of the MHD_UpgradeResponseHandle structure > > without including internal.h. Am I expected to define the structure > > within my own project headers and use the provided > > MHD_UpgradeResponseHandle pointer as somewhat of an opaque type? > > > > I don't mind doing this, I just want to make sure this is the correct > > approach. > > > > Thanks; > > ~JD > >
