libmicrohttpd demo

/* This file is part of libmicrohttpd Copyright (C) 2016 Christian Grothoff (and other contributing authors) This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file upgrade_example.c * @brief example for how to use libmicrohttpd upgrade * @author Christian Grothoff * * Telnet to the HTTP server, use this in the request: * GET / http/1.1 * Connection: Upgrade * * After this, whatever you type will be echo'ed back to you. */ #include "platform.h" #include #include #define PAGE "libmicrohttpd demolibmicrohttpd demo" /** * Change socket to blocking. * * @param fd the socket to manipulate * @return non-zero if succeeded, zero otherwise */ static void make_blocking (MHD_socket fd) { #if defined(MHD_POSIX_SOCKETS) int flags; flags = fcntl (fd, F_GETFL); if (-1 == flags) return; if ((flags & ~O_NONBLOCK) != flags) if (-1 == fcntl (fd, F_SETFL, flags & ~O_NONBLOCK)) abort (); #elif defined(MHD_WINSOCK_SOCKETS) unsigned long flags = 1; ioctlsocket (fd, FIONBIO, &flags); #endif /* MHD_WINSOCK_SOCKETS */ } static void send_all (MHD_socket sock, const char *buf, size_t len) { ssize_t ret; size_t off; make_blocking (sock); for (off = 0; off < len; off += ret) { ret = send (sock, &buf[off], len - off, 0); if (0 > ret) { if (EAGAIN == errno) { ret = 0; continue; } break; } if (0 == ret) break; } } struct MyData { struct MHD_UpgradeResponseHandle *urh; char *extra_in; size_t extra_in_size; MHD_socket sock; }; /** * Main function for the thread that runs the interaction with * the upgraded socket. Writes what it reads. * * @param cls the `struct MyData` */ static void * run_usock (void *cls) { struct MyData *md = cls; struct MHD_UpgradeResponseHandle *urh = md->urh; char buf[128]; ssize_t got; make_blocking (md->sock); /* start by sending extra data MHD may have already read, if any */ if (0 != md->extra_in_size) { send_all (md->sock, md->extra_in, md->extra_in_size); free (md->extra_in); } /* now echo in a loop */ while (1) { got = recv (md->sock, buf, sizeof (buf), 0); if (0 >= got) break; send_all (md->sock, buf, got); } free (md); MHD_upgrade_action (urh, MHD_UPGRADE_ACTION_CLOSE); return NULL; } /** * Function called after a protocol "upgrade" response was sent * successfully and the socket should now be controlled by some * protocol other than HTTP. * * Any data already received on the socket will be made available in * @e extra_in. This can happen if the application sent extra data * before MHD send the upgrade response. The application should * treat data from @a extra_in as if it had read it from the socket. * * Note that the application must not close() @a sock directly, * but instead use #MHD_upgrade_action() for special operations * on @a sock. * * Data forwarding to "upgraded" @a sock will be started as soon * as this function return. * * Except when in 'thread-per-connection' mode, implementations * of this function should never block (as it will still be called * from within the main event loop). * * @param cls closure, whatever was given to #MHD_create_response_for_upgrade(). * @param connection original HTTP connection handle, * giving the function a last chance * to inspect the original HTTP request * @param con_cls last value left in `con_cls` of the `MHD_AccessHandlerCallback` * @param extra_in if we happened to have read bytes after the * HTTP header already (because the client sent * more than the HTTP header of the request before * we sent the upgrade response), * these are the extra bytes already read from @a sock * by MHD. The application should treat these as if * it had read them from @a sock. * @param extra_in_size number of bytes in @a extra_in * @param sock socket to use for bi-directional communication * with the client. For HTTPS, this may not be a socket * that is directly connected to the client and thus certain * operations (TCP-specific setsockopt(), getsockopt(), etc.) * may not work as expected (as the socket could be from a * socketpair() or a TCP-loopback). The application is expected * to perform read()/recv() and write()/send() calls on the socket. * The application may also call shutdown(), but must not call * close() directly. * @param urh argument for #MHD_upgrade_action()s on this @a connection. * Applications must eventually use this callback to (indirectly) * perform the close() action on the @a sock. */ static void uh_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) { struct MyData *md; pthread_t pt; (void)cls; /* Unused. Silent compiler warning. */ (void)connection; /* Unused. Silent compiler warning. */ (void)con_cls; /* Unused. Silent compiler warning. */ md = malloc (sizeof (struct MyData)); if (NULL == md) abort (); memset (md, 0, sizeof (struct MyData)); if (0 != extra_in_size) { md->extra_in = malloc (extra_in_size); if (NULL == md->extra_in) abort (); memcpy (md->extra_in, extra_in, extra_in_size); } md->extra_in_size = extra_in_size; md->sock = sock; md->urh = urh; if (0 != pthread_create (&pt, NULL, &run_usock, md)) abort (); /* Note that by detaching like this we make it impossible to ensure a clean shutdown, as the we stop the daemon even if a worker thread is still running. Alas, this is a simple example... */ pthread_detach (pt); /* This callback must return as soon as possible. */ /* Data forwarding to "upgraded" socket will be started * after return from this callback. */ } static int ahc_echo (void *cls, struct MHD_Connection *connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **ptr) { static int aptr; struct MHD_Response *response; int ret; (void)cls; /* Unused. Silent compiler warning. */ (void)url; /* Unused. Silent compiler warning. */ (void)version; /* Unused. Silent compiler warning. */ (void)upload_data; /* Unused. Silent compiler warning. */ (void)upload_data_size; /* Unused. Silent compiler warning. */ if (0 != strcmp (method, "GET")) return MHD_NO; /* unexpected method */ if (&aptr != *ptr) { /* do never respond on first call */ *ptr = &aptr; return MHD_YES; } *ptr = NULL; /* reset when done */ response = MHD_create_response_for_upgrade (&uh_cb, NULL); MHD_add_response_header (response, MHD_HTTP_HEADER_UPGRADE, "Echo Server"); ret = MHD_queue_response (connection, MHD_HTTP_SWITCHING_PROTOCOLS, response); MHD_destroy_response (response); return ret; } int main (int argc, char *const *argv) { struct MHD_Daemon *d; if (argc != 2) { printf ("%s PORT\n", argv[0]); return 1; } d = MHD_start_daemon (MHD_ALLOW_UPGRADE | MHD_USE_AUTO | MHD_USE_INTERNAL_POLLING_THREAD | MHD_USE_ERROR_LOG, atoi (argv[1]), NULL, NULL, &ahc_echo, NULL, MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int) 120, MHD_OPTION_END); if (d == NULL) return 1; (void) getc (stdin); MHD_stop_daemon (d); return 0; }