webcit-ng/webserver.c

   1 //
   2 // webserver.c
   3 //
   4 // This module handles the task of setting up a listening socket, accepting
   5 // connections, and dispatching active connections onto a pool of worker
   6 // threads.
   7 //
   8 // Copyright (c) 1996-2022 by the citadel.org team
   9 //
  10 // This program is open source software.  Use, duplication, or
  11 // disclosure are subject to the GNU General Public License v3.
  12
  13 #include "webcit.h"                     // All other headers are included from this header.
  14
  15 int num_threads_executing = 1;          // Number of worker threads currently bound to a connected client
  16 int num_threads_existing = 1;           // Total number of worker threads that exist right now
  17 int is_https = 0;                       // Set to nonzero if we are running as an HTTPS server today.
  18 static void *original_brk = NULL;       // Remember the original program break so we can test for leaks
  19
  20
  21 // Spawn an additional worker thread into the pool.
  22 void spawn_another_worker_thread(int *pointer_to_master_socket) {
  23         pthread_t th;           // Thread descriptor
  24         pthread_attr_t attr;    // Thread attributes
  25
  26         // set attributes for the new thread
  27         pthread_attr_init(&attr);
  28         pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  29         pthread_attr_setstacksize(&attr, 1048576);      // Large stacks to prevent MIME parser crash on FreeBSD
  30
  31         // now create the thread
  32         if (pthread_create(&th, &attr, (void *(*)(void *)) worker_entry, (void *) pointer_to_master_socket) != 0) {
  33                 syslog(LOG_WARNING, "Can't create thread: %s", strerror(errno));
  34         }
  35         else {
  36                 ++num_threads_existing;
  37                 ++num_threads_executing;
  38         }
  39
  40         // free up the attributes
  41         pthread_attr_destroy(&attr);
  42 }
  43
  44
  45 // Entry point for worker threads
  46 void worker_entry(int *pointer_to_master_socket) {
  47         int master_socket = *pointer_to_master_socket;
  48         int i = 0;
  49         int fail_this_transaction = 0;
  50         struct client_handle ch;
  51
  52         while (1) {
  53                 // Each worker thread blocks on accept() while waiting for something to do.
  54                 // We don't have to worry about the "thundering herd" problem on modern kernels; for an explanation see
  55                 // https://stackoverflow.com/questions/2213779/does-the-thundering-herd-problem-exist-on-linux-anymore
  56                 memset(&ch, 0, sizeof ch);
  57                 ch.sock = -1;
  58                 errno = EAGAIN;
  59                 do {
  60                         --num_threads_executing;
  61                         syslog(LOG_DEBUG, "Additional memory allocated since startup: %d bytes", (int) (sbrk(0) - original_brk));
  62                         syslog(LOG_DEBUG, "Thread 0x%x calling accept() on master socket %d", (unsigned int) pthread_self(),
  63                                master_socket);
  64                         ch.sock = accept(master_socket, NULL, 0);
  65                         if (ch.sock < 0) {
  66                                 syslog(LOG_DEBUG, "accept() : %s", strerror(errno));
  67                         }
  68                         ++num_threads_executing;
  69                         syslog(LOG_DEBUG, "socket %d is awake , threads executing: %d , threads total: %d", ch.sock,
  70                                num_threads_executing, num_threads_existing);
  71                 } while ((master_socket > 0) && (ch.sock < 0));
  72
  73                 // If all threads are executing, spawn more, up to the maximum
  74                 if ((num_threads_executing >= num_threads_existing) && (num_threads_existing <= MAX_WORKER_THREADS)) {
  75                         spawn_another_worker_thread(pointer_to_master_socket);
  76                 }
  77
  78                 // We have a client.  Do some work.
  79
  80                 // Set the SO_REUSEADDR socket option
  81                 i = 1;
  82                 setsockopt(ch.sock, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
  83
  84                 // If we are an HTTPS server, go crypto now.
  85                 if (is_https) {
  86                         starttls(&ch);
  87                         if (ch.ssl_handle == NULL) {
  88                                 fail_this_transaction = 1;
  89                         }
  90                 }
  91                 else {
  92                         int fdflags;
  93                         fdflags = fcntl(ch.sock, F_GETFL);
  94                         if (fdflags < 0) {
  95                                 syslog(LOG_WARNING, "unable to get server socket flags! %s", strerror(errno));
  96                         }
  97                 }
  98
  99                 // Perform an HTTP transaction...
 100                 if (fail_this_transaction == 0) {
 101                         perform_one_http_transaction(&ch);
 102                 }
 103
 104                 // Shut down SSL/TLS if required...
 105                 if (is_https) {
 106                         endtls(&ch);
 107                 }
 108                 // ...and close the socket.
 109                 //syslog(LOG_DEBUG, "Closing socket %d...", ch.sock);
 110                 //lingering_close(ch.sock);
 111                 close(ch.sock);
 112                 syslog(LOG_DEBUG, "Closed socket %d.", ch.sock);
 113         }
 114 }
 115
 116
 117 // Start up a TCP HTTP[S] server on the requested port
 118 int webserver(char *webserver_interface, int webserver_port, int webserver_protocol) {
 119         int master_socket = (-1);
 120         original_brk = sbrk(0);
 121
 122         switch (webserver_protocol) {
 123         case WEBSERVER_HTTP:
 124                 syslog(LOG_DEBUG, "Starting HTTP server on %s:%d", webserver_interface, webserver_port);
 125                 master_socket = webcit_tcp_server(webserver_interface, webserver_port, 10);
 126                 break;
 127         case WEBSERVER_HTTPS:
 128                 syslog(LOG_DEBUG, "Starting HTTPS server on %s:%d", webserver_interface, webserver_port);
 129                 master_socket = webcit_tcp_server(webserver_interface, webserver_port, 10);
 130                 init_ssl();
 131                 is_https = 1;
 132                 break;
 133         default:
 134                 syslog(LOG_ERR, "unknown protocol");
 135                 ;;
 136         }
 137
 138         if (master_socket < 1) {
 139                 syslog(LOG_ERR, "Unable to bind the web server listening socket");
 140                 return (1);
 141         }
 142
 143         syslog(LOG_INFO, "Listening on socket %d", master_socket);
 144         signal(SIGPIPE, SIG_IGN);
 145
 146         worker_entry(&master_socket);   // this thread becomes a worker
 147         return (0);
 148 }