testing/web2io/webserver.c

   1 /**
   2  * @file webserver.c
   3  * @purpose Test implementing a minimalistic webserver
   4  *
   5  */
   6
   7 #define _POSIX_C_SOURCE 200809L // needed for some POSIX stuff to work
   8
   9 // --- Standard headers --- //
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include <string.h> // string helper functions
  13 #include <ctype.h> // character types
  14 #include <signal.h> // for signal handling
  15
  16 // --- Custom headers --- //
  17 #include "log.h" // C functions to handle logging
  18 #include "options.h" // Options structure
  19 #include "network.h" // C functions to handle low level networking
  20
  21 // --- Variable definitions --- //
  22 Options options; // declared in "options.h"
  23
  24 // --- Function definitions --- //
  25
  26 /**
  27  * @funct ParseArguments
  28  * @purpose Parse Arguments and setup the global options variable
  29  * @param argc - Num args
  30  * @param argv - Array of args
  31  */
  32 void ParseArguments(int argc, char ** argv)
  33 {
  34         options.program = argv[0];
  35         options.verbosity = LOGDEBUG;
  36         if (argc > 1)
  37                 options.port = atoi(argv[1]); // Allow us change the port for testing (I keep getting "address in use" errors)
  38         else
  39                 options.port = 8080; // Using 8080 instead of 80 for now because to use 80 you have to run the program as root
  40         options.sfd = -1;
  41         options.bound_sfd = -1;
  42         log_print(LOGDEBUG, "ParseArguments", "Called as %s with %d arguments.", options.program, argc);
  43 }
  44
  45 /**
  46  * @funct SignalHandler
  47  * @purpose Handle signals
  48  * @param sig - The signal
  49  */
  50 void SignalHandler(int sig)
  51 {
  52         // At the moment just always exit.
  53         // Call `exit` so that Cleanup will be called to... clean up.
  54         log_print(LOGWARN, "SignalHandler", "Got signal %d (%s). Exiting.", sig, strsignal(sig));
  55         exit(sig);
  56 }
  57
  58 /**
  59  * @funct Cleanup
  60  * @purpose Called when program exits
  61  */
  62 void Cleanup()
  63 {
  64         log_print(LOGDEBUG, "Cleanup", "Begin cleanup.");
  65         if (options.sfd >= 0)
  66         {
  67                 Network_close(options.sfd); // close socket
  68                 options.sfd = -1;
  69         }
  70         if (options.bound_sfd >= 0)
  71         {
  72                 Network_close(options.bound_sfd); // unbind
  73                 options.bound_sfd = -1;
  74         }
  75         log_print(LOGDEBUG, "Cleanup", "Unbound from port %d successfully", options.port);
  76         log_print(LOGDEBUG, "Cleanup", "Done.");
  77
  78 }
  79
  80
  81 /**
  82  * @funct Get
  83  * @purpose Respond to a GET request
  84  * @param request - The request string
  85  * @param sfd - Socket to respond through
  86  */
  87 void Get(char * request, int sfd)
  88 {
  89         log_print(LOGDEBUG, "Get", "Got GET request: \"%s\"", request);
  90
  91         int i = 0;
  92         while (!isspace(request[++i]) && request[i] != '\0'); //NOTE: Don't need to check first character
  93         request[i] = '\0';
  94
  95         char response[BUFSIZ];
  96         int len = 0;
  97         // TODO: Magical low level interfacing stuff!
  98         if (strcmp("/sensor", request) == 0) // dummy test
  99         {
 100                 len = sprintf(response, "SENSOR OFFLINE\n");
 101         }
 102         else
 103         {
 104                 FILE * f = fopen(request+1, "r");
 105                 if (f == NULL)
 106                 {
 107                         log_print(LOGWARN, "Get", "File \"%s\" doesn't exist", request+1);
 108                         len = sprintf(response, "You requested \"%s\" using GET\n", request);
 109                 }
 110                 else
 111                 {
 112                         while (fgets(response, sizeof(response), f) != NULL)
 113                         {
 114                                 write(sfd, response, strlen(response));
 115                         }
 116                 }
 117         }
 118         if (len > 0)
 119                 write(sfd, response, len);
 120 }
 121
 122 /**
 123  * @funct Post
 124  * @purpose Respond to a POST request
 125  * @param request - The request string
 126  * @param sfd - Socket to respond through
 127  */
 128 void Post(char * request, int sfd)
 129 {
 130         log_print(LOGDEBUG, "Post", "Got POST request: \"%s\"", request);
 131         int i = 0;
 132         while (!isspace(request[++i]) && request[i] != '\0'); //NOTE: Don't need to check first character
 133         request[i] = '\0';
 134
 135         char response[BUFSIZ];
 136         int len = 0;
 137
 138         // TODO: Magical low level interfacing stuff!
 139
 140
 141         if (strcmp("/actuator", request) == 0) // dummy test
 142         {
 143                 len = sprintf(response, "ACTUATOR OFFLINE\n");
 144         }
 145         else
 146         {
 147                 len = sprintf(response, "You requested \"%s\" using POST\n", request);
 148         }
 149         if (len > 0)
 150                 write(sfd, response, len);
 151
 152 }
 153
 154 /**
 155  * @funct main
 156  * @purpose Main program
 157  * @param argc - Num arguments
 158  * @param argv - Argument string array
 159  * @returns error code (0 for no error)
 160  */
 161
 162 int main(int argc, char ** argv)
 163 {
 164         // Parse Arguments
 165         ParseArguments(argc, argv);
 166         // Set Cleanup to be called on program exit
 167         atexit(Cleanup);
 168
 169         // Setup signal handlers
 170         int signals_to_handle[] = {SIGTERM, SIGINT, SIGHUP, SIGPIPE};
 171         for (int i = 0; i < sizeof(signals_to_handle)/sizeof(int); ++i)
 172         {
 173                 int s = signals_to_handle[i];
 174                 if (signal(s, SignalHandler) == SIG_ERR)
 175                         error("main", "Setting signal handler for %d (%s): %s", s, strsignal(s), strerror(errno));
 176         }
 177
 178         // Bind to the port
 179         options.bound_sfd = Network_server_bind(options.port, &(options.port));
 180         log_print(LOGDEBUG, "main", "Bound to port %d succesfully", options.port);
 181
 182         while (true)
 183         {
 184                         // Listen for a client
 185                         options.sfd = Network_server_listen(options.bound_sfd, NULL);
 186
 187                         log_print(LOGDEBUG, "main", "Connected to client");
 188
 189                         char buffer[BUFSIZ]; //NOTE: Won't be able to respond to requests longer than BUFSIZ
 190                         // read a request
 191                         int len = read(options.sfd, buffer, sizeof(buffer));
 192                         log_print(LOGDEBUG, "main", "Read %d characters. Buffer is \"%s\"", len, buffer);
 193
 194                         // Parse request
 195                         for (int i = 0; i < sizeof(buffer) && buffer[i] != '\0'; ++i)
 196                         {
 197                                 // Look for "GET" or "POST" followed by a whitespace
 198                                 if (isspace(buffer[i])) // whitespace
 199                                 {
 200                                         while (isspace(buffer[++i]) && buffer[i] != '\0'); // Skip whitespace
 201                                         char * req = buffer+i; // set request string
 202
 203                                         buffer[i-1] = '\0'; // terminate request type
 204                                         while (buffer[++i] != '\n' && buffer[i] != '\0'); // find next newline
 205                                         buffer[i-1] = '\0';
 206
 207                                         if (strcmp("GET", buffer) == 0) // Compare with "GET"
 208                                         {
 209                                                 Get(req, options.sfd);
 210                                         }
 211                                         else if (strcmp("POST", buffer) == 0) // Compare with "POST"
 212                                         {
 213                                                 Post(req, options.sfd);
 214                                         }
 215                                         else // Unknown request
 216                                         {
 217                                                 log_print(LOGWARN, "main", "Unrecognised request type \"%s\" (request \"%s\")", buffer, req);
 218                                                 char response[] = "Error: Unrecognised request\n";
 219                                                 write(options.sfd, response, sizeof(response));
 220                                         }
 221                                         break;
 222                                 }
 223                         }
 224
 225                         // Close connection
 226                         Network_close(options.sfd);
 227                         Network_close(options.bound_sfd);
 228                         options.sfd = -1;
 229                         log_print(LOGDEBUG, "main", "Closed connection to client");
 230                         break;
 231         }
 232
 233
 234
 235
 236         return 0;
 237 }
 238
 239