src/server/server.c

   1 /*
   2  * OpenDispense 2
   3  * UCC (University [of WA] Computer Club) Electronic Accounting System
   4  *
   5  * server.c - Client Server Code
   6  *
   7  * This file is licenced under the 3-clause BSD Licence. See the file
   8  * COPYING for full details.
   9  */
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include "common.h"
  13 #include <sys/socket.h>
  14 #include <netinet/in.h>
  15 #include <arpa/inet.h>
  16 #include <unistd.h>
  17 #include <string.h>
  18
  19 #define MAX_CONNECTION_QUEUE    5
  20 #define INPUT_BUFFER_SIZE       256
  21
  22 #define HASH_TYPE       SHA512
  23 #define HASH_LENGTH     64
  24
  25 #define MSG_STR_TOO_LONG        "499 Command too long (limit "EXPSTR(INPUT_BUFFER_SIZE)")\n"
  26
  27 // === TYPES ===
  28 typedef struct sClient
  29 {
  30          int    ID;     // Client ID
  31
  32          int    bIsTrusted;     // Is the connection from a trusted host/port
  33
  34         char    *Username;
  35         char    Salt[9];
  36
  37          int    UID;
  38          int    bIsAuthed;
  39 }       tClient;
  40
  41 // === PROTOTYPES ===
  42 void    Server_Start(void);
  43 void    Server_HandleClient(int Socket, int bTrusted);
  44 char    *Server_ParseClientCommand(tClient *Client, char *CommandString);
  45 // --- Commands ---
  46 char    *Server_Cmd_USER(tClient *Client, char *Args);
  47 char    *Server_Cmd_PASS(tClient *Client, char *Args);
  48 char    *Server_Cmd_AUTOAUTH(tClient *Client, char *Args);
  49 char    *Server_Cmd_ENUMITEMS(tClient *Client, char *Args);
  50 char    *Server_Cmd_ITEMINFO(tClient *Client, char *Args);
  51 // --- Helpers ---
  52 void    HexBin(uint8_t *Dest, char *Src, int BufSize);
  53
  54 // === GLOBALS ===
  55  int    giServer_Port = 1020;
  56  int    giServer_NextClientID = 1;
  57 // - Commands
  58 struct sClientCommand {
  59         char    *Name;
  60         char    *(*Function)(tClient *Client, char *Arguments);
  61 }       gaServer_Commands[] = {
  62         {"USER", Server_Cmd_USER},
  63         {"PASS", Server_Cmd_PASS},
  64         {"AUTOAUTH", Server_Cmd_AUTOAUTH},
  65         {"ENUM_ITEMS", Server_Cmd_ENUMITEMS},
  66         {"ITEM_INFO", Server_Cmd_ITEMINFO}
  67 };
  68 #define NUM_COMMANDS    (sizeof(gaServer_Commands)/sizeof(gaServer_Commands[0]))
  69
  70 // === CODE ===
  71 /**
  72  * \brief Open listenting socket and serve connections
  73  */
  74 void Server_Start(void)
  75 {
  76          int    server_socket, client_socket;
  77         struct sockaddr_in      server_addr, client_addr;
  78
  79         // Create Server
  80         server_socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
  81         if( server_socket < 0 ) {
  82                 fprintf(stderr, "ERROR: Unable to create server socket\n");
  83                 return ;
  84         }
  85
  86         // Make listen address
  87         memset(&server_addr, 0, sizeof(server_addr));
  88         server_addr.sin_family = AF_INET;       // Internet Socket
  89         server_addr.sin_addr.s_addr = htonl(INADDR_ANY);        // Listen on all interfaces
  90         server_addr.sin_port = htons(giServer_Port);    // Port
  91
  92         // Bind
  93         if( bind(server_socket, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0 ) {
  94                 fprintf(stderr, "ERROR: Unable to bind to 0.0.0.0:%i\n", giServer_Port);
  95                 return ;
  96         }
  97
  98         // Listen
  99         if( listen(server_socket, MAX_CONNECTION_QUEUE) < 0 ) {
 100                 fprintf(stderr, "ERROR: Unable to listen to socket\n");
 101                 return ;
 102         }
 103
 104         printf("Listening on 0.0.0.0:%i\n", giServer_Port);
 105
 106         for(;;)
 107         {
 108                 uint    len = sizeof(client_addr);
 109                  int    bTrusted = 0;
 110
 111                 client_socket = accept(server_socket, (struct sockaddr *) &client_addr, &len);
 112                 if(client_socket < 0) {
 113                         fprintf(stderr, "ERROR: Unable to accept client connection\n");
 114                         return ;
 115                 }
 116
 117                 if(giDebugLevel >= 2) {
 118                         char    ipstr[INET_ADDRSTRLEN];
 119                         inet_ntop(AF_INET, &client_addr.sin_addr, ipstr, INET_ADDRSTRLEN);
 120                         printf("Client connection from %s:%i\n",
 121                                 ipstr, ntohs(client_addr.sin_port));
 122                 }
 123
 124                 // Trusted Connections
 125                 if( ntohs(client_addr.sin_port) < 1024 )
 126                 {
 127                         // TODO: Make this runtime configurable
 128                         switch( ntohl( client_addr.sin_addr.s_addr ) )
 129                         {
 130                         case 0x7F000001:        // 127.0.0.1    localhost
 131                         //case 0x825E0D00:      // 130.95.13.0
 132                         case 0x825E0D12:        // 130.95.13.18 mussel
 133                         case 0x825E0D17:        // 130.95.13.23 martello
 134                                 bTrusted = 1;
 135                                 break;
 136                         default:
 137                                 break;
 138                         }
 139                 }
 140
 141                 // TODO: Multithread this?
 142                 Server_HandleClient(client_socket, bTrusted);
 143
 144                 close(client_socket);
 145         }
 146 }
 147
 148 /**
 149  * \brief Reads from a client socket and parses the command strings
 150  * \param Socket        Client socket number/handle
 151  * \param bTrusted      Is the client trusted?
 152  */
 153 void Server_HandleClient(int Socket, int bTrusted)
 154 {
 155         char    inbuf[INPUT_BUFFER_SIZE];
 156         char    *buf = inbuf;
 157          int    remspace = INPUT_BUFFER_SIZE-1;
 158          int    bytes = -1;
 159         tClient clientInfo = {0};
 160
 161         // Initialise Client info
 162         clientInfo.ID = giServer_NextClientID ++;
 163         clientInfo.bIsTrusted = bTrusted;
 164
 165         // Read from client
 166         /*
 167          * Notes:
 168          * - The `buf` and `remspace` variables allow a line to span several
 169          *   calls to recv(), if a line is not completed in one recv() call
 170          *   it is saved to the beginning of `inbuf` and `buf` is updated to
 171          *   the end of it.
 172          */
 173         while( (bytes = recv(Socket, buf, remspace, 0)) > 0 )
 174         {
 175                 char    *eol, *start;
 176                 buf[bytes] = '\0';      // Allow us to use stdlib string functions on it
 177
 178                 // Split by lines
 179                 start = inbuf;
 180                 while( (eol = strchr(start, '\n')) )
 181                 {
 182                         char    *ret;
 183                         *eol = '\0';
 184                         ret = Server_ParseClientCommand(&clientInfo, start);
 185                         // `ret` is a string on the heap
 186                         send(Socket, ret, strlen(ret), 0);
 187                         free(ret);
 188                         start = eol + 1;
 189                 }
 190
 191                 // Check if there was an incomplete line
 192                 if( *start != '\0' ) {
 193                          int    tailBytes = bytes - (start-buf);
 194                         // Roll back in buffer
 195                         memcpy(inbuf, start, tailBytes);
 196                         remspace -= tailBytes;
 197                         if(remspace == 0) {
 198                                 send(Socket, MSG_STR_TOO_LONG, sizeof(MSG_STR_TOO_LONG), 0);
 199                                 buf = inbuf;
 200                                 remspace = INPUT_BUFFER_SIZE - 1;
 201                         }
 202                 }
 203                 else {
 204                         buf = inbuf;
 205                         remspace = INPUT_BUFFER_SIZE - 1;
 206                 }
 207         }
 208
 209         // Check for errors
 210         if( bytes < 0 ) {
 211                 fprintf(stderr, "ERROR: Unable to recieve from client on socket %i\n", Socket);
 212                 return ;
 213         }
 214
 215         if(giDebugLevel >= 2) {
 216                 printf("Client %i: Disconnected\n", clientInfo.ID);
 217         }
 218 }
 219
 220 /**
 221  * \brief Parses a client command and calls the required helper function
 222  * \param Client        Pointer to client state structure
 223  * \param CommandString Command from client (single line of the command)
 224  * \return Heap String to return to the client
 225  */
 226 char *Server_ParseClientCommand(tClient *Client, char *CommandString)
 227 {
 228         char    *space, *args;
 229          int    i;
 230
 231         // Split at first space
 232         space = strchr(CommandString, ' ');
 233         if(space == NULL) {
 234                 args = NULL;
 235         }
 236         else {
 237                 *space = '\0';
 238                 args = space + 1;
 239         }
 240
 241         // Find command
 242         for( i = 0; i < NUM_COMMANDS; i++ )
 243         {
 244                 if(strcmp(CommandString, gaServer_Commands[i].Name) == 0)
 245                         return gaServer_Commands[i].Function(Client, args);
 246         }
 247
 248         return strdup("400 Unknown Command\n");
 249 }
 250
 251 // ---
 252 // Commands
 253 // ---
 254 /**
 255  * \brief Set client username
 256  *
 257  * Usage: USER <username>
 258  */
 259 char *Server_Cmd_USER(tClient *Client, char *Args)
 260 {
 261         char    *ret;
 262
 263         // Debug!
 264         if( giDebugLevel )
 265                 printf("Client %i authenticating as '%s'\n", Client->ID, Args);
 266
 267         // Save username
 268         if(Client->Username)
 269                 free(Client->Username);
 270         Client->Username = strdup(Args);
 271
 272         #if USE_SALT
 273         // Create a salt (that changes if the username is changed)
 274         // Yes, I know, I'm a little paranoid, but who isn't?
 275         Client->Salt[0] = 0x21 + (rand()&0x3F);
 276         Client->Salt[1] = 0x21 + (rand()&0x3F);
 277         Client->Salt[2] = 0x21 + (rand()&0x3F);
 278         Client->Salt[3] = 0x21 + (rand()&0x3F);
 279         Client->Salt[4] = 0x21 + (rand()&0x3F);
 280         Client->Salt[5] = 0x21 + (rand()&0x3F);
 281         Client->Salt[6] = 0x21 + (rand()&0x3F);
 282         Client->Salt[7] = 0x21 + (rand()&0x3F);
 283
 284         // "100 Salt xxxxXXXX\n"
 285         ret = strdup("100 SALT xxxxXXXX\n");
 286         sprintf(ret, "100 SALT %s\n", Client->Salt);
 287         #else
 288         ret = strdup("100 User Set\n");
 289         #endif
 290         return ret;
 291 }
 292
 293 /**
 294  * \brief Authenticate as a user
 295  *
 296  * Usage: PASS <hash>
 297  */
 298 char *Server_Cmd_PASS(tClient *Client, char *Args)
 299 {
 300         uint8_t clienthash[HASH_LENGTH] = {0};
 301
 302         // Read user's hash
 303         HexBin(clienthash, Args, HASH_LENGTH);
 304
 305         if( giDebugLevel ) {
 306                  int    i;
 307                 printf("Client %i: Password hash ", Client->ID);
 308                 for(i=0;i<HASH_LENGTH;i++)
 309                         printf("%02x", clienthash[i]&0xFF);
 310                 printf("\n");
 311         }
 312
 313         return strdup("401 Auth Failure\n");
 314 }
 315
 316 /**
 317  * \brief Authenticate as a user without a password
 318  *
 319  * Usage: AUTOAUTH <user>
 320  */
 321 char *Server_Cmd_AUTOAUTH(tClient *Client, char *Args)
 322 {
 323         char    *spos = strchr(Args, ' ');
 324         if(spos)        *spos = '\0';   // Remove characters after the ' '
 325
 326         // Check if trusted
 327         if( !Client->bIsTrusted ) {
 328                 if(giDebugLevel)
 329                         printf("Client %i: Untrusted client attempting to AUTOAUTH\n", Client->ID);
 330                 return strdup("401 Untrusted\n");
 331         }
 332
 333         // Get UID
 334         Client->UID = GetUserID( Args );
 335         if( Client->UID < 0 ) {
 336                 if(giDebugLevel)
 337                         printf("Client %i: Unknown user '%s'\n", Client->ID, Args);
 338                 return strdup("401 Auth Failure\n");
 339         }
 340
 341         if(giDebugLevel)
 342                 printf("Client %i: Authenticated as '%s' (%i)\n", Client->ID, Args, Client->UID);
 343
 344         return strdup("200 Auth OK\n");
 345 }
 346
 347 /**
 348  * \brief Enumerate the items that the server knows about
 349  */
 350 char *Server_Cmd_ENUMITEMS(tClient *Client, char *Args)
 351 {
 352 //       int    nItems = giNumItems;
 353          int    retLen;
 354          int    i;
 355         char    *ret;
 356
 357         retLen = snprintf(NULL, 0, "201 Items %i", giNumItems);
 358
 359         for( i = 0; i < giNumItems; i ++ )
 360         {
 361                 retLen += snprintf(NULL, 0, " %s:%i", gaItems[i].Handler->Name, gaItems[i].ID);
 362         }
 363
 364         ret = malloc(retLen+1);
 365         retLen = 0;
 366         retLen += sprintf(ret+retLen, "201 Items %i", giNumItems);
 367
 368         for( i = 0; i < giNumItems; i ++ ) {
 369                 retLen += sprintf(ret+retLen, " %s:%i", gaItems[i].Handler->Name, gaItems[i].ID);
 370         }
 371
 372         strcat(ret, "\n");
 373
 374         return ret;
 375 }
 376
 377 /**
 378  * \brief Fetch information on a specific item
 379  */
 380 char *Server_Cmd_ITEMINFO(tClient *Client, char *Args)
 381 {
 382          int    retLen = 0;
 383         char    *ret;
 384         tItem   *item;
 385         tHandler        *handler;
 386         char    *type = Args;
 387         char    *colon = strchr(Args, ':');
 388          int    num, i;
 389
 390         if( !colon ) {
 391                 return strdup("406 Bad Item ID\n");
 392         }
 393
 394         num = atoi(colon+1);
 395         *colon = '\0';
 396
 397         // Find handler
 398         handler = NULL;
 399         for( i = 0; i < giNumHandlers; i ++ )
 400         {
 401                 if( strcmp(gaHandlers[i]->Name, type) == 0) {
 402                         handler = gaHandlers[i];
 403                         break;
 404                 }
 405         }
 406         if( !handler ) {
 407                 return strdup("406 Bad Item ID\n");
 408         }
 409
 410         // Find item
 411         for( i = 0; i < giNumItems; i ++ )
 412         {
 413                 if( gaItems[i].Handler != handler )     continue;
 414                 if( gaItems[i].ID != num )      continue;
 415                 item = &gaItems[i];
 416                 break;
 417         }
 418         if( !item ) {
 419                 return strdup("406 Bad Item ID\n");
 420         }
 421
 422         // Create return
 423         retLen = snprintf(NULL, 0, "202 Item %s:%i %i %s\n",
 424                 handler->Name, item->ID, item->Price, item->Name);
 425         ret = malloc(retLen+1);
 426         sprintf(ret, "202 Item %s:%i %i %s\n",
 427                 handler->Name, item->ID, item->Price, item->Name);
 428
 429         return ret;
 430 }
 431
 432 // --- INTERNAL HELPERS ---
 433 // TODO: Move to another file
 434 void HexBin(uint8_t *Dest, char *Src, int BufSize)
 435 {
 436          int    i;
 437         for( i = 0; i < BufSize; i ++ )
 438         {
 439                 uint8_t val = 0;
 440
 441                 if('0' <= *Src && *Src <= '9')
 442                         val |= (*Src-'0') << 4;
 443                 else if('A' <= *Src && *Src <= 'F')
 444                         val |= (*Src-'A'+10) << 4;
 445                 else if('a' <= *Src && *Src <= 'f')
 446                         val |= (*Src-'a'+10) << 4;
 447                 else
 448                         break;
 449                 Src ++;
 450
 451                 if('0' <= *Src && *Src <= '9')
 452                         val |= (*Src-'0');
 453                 else if('A' <= *Src && *Src <= 'F')
 454                         val |= (*Src-'A'+10);
 455                 else if('a' <= *Src && *Src <= 'f')
 456                         val |= (*Src-'a'+10);
 457                 else
 458                         break;
 459                 Src ++;
 460
 461                 Dest[i] = val;
 462         }
 463         for( ; i < BufSize; i++ )
 464                 Dest[i] = 0;
 465 }
 466
 467 /**
 468  * \brief Decode a Base64 value
 469  */
 470 int UnBase64(uint8_t *Dest, char *Src, int BufSize)
 471 {
 472         uint32_t        val;
 473          int    i, j;
 474         char    *start_src = Src;
 475
 476         for( i = 0; i+2 < BufSize; i += 3 )
 477         {
 478                 val = 0;
 479                 for( j = 0; j < 4; j++, Src ++ ) {
 480                         if('A' <= *Src && *Src <= 'Z')
 481                                 val |= (*Src - 'A') << ((3-j)*6);
 482                         else if('a' <= *Src && *Src <= 'z')
 483                                 val |= (*Src - 'a' + 26) << ((3-j)*6);
 484                         else if('0' <= *Src && *Src <= '9')
 485                                 val |= (*Src - '0' + 52) << ((3-j)*6);
 486                         else if(*Src == '+')
 487                                 val |= 62 << ((3-j)*6);
 488                         else if(*Src == '/')
 489                                 val |= 63 << ((3-j)*6);
 490                         else if(!*Src)
 491                                 break;
 492                         else if(*Src != '=')
 493                                 j --;   // Ignore invalid characters
 494                 }
 495                 Dest[i  ] = (val >> 16) & 0xFF;
 496                 Dest[i+1] = (val >> 8) & 0xFF;
 497                 Dest[i+2] = val & 0xFF;
 498                 if(j != 4)      break;
 499         }
 500
 501         // Finish things off
 502         if(i   < BufSize)
 503                 Dest[i] = (val >> 16) & 0xFF;
 504         if(i+1 < BufSize)
 505                 Dest[i+1] = (val >> 8) & 0xFF;
 506
 507         return Src - start_src;
 508 }