server/src/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 // --- Helpers ---
  50 void    HexBin(uint8_t *Dest, char *Src, int BufSize);
  51
  52 // === GLOBALS ===
  53  int    giServer_Port = 1020;
  54  int    giServer_NextClientID = 1;
  55 // - Commands
  56 struct sClientCommand {
  57         char    *Name;
  58         char    *(*Function)(tClient *Client, char *Arguments);
  59 }       gaServer_Commands[] = {
  60         {"USER", Server_Cmd_USER},
  61         {"PASS", Server_Cmd_PASS},
  62         {"AUTOAUTH", Server_Cmd_AUTOAUTH}
  63 };
  64 #define NUM_COMMANDS    (sizeof(gaServer_Commands)/sizeof(gaServer_Commands[0]))
  65
  66 // === CODE ===
  67 /**
  68  * \brief Open listenting socket and serve connections
  69  */
  70 void Server_Start(void)
  71 {
  72          int    server_socket, client_socket;
  73         struct sockaddr_in      server_addr, client_addr;
  74
  75         // Create Server
  76         server_socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
  77         if( server_socket < 0 ) {
  78                 fprintf(stderr, "ERROR: Unable to create server socket\n");
  79                 return ;
  80         }
  81
  82         // Make listen address
  83         memset(&server_addr, 0, sizeof(server_addr));
  84         server_addr.sin_family = AF_INET;       // Internet Socket
  85         server_addr.sin_addr.s_addr = htonl(INADDR_ANY);        // Listen on all interfaces
  86         server_addr.sin_port = htons(giServer_Port);    // Port
  87
  88         // Bind
  89         if( bind(server_socket, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0 ) {
  90                 fprintf(stderr, "ERROR: Unable to bind to 0.0.0.0:%i\n", giServer_Port);
  91                 return ;
  92         }
  93
  94         // Listen
  95         if( listen(server_socket, MAX_CONNECTION_QUEUE) < 0 ) {
  96                 fprintf(stderr, "ERROR: Unable to listen to socket\n");
  97                 return ;
  98         }
  99
 100         printf("Listening on 0.0.0.0:%i\n", giServer_Port);
 101
 102         for(;;)
 103         {
 104                 uint    len = sizeof(client_addr);
 105                  int    bTrusted = 0;
 106
 107                 client_socket = accept(server_socket, (struct sockaddr *) &client_addr, &len);
 108                 if(client_socket < 0) {
 109                         fprintf(stderr, "ERROR: Unable to accept client connection\n");
 110                         return ;
 111                 }
 112
 113                 if(giDebugLevel >= 2) {
 114                         char    ipstr[INET_ADDRSTRLEN];
 115                         inet_ntop(AF_INET, &client_addr.sin_addr, ipstr, INET_ADDRSTRLEN);
 116                         printf("Client connection from %s:%i\n",
 117                                 ipstr, ntohs(client_addr.sin_port));
 118                 }
 119
 120                 // Trusted Connections
 121                 if( ntohs(client_addr.sin_port) < 1024 )
 122                 {
 123                         // TODO: Make this runtime configurable
 124                         switch( ntohl( client_addr.sin_addr.s_addr ) )
 125                         {
 126                         case 0x7F000001:        // 127.0.0.1    localhost
 127                         //case 0x825E0D00:      // 130.95.13.0
 128                         case 0x825E0D12:        // 130.95.13.18 mussel
 129                         case 0x825E0D17:        // 130.95.13.23 martello
 130                                 bTrusted = 1;
 131                                 break;
 132                         default:
 133                                 break;
 134                         }
 135                 }
 136
 137                 // TODO: Multithread this?
 138                 Server_HandleClient(client_socket, bTrusted);
 139
 140                 close(client_socket);
 141         }
 142 }
 143
 144 /**
 145  * \brief Reads from a client socket and parses the command strings
 146  * \param Socket        Client socket number/handle
 147  * \param bTrusted      Is the client trusted?
 148  */
 149 void Server_HandleClient(int Socket, int bTrusted)
 150 {
 151         char    inbuf[INPUT_BUFFER_SIZE];
 152         char    *buf = inbuf;
 153          int    remspace = INPUT_BUFFER_SIZE-1;
 154          int    bytes = -1;
 155         tClient clientInfo = {0};
 156
 157         // Initialise Client info
 158         clientInfo.ID = giServer_NextClientID ++;
 159         clientInfo.bIsTrusted = bTrusted;
 160
 161         // Read from client
 162         /*
 163          * Notes:
 164          * - The `buf` and `remspace` variables allow a line to span several
 165          *   calls to recv(), if a line is not completed in one recv() call
 166          *   it is saved to the beginning of `inbuf` and `buf` is updated to
 167          *   the end of it.
 168          */
 169         while( (bytes = recv(Socket, buf, remspace, 0)) > 0 )
 170         {
 171                 char    *eol, *start;
 172                 buf[bytes] = '\0';      // Allow us to use stdlib string functions on it
 173
 174                 // Split by lines
 175                 start = inbuf;
 176                 while( (eol = strchr(start, '\n')) )
 177                 {
 178                         char    *ret;
 179                         *eol = '\0';
 180                         ret = Server_ParseClientCommand(&clientInfo, start);
 181                         // `ret` is a string on the heap
 182                         send(Socket, ret, strlen(ret), 0);
 183                         free(ret);
 184                         start = eol + 1;
 185                 }
 186
 187                 // Check if there was an incomplete line
 188                 if( *start != '\0' ) {
 189                          int    tailBytes = bytes - (start-buf);
 190                         // Roll back in buffer
 191                         memcpy(inbuf, start, tailBytes);
 192                         remspace -= tailBytes;
 193                         if(remspace == 0) {
 194                                 send(Socket, MSG_STR_TOO_LONG, sizeof(MSG_STR_TOO_LONG), 0);
 195                                 buf = inbuf;
 196                                 remspace = INPUT_BUFFER_SIZE - 1;
 197                         }
 198                 }
 199                 else {
 200                         buf = inbuf;
 201                         remspace = INPUT_BUFFER_SIZE - 1;
 202                 }
 203         }
 204
 205         // Check for errors
 206         if( bytes < 0 ) {
 207                 fprintf(stderr, "ERROR: Unable to recieve from client on socket %i\n", Socket);
 208                 return ;
 209         }
 210
 211         if(giDebugLevel >= 2) {
 212                 printf("Client %i: Disconnected\n", clientInfo.ID);
 213         }
 214 }
 215
 216 /**
 217  * \brief Parses a client command and calls the required helper function
 218  * \param Client        Pointer to client state structure
 219  * \param CommandString Command from client (single line of the command)
 220  * \return Heap String to return to the client
 221  */
 222 char *Server_ParseClientCommand(tClient *Client, char *CommandString)
 223 {
 224         char    *space, *args;
 225          int    i;
 226
 227         // Split at first space
 228         space = strchr(CommandString, ' ');
 229         if(space == NULL) {
 230                 args = NULL;
 231         }
 232         else {
 233                 *space = '\0';
 234                 args = space + 1;
 235         }
 236
 237         // Find command
 238         for( i = 0; i < NUM_COMMANDS; i++ )
 239         {
 240                 if(strcmp(CommandString, gaServer_Commands[i].Name) == 0)
 241                         return gaServer_Commands[i].Function(Client, args);
 242         }
 243
 244         return strdup("400      Unknown Command\n");
 245 }
 246
 247 // ---
 248 // Commands
 249 // ---
 250 /**
 251  * \brief Set client username
 252  *
 253  * Usage: USER <username>
 254  */
 255 char *Server_Cmd_USER(tClient *Client, char *Args)
 256 {
 257         char    *ret;
 258
 259         // Debug!
 260         if( giDebugLevel )
 261                 printf("Client %i authenticating as '%s'\n", Client->ID, Args);
 262
 263         // Save username
 264         if(Client->Username)
 265                 free(Client->Username);
 266         Client->Username = strdup(Args);
 267
 268         #if USE_SALT
 269         // Create a salt (that changes if the username is changed)
 270         // Yes, I know, I'm a little paranoid, but who isn't?
 271         Client->Salt[0] = 0x21 + (rand()&0x3F);
 272         Client->Salt[1] = 0x21 + (rand()&0x3F);
 273         Client->Salt[2] = 0x21 + (rand()&0x3F);
 274         Client->Salt[3] = 0x21 + (rand()&0x3F);
 275         Client->Salt[4] = 0x21 + (rand()&0x3F);
 276         Client->Salt[5] = 0x21 + (rand()&0x3F);
 277         Client->Salt[6] = 0x21 + (rand()&0x3F);
 278         Client->Salt[7] = 0x21 + (rand()&0x3F);
 279
 280         // "100 Salt xxxxXXXX\n"
 281         ret = strdup("100 SALT xxxxXXXX\n");
 282         sprintf(ret, "100 SALT %s\n", Client->Salt);
 283         #else
 284         ret = strdup("100 User Set\n");
 285         #endif
 286         return ret;
 287 }
 288
 289 /**
 290  * \brief Authenticate as a user
 291  *
 292  * Usage: PASS <hash>
 293  */
 294 char *Server_Cmd_PASS(tClient *Client, char *Args)
 295 {
 296         uint8_t clienthash[HASH_LENGTH] = {0};
 297
 298         // Read user's hash
 299         HexBin(clienthash, Args, HASH_LENGTH);
 300
 301         if( giDebugLevel ) {
 302                  int    i;
 303                 printf("Client %i: Password hash ", Client->ID);
 304                 for(i=0;i<HASH_LENGTH;i++)
 305                         printf("%02x", clienthash[i]&0xFF);
 306                 printf("\n");
 307         }
 308
 309         return strdup("401 Auth Failure\n");
 310 }
 311
 312 /**
 313  * \brief Authenticate as a user without a password
 314  *
 315  * Usage: AUTOAUTH <user>
 316  */
 317 char *Server_Cmd_AUTOAUTH(tClient *Client, char *Args)
 318 {
 319         char    *spos = strchr(Args, ' ');
 320         if(spos)        *spos = '\0';   // Remove characters after the ' '
 321
 322         // Check if trusted
 323         if( !Client->bIsTrusted ) {
 324                 if(giDebugLevel)
 325                         printf("Client %i: Untrusted client attempting to AUTOAUTH\n", Client->ID);
 326                 return strdup("401 Untrusted\n");
 327         }
 328
 329         // Get UID
 330         Client->UID = GetUserID( Args );
 331         if( Client->UID <= 0 ) {
 332                 if(giDebugLevel)
 333                         printf("Client %i: Unknown user '%s'\n", Client->ID, Args);
 334                 return strdup("401 Auth Failure\n");
 335         }
 336
 337         if(giDebugLevel)
 338                 printf("Client %i: Authenticated as '%s' (%i)\n", Client->ID, Args, Client->UID);
 339
 340         return strdup("200 Auth OK\n");
 341 }
 342
 343 // --- INTERNAL HELPERS ---
 344 // TODO: Move to another file
 345 void HexBin(uint8_t *Dest, char *Src, int BufSize)
 346 {
 347          int    i;
 348         for( i = 0; i < BufSize; i ++ )
 349         {
 350                 uint8_t val = 0;
 351
 352                 if('0' <= *Src && *Src <= '9')
 353                         val |= (*Src-'0') << 4;
 354                 else if('A' <= *Src && *Src <= 'F')
 355                         val |= (*Src-'A'+10) << 4;
 356                 else if('a' <= *Src && *Src <= 'f')
 357                         val |= (*Src-'a'+10) << 4;
 358                 else
 359                         break;
 360                 Src ++;
 361
 362                 if('0' <= *Src && *Src <= '9')
 363                         val |= (*Src-'0');
 364                 else if('A' <= *Src && *Src <= 'F')
 365                         val |= (*Src-'A'+10);
 366                 else if('a' <= *Src && *Src <= 'f')
 367                         val |= (*Src-'a'+10);
 368                 else
 369                         break;
 370                 Src ++;
 371
 372                 Dest[i] = val;
 373         }
 374         for( ; i < BufSize; i++ )
 375                 Dest[i] = 0;
 376 }