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 <string.h>
  15
  16 #define MAX_CONNECTION_QUEUE    5
  17 #define INPUT_BUFFER_SIZE       128
  18
  19 #define MSG_STR_TOO_LONG        "499 Command too long (limit "EXPSTR(INPUT_BUFFER_SIZE)")\n"
  20
  21 // === TYPES ===
  22 typedef struct sClient
  23 {
  24          int    ID;     // Client ID
  25
  26         char    *Username;
  27         char    Salt[9];
  28
  29          int    UID;
  30          int    bIsAuthed;
  31 }       tClient;
  32
  33 // === PROTOTYPES ===
  34 void    Server_Start(void);
  35 void    Server_HandleClient(int Socket);
  36 char    *Server_ParseClientCommand(tClient *Client, char *CommandString);
  37 char    *Server_Cmd_USER(tClient *Client, char *Args);
  38
  39 // === GLOBALS ===
  40  int    giServer_Port = 1020;
  41  int    giServer_NextClientID = 1;
  42 // - Commands
  43 struct sClientCommand {
  44         char    *Name;
  45         char    *(*Function)(tClient *Client, char *Arguments);
  46 }       gaServer_Commands[] = {
  47         {"USER", Server_Cmd_USER}
  48 };
  49 #define NUM_COMMANDS    (sizeof(gaServer_Commands)/sizeof(gaServer_Commands[0]))
  50
  51 // === CODE ===
  52 /**
  53  * \brief Open listenting socket and serve connections
  54  */
  55 void Server_Start(void)
  56 {
  57         // Create Server
  58 }
  59
  60 /**
  61  * \brief Reads from a client socket and parses the command strings
  62  */
  63 void Server_HandleClient(int Socket)
  64 {
  65         char    inbuf[INPUT_BUFFER_SIZE];
  66         char    *buf = inbuf;
  67          int    remspace = INPUT_BUFFER_SIZE-1;
  68          int    bytes = -1;
  69         tClient clientInfo = {0};
  70
  71         // Initialise Client info
  72         clientInfo.ID = giServer_NextClientID ++;
  73
  74         // Read from client
  75         /*
  76          * Notes:
  77          * - The `buf` and `remspace` variables allow a line to span several
  78          *   calls to recv(), if a line is not completed in one recv() call
  79          *   it is saved to the beginning of `inbuf` and `buf` is updated to
  80          *   the end of it.
  81          */
  82         while( (bytes = recv(Socket, buf, remspace, 0)) > 0 )
  83         {
  84                 char    *eol, *start;
  85                 buf[bytes] = '\0';      // Allow us to use stdlib string functions on it
  86
  87                 // Split by lines
  88                 start = inbuf;
  89                 while( (eol = strchr(start, '\n')) )
  90                 {
  91                         char    *ret;
  92                         *eol = '\0';
  93                         ret = Server_ParseClientCommand(&clientInfo, start);
  94                         // `ret` is a string on the heap
  95                         send(Socket, ret, strlen(ret), 0);
  96                         free(ret);
  97                         start = eol + 1;
  98                 }
  99
 100                 // Check if there was an incomplete line
 101                 if( *start != '\0' ) {
 102                          int    tailBytes = bytes - (start-buf);
 103                         // Roll back in buffer
 104                         memcpy(inbuf, start, tailBytes);
 105                         remspace -= tailBytes;
 106                         if(remspace == 0) {
 107                                 send(Socket, MSG_STR_TOO_LONG, sizeof(MSG_STR_TOO_LONG), 0);
 108                                 buf = inbuf;
 109                                 remspace = INPUT_BUFFER_SIZE - 1;
 110                         }
 111                 }
 112                 else {
 113                         buf = inbuf;
 114                         remspace = INPUT_BUFFER_SIZE - 1;
 115                 }
 116         }
 117
 118         // Check for errors
 119         if( bytes < 0 ) {
 120                 fprintf(stderr, "ERROR: Unable to recieve from client on socket %i\n", Socket);
 121                 return ;
 122         }
 123 }
 124
 125 /**
 126  * \brief Parses a client command and calls the required helper function
 127  * \param Client        Pointer to client state structure
 128  */
 129 char *Server_ParseClientCommand(tClient *Client, char *CommandString)
 130 {
 131         char    *space, *args;
 132          int    i;
 133
 134         // Split at first space
 135         space = strchr(CommandString, ' ');
 136         if(space == NULL) {
 137                 args = NULL;
 138         }
 139         else {
 140                 *space = '\0';
 141                 args = space + 1;
 142         }
 143
 144         // Find command
 145         for( i = 0; i < NUM_COMMANDS; i++ )
 146         {
 147                 if(strcmp(CommandString, gaServer_Commands[i].Name) == 0)
 148                         return gaServer_Commands[i].Function(Client, args);
 149         }
 150
 151         return strdup("400      Unknown Command\n");
 152 }
 153
 154 // ---
 155 // Commands
 156 // ---
 157 /**
 158  * \brief Set client username
 159  */
 160 char *Server_Cmd_USER(tClient *Client, char *Args)
 161 {
 162         char    *ret;
 163
 164         // Debug!
 165         if( giDebugLevel )
 166                 printf("Client %i authenticating as '%s'\n", Client->ID, Args);
 167
 168         // Save username
 169         if(Client->Username)
 170                 free(Client->Username);
 171         Client->Username = strdup(Args);
 172
 173         // Create a salt (that changes if the username is changed)
 174         Client->Salt[0] = 0x21 + (rand()&0x3F);
 175         Client->Salt[1] = 0x21 + (rand()&0x3F);
 176         Client->Salt[2] = 0x21 + (rand()&0x3F);
 177         Client->Salt[3] = 0x21 + (rand()&0x3F);
 178         Client->Salt[4] = 0x21 + (rand()&0x3F);
 179         Client->Salt[5] = 0x21 + (rand()&0x3F);
 180         Client->Salt[6] = 0x21 + (rand()&0x3F);
 181         Client->Salt[7] = 0x21 + (rand()&0x3F);
 182
 183         // "100 Salt xxxxXXXX\n"
 184         ret = strdup("100 SALT xxxxXXXX\n");
 185         sprintf(ret, "100 SALT %s\n", Client->Salt);
 186
 187         return ret;
 188 }