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    UID;
  25          int    bIsAuthed;
  26 }       tClient;
  27
  28 // === PROTOTYPES ===
  29 void    Server_Start(void);
  30 void    Server_HandleClient(int Socket);
  31 char    *Server_ParseClientCommand(tClient *Client, char *CommandString);
  32 char    *Server_Cmd_USER(tClient *Client, char *Args);
  33
  34 // === GLOBALS ===
  35  int    giServer_Port = 1020;
  36  int    giServer_NextClientID = 1;
  37 // - Commands
  38 struct sClientCommand {
  39         char    *Name;
  40         char    *(*Function)(tClient *Client, char *Arguments);
  41 }       gaServer_Commands[] = {
  42         {"USER", Server_Cmd_USER}
  43 };
  44 #define NUM_COMMANDS    (sizeof(gaServer_Commands)/sizeof(gaServer_Commands[0]))
  45
  46 // === CODE ===
  47 /**
  48  * \brief Open listenting socket and serve connections
  49  */
  50 void Server_Start(void)
  51 {
  52         // Create Server
  53 }
  54
  55 /**
  56  * \brief Reads from a client socket and parses the command strings
  57  */
  58 void Server_HandleClient(int Socket)
  59 {
  60         char    inbuf[INPUT_BUFFER_SIZE];
  61         char    *buf = inbuf;
  62          int    remspace = INPUT_BUFFER_SIZE-1;
  63          int    bytes = -1;
  64         tClient clientInfo = {0};
  65
  66         // Read from client
  67         while( (bytes = recv(Socket, buf, remspace, 0)) > 0 )
  68         {
  69                 char    *eol, *start;
  70                 buf[bytes] = '\0';      // Allow us to use stdlib string functions on it
  71
  72                 // Split by lines
  73                 start = inbuf;
  74                 while( (eol = strchr(start, '\n')) )
  75                 {
  76                         char    *ret;
  77                         *eol = '\0';
  78                         ret = Server_ParseClientCommand(&clientInfo, start);
  79                         // `ret` is a string on the heap
  80                         send(Socket, ret, strlen(ret), 0);
  81                         free(ret);
  82                         start = eol + 1;
  83                 }
  84
  85                 // Check if there was an incomplete line
  86                 if( *start != '\0' ) {
  87                          int    tailBytes = bytes - (start-buf);
  88                         // Roll back in buffer
  89                         memcpy(inbuf, start, tailBytes);
  90                         remspace -= tailBytes;
  91                         if(remspace == 0) {
  92                                 send(Socket, MSG_STR_TOO_LONG, sizeof(MSG_STR_TOO_LONG), 0);
  93                                 buf = inbuf;
  94                                 remspace = INPUT_BUFFER_SIZE - 1;
  95                         }
  96                 }
  97                 else {
  98                         buf = inbuf;
  99                         remspace = INPUT_BUFFER_SIZE - 1;
 100                 }
 101         }
 102
 103         // Check for errors
 104         if( bytes < 0 ) {
 105                 fprintf(stderr, "ERROR: Unable to recieve from client on socket %i\n", Socket);
 106                 return ;
 107         }
 108 }
 109
 110 /**
 111  * \brief Parses a client command and calls the required helper function
 112  * \param Client        Pointer to client state structure
 113  */
 114 char *Server_ParseClientCommand(tClient *Client, char *CommandString)
 115 {
 116         char    *space, *args;
 117          int    i;
 118
 119         // Split at first space
 120         space = strchr(CommandString, ' ');
 121         if(space == NULL) {
 122                 args = NULL;
 123         }
 124         else {
 125                 *space = '\0';
 126                 args = space + 1;
 127         }
 128
 129         // Find command
 130         for( i = 0; i < NUM_COMMANDS; i++ )
 131         {
 132                 if(strcmp(CommandString, gaServer_Commands[i].Name) == 0)
 133                         return gaServer_Commands[i].Function(Client, args);
 134         }
 135
 136         return strdup("400      Unknown Command\n");
 137 }
 138
 139 // ---
 140 // Commands
 141 // ---
 142 /**
 143  * \brief Set client username
 144  */
 145 char *Server_Cmd_USER(tClient *Client, char *Args)
 146 {
 147         char    *ret;
 148
 149         // Debug!
 150         if( gbDebugLevel )
 151                 printf("Client %i authenticating as '%s'\n", Args);
 152
 153         // Save username
 154         if(Client->Username)
 155                 free(Client->Username);
 156         Client->Username = strdup(Args);
 157
 158         // Create a salt (that changes if the username is changed)
 159         if(!Client->Salt)
 160                 Client->Salt = malloc(9);
 161         Client->Salt[0] = 0x21 + (rand()&0x3F);
 162         Client->Salt[1] = 0x21 + (rand()&0x3F);
 163         Client->Salt[2] = 0x21 + (rand()&0x3F);
 164         Client->Salt[3] = 0x21 + (rand()&0x3F);
 165         Client->Salt[4] = 0x21 + (rand()&0x3F);
 166         Client->Salt[5] = 0x21 + (rand()&0x3F);
 167         Client->Salt[6] = 0x21 + (rand()&0x3F);
 168         Client->Salt[7] = 0x21 + (rand()&0x3F);
 169
 170         // "100 Salt xxxxXXXX\n"
 171         ret = strdup("100 SALT xxxxXXXX\n");
 172         sprintf(ret, "100 SALT %s\n", Client->Salt);
 173
 174         return ret;
 175 }