src/misc-progs/captivectrl.c

   1 /* This file is part of the IPFire Firewall.
   2 *
   3 * This program is distributed under the terms of the GNU General Public
   4 * Licence.  See the file COPYING for details. */
   5
   6 #define _BSD_SOURCE
   7 #define _XOPEN_SOURCE
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <time.h>
  13
  14 #include "libsmooth.h"
  15 #include "setuid.h"
  16
  17 #define CAPTIVE_PORTAL_SETTINGS         CONFIG_ROOT "/captive/settings"
  18 #define ETHERNET_SETTINGS               CONFIG_ROOT "/ethernet/settings"
  19
  20 #define CLIENTS                         CONFIG_ROOT "/captive/clients"
  21 #define IPTABLES                        "/sbin/iptables --wait"
  22 #define HTTP_PORT                       80
  23 #define REDIRECT_PORT                   1013
  24
  25 typedef struct client {
  26         char etheraddr[STRING_SIZE];
  27         char ipaddr[STRING_SIZE];
  28         time_t time_start;
  29         int expires;
  30
  31         struct client* next;
  32 } client_t;
  33
  34 static time_t parse_time(const char* s) {
  35         int t = 0;
  36
  37         if (sscanf(s, "%d", &t) == 1) {
  38                 return (time_t)t;
  39         }
  40
  41         return -1;
  42 }
  43
  44 static char* format_time(const time_t* t) {
  45         char buffer[STRING_SIZE];
  46
  47         struct tm* tm = gmtime(t);
  48         if (tm == NULL)
  49                 return NULL;
  50
  51         strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M", tm);
  52
  53         return strdup(buffer);
  54 }
  55
  56 static client_t* read_clients(char* filename) {
  57         FILE* f = NULL;
  58
  59         if (!(f = fopen(filename, "r"))) {
  60                 fprintf(stderr, "Could not open configuration file: %s\n", filename);
  61                 return NULL;;
  62         }
  63
  64         char line[STRING_SIZE];
  65
  66         client_t* client_first = NULL;
  67         client_t* client_last = NULL;
  68         client_t* client_curr;
  69
  70         while ((fgets(line, STRING_SIZE, f) != NULL)) {
  71                 if (line[strlen(line) - 1] == '\n')
  72                         line[strlen(line) - 1] = '\0';
  73
  74                 // Skip all commented lines
  75                 if (*line == '#')
  76                         continue;
  77
  78                 client_curr = (client_t*)malloc(sizeof(client_t));
  79                 memset(client_curr, 0, sizeof(client_t));
  80
  81                 if (client_first == NULL)
  82                         client_first = client_curr;
  83                 else
  84                         client_last->next = client_curr;
  85                 client_last = client_curr;
  86
  87                 unsigned int count = 0;
  88                 char* lineptr = line;
  89                 while (1) {
  90                         if (!*lineptr)
  91                                 break;
  92
  93                         char* word = lineptr;
  94                         while (*lineptr != '\0') {
  95                                 if (*lineptr == ',') {
  96                                         *lineptr = '\0';
  97                                         lineptr++;
  98                                         break;
  99                                 }
 100                                 lineptr++;
 101                         }
 102
 103                         switch (count++) {
 104                                 // Ethernet address
 105                                 case 1:
 106                                         strcpy(client_curr->etheraddr, word);
 107                                         break;
 108
 109                                 // IP address
 110                                 case 2:
 111                                         strcpy(client_curr->ipaddr, word);
 112                                         break;
 113
 114                                 // Start time
 115                                 case 3:
 116                                         client_curr->time_start = parse_time(word);
 117                                         break;
 118
 119                                 // Expire duration
 120                                 case 4:
 121                                         client_curr->expires = atoi(word);
 122                                         break;
 123
 124                                 default:
 125                                         break;
 126                         }
 127                 }
 128         }
 129
 130         if (f)
 131                 fclose(f);
 132
 133         return client_first;
 134 }
 135
 136 static void flush_chains() {
 137         // filter
 138         safe_system(IPTABLES " -F CAPTIVE_PORTAL");
 139         safe_system(IPTABLES " -F CAPTIVE_PORTAL_CLIENTS");
 140
 141         // nat
 142         safe_system(IPTABLES " -t nat -F CAPTIVE_PORTAL");
 143 }
 144
 145 static int setup_dns_filters() {
 146         const char* protos[] = { "udp", "tcp", NULL };
 147
 148         // Limits the number of DNS requests to 3 kByte/s
 149         // A burst of 1MB is permitted at the start
 150         const char* limiter = "-m hashlimit --hashlimit-name dns-filter"
 151                 " --hashlimit-mode srcip --hashlimit-upto 3kb/sec --hashlimit-burst 1024kb";
 152
 153         char command[STRING_SIZE];
 154
 155         const char** proto = protos;
 156         while (*proto) {
 157                 snprintf(command, sizeof(command), IPTABLES " -A CAPTIVE_PORTAL_CLIENTS -p %s"
 158                         " --dport 53 %s -j RETURN", *proto, limiter);
 159
 160                 int r = safe_system(command);
 161                 if (r)
 162                         return r;
 163
 164                 proto++;
 165         }
 166
 167         return 0;
 168 }
 169
 170 static int add_client_rules(const client_t* clients) {
 171         char command[STRING_SIZE];
 172         char match[STRING_SIZE];
 173
 174         while (clients) {
 175                 size_t len = 0;
 176
 177                 if (*clients->ipaddr && clients->expires > 0) {
 178                         len += snprintf(match + len, sizeof(match) - len,
 179                                 "-s %s", clients->ipaddr);
 180                 }
 181
 182                 len += snprintf(match + len, sizeof(match) - len,
 183                         " -m mac --mac-source %s", clients->etheraddr);
 184
 185                 if (clients->expires > 0) {
 186                         time_t expires = clients->time_start + clients->expires;
 187
 188                         char* time_start = format_time(&clients->time_start);
 189                         char* time_end = format_time(&expires);
 190
 191                         len += snprintf(match + len, sizeof(match) - len,
 192                                 " -m time --datestart %s --datestop %s",
 193                                 time_start, time_end);
 194
 195                         free(time_start);
 196                         free(time_end);
 197                 }
 198
 199                 // filter
 200                 snprintf(command, sizeof(command), IPTABLES " -A CAPTIVE_PORTAL_CLIENTS"
 201                         " %s -j RETURN", match);
 202                 safe_system(command);
 203
 204                 // nat
 205                 snprintf(command, sizeof(command), IPTABLES " -t nat -A CAPTIVE_PORTAL"
 206                         " %s -j RETURN", match);
 207                 safe_system(command);
 208
 209                 // Move on to the next client
 210                 clients = clients->next;
 211         }
 212
 213         return 0;
 214 }
 215
 216 static char* get_key(struct keyvalue* settings, char* key) {
 217         char value[STRING_SIZE];
 218
 219         if (!findkey(settings, key, value))
 220                 return NULL;
 221
 222         return strdup(value);
 223 }
 224
 225 static int add_interface_rule(const char* intf, int allow_webif_access) {
 226         int r;
 227         char command[STRING_SIZE];
 228
 229         if ((intf == NULL) || (strlen(intf) == 0)) {
 230                 fprintf(stderr, "Empty interface given\n");
 231                 return -1;
 232         }
 233
 234         snprintf(command, sizeof(command), IPTABLES " -A CAPTIVE_PORTAL -i %s"
 235                 " -j CAPTIVE_PORTAL_CLIENTS", intf);
 236         r = safe_system(command);
 237         if (r)
 238                 return r;
 239
 240         if (allow_webif_access) {
 241                 snprintf(command, sizeof(command), IPTABLES " -A CAPTIVE_PORTAL_CLIENTS"
 242                         " -i %s -p tcp --dport 444 -j RETURN", intf);
 243                 r = safe_system(command);
 244                 if (r)
 245                         return r;
 246         }
 247
 248         // Redirect all unauthenticated clients
 249         snprintf(command, sizeof(command), IPTABLES " -t nat -A CAPTIVE_PORTAL -i %s"
 250                 " -p tcp --dport %d -j REDIRECT --to-ports %d", intf, HTTP_PORT, REDIRECT_PORT);
 251         r = safe_system(command);
 252         if (r)
 253                 return r;
 254
 255         // Allow access to captive portal site
 256         snprintf(command, sizeof(command), IPTABLES " -A CAPTIVE_PORTAL_CLIENTS"
 257                 " -i %s -p tcp --dport %d -j RETURN", intf, REDIRECT_PORT);
 258         r = safe_system(command);
 259         if (r)
 260                 return r;
 261
 262         return 0;
 263 }
 264
 265 static int add_interface_rules(struct keyvalue* captive_portal_settings, struct keyvalue* ethernet_settings) {
 266         const char* intf;
 267         char* setting;
 268         int r = 0;
 269
 270         setting = get_key(captive_portal_settings, "ENABLE_GREEN");
 271         if (setting && (strcmp(setting, "on") == 0)) {
 272                 free(setting);
 273
 274                 intf = get_key(ethernet_settings, "GREEN_DEV");
 275                 r = add_interface_rule(intf, /* allow webif access from green */ 1);
 276                 if (r)
 277                         return r;
 278         }
 279
 280         setting = get_key(captive_portal_settings, "ENABLE_BLUE");
 281         if (setting && (strcmp(setting, "on") == 0)) {
 282                 free(setting);
 283
 284                 intf = get_key(ethernet_settings, "BLUE_DEV");
 285                 r = add_interface_rule(intf, /* do not allow webif access */ 0);
 286                 if (r)
 287                         return r;
 288         }
 289
 290         // Always pass DNS packets through all firewall rules
 291         r = setup_dns_filters();
 292         if (r)
 293                 return r;
 294
 295         // Add the last rule
 296         r = safe_system(IPTABLES " -A CAPTIVE_PORTAL_CLIENTS -j DROP");
 297         if (r)
 298                 return r;
 299
 300         return r;
 301 }
 302
 303 int main(int argc, char** argv) {
 304         int r = 0;
 305         char* intf = NULL;
 306         client_t* clients = NULL;
 307
 308         struct keyvalue* captive_portal_settings = NULL;
 309         struct keyvalue* ethernet_settings = NULL;
 310
 311         if (!(initsetuid()))
 312                 exit(2);
 313
 314         ethernet_settings = initkeyvalues();
 315         if (!readkeyvalues(ethernet_settings, ETHERNET_SETTINGS)) {
 316                 fprintf(stderr, "Could not read %s\n", ETHERNET_SETTINGS);
 317                 r = 1;
 318                 goto END;
 319         }
 320
 321         captive_portal_settings = initkeyvalues();
 322         if (!readkeyvalues(captive_portal_settings, CAPTIVE_PORTAL_SETTINGS)) {
 323                 fprintf(stderr, "Could not read %s\n", CAPTIVE_PORTAL_SETTINGS);
 324                 r = 1;
 325                 goto END;
 326         }
 327
 328         clients = read_clients(CLIENTS);
 329
 330         // Clean up all old rules
 331         flush_chains();
 332
 333         // Add all client rules
 334         r = add_client_rules(clients);
 335         if (r)
 336                 goto END;
 337
 338         // Add all interface rules
 339         r = add_interface_rules(captive_portal_settings, ethernet_settings);
 340         if (r)
 341                 goto END;
 342
 343 END:
 344         while (clients) {
 345                 client_t* head = clients;
 346                 clients = clients->next;
 347
 348                 free(head);
 349         }
 350
 351         if (ethernet_settings)
 352                 freekeyvalues(ethernet_settings);
 353
 354         if (captive_portal_settings)
 355                 freekeyvalues(captive_portal_settings);
 356
 357         if (intf)
 358                 free(intf);
 359
 360         return r;
 361 }