Merge pull request #26 from bonfus/master

Limit allowed hostnames and ports

2 files changed, 130 insertions, 1 deletions

diff --git a/main.c b/main.c
index 2acafa6..942c395 100644
--- a/main.c
+++ b/main.c
@@ -31,6 +31,12 @@ char *remote_tox_id = NULL;
 /* Directory with config and tox save */
 char config_path[500] = "/etc/tuntox/";
 
+/* Limit hostname and port in server */
+int nrules = 0;
+char rules_file[500] = "/etc/tuntox/rules";
+enum rules_policy_enum rules_policy = NONE;
+rule *rules = NULL;
+
 /* Ports and hostname for port forwarding */
 int remote_port = 0;
 char *remote_host = NULL;
@@ -88,6 +94,16 @@ int allowed_toxid_cmp(allowed_toxid *a, allowed_toxid *b)
     return memcmp(a->toxid, b->toxid, TOX_PUBLIC_KEY_SIZE);
 }
 
+/* Comparison function for rule objects */
+int rule_cmp(rule *a, rule *b)
+{
+    //log_printf(L_INFO, "Comparison result: %d %d\n", strcmp(a->host, b->host), (a->port == b->port));
+    if ((strcmp(a->host, b->host)==0) && (a->port == b->port))
+        return 0;
+    else
+        return -1;
+}
+
 void update_select_nfds(int fd)
 {
     /* TODO maybe replace with a scan every time to make select() more efficient in the long run? */
@@ -389,6 +405,26 @@ int handle_request_tunnel_frame(protocol_frame *rcvd_frame)
     hostname[rcvd_frame->data_length] = '\0';
 
     log_printf(L_INFO, "Got a request to forward data from %s:%d\n", hostname, port);
+    
+    // check rules
+    if (rules_policy == VALIDATE && nrules > 0 ) {
+        
+        rule rtmp, *found = NULL;
+        rtmp.host = hostname;
+        rtmp.port = port;
+        
+        LL_SEARCH(rules, found, &rtmp, rule_cmp);
+        if(!found)
+        {
+            log_printf(L_WARNING, "Rejected, request not in rules\n");
+            return -1;
+        }
+    } else if (rules_policy != NONE) {
+        log_printf(L_WARNING, "Filter option active but no allowed host/port. All requests will be dropped.\n");
+        return -1;
+    }
+
+
 
     tunnel_id = get_random_tunnel_id();
     log_printf(L_DEBUG, "Tunnel ID: %d\n", tunnel_id);
@@ -707,6 +743,80 @@ static size_t load_save(uint8_t **out_data)
     }
 }
 
+/* Loads a list of allowed hostnames and ports from file. Format is hostname:port*/
+void load_rules()
+{
+    char * ahost=NULL;
+    int aport=0;
+    char line[100 + 1] = "";
+    FILE *file = NULL;
+    rule *rule_obj = NULL;
+    int valid_rules = 0;
+
+    file = fopen(rules_file, "r");
+    
+    if (file == NULL) {
+        log_printf(L_WARNING, "Could not open rules file (%s)\n", rules_file);
+        return;
+    }
+    
+    while (fgets(line, sizeof(line), file)) {
+        if(line)
+        {
+            /* allow comments & white lines */
+            if (line[0]=='#'||line[0]=='\n') {
+                continue;
+            }
+            if (parse_pipe_port_forward(line, &ahost, &aport) >= 0) {
+                if (aport > 0 && aport < 65535) {
+                    
+                    rule_obj = (rule *)calloc(sizeof(rule), 1);
+                    if(!rule_obj)
+                    {
+                        log_printf(L_ERROR, "Could not allocate memory for rule");
+                        exit(1);
+                    }
+                    
+                    rule_obj->port = aport;
+                    rule_obj->host = strdup(ahost);
+                    
+                    LL_APPEND(rules, rule_obj);
+                    valid_rules++;
+                } else {
+                    log_printf(L_WARNING, "Invalid port in line: %s\n", line);
+                }
+            } else {
+                log_printf(L_WARNING, "Could not parse line: %s\n", line);
+            }
+        } else {
+            /* reached end of file*/ 
+            break;
+        }
+    }
+    fclose(file);
+    
+    /* save valid rules in global variable */
+    nrules = valid_rules;
+    
+    log_printf(L_INFO, "Loaded %d rules\n", nrules);
+    if (nrules==0 && rules_policy != NONE){
+        log_printf(L_WARNING, "No rules loaded! NO CONNECTIONS WILL BE ALLOWED!\n");
+    }
+}
+
+/* Clear rules loaded into memory */
+void clear_rules()
+{
+    int i;
+    rule * elt, *tmp;
+    /* delete each elemen using the safe iterator */
+    LL_FOREACH_SAFE(rules,elt,tmp) {
+      LL_DELETE(rules,elt);
+      free(elt->host);
+      free(elt);
+    }
+}
+
 void accept_friend_request(Tox *tox, const uint8_t *public_key, const uint8_t *message, size_t length, void *userdata)
 {
     unsigned char tox_printable_id[TOX_ADDRESS_SIZE * 2 + 1];
@@ -1060,6 +1170,7 @@ void help()
     fprintf(stderr, "-p - ping the server from -i and exit\n");
     fprintf(stderr, "-C <dir> - save private key in <dir> instead of /etc/tuntox in server mode\n");
     fprintf(stderr, "-s <secret> - shared secret used for connection authentication (max %u characters)\n", TOX_MAX_FRIEND_REQUEST_LENGTH-1);
+    fprintf(stderr, "-f <file> - only allow connections to hostname/port combinations contained in <file>. Rules must by entered one per line with the <hostname>:<port> format\n");
     fprintf(stderr, "-d - debug mode\n");
     fprintf(stderr, "-q - quiet mode\n");
     fprintf(stderr, "-S - send output to syslog instead of stderr\n");
@@ -1081,7 +1192,7 @@ int main(int argc, char *argv[])
 
     log_init();
 
-    while ((oc = getopt(argc, argv, "L:pi:C:s:P:dqhSF:DU:")) != -1)
+    while ((oc = getopt(argc, argv, "L:pi:C:s:f:P:dqhSF:DU:")) != -1)
     {
         switch(oc)
         {
@@ -1154,6 +1265,11 @@ int main(int argc, char *argv[])
                 }
                 load_saved_toxid_in_client_mode = 1;
                 break;
+            case 'f':
+                strncpy(rules_file, optarg, sizeof(rules_file) - 1);
+                rules_policy = VALIDATE;
+                log_printf(L_INFO, "Filter policy set to VALIDATE\n");
+                break;
             case 's':
                 /* Shared secret */
                 use_shared_secret = 1;
@@ -1197,6 +1313,11 @@ int main(int argc, char *argv[])
     {
         log_printf(L_INFO, "Server in ToxID whitelisting mode - only clients listed with -i can connect");
     }
+    
+    if((!client_mode) && (rules_policy != NONE))
+    {
+        load_rules();
+    }
 
     if(daemonize)
     {
@@ -1281,6 +1402,7 @@ int main(int argc, char *argv[])
 
         tox_callback_friend_request(tox, accept_friend_request, NULL);
         do_server_loop();
+        clear_rules();
     }
 
     return 0;
diff --git a/main.h b/main.h
index 65494ef..329135f 100644
--- a/main.h
+++ b/main.h
@@ -73,6 +73,13 @@ typedef struct protocol_frame_t {
         uint8_t *data;
 } protocol_frame;
 
+/* Rules policy */
+enum rules_policy_enum { VALIDATE, NONE };
+typedef struct rule {
+    uint16_t port;
+    char * host;
+    struct rule *next;
+} rule;
 
 /**** GLOBAL VARIABLES ****/
 extern Tox *tox;