Added protection against botsHEADmaster

After 30 seconds a signal is sent after the first player is connected. During
this period the second player must connect, otherwise the first player will be
disconnected.

1 files changed, 59 insertions, 12 deletions

diff --git a/server/server.c b/server/server.c
index 0017888..bfc71ef 100644
--- a/server/server.c
+++ b/server/server.c
@@ -15,10 +15,17 @@
 #include "card_stack.h"
 #include "card_queue.h"
 
+static volatile sig_atomic_t timeout_is_over = 0;
+
 void handler(int s)
 {
-    if(s == SIGPIPE)
-        signal(SIGPIPE, handler);
+    switch(s) {
+    case SIGPIPE:
+            signal(SIGPIPE, handler);
+            break;
+    case SIGALRM:
+            timeout_is_over = 1;
+    }
 }
 
 static void init_session(struct session *new_session, struct sockaddr_in *from,
@@ -98,8 +105,7 @@ static void close_connection(struct server *serv)
 
 static int check_playable_player_number(struct server *serv)
 {
-    return serv->connected_players_counter >= 2 &&
-            serv->connected_players_counter < 8;
+    return serv->connected_players_counter >= 2;
 }
 
 static int is_max_playable_player_number(struct server *serv)
@@ -593,10 +599,21 @@ static void determine_server_state(struct server *serv)
     switch(serv->state) {
     case no_players:
         serv->state = first_player;
+        /*
+         * The second player must connect no later than TIMEOUT.
+         * This is done to protect against bots.
+         */
+        signal(SIGALRM, handler);
+        alarm(timeout);
         break;
     case first_player:
-        if(check_playable_player_number(serv))
+        if(check_playable_player_number(serv)) {
             serv->state = confirmation_waiting;
+            /* cancel alarm */
+            alarm(0);
+            /* default disposition */
+            signal(SIGALRM, SIG_DFL);
+        }
         break;
     case confirmation_waiting:
             set_record_status_for_all(serv);
@@ -658,7 +675,7 @@ static int new_player_tracking_condition(enum server_states state)
 /*
  * when accepting new players
  */
-static int server_state_change_condition(struct server *serv)
+static int check_server_state_change_conditions_before_game(struct server *serv)
 {
     return
         serv->state == no_players ||
@@ -678,7 +695,7 @@ static int accept_new_player(struct server *serv)
     }
     /* update info about connected players */
     set_record_status_for_all(serv);
-    if(server_state_change_condition(serv))
+    if(check_server_state_change_conditions_before_game(serv))
         serv->change_server_state = 1;
     return 1;
 }
@@ -736,7 +753,10 @@ static void set_up_player_tracking(struct server *serv, fd_set *readfds,
     }
 }
 
-static int check_server_state_change_conditions(struct server *serv)
+/*
+ * is checked after a write or read operation in make_data_transfer
+ */
+static int check_server_state_change_conditions_in_game(struct server *serv)
 {
     switch(serv->state) {
     case start_game:
@@ -763,7 +783,7 @@ static int check_server_state_change_conditions(struct server *serv)
 static void make_data_transfer(struct server *serv, fd_set *readfds,
                                fd_set *writefds)
 {
-    int i, result, close_connection_status = 0;
+    int i, result = 1, close_connection_status = 0;
     for(i = 0; i < serv->max_sess_arr_size; ++i) {
         if(!serv->sess_arr[i])
             continue;
@@ -840,13 +860,18 @@ static void make_data_transfer(struct server *serv, fd_set *readfds,
             close(i);
             serv->sess_arr[i]->fd = -1;
             close_connection_status = 1;
-            result = 1; /* next can be reading that's not ready */
+            /*
+             * Flag reset
+             * The following clients may not have requested read or
+             * write operations
+             */
+            result = 1;
         }
     }
     if(serv->state == start_game || serv->state == end_round ||
                                                 serv->state == end_game)
         sleep(2);
-    if(check_server_state_change_conditions(serv))
+    if(check_server_state_change_conditions_in_game(serv))
         serv->change_server_state = 1;
     /* connection is closed */
     if(close_connection_status) {
@@ -856,6 +881,23 @@ static void make_data_transfer(struct server *serv, fd_set *readfds,
     }
 }
 
+static void close_bot_connection(struct server *serv)
+{
+    int i;
+
+    for(i = 0; i < serv->max_sess_arr_size; ++i) {
+        if(!serv->sess_arr[i])
+            continue;
+        close(serv->sess_arr[i]->fd);
+        serv->sess_arr[i]->fd = -1;
+        free(serv->sess_arr[i]);
+        serv->sess_arr[i] = NULL;
+    }
+    serv->change_server_state = 0;
+    serv->connected_players_counter = 0;
+    serv->state = no_players;
+}
+
 int main_loop(struct server *serv)
 {
     int maxfd, accept_result, select_result;
@@ -875,8 +917,13 @@ int main_loop(struct server *serv)
         set_up_player_tracking(serv, &readfds, &writefds, &maxfd);
 
         select_result = select(maxfd + 1, &readfds, &writefds, NULL, NULL);
-        if(select_result == -1)
+        if(select_result == -1 && !timeout_is_over)
             return 3;
+        if(timeout_is_over && serv->connected_players_counter == 1) {
+            close_bot_connection(serv);
+            timeout_is_over = 0;
+            continue;
+        }
 
         if(FD_ISSET(serv->listen_socket, &readfds)) {
             accept_result = accept_new_player(serv);