Avoiding a race condition during server-server registration process.

git-svn-id: https://oss.gonicus.de/repositories/gosa/trunk@13635 594d385d-05f5-0310-b6e9-bd551577e9d8

diff --git a/gosa-si/gosa-si-server b/gosa-si/gosa-si-server
index 079e867615b5748b0af58371bc30a67e1b6b9160..67d21a7709f944a511cc29d45e2b9ff801c1da23 100755 (executable)
--- a/gosa-si/gosa-si-server
+++ b/gosa-si/gosa-si-server
@@ -154,7 +154,7 @@ my @job_queue_col_names = ("id INTEGER PRIMARY KEY",
 our $known_server_db;
 our $known_server_tn = "known_server";
 my $known_server_file_name;
-my @known_server_col_names = ("hostname VARCHAR(255)", "macaddress VARCHAR(17)", "status VARCHAR(255)", "hostkey VARCHAR(255)", "loaded_modules TEXT", "timestamp VARCHAR(14)");
+my @known_server_col_names = ("hostname VARCHAR(255)", "macaddress VARCHAR(17)", "status VARCHAR(255)", "hostkey VARCHAR(255)", "loaded_modules TEXT", "timestamp VARCHAR(14)", "update_time VARCHAR(14)");
 
 # holds all registrated clients
 our $known_clients_db;
@@ -1080,15 +1080,26 @@ sub msg_to_decrypt {
        }
        # an error occurred
        if(( !$msg ) || ( !$msg_hash ) || ( !$module )){
-               # if an incoming msg could not be decrypted (maybe a wrong key), send client a ping. If the client
-               # could not understand a msg from its server the client cause a re-registering process
-               daemon_log("$session_id WARNING cannot understand incoming msg, send 'ping'-msg to all host with ip '".$heap->{remote_ip}.
-                                               "' to cause a re-registering of the client if necessary", 3);
-               my $remote_ip = $heap->{'remote_ip'};
-        my $remote_port = $heap->{'remote_port'};
-        my $ping_msg = "<xml> <header>gosa_ping</header> <source>$server_address</source><target>$msg_source</target></xml>";
-        my ($test_error, $test_error_string) = &send_msg_to_target($ping_msg, "$msg_source", "dummy-key", "gosa_ping", $session_id);
-
+               # If an incoming msg could not be decrypted (maybe a wrong key), decide if msg comes from a client 
+               # or a server.  In case of a client, send a ping. If the client could not understand a msg from its 
+               # server the client cause a re-registering process. In case of a server, decrease update_time in kown_server_db
+               # and trigger a re-registering process for servers
+               if (defined $msg_source && $msg_source =~ /^\d+:$server_port$/)
+               {
+                       daemon_log("$session_id WARNING: Cannot understand incoming msg from server '$msg_source'. Cause re-registration process for servers.", 3);
+                       my $update_statement = "UPDATE $known_server_tn SET update_time='19700101000000' WHERE hostname='$msg_source'"; 
+                       daemon_log("$session_id DEBUG: $update_statement", 7);
+                       my $upadte_res = $known_server_db->exec_statement($update_statement);
+                       $kernel->yield("register_at_foreign_servers");
+               }
+               else
+               {
+                       daemon_log("$session_id WARNING: Cannot understand incoming msg from client '".$heap->{remote_ip}."'. Send ping-msg to cause a re-registering of the client if necessary", 3);
+                       my $remote_ip = $heap->{'remote_ip'};
+                       my $remote_port = $heap->{'remote_port'};
+                       my $ping_msg = "<xml> <header>gosa_ping</header> <source>$server_address</source><target>$msg_source</target></xml>";
+                       my ($test_error, $test_error_string) = &send_msg_to_target($ping_msg, "$msg_source", "dummy-key", "gosa_ping", $session_id);
+               }
                $error++;
        }
 
@@ -3140,54 +3151,93 @@ sub cleanup_and_extract {
 sub register_at_foreign_servers {   
     my ($kernel) = $_[KERNEL];
 
-    # hole alle bekannten server aus known_server_db
-    my $server_sql = "SELECT * FROM $known_server_tn";
-    my $server_res = $known_server_db->exec_statement($server_sql);
+       # Set current delay of register_at_foreign_servers to 0
 
-    # no entries in known_server_db
-    if (not ref(@$server_res[0]) eq "ARRAY") { 
-        # TODO
-    }
+       # Update status and update-time of all si-server with expired update_time and 
+       # block them for race conditional registration processes of other si-servers.
+       my $act_time = &get_time();
+       my $block_statement = "UPDATE $known_server_tn SET status='new_server',update_time='19700101000000' WHERE (CAST(update_time AS UNSIGNED))<$act_time ";
+       &daemon_log("0 DEBUG: $block_statement", 5);
+       my $block_res = $known_server_db->exec_statement($block_statement);
+
+       # Fetch all si-server from db where update_time is younger than act_time
+       my $fetch_statement = "SELECT * FROM $known_server_tn WHERE update_time='19700101000000'"; 
+       &daemon_log("0 DEBUG: $fetch_statement", 5);
+       my $fetch_res = $known_server_db->exec_statement($fetch_statement);
 
-    # detect already connected clients
+    # Detect already connected clients. Will be added to registration msg later. 
     my $client_sql = "SELECT * FROM $known_clients_tn"; 
     my $client_res = $known_clients_db->exec_statement($client_sql);
 
-    # send my server details to all other gosa-si-server within the network
-    foreach my $hit (@$server_res) {
+       # Send registration messag to all fetched si-server
+    foreach my $hit (@$fetch_res) {
         my $hostname = @$hit[0];
         my $hostkey = &create_passwd;
 
-        # add already connected clients to registration message 
+        # Add already connected clients to registration message 
         my $myhash = &create_xml_hash('new_server', $server_address, $hostname);
         &add_content2xml_hash($myhash, 'key', $hostkey);
         map(&add_content2xml_hash($myhash, 'client', @{$_}[0].",".@{$_}[4]), @$client_res);
 
-        # add locally loaded gosa-si modules to registration message
+        # Add locally loaded gosa-si modules to registration message
         my $loaded_modules = {};
         while (my ($package, $pck_info) = each %$known_modules) {
-                                               next if ((!defined(@$pck_info[2])) || (!(ref (@$pck_info[2]) eq 'HASH')));
-                                               foreach my $act_module (keys(%{@$pck_info[2]})) {
-                                                       $loaded_modules->{$act_module} = ""; 
-                                               }
-        }
-
+                       next if ((!defined(@$pck_info[2])) || (!(ref (@$pck_info[2]) eq 'HASH')));
+                       foreach my $act_module (keys(%{@$pck_info[2]})) {
+                               $loaded_modules->{$act_module} = ""; 
+                       }
+               }
         map(&add_content2xml_hash($myhash, "loaded_modules", $_), keys(%$loaded_modules));
 
-        # add macaddress to registration message
+        # Add macaddress to registration message
         my ($host_ip, $host_port) = split(/:/, $hostname);
         my $local_ip = &get_local_ip_for_remote_ip($host_ip);
         my $network_interface= &get_interface_for_ip($local_ip);
         my $host_mac = &get_mac_for_interface($network_interface);
         &add_content2xml_hash($myhash, 'macaddress', $host_mac);
         
-        # build registration message and send it
+        # Build registration message and send it
         my $foreign_server_msg = &create_xml_string($myhash);
         my $error = &send_msg_to_target($foreign_server_msg, $hostname, $ServerPackages_key, "new_server", 0); 
     }
-    
-    $kernel->delay_set("register_at_foreign_servers", $foreign_servers_register_delay); 
-    return;
+
+
+       # After n sec perform a check of all server registration processes
+    $kernel->delay_set("control_server_registration", 2); 
+
+       return;
+}
+
+
+sub control_server_registration {
+       my ($kernel) = $_[KERNEL];
+       
+       # Check if all registration processes succeed or not
+       my $select_statement = "SELECT * FROM $known_server_tn WHERE status='new_server'"; 
+       &daemon_log("0 DEBUG $select_statement", 5);
+       my $select_res = $known_server_db->exec_statement($select_statement);
+
+       # If at least one registration process failed, maybe in case of a race condition
+       # with a foreign registration process
+       if (@$select_res > 0) 
+       {
+               # Release block statement 'new_server' to make the server accessible
+               # for foreign registration processes
+               my $update_statement = "UPDATE $known_server_tn SET status='waiting' WHERE status='new_server'";        
+               &daemon_log("0 DEBUG: $update_statement", 5);
+               my $update_res = $known_server_db->exec_statement($update_statement);
+
+               # Set a random delay to avoid the registration race condition
+               my $new_foreign_servers_register_delay = int(rand(4))+1;
+               $kernel->delay_set("register_at_foreign_servers", $new_foreign_servers_register_delay);
+       }
+       # If all registration processes succeed
+       else
+       {
+               $kernel->delay_set("register_at_foreign_servers", $foreign_servers_register_delay);
+       }
+
+       return;
 }
 
 
@@ -3441,6 +3491,7 @@ foreach my $foreign_server (@foreign_server_list) {
             hostkey=>"none",
             loaded_modules => "none", 
             timestamp=>$cur_timestamp,
+                       update_time=>'19700101000000',
             } );
 }
 
@@ -3488,6 +3539,7 @@ POE::Session->create(
        inline_states => {
                _start => \&session_start,
         register_at_foreign_servers => \&register_at_foreign_servers,
+               control_server_registration => \&control_server_registration,
         sig_handler => \&sig_handler,
         next_task => \&next_task,
         task_result => \&handle_task_result,

diff --git a/gosa-si/server/events/server_server_com.pm b/gosa-si/server/events/server_server_com.pm
index 06e87cf2ec4b5391f1bbdd64e7ba267476e83a0b..66eaf77fa869f38099a3b1409c9ca79db7573ea0 100644 (file)
--- a/gosa-si/server/events/server_server_com.pm
+++ b/gosa-si/server/events/server_server_com.pm
@@ -152,12 +152,23 @@ sub new_server {
     my @clients = exists $msg_hash->{'client'} ? @{$msg_hash->{'client'}} : qw();
     my @loaded_modules = exists $msg_hash->{'loaded_modules'} ? @{$msg_hash->{'loaded_modules'}} : qw();
 
-    # sanity check
+       # Ignor message if I'm already within a registration process for server $source
+       my $check_statement = "SELECT * FROM $main::known_server_tn WHERE status='new_server' AND hostname='$source'"; 
+       &main::daemon_log("$session_id DEBUG $check_statement", 7);
+       my $check_res = $main::known_server_db->select_dbentry($check_statement);
+       my $blocking_process = keys(%$check_res);
+       if ($blocking_process)
+       {
+               return;
+       }
+
+    # Sanity check
     if (ref $key eq 'HASH') {
         &main::daemon_log("$session_id ERROR: 'new_server'-message from host '$source' contains no key!", 1);
         return;
     }
-    # add foreign server to known_server_db
+    # Add foreign server to known_server_db
+       my $new_update_time = &calc_timestamp(&get_time(), 'plus', $main::foreign_servers_register_delay);
     my $func_dic = {table=>$main::known_server_tn,
         primkey=>['hostname'],
         hostname => $source,
@@ -166,6 +177,7 @@ sub new_server {
         hostkey => $key,
         loaded_modules => join(',', @loaded_modules),
         timestamp=>&get_time(),
+               update_time=>$new_update_time,
     };
     my $res = $main::known_server_db->add_dbentry($func_dic);
     if (not $res == 0) {
@@ -244,8 +256,9 @@ sub confirm_new_server {
     my @clients = exists $msg_hash->{'client'} ? @{$msg_hash->{'client'}} : qw();
     my @loaded_modules = exists $msg_hash->{'loaded_modules'} ? @{$msg_hash->{'loaded_modules'}} : qw();
 
+       my $new_update_time = &calc_timestamp(&get_time(), 'plus', $main::foreign_servers_register_delay);
     my $sql = "UPDATE $main::known_server_tn".
-        " SET status='$header', hostkey='$key', loaded_modules='".join(",",@loaded_modules)."', macaddress='$mac'".
+        " SET status='$header', hostkey='$key', loaded_modules='".join(",",@loaded_modules)."', macaddress='$mac', update_time='$new_update_time'".
         " WHERE hostname='$source'"; 
     my $res = $main::known_server_db->update_dbentry($sql);
 
@@ -259,10 +272,10 @@ sub confirm_new_server {
         push(@sql_list, $del_sql);
 
         my $sql = "INSERT INTO $main::foreign_clients_tn VALUES ("
-            ."'".$client_details[0]."',"   # hostname
-            ."'".$client_details[1]."',"   # macaddress
-            ."'".$source."',"              # regserver
-            ."'".&get_time()."')";         # timestamp
+            ."'".$client_details[0]."',"       # hostname
+            ."'".$client_details[1]."',"       # macaddress
+            ."'".$source."',"                  # regserver
+            ."'".&get_time()."')";                     # timestamp
         push(@sql_list, $sql);
     }
     if (@sql_list) {