login proxy: If proxy_timeout is set, try to reconnect until the timeout is reached.

This allows quickly restarting/upgrading backend servers without returning
login failures.

diff --git a/src/login-common/login-proxy.c b/src/login-common/login-proxy.c
index bdbbb89242eccf02a745ea85f25d9892997a3462..f5a565bef7869d5a34794523d99e6cb8bd82107b 100644 (file)
--- a/src/login-common/login-proxy.c
+++ b/src/login-common/login-proxy.c
@@ -23,6 +23,7 @@
 #define LOGIN_PROXY_IPC_NAME "proxy"
 #define KILLED_BY_ADMIN_REASON "Killed by admin"
 #define PROXY_IMMEDIATE_FAILURE_SECS 30
+#define PROXY_CONNECT_RETRY_MSECS 1000
 
 struct login_proxy {
        struct login_proxy *prev, *next;
@@ -44,6 +45,7 @@ struct login_proxy {
        unsigned int port;
        unsigned int connect_timeout_msecs;
        unsigned int notify_refresh_secs;
+       unsigned int reconnect_count;
        enum login_proxy_ssl_flags ssl_flags;
 
        proxy_callback_t *callback;
@@ -58,6 +60,8 @@ static struct login_proxy *login_proxies = NULL;
 static struct login_proxy *login_proxies_pending = NULL;
 static struct ipc_server *login_proxy_ipc_server;
 
+static int login_proxy_connect(struct login_proxy *proxy);
+static void login_proxy_disconnect(struct login_proxy *proxy);
 static void login_proxy_ipc_cmd(struct ipc_cmd *cmd, const char *line);
 
 static void
@@ -224,6 +228,8 @@ proxy_log_connect_error(struct login_proxy *proxy)
        }
        str_printfa(str, " (after %u secs",
                    (unsigned int)(ioloop_time - proxy->created.tv_sec));
+       if (proxy->reconnect_count > 0)
+               str_printfa(str, ", %u reconnects", proxy->reconnect_count);
 
        if (proxy->server_fd != -1 &&
            net_getsockname(proxy->server_fd, &local_ip, &local_port) == 0) {
@@ -238,13 +244,40 @@ proxy_log_connect_error(struct login_proxy *proxy)
        i_error("%s", str_c(str));
 }
 
+static void proxy_reconnect_timeout(struct login_proxy *proxy)
+{
+       timeout_remove(&proxy->to);
+       (void)login_proxy_connect(proxy);
+}
+
+static bool proxy_try_reconnect(struct login_proxy *proxy)
+{
+       int since_started_msecs, left_msecs;
+
+       since_started_msecs =
+               timeval_diff_msecs(&ioloop_timeval, &proxy->created);
+       if (since_started_msecs < 0)
+               return FALSE; /* time moved backwards */
+       left_msecs = proxy->connect_timeout_msecs - since_started_msecs;
+       if (left_msecs <= 0)
+               return FALSE;
+
+       login_proxy_disconnect(proxy);
+       proxy->to = timeout_add(I_MIN(PROXY_CONNECT_RETRY_MSECS, left_msecs),
+                               proxy_reconnect_timeout, proxy);
+       proxy->reconnect_count++;
+       return TRUE;
+}
+
 static void proxy_wait_connect(struct login_proxy *proxy)
 {
        errno = net_geterror(proxy->server_fd);
        if (errno != 0) {
-               proxy_log_connect_error(proxy);
                proxy_fail_connect(proxy);
-                login_proxy_free(&proxy);
+               if (!proxy_try_reconnect(proxy)) {
+                       proxy_log_connect_error(proxy);
+                       login_proxy_free(&proxy);
+               }
                return;
        }
        proxy->connected = TRUE;
@@ -278,6 +311,11 @@ static int login_proxy_connect(struct login_proxy *proxy)
        struct login_proxy_record *rec;
 
        rec = login_proxy_state_get(proxy_state, &proxy->ip, proxy->port);
+       if (rec->last_success.tv_sec == 0) {
+               /* first connect to this IP. don't start immediately failing
+                  the check below. */
+               rec->last_success.tv_sec = ioloop_timeval.tv_sec - 1;
+       }
        if (timeval_cmp(&rec->last_failure, &rec->last_success) > 0 &&
            rec->last_failure.tv_sec - rec->last_success.tv_sec > PROXY_IMMEDIATE_FAILURE_SECS &&
            rec->num_waiting_connections != 0) {
@@ -358,19 +396,8 @@ int login_proxy_new(struct client *client,
        return 0;
 }
 
-static void ATTR_NULL(2)
-login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
+static void login_proxy_disconnect(struct login_proxy *proxy)
 {
-       struct login_proxy *proxy = *_proxy;
-       struct client *client = proxy->client;
-       const char *ipstr;
-
-       *_proxy = NULL;
-
-       if (proxy->destroying)
-               return;
-       proxy->destroying = TRUE;
-
        if (proxy->to != NULL)
                timeout_remove(&proxy->to);
        if (proxy->to_notify != NULL)
@@ -378,8 +405,6 @@ login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
 
        if (proxy->state_rec != NULL)
                proxy->state_rec->num_waiting_connections--;
-       if (proxy->to != NULL)
-               timeout_remove(&proxy->to);
 
        if (proxy->server_io != NULL)
                io_remove(&proxy->server_io);
@@ -387,6 +412,24 @@ login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
                i_stream_destroy(&proxy->server_input);
        if (proxy->server_output != NULL)
                o_stream_destroy(&proxy->server_output);
+       if (proxy->server_fd != -1)
+               net_disconnect(proxy->server_fd);
+}
+
+static void ATTR_NULL(2)
+login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
+{
+       struct login_proxy *proxy = *_proxy;
+       struct client *client = proxy->client;
+       const char *ipstr;
+
+       *_proxy = NULL;
+
+       if (proxy->destroying)
+               return;
+       proxy->destroying = TRUE;
+
+       login_proxy_disconnect(proxy);
 
        if (proxy->client_fd != -1) {
                /* detached proxy */
@@ -414,9 +457,6 @@ login_proxy_free_reason(struct login_proxy **_proxy, const char *reason)
                        proxy->callback(proxy->client);
        }
 
-       if (proxy->server_fd != -1)
-               net_disconnect(proxy->server_fd);
-
        if (proxy->ssl_server_proxy != NULL)
                ssl_proxy_free(&proxy->ssl_server_proxy);
        i_free(proxy->host);