lib-http: Always try to connect to host's all IPs when connections fail.

Previously this was done only when the new connections started from the
first IP.

diff --git a/src/lib-http/http-client-host.c b/src/lib-http/http-client-host.c
index aa29744888db03072d19234b8d1a24e3ee87bc67..74a220a2bfd88646c7c1a3de55c007449ec96bfc 100644 (file)
--- a/src/lib-http/http-client-host.c
+++ b/src/lib-http/http-client-host.c
@@ -114,6 +114,20 @@ http_client_host_port_drop_request(struct http_client_host_port *hport,
        }
 }
 
+static bool
+http_client_hport_is_last_connect_ip(struct http_client_host_port *hport)
+{
+       i_assert(hport->ips_connect_idx < hport->host->ips_count);
+       i_assert(hport->ips_connect_start_idx < hport->host->ips_count);
+
+       /* we'll always go through all the IPs. we don't necessarily start
+          connecting from the first IP, so we'll need to treat the IPs as
+          a ring buffer where we automatically wrap back to the first IP
+          when necessary. */
+       return (hport->ips_connect_idx + 1) % hport->host->ips_count ==
+               hport->ips_connect_start_idx;
+}
+
 static void
 http_client_host_port_soft_connect_timeout(struct http_client_host_port *hport)
 {
@@ -122,7 +136,7 @@ http_client_host_port_soft_connect_timeout(struct http_client_host_port *hport)
        if (hport->to_connect != NULL)
                timeout_remove(&hport->to_connect);
 
-       if (hport->ips_connect_idx + 1 >= host->ips_count)
+       if (http_client_hport_is_last_connect_ip(hport))
                return;
 
        /* if our our previous connection attempt takes longer than the
@@ -135,7 +149,7 @@ http_client_host_port_soft_connect_timeout(struct http_client_host_port *hport)
                hport->https_name == NULL ? "" :
                        t_strdup_printf(" (SSL=%s)", hport->https_name));
 
-       hport->ips_connect_idx++;
+       hport->ips_connect_idx = (hport->ips_connect_idx + 1) % host->ips_count;
        http_client_host_port_connection_setup(hport);
 }
 
@@ -161,7 +175,7 @@ http_client_host_port_connection_setup(struct http_client_host_port *hport)
 
        /* start soft connect time-out (but only if we have another IP left) */
        msecs = host->client->set.soft_connect_timeout_msecs;
-       if (host->ips_count - hport->ips_connect_idx > 1 && msecs > 0 &&
+       if (!http_client_hport_is_last_connect_ip(hport) && msecs > 0 &&
            hport->to_connect == NULL) {
                hport->to_connect =
                        timeout_add(msecs, http_client_host_port_soft_connect_timeout, hport);
@@ -200,11 +214,26 @@ http_client_host_drop_pending_connections(struct http_client_host_port *hport,
        }
 }
 
+static unsigned int
+http_client_host_get_ip_idx(struct http_client_host *host,
+                           const struct ip_addr *ip)
+{
+       unsigned int i;
+
+       for (i = 0; i < host->ips_count; i++) {
+               if (net_ip_compare(&host->ips[i], ip))
+                       return i;
+       }
+       i_unreached();
+}
+
 static void
 http_client_host_port_connection_success(struct http_client_host_port *hport,
                                         const struct http_client_peer_addr *addr)
 {
        /* we achieved at least one connection the the addr->ip */
+       hport->ips_connect_start_idx =
+               http_client_host_get_ip_idx(hport->host, &addr->ip);
 
        /* stop soft connect time-out */
        if (hport->to_connect != NULL)
@@ -237,15 +266,16 @@ http_client_host_port_connection_failure(struct http_client_host_port *hport,
        if (hport->to_connect != NULL)
                timeout_remove(&hport->to_connect);
 
-       i_assert(hport->ips_connect_idx < host->ips_count);
-       if (++hport->ips_connect_idx == host->ips_count) {
+       if (http_client_hport_is_last_connect_ip(hport)) {
                /* all IPs failed, but retry all of them again on the
                   next request. */
-               hport->ips_connect_idx = 0;
+               hport->ips_connect_idx = hport->ips_connect_start_idx =
+                       (hport->ips_connect_idx + 1) % host->ips_count;
                http_client_host_port_error(hport,
                        HTTP_CLIENT_REQUEST_ERROR_CONNECT_FAILED, reason);
                return FALSE;
        }
+       hport->ips_connect_idx = (hport->ips_connect_idx + 1) % host->ips_count;
 
        http_client_host_port_connection_setup(hport);
        return TRUE;
@@ -329,7 +359,7 @@ http_client_host_dns_callback(const struct dns_lookup_result *result,
        /* make connections to requested ports */
        array_foreach_modifiable(&host->ports, hport) {
                unsigned int count = array_count(&hport->request_queue);
-               hport->ips_connect_idx = 0;
+               hport->ips_connect_idx = hport->ips_connect_start_idx = 0;
                if (count > 0)
                        http_client_host_port_connection_setup(hport);
                requests += count;

diff --git a/src/lib-http/http-client-private.h b/src/lib-http/http-client-private.h
index 4d9f6f9f3f7e361e17030cf1af4b5235be3fd89e..dbbad8ccd8d780a6fe6dd78cc222eea230cf0ad8 100644 (file)
--- a/src/lib-http/http-client-private.h
+++ b/src/lib-http/http-client-private.h
@@ -78,6 +78,10 @@ struct http_client_host_port {
 
        /* current index in host->ips */
        unsigned int ips_connect_idx;
+       /* the first IP that started the current round of connection attempts.
+          initially 0, and later set to the (ip_idx+1) of the last successful
+          connected IP */
+       unsigned int ips_connect_start_idx;
        /* number of connections trying to connect for this host+port */
        unsigned int pending_connection_count;