CURLOPT_MAXLIFETIME_CONN: maximum allowed lifetime for conn reuse

... and close connections that are too old instead of reusing them.

By default, this behavior is disabled.

Bug: https://curl.se/mail/lib-2021-09/0058.html
Closes #7751

4 files changed, 30 insertions, 5 deletions

diff --git a/lib/easyoptions.c b/lib/easyoptions.c
index bc149e7be..b6131d432 100644
--- a/lib/easyoptions.c
+++ b/lib/easyoptions.c
@@ -165,6 +165,7 @@ struct curl_easyoption Curl_easyopts[] = {
   {"MAXCONNECTS", CURLOPT_MAXCONNECTS, CURLOT_LONG, 0},
   {"MAXFILESIZE", CURLOPT_MAXFILESIZE, CURLOT_LONG, 0},
   {"MAXFILESIZE_LARGE", CURLOPT_MAXFILESIZE_LARGE, CURLOT_OFF_T, 0},
+  {"MAXLIFETIME_CONN", CURLOPT_MAXLIFETIME_CONN, CURLOT_LONG, 0},
   {"MAXREDIRS", CURLOPT_MAXREDIRS, CURLOT_LONG, 0},
   {"MAX_RECV_SPEED_LARGE", CURLOPT_MAX_RECV_SPEED_LARGE, CURLOT_OFF_T, 0},
   {"MAX_SEND_SPEED_LARGE", CURLOPT_MAX_SEND_SPEED_LARGE, CURLOT_OFF_T, 0},
@@ -358,6 +359,6 @@ struct curl_easyoption Curl_easyopts[] = {
  */
 int Curl_easyopts_check(void)
 {
-  return ((CURLOPT_LASTENTRY%10000) != (313 + 1));
+  return ((CURLOPT_LASTENTRY%10000) != (314 + 1));
 }
 #endif
diff --git a/lib/setopt.c b/lib/setopt.c
index 8e19389ae..65fe252f4 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -2938,6 +2938,12 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
       return CURLE_BAD_FUNCTION_ARGUMENT;
     data->set.maxage_conn = arg;
     break;
+  case CURLOPT_MAXLIFETIME_CONN:
+    arg = va_arg(param, long);
+    if(arg < 0)
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+    data->set.maxlifetime_conn = arg;
+    break;
   case CURLOPT_TRAILERFUNCTION:
 #ifndef CURL_DISABLE_HTTP
     data->set.trailer_callback = va_arg(param, curl_trailer_callback);
diff --git a/lib/url.c b/lib/url.c
index 5c31cadd6..1603b3072 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -622,6 +622,7 @@ CURLcode Curl_init_userdefined(struct Curl_easy *data)
   set->upkeep_interval_ms = CURL_UPKEEP_INTERVAL_DEFAULT;
   set->maxconnects = DEFAULT_CONNCACHE_SIZE; /* for easy handles */
   set->maxage_conn = 118;
+  set->maxlifetime_conn = 0;
   set->http09_allowed = FALSE;
   set->httpwant =
 #ifdef USE_NGHTTP2
@@ -962,21 +963,36 @@ socks_proxy_info_matches(const struct proxy_info *data,
 #define socks_proxy_info_matches(x,y) FALSE
 #endif
 
-/* A connection has to have been idle for a shorter time than 'maxage_conn' to
-   be subject for reuse. The success rate is just too low after this. */
+/* A connection has to have been idle for a shorter time than 'maxage_conn'
+   (the success rate is just too low after this), or created less than
+   'maxlifetime_conn' ago, to be subject for reuse. */
 
 static bool conn_maxage(struct Curl_easy *data,
                         struct connectdata *conn,
                         struct curltime now)
 {
-  timediff_t idletime = Curl_timediff(now, conn->lastused);
+  timediff_t idletime, lifetime;
+
+  idletime = Curl_timediff(now, conn->lastused);
   idletime /= 1000; /* integer seconds is fine */
 
   if(idletime > data->set.maxage_conn) {
-    infof(data, "Too old connection (%ld seconds), disconnect it",
+    infof(data, "Too old connection (%ld seconds idle), disconnect it",
           idletime);
     return TRUE;
   }
+
+  lifetime = Curl_timediff(now, conn->created);
+  lifetime /= 1000; /* integer seconds is fine */
+
+  if(data->set.maxlifetime_conn && lifetime > data->set.maxlifetime_conn) {
+    infof(data,
+          "Too old connection (%ld seconds since creation), disconnect it",
+          lifetime);
+    return TRUE;
+  }
+
+
   return FALSE;
 }
 
diff --git a/lib/urldata.h b/lib/urldata.h
index 47cb9e282..92df52467 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1678,6 +1678,8 @@ struct UserDefined {
   long server_response_timeout; /* in milliseconds, 0 means no timeout */
   long maxage_conn;     /* in seconds, max idle time to allow a connection that
                            is to be reused */
+  long maxlifetime_conn; /* in seconds, max time since creation to allow a
+                            connection that is to be reused */
   long tftp_blksize;    /* in bytes, 0 means use default */
   curl_off_t filesize;  /* size of file to upload, -1 means unknown */
   long low_speed_limit; /* bytes/second */