upkeep: add a connection upkeep API: curl_easy_conn_upkeep()

Add functionality so that protocols can do custom keepalive on their
connections, when an external API function is called.

Add docs for the new options in 7.62.0

Closes #1641

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/setopt.c b/lib/setopt.c
index 4a71f9ae4..13c7da960 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -2624,6 +2624,12 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option,
                             va_arg(param, char *));
     data->set.doh = data->set.str[STRING_DOH]?TRUE:FALSE;
     break;
+  case CURLOPT_CONN_UPKEEP_INTERVAL_MS:
+    arg = va_arg(param, long);
+    if(arg < 0)
+      return CURLE_BAD_FUNCTION_ARGUMENT;
+    data->set.upkeep_interval_ms = arg;
+    break;
   default:
     /* unknown tag and its companion, just ignore: */
     result = CURLE_UNKNOWN_OPTION;