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, 20 insertions, 0 deletions

diff --git a/lib/easy.c b/lib/easy.c
index 027d0bef3..83433f1f5 100644
--- a/lib/easy.c
+++ b/lib/easy.c
@@ -1197,3 +1197,23 @@ CURLcode curl_easy_send(struct Curl_easy *data, const void *buffer,
 
   return result;
 }
+
+/*
+ * Performs connection upkeep for the given session handle.
+ */
+CURLcode curl_easy_conn_upkeep(struct Curl_easy *data)
+{
+  /* Verify that we got an easy handle we can work with. */
+  if(!GOOD_EASY_HANDLE(data))
+    return CURLE_BAD_FUNCTION_ARGUMENT;
+
+  if(data->multi_easy) {
+    /* Use the common function to keep connections alive. */
+    return Curl_conn_upkeep(&data->multi_easy->conn_cache, data);
+  }
+  else {
+    /* No connections, so just return success */
+    return CURLE_OK;
+  }
+}
+