housekeeping: Add housekeeping for connections

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

include/curl/easy.h

@@ -29,6 +29,7 @@ CURL_EXTERN CURL *curl_easy_init(void);
 CURL_EXTERN CURLcode curl_easy_setopt(CURL *curl, CURLoption option, ...);
 CURL_EXTERN CURLcode curl_easy_perform(CURL *curl);
 CURL_EXTERN void curl_easy_cleanup(CURL *curl);
+CURL_EXTERN CURLcode curl_easy_housekeeping(CURL *curl);
 
 /*
  * NAME curl_easy_getinfo()

lib/easy.c

@@ -1137,3 +1137,18 @@ CURLcode curl_easy_send(struct Curl_easy *data, const void *buffer,
 
   return result;
 }
+
+/*
+ * Performs housekeeping functions.
+ */
+CURLcode curl_easy_housekeeping(struct Curl_easy *data)
+{
+  if(data->multi_easy) {
+    /* Use the common function to do housekeeping for connections. */
+    return Curl_housekeeping(&data->multi_easy->conn_cache, data);
+  }
+  else {
+    /* No connections, so just return success */
+    return CURLE_OK;
+  }
+}

lib/http2.c

@@ -181,17 +181,43 @@ static bool http2_connisdead(struct connectdata *check)
   return ret_val;
 }
 
-
 static unsigned int http2_conncheck(struct connectdata *check,
                                     unsigned int checks_to_perform)
 {
   unsigned int ret_val = CONNRESULT_NONE;
+  struct http_conn *c = &check->proto.httpc;
+  int rc;
+  bool send_frames = false;
 
   if(checks_to_perform & CONNCHECK_ISDEAD) {
     if(http2_connisdead(check))
       ret_val |= CONNRESULT_DEAD;
   }
 
+  if(checks_to_perform & CONNCHECK_KEEPALIVE) {
+    struct timeval now = Curl_tvnow();
+    time_t elapsed = Curl_tvdiff(now, check->keepalive);
+
+    if(elapsed > 60000L) {
+      /* Perform an HTTP/2 PING */
+      rc = nghttp2_submit_ping(c->h2, 0, ZERO_NULL);
+      infof(check->data, "Sending HTTP/2 PING (returned %d)\n", rc);
+
+      if(!rc) {
+        /* Successfully added a PING frame to the session. Need to flag this
+           so the frame is sent. */
+        send_frames = true;
+      }
+
+      check->keepalive = now;
+    }
+  }
+
+  if(send_frames) {
+    rc = nghttp2_session_send(c->h2);
+    infof(check->data, "HTTP/2 session send returned %d \n", rc);
+  }
+
   return ret_val;
 }
 

lib/url.c

@@ -4196,6 +4196,9 @@ static struct connectdata *allocate_conn(struct Curl_easy *data)
   /* Store creation time to help future close decision making */
   conn->created = Curl_tvnow();
 
+  /* Store current time to give a baseline to keepalive connection times. */
+  conn->keepalive = Curl_tvnow();
+
   conn->data = data; /* Setup the association between this connection
                         and the Curl_easy */
 
@@ -7153,3 +7156,29 @@ static unsigned int get_protocol_family(unsigned int protocol)
 
   return family;
 }
+
+/*
+ * Wrapper to call housekeeping functions in Curl_conncache_foreach()
+ *
+ * Returns always 0.
+ */
+static int housekeeping(struct connectdata *conn,
+                        void *param)
+{
+  if(conn->handler->connection_check) {
+    /* Do a protocol-specific keepalive check on the connection. */
+    conn->handler->connection_check(conn, CONNCHECK_KEEPALIVE);
+  }
+
+  return 0; /* continue iteration */
+}
+
+CURLcode Curl_housekeeping(struct conncache *conn_cache,
+                           void *data)
+{
+  /* Loop over every connection and do housekeeping. */
+  Curl_conncache_foreach(conn_cache,
+                         data,
+                         housekeeping);
+  return CURLE_OK;
+}

lib/url.h

@@ -90,4 +90,7 @@ void Curl_verboseconnect(struct connectdata *conn);
   (conn->http_proxy.proxytype == CURLPROXY_HTTPS &&\
   !conn->bits.proxy_ssl_connected[SECONDARYSOCKET])
 
+CURLcode Curl_housekeeping(struct conncache *conn_cache,
+                           void *data);
+
 #endif /* HEADER_CURL_URL_H */

lib/urldata.h

@@ -867,6 +867,7 @@ struct Curl_handler {
 
 #define CONNCHECK_NONE 0                 /* No checks */
 #define CONNCHECK_ISDEAD (1<<0)          /* Check if the connection is dead. */
+#define CONNCHECK_KEEPALIVE (1<<1)       /* Perform any keepalive function. */
 
 #define CONNRESULT_NONE 0                /* No extra information. */
 #define CONNRESULT_DEAD (1<<0)           /* The connection is dead. */
@@ -1051,6 +1052,11 @@ struct connectdata {
 
   long ip_version; /* copied from the Curl_easy at creation time */
 
+  /* Protocols can use a custom keepalive mechanism to keep connections alive.
+     This allows those protocols to track the last time the keepalive mechanism
+     was used on this connection. */
+  struct timeval keepalive;
+
   /**** curl_get() phase fields */
 
   curl_socket_t sockfd;   /* socket to read from or CURL_SOCKET_BAD */