CURLINFO_RETRY_AFTER: parse the Retry-After header value

This is only the libcurl part that provides the information. There's no
user of the parsed value. This change includes three new tests for the
parser.

Ref: #3794

3 files changed, 17 insertions, 3 deletions

diff --git a/lib/getinfo.c b/lib/getinfo.c
index 5fd8dc018..2b8f2303e 100644
--- a/lib/getinfo.c
+++ b/lib/getinfo.c
@@ -246,7 +246,6 @@ static CURLcode getinfo_long(struct Curl_easy *data, CURLINFO info,
   case CURLINFO_PROTOCOL:
     *param_longp = data->info.conn_protocol;
     break;
-
   default:
     return CURLE_UNKNOWN_OPTION;
   }
@@ -304,7 +303,9 @@ static CURLcode getinfo_offt(struct Curl_easy *data, CURLINFO info,
   case CURLINFO_REDIRECT_TIME_T:
     *param_offt = data->progress.t_redirect;
     break;
-
+  case CURLINFO_RETRY_AFTER:
+    *param_offt = data->info.retry_after;
+    break;
   default:
     return CURLE_UNKNOWN_OPTION;
   }
diff --git a/lib/http.c b/lib/http.c
index 9d8cd5570..cfa7093b2 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -3953,6 +3953,19 @@ CURLcode Curl_http_readwrite_headers(struct Curl_easy *data,
       if(result)
         return result;
     }
+    else if(checkprefix("Retry-After:", k->p)) {
+      /* Retry-After = HTTP-date / delay-seconds */
+      curl_off_t retry_after = 0; /* zero for unknown or "now" */
+      time_t date = curl_getdate(&k->p[12], NULL);
+      if(-1 == date) {
+        /* not a date, try it as a decimal number */
+        (void)curlx_strtoofft(&k->p[12], NULL, 10, &retry_after);
+      }
+      else
+        /* convert date to number of seconds into the future */
+        retry_after = date - time(NULL);
+      data->info.retry_after = retry_after; /* store it */
+    }
     else if(!k->http_bodyless && checkprefix("Content-Range:", k->p)) {
       /* Content-Range: bytes [num]-
          Content-Range: bytes: [num]-
diff --git a/lib/urldata.h b/lib/urldata.h
index eabb1b5c7..fec3f755a 100644
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -1071,6 +1071,7 @@ struct PureInfo {
   long numconnects; /* how many new connection did libcurl created */
   char *contenttype; /* the content type of the object */
   char *wouldredirect; /* URL this would've been redirected to if asked to */
+  curl_off_t retry_after; /* info from Retry-After: header */
 
   /* PureInfo members 'conn_primary_ip', 'conn_primary_port', 'conn_local_ip'
      and, 'conn_local_port' are copied over from the connectdata struct in
@@ -1090,7 +1091,6 @@ struct PureInfo {
                                  OpenSSL, GnuTLS, Schannel, NSS and GSKit
                                  builds. Asked for with CURLOPT_CERTINFO
                                  / CURLINFO_CERTINFO */
-
   bit timecond:1;  /* set to TRUE if the time condition didn't match, which
                       thus made the document NOT get fetched */
 };