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

4 files changed, 68 insertions, 0 deletions

diff --git a/docs/libcurl/curl_easy_getinfo.3 b/docs/libcurl/curl_easy_getinfo.3
index bd66fd51a..c7b124a24 100644
--- a/docs/libcurl/curl_easy_getinfo.3
+++ b/docs/libcurl/curl_easy_getinfo.3
@@ -157,6 +157,9 @@ Upload size.  See \fICURLINFO_CONTENT_LENGTH_UPLOAD_T(3)\fP
 .IP CURLINFO_CONTENT_TYPE
 Content type from the Content-Type header.
 See \fICURLINFO_CONTENT_TYPE(3)\fP
+.IP CURLINFO_RETRY_AFTER
+The value from the from the Retry-After header.
+See \fICURLINFO_RETRY_AFTER(3)\fP
 .IP CURLINFO_PRIVATE
 User's private data pointer.
 See \fICURLINFO_PRIVATE(3)\fP
diff --git a/docs/libcurl/opts/CURLINFO_RETRY_AFTER.3 b/docs/libcurl/opts/CURLINFO_RETRY_AFTER.3
new file mode 100644
index 000000000..9e58ca62d
--- /dev/null
+++ b/docs/libcurl/opts/CURLINFO_RETRY_AFTER.3
@@ -0,0 +1,63 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" *
+.\" * This software is licensed as described in the file COPYING, which
+.\" * you should have received as part of this distribution. The terms
+.\" * are also available at https://curl.haxx.se/docs/copyright.html.
+.\" *
+.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+.\" * copies of the Software, and permit persons to whom the Software is
+.\" * furnished to do so, under the terms of the COPYING file.
+.\" *
+.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+.\" * KIND, either express or implied.
+.\" *
+.\" **************************************************************************
+.\"
+.TH CURLINFO_RETRY_AFTER 3 "6 Aug 2019" "libcurl 7.66.0" "curl_easy_getinfo options"
+.SH NAME
+CURLINFO_RETRY_AFTER \- returns the Retry-After retry delay
+.SH SYNOPSIS
+#include <curl/curl.h>
+
+CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_RETRY_AFTER, curl_off_t *retry);
+.SH DESCRIPTION
+Pass a pointer to a curl_off_t variable to receive the number of seconds the
+HTTP server suggesets the client should wait until the next request is
+issued. The information from the "Retry-After:" header.
+
+While the HTTP header might contain a fixed date string, the
+\fICURLINFO_RETRY_AFTER(3)\fP will alwaus return number of seconds to wait -
+or zero if there was no header or the header couldn't be parsed.
+.SH DEFAULT
+Returns zero delay if there was no header.
+.SH PROTOCOLS
+HTTP(S)
+.SH EXAMPLE
+.nf
+CURL *curl = curl_easy_init();
+if(curl) {
+  CURLcode res;
+  curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
+  res = curl_easy_perform(curl);
+  if(res == CURLE_OK) {
+    curl_off_t wait = 0;
+    curl_easy_getinfo(curl, CURLINFO_RETRY_AFTER, &wait);
+    if(wait)
+      printf("Wait for %" CURL_FORMAT_CURL_OFF_T " seconds\\n", wait);
+  }
+  curl_easy_cleanup(curl);
+}
+.fi
+.SH AVAILABILITY
+Added in curl 7.66.0
+.SH RETURN VALUE
+Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
+.SH "SEE ALSO"
+.BR CURLOPT_STDERR "(3), " CURLOPT_HEADERFUNCTION "(3), "
diff --git a/docs/libcurl/opts/Makefile.inc b/docs/libcurl/opts/Makefile.inc
index 094c58f42..b7cd7a698 100644
--- a/docs/libcurl/opts/Makefile.inc
+++ b/docs/libcurl/opts/Makefile.inc
@@ -43,6 +43,7 @@ man_MANS =                                      \
   CURLINFO_REDIRECT_URL.3                       \
   CURLINFO_REQUEST_SIZE.3                       \
   CURLINFO_RESPONSE_CODE.3                      \
+  CURLINFO_RETRY_AFTER.3                        \
   CURLINFO_RTSP_CLIENT_CSEQ.3                   \
   CURLINFO_RTSP_CSEQ_RECV.3                     \
   CURLINFO_RTSP_SERVER_CSEQ.3                   \
diff --git a/docs/libcurl/symbols-in-versions b/docs/libcurl/symbols-in-versions
index 49175e0f5..79243e25b 100644
--- a/docs/libcurl/symbols-in-versions
+++ b/docs/libcurl/symbols-in-versions
@@ -267,6 +267,7 @@ CURLINFO_REDIRECT_TIME_T        7.61.0
 CURLINFO_REDIRECT_URL           7.18.2
 CURLINFO_REQUEST_SIZE           7.4.1
 CURLINFO_RESPONSE_CODE          7.10.8
+CURLINFO_RETRY_AFTER            7.66.0
 CURLINFO_RTSP_CLIENT_CSEQ       7.20.0
 CURLINFO_RTSP_CSEQ_RECV         7.20.0
 CURLINFO_RTSP_SERVER_CSEQ       7.20.0