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

14 files changed, 317 insertions, 6 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
diff --git a/include/curl/curl.h b/include/curl/curl.h
index 6011e416f..9b9ec80c0 100644
--- a/include/curl/curl.h
+++ b/include/curl/curl.h
@@ -2623,8 +2623,9 @@ typedef enum {
   CURLINFO_STARTTRANSFER_TIME_T = CURLINFO_OFF_T + 54,
   CURLINFO_REDIRECT_TIME_T  = CURLINFO_OFF_T + 55,
   CURLINFO_APPCONNECT_TIME_T = CURLINFO_OFF_T + 56,
+  CURLINFO_RETRY_AFTER      = CURLINFO_OFF_T + 57,
 
-  CURLINFO_LASTONE          = 56
+  CURLINFO_LASTONE          = 57
 } CURLINFO;
 
 /* CURLINFO_RESPONSE_CODE is the new name for the option previously known as
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 */
 };
diff --git a/tests/data/Makefile.inc b/tests/data/Makefile.inc
index 0657d2120..1e9aef9d2 100644
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -178,7 +178,7 @@ test1540 test1541 \
 test1550 test1551 test1552 test1553 test1554 test1555 test1556 test1557 \
 test1558 test1559 test1560 test1561 test1562 test1563 \
 \
-test1590 test1591 test1592 test1593 \
+test1590 test1591 test1592 test1593 test1594 \
 \
 test1600 test1601 test1602 test1603 test1604 test1605 test1606 test1607 \
 test1608 test1609 test1620 test1621 \
diff --git a/tests/data/test1594 b/tests/data/test1594
new file mode 100644
index 000000000..4907ca2be
--- /dev/null
+++ b/tests/data/test1594
@@ -0,0 +1,52 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+HTTP replaced headers
+CURLOPT_TIMECONDITION
+If-Modified-Since
+</keywords>
+</info>
+
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 503 Error
+Date: Thu, 11 Jul 2019 02:26:59 GMT
+Server: test-server/swsclose
+Retry-After: 22
+
+</data>
+</reply>
+# Client-side
+<client>
+<server>
+http
+</server>
+<name>
+HTTP Retry-After header parsing and extraction
+</name>
+<tool>
+lib1594
+</tool>
+<command>
+http://%HOSTIP:%HTTPPORT/1594
+</command>
+</client>
+
+<verify>
+<strip>
+^User-Agent:.*
+</strip>
+<protocol>
+GET /1594 HTTP/1.1

+Host: %HOSTIP:%HTTPPORT

+Accept: */*

+

+</protocol>
+<stdout>
+Retry-After: 22
+</stdout>
+</verify>
+</testcase>
diff --git a/tests/data/test1595 b/tests/data/test1595
new file mode 100644
index 000000000..29b2b865f
--- /dev/null
+++ b/tests/data/test1595
@@ -0,0 +1,51 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+HTTP replaced headers
+CURLOPT_TIMECONDITION
+If-Modified-Since
+</keywords>
+</info>
+
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 503 Error
+Date: Thu, 11 Jul 2019 02:26:59 GMT
+Server: test-server/swsclose
+
+</data>
+</reply>
+# Client-side
+<client>
+<server>
+http
+</server>
+<name>
+HTTP Retry-After header extraction (without header)
+</name>
+<tool>
+lib1594
+</tool>
+<command>
+http://%HOSTIP:%HTTPPORT/1595
+</command>
+</client>
+
+<verify>
+<strip>
+^User-Agent:.*
+</strip>
+<protocol>
+GET /1595 HTTP/1.1

+Host: %HOSTIP:%HTTPPORT

+Accept: */*

+

+</protocol>
+<stdout>
+Retry-After: 0
+</stdout>
+</verify>
+</testcase>
diff --git a/tests/data/test1596 b/tests/data/test1596
new file mode 100644
index 000000000..9a8cb480e
--- /dev/null
+++ b/tests/data/test1596
@@ -0,0 +1,52 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP GET
+HTTP replaced headers
+CURLOPT_TIMECONDITION
+If-Modified-Since
+</keywords>
+</info>
+
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 503 Error
+Date: Thu, 11 Jul 2019 02:26:59 GMT
+Server: test-server/swsclose
+Retry-After: Thu, 11 Jul 2024 02:26:59 GMT
+
+</data>
+</reply>
+# Client-side
+<client>
+<server>
+http
+</server>
+<name>
+HTTP Retry-After header parsing using a date
+</name>
+<tool>
+lib1596
+</tool>
+<command>
+http://%HOSTIP:%HTTPPORT/1596
+</command>
+</client>
+
+<verify>
+<strip>
+^User-Agent:.*
+</strip>
+<protocol>
+GET /1596 HTTP/1.1

+Host: %HOSTIP:%HTTPPORT

+Accept: */*

+

+</protocol>
+<stdout>
+Retry-After: 172066
+</stdout>
+</verify>
+</testcase>
diff --git a/tests/libtest/Makefile.inc b/tests/libtest/Makefile.inc
index f5effd97d..4ea9cf2a7 100644
--- a/tests/libtest/Makefile.inc
+++ b/tests/libtest/Makefile.inc
@@ -32,7 +32,7 @@ noinst_PROGRAMS = chkhostname libauthretry libntlmconnect                \
  lib1540 lib1541 \
  lib1550 lib1551 lib1552 lib1553 lib1554 lib1555 lib1556 lib1557 \
  lib1558 lib1559 lib1560 \
- lib1591 lib1592 lib1593 \
+ lib1591 lib1592 lib1593 lib1594 lib1596 \
  lib1900 lib1905 lib1906 \
  lib2033
 
@@ -544,6 +544,13 @@ lib1592_CPPFLAGS = $(AM_CPPFLAGS) -DLIB1592
 lib1593_SOURCES = lib1593.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib1593_LDADD = $(TESTUTIL_LIBS)
 
+lib1594_SOURCES = lib1594.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
+lib1594_LDADD = $(TESTUTIL_LIBS)
+
+lib1596_SOURCES = lib1594.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
+lib1596_LDADD = $(TESTUTIL_LIBS)
+lib1596_CPPFLAGS = $(AM_CPPFLAGS) -DLIB1596
+
 lib1900_SOURCES = lib1900.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
 lib1900_LDADD = $(TESTUTIL_LIBS)
 lib1900_CPPFLAGS = $(AM_CPPFLAGS)
diff --git a/tests/libtest/lib1594.c b/tests/libtest/lib1594.c
new file mode 100644
index 000000000..a76971590
--- /dev/null
+++ b/tests/libtest/lib1594.c
@@ -0,0 +1,66 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  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.
+ *
+ ***************************************************************************/
+
+/* Testing Retry-After header parser */
+
+#include "test.h"
+
+#include "memdebug.h"
+
+int test(char *URL)
+{
+  struct curl_slist *header = NULL;
+  curl_off_t retry;
+  CURL *curl = NULL;
+  int res = 0;
+
+  global_init(CURL_GLOBAL_ALL);
+
+  easy_init(curl);
+
+  easy_setopt(curl, CURLOPT_URL, URL);
+
+  res = curl_easy_perform(curl);
+  if(res)
+    goto test_cleanup;
+
+  res = curl_easy_getinfo(curl, CURLINFO_RETRY_AFTER, &retry);
+  if(res)
+    goto test_cleanup;
+
+#ifdef LIB1596
+  /* we get a relative number of seconds, so add the number of seconds
+     we're at to make it a somewhat stable number. Then remove accuracy. */
+  retry += time(NULL);
+  retry /= 10000;
+#endif
+  printf("Retry-After: %" CURL_FORMAT_CURL_OFF_T "\n", retry);
+
+test_cleanup:
+
+  /* always cleanup */
+  curl_easy_cleanup(curl);
+  curl_slist_free_all(header);
+  curl_global_cleanup();
+
+  return res;
+}