http: write last header line late

- HEADERFUNCTIONS might inspect response properties like
  CURLINFO_CONTENT_LENGTH_DOWNLOAD_T on seeing the last header line. If
  the line is being written before this is initialized, values are not
  available.

- write the last header line late when analyzing a HTTP response so that
  all information is available at the time of the writing.

- add test1485 to verify that CURLINFO_CONTENT_LENGTH_DOWNLOAD_T works
  on seeing the last header.

Fixes #13752
Reported-by: Harry Sintonen
Closes #13757

tests/libtest/Makefile.inc

@@ -54,6 +54,7 @@ noinst_PROGRAMS = chkhostname libauthretry libntlmconnect libprereq      \
  lib670 lib671 lib672 lib673 lib674 lib676 lib677 lib678 \
  lib1156 \
  lib1301 \
+ lib1485 \
  lib1500 lib1501 lib1502 lib1503 lib1504 lib1505 lib1506 lib1507 lib1508 \
  lib1509 lib1510 lib1511 lib1512 lib1513 lib1514 lib1515         lib1517 \
  lib1518         lib1520 lib1521 lib1522 lib1523 \
@@ -346,6 +347,9 @@ lib678_LDADD = $(TESTUTIL_LIBS)
 lib1301_SOURCES = lib1301.c $(SUPPORTFILES) $(TESTUTIL)
 lib1301_LDADD = $(TESTUTIL_LIBS)
 
+lib1485_SOURCES = lib1485.c $(SUPPORTFILES) $(TESTUTIL) $(WARNLESS)
+lib1485_LDADD = $(TESTUTIL_LIBS)
+
 lib1500_SOURCES = lib1500.c $(SUPPORTFILES) $(TESTUTIL)
 lib1500_LDADD = $(TESTUTIL_LIBS)
 

tests/libtest/lib1485.c

@@ -0,0 +1,120 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 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.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.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+#include "test.h"
+
+#include "testutil.h"
+#include "warnless.h"
+#include "memdebug.h"
+
+struct transfer_status {
+  CURL *easy;
+  curl_off_t out_len;
+  size_t hd_line;
+  CURLcode result;
+  int http_status;
+};
+
+static size_t header_callback(void *ptr, size_t size, size_t nmemb,
+                              void *userp)
+{
+  struct transfer_status *st = (struct transfer_status *)userp;
+  const char *hd = ptr;
+  size_t len = size * nmemb;
+  CURLcode result;
+
+  (void)fwrite(ptr, size, nmemb, stdout);
+  ++st->hd_line;
+  if(len == 2 && hd[0] == '\r' && hd[1] == '\n') {
+    curl_off_t clen;
+    long httpcode = 0;
+    /* end of a response */
+    result = curl_easy_getinfo(st->easy, CURLINFO_RESPONSE_CODE, &httpcode);
+    fprintf(stderr, "header_callback, get status: %ld, %d\n",
+            httpcode, result);
+    if(httpcode < 100 || httpcode >= 1000) {
+      fprintf(stderr, "header_callback, invalid status: %ld, %d\n",
+              httpcode, result);
+      return CURLE_WRITE_ERROR;
+    }
+    st->http_status = (int)httpcode;
+    if(st->http_status >= 200 && st->http_status < 300) {
+      result = curl_easy_getinfo(st->easy, CURLINFO_CONTENT_LENGTH_DOWNLOAD_T,
+                                 &clen);
+      fprintf(stderr, "header_callback, info Content-Length: %ld, %d\n",
+              (long)clen, result);
+      if(result) {
+        st->result = result;
+        return CURLE_WRITE_ERROR;
+      }
+      if(clen < 0) {
+        fprintf(stderr, "header_callback, expected known Content-Length, "
+                "got: %ld\n", (long)clen);
+        return CURLE_WRITE_ERROR;
+      }
+    }
+  }
+  return len;
+}
+
+static size_t write_callback(void *ptr, size_t size, size_t nmemb, void *userp)
+{
+  struct transfer_status *st = (struct transfer_status *)userp;
+  size_t len = size * nmemb;
+  fwrite(ptr, size, nmemb, stdout);
+  st->out_len += (curl_off_t)len;
+  return len;
+}
+
+CURLcode test(char *URL)
+{
+  CURL *curls = NULL;
+  CURLcode res = CURLE_OK;
+  struct transfer_status st;
+
+  start_test_timing();
+
+  memset(&st, 0, sizeof(st));
+
+  global_init(CURL_GLOBAL_ALL);
+
+  easy_init(curls);
+  st.easy = curls; /* to allow callbacks access */
+
+  easy_setopt(curls, CURLOPT_URL, URL);
+  easy_setopt(curls, CURLOPT_WRITEFUNCTION, write_callback);
+  easy_setopt(curls, CURLOPT_WRITEDATA, &st);
+  easy_setopt(curls, CURLOPT_HEADERFUNCTION, header_callback);
+  easy_setopt(curls, CURLOPT_HEADERDATA, &st);
+
+  easy_setopt(curls, CURLOPT_NOPROGRESS, 1L);
+
+  res = curl_easy_perform(curls);
+
+test_cleanup:
+
+  curl_easy_cleanup(curls);
+  curl_global_cleanup();
+
+  return res; /* return the final return code */
+}