From: Stefan Eissing <stefan@eissing.org>
Date: Tue, 21 May 2024 09:21:14 +0000 (+0200)
Subject: http: HEAD response body tolerance
X-Git-Tag: curl-8_8_0~7
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5a4769b6d5d14090160eb3aed772f1b30e5e3d2d;p=thirdparty%2Fcurl.git

http: HEAD response body tolerance

- as reported in #13725, some servers wrongly send body bytes in
  responses to a HEAD request. This used to be tolerated in curl
  8.4 and before and leads to failed transfers in newer versions.
- restore previous behaviour for HTTP/1.1 and HTTP/2:
  * 1.1: do not add 'Transfer-Encoding' writers from HEAD
    responses. RFC 9112 says they do not apply.
  * 2: when the transfer expects 'no_body', to not report stream
    resets as error when all response headers have been received.

Reported-by: Jeroen Ooms
Fixes #13725
Closes #13732
---

diff --git a/lib/http.c b/lib/http.c
index 01f26bf85a..2a41f80786 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -3139,19 +3139,23 @@ CURLcode Curl_http_header(struct Curl_easy *data,
     break;
   case 't':
   case 'T':
-    v = !k->http_bodyless? HD_VAL(hd, hdlen, "Transfer-Encoding:") : NULL;
+    /* RFC 9112, ch. 6.1
+     * "Transfer-Encoding MAY be sent in a response to a HEAD request or
+     *  in a 304 (Not Modified) response (Section 15.4.5 of [HTTP]) to a
+     *  GET request, neither of which includes a message body, to indicate
+     *  that the origin server would have applied a transfer coding to the
+     *  message body if the request had been an unconditional GET."
+     *
+     * Read: in these cases the 'Transfer-Encoding' does not apply
+     * to any data following the response headers. Do not add any decoders.
+     */
+    v = (!k->http_bodyless &&
+         (data->state.httpreq != HTTPREQ_HEAD) &&
+         (k->httpcode != 304))?
+        HD_VAL(hd, hdlen, "Transfer-Encoding:") : NULL;
     if(v) {
       /* One or more encodings. We check for chunked and/or a compression
          algorithm. */
-      /*
-       * [RFC 2616, section 3.6.1] A 'chunked' transfer encoding
-       * means that the server will send a series of "chunks". Each
-       * chunk starts with line with info (including size of the
-       * coming block) (terminated with CRLF), then a block of data
-       * with the previously mentioned size. There can be any amount
-       * of chunks, and a chunk-data set to zero signals the
-       * end-of-chunks. */
-
       result = Curl_build_unencoding_stack(data, v, TRUE);
       if(result)
         return result;
diff --git a/lib/http2.c b/lib/http2.c
index 50dd878bb0..f0f7b566e2 100644
--- a/lib/http2.c
+++ b/lib/http2.c
@@ -1716,6 +1716,15 @@ static ssize_t http2_handle_stream_close(struct Curl_cfilter *cf,
     return -1;
   }
   else if(stream->error != NGHTTP2_NO_ERROR) {
+    if(stream->resp_hds_complete && data->req.no_body) {
+      CURL_TRC_CF(data, cf, "[%d] error after response headers, but we did "
+                  "not want a body anyway, ignore: %s (err %u)",
+                  stream->id, nghttp2_http2_strerror(stream->error),
+                  stream->error);
+      stream->close_handled = TRUE;
+      *err = CURLE_OK;
+      goto out;
+    }
     failf(data, "HTTP/2 stream %u was not closed cleanly: %s (err %u)",
           stream->id, nghttp2_http2_strerror(stream->error),
           stream->error);