gnu: http-parser: Update to 2.9.4-1.ec8b5ee [fixes CVE-2020-8287].

Fixes CVE-2020-8287.

* gnu/packages/web.scm (http-parser): Update to 2.9.4-1.ec8b5ee.
  [source]: Add patch to mitigate CVE.
* gnu/packages/patches/patches/http-parser-CVE-2020-8287.patch: New file.
* gnu/local.mk [dist_patch_DATA]: New patch.

gnu/packages/patches/http-parser-CVE-2020-8287.patch

@@ -0,0 +1,75 @@
+From fc70ce08f5818a286fb5899a1bc3aff5965a745e Mon Sep 17 00:00:00 2001
+From: Fedor Indutny <fedor@indutny.com>
+Date: Wed, 18 Nov 2020 20:50:21 -0800
+Subject: [PATCH] http: unset `F_CHUNKED` on new `Transfer-Encoding`
+
+Duplicate `Transfer-Encoding` header should be a treated as a single,
+but with original header values concatenated with a comma separator. In
+the light of this, even if the past `Transfer-Encoding` ended with
+`chunked`, we should be not let the `F_CHUNKED` to leak into the next
+header, because mere presence of another header indicates that `chunked`
+is not the last transfer-encoding token.
+
+CVE-ID: CVE-2020-8287
+PR-URL: https://github.com/nodejs-private/node-private/pull/235
+Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
+---
+ http_parser.c |  7 +++++++
+ test.c        | 26 ++++++++++++++++++++++++++
+ 2 files changed, 33 insertions(+)
+
+diff --git a/http_parser.c b/http_parser.c
+index 9be003e7322..e9b2b9e83b9 100644
+--- a/http_parser.c
++++ b/http_parser.c
+@@ -1344,6 +1344,13 @@ size_t http_parser_execute (http_parser *parser,
+               } else if (parser->index == sizeof(TRANSFER_ENCODING)-2) {
+                 parser->header_state = h_transfer_encoding;
+                 parser->uses_transfer_encoding = 1;
++
++                /* Multiple `Transfer-Encoding` headers should be treated as
++                 * one, but with values separate by a comma.
++                 *
++                 * See: https://tools.ietf.org/html/rfc7230#section-3.2.2
++                 */
++                parser->flags &= ~F_CHUNKED;
+               }
+               break;
+ 
+diff --git a/test.c b/test.c
+index 3f7c77b3494..2e5a9ebd678 100644
+--- a/test.c
++++ b/test.c
+@@ -2154,6 +2154,32 @@ const struct message responses[] =
+   ,.body= "2\r\nOK\r\n0\r\n\r\n"
+   ,.num_chunks_complete= 0
+   }
++#define HTTP_200_DUPLICATE_TE_NOT_LAST_CHUNKED 30
++, {.name= "HTTP 200 response with `chunked` and duplicate Transfer-Encoding"
++  ,.type= HTTP_RESPONSE
++  ,.raw= "HTTP/1.1 200 OK\r\n"
++         "Transfer-Encoding: chunked\r\n"
++         "Transfer-Encoding: identity\r\n"
++         "\r\n"
++         "2\r\n"
++         "OK\r\n"
++         "0\r\n"
++         "\r\n"
++  ,.should_keep_alive= FALSE
++  ,.message_complete_on_eof= TRUE
++  ,.http_major= 1
++  ,.http_minor= 1
++  ,.status_code= 200
++  ,.response_status= "OK"
++  ,.content_length= -1
++  ,.num_headers= 2
++  ,.headers=
++    { { "Transfer-Encoding", "chunked" }
++    , { "Transfer-Encoding", "identity" }
++    }
++  ,.body= "2\r\nOK\r\n0\r\n\r\n"
++  ,.num_chunks_complete= 0
++  }
+ };
+ 
+ /* strnlen() is a POSIX.2008 addition. Can't rely on it being available so