From 70123da95418f5d6e00e8ac2d586fb6c5d02cdc6 Mon Sep 17 00:00:00 2001
From: Michael Catanzaro <mcatanzaro@redhat.com>
Date: Wed, 7 Jan 2026 14:50:33 -0600
Subject: [PATCH] Reject duplicate Host headers

RFC 9112 section 3.2 says:

A server MUST respond with a 400 (Bad Request) status code to any
HTTP/1.1 request message that lacks a Host header field and to any
request message that contains more than one Host header field line or a
Host header field with an invalid field value.

In addition to rejecting a duplicate header when parsing headers, also
reject attempts to add the duplicate header using the
soup_message_headers_append() API, and add tests for both cases.

These checks will also apply to HTTP/2. I'm not sure whether this is
actually desired or not, but the header processing code is not aware of
which HTTP version is in use.

(Note that while SoupMessageHeaders does not require the Host header to
be present in an HTTP/1.1 request, SoupServer itself does. So we can't
test the case of missing Host header via the header parsing test, but it
really is enforced.)

Fixes #472

Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libsoup/-/commit/aecd8daadc110f8561fb2d6b2806a4cacf2e4c85]
CVE: CVE-2025-14523

Signed-off-by: Changqing Li <changqing.li@windriver.com>
---
 libsoup/soup-headers.c                 |   3 +-
 libsoup/soup-message-headers-private.h |   4 +-
 libsoup/soup-message-headers.c         |  80 +++++++------
 tests/header-parsing-test.c            | 148 +++++++++++++++++--------
 4 files changed, 153 insertions(+), 82 deletions(-)

diff --git a/libsoup/soup-headers.c b/libsoup/soup-headers.c
index 155c11d..3fec9b3 100644
--- a/libsoup/soup-headers.c
+++ b/libsoup/soup-headers.c
@@ -139,7 +139,8 @@ soup_headers_parse (const char *str, int len, SoupMessageHeaders *dest)
 		for (p = strchr (value, '\r'); p; p = strchr (p, '\r'))
 			*p = ' ';
 
-		soup_message_headers_append_untrusted_data (dest, name, value);
+		if (!soup_message_headers_append_untrusted_data (dest, name, value))
+                        goto done;
         }
 	success = TRUE;
 
diff --git a/libsoup/soup-message-headers-private.h b/libsoup/soup-message-headers-private.h
index 9815464..770f3ef 100644
--- a/libsoup/soup-message-headers-private.h
+++ b/libsoup/soup-message-headers-private.h
@@ -10,10 +10,10 @@
 
 G_BEGIN_DECLS
 
-void        soup_message_headers_append_untrusted_data  (SoupMessageHeaders *hdrs,
+gboolean    soup_message_headers_append_untrusted_data  (SoupMessageHeaders *hdrs,
                                                          const char         *name,
                                                          const char         *value);
-void        soup_message_headers_append_common          (SoupMessageHeaders *hdrs,
+gboolean    soup_message_headers_append_common          (SoupMessageHeaders *hdrs,
                                                          SoupHeaderName      name,
                                                          const char         *value);
 const char *soup_message_headers_get_one_common         (SoupMessageHeaders *hdrs,
diff --git a/libsoup/soup-message-headers.c b/libsoup/soup-message-headers.c
index d69d6e8..ce4b3b3 100644
--- a/libsoup/soup-message-headers.c
+++ b/libsoup/soup-message-headers.c
@@ -267,12 +267,16 @@ soup_message_headers_clean_connection_headers (SoupMessageHeaders *hdrs)
 	soup_header_free_list (tokens);
 }
 
-void
+gboolean
 soup_message_headers_append_common (SoupMessageHeaders *hdrs,
                                     SoupHeaderName      name,
                                     const char         *value)
 {
         SoupCommonHeader header;
+        if (name == SOUP_HEADER_HOST && soup_message_headers_get_one (hdrs, "Host")) {
+                g_warning ("soup_message_headers_append_common: Rejecting duplicate Host header");
+                return FALSE;
+        }
 
         if (!hdrs->common_headers)
                 hdrs->common_headers = g_array_sized_new (FALSE, FALSE, sizeof (SoupCommonHeader), 6);
@@ -284,32 +288,18 @@ soup_message_headers_append_common (SoupMessageHeaders *hdrs,
                 g_hash_table_remove (hdrs->common_concat, GUINT_TO_POINTER (header.name));
 
         soup_message_headers_set (hdrs, name, value);
+        return TRUE;
 }
 
-/**
- * soup_message_headers_append:
- * @hdrs: a #SoupMessageHeaders
- * @name: the header name to add
- * @value: the new value of @name
- *
- * Appends a new header with name @name and value @value to @hdrs.
- *
- * (If there is an existing header with name @name, then this creates a second
- * one, which is only allowed for list-valued headers; see also
- * [method@MessageHeaders.replace].)
- *
- * The caller is expected to make sure that @name and @value are
- * syntactically correct.
- **/
-void
-soup_message_headers_append (SoupMessageHeaders *hdrs,
-			     const char *name, const char *value)
+static gboolean
+soup_message_headers_append_internal (SoupMessageHeaders *hdrs,
+                         const char *name, const char *value)
 {
 	SoupUncommonHeader header;
         SoupHeaderName header_name;
 
-	g_return_if_fail (name != NULL);
-	g_return_if_fail (value != NULL);
+	g_return_val_if_fail (name != NULL, FALSE);
+	g_return_val_if_fail (value != NULL, FALSE);
 
 	/* Setting a syntactically invalid header name or value is
 	 * considered to be a programming error. However, it can also
@@ -317,23 +307,22 @@ soup_message_headers_append (SoupMessageHeaders *hdrs,
 	 * compiled with G_DISABLE_CHECKS.
 	 */
 #ifndef G_DISABLE_CHECKS
-	g_return_if_fail (*name && strpbrk (name, " \t\r\n:") == NULL);
-	g_return_if_fail (strpbrk (value, "\r\n") == NULL);
+	g_return_val_if_fail (*name && strpbrk (name, " \t\r\n:") == NULL, FALSE);
+	g_return_val_if_fail (strpbrk (value, "\r\n") == NULL, FALSE);
 #else
 	if (*name && strpbrk (name, " \t\r\n:")) {
-		g_warning ("soup_message_headers_append: Ignoring bad name '%s'", name);
-		return;
+		g_warning ("soup_message_headers_append: Rejecting bad name '%s'", name);
+		return FALSE;
 	}
 	if (strpbrk (value, "\r\n")) {
-		g_warning ("soup_message_headers_append: Ignoring bad value '%s'", value);
-		return;
+		g_warning ("soup_message_headers_append: Rejecting bad value '%s'", value);
+		return FALSE;
 	}
 #endif
 
         header_name = soup_header_name_from_string (name);
         if (header_name != SOUP_HEADER_UNKNOWN) {
-                soup_message_headers_append_common (hdrs, header_name, value);
-                return;
+                return soup_message_headers_append_common (hdrs, header_name, value);
         }
 
         if (!hdrs->uncommon_headers)
@@ -344,21 +333,48 @@ soup_message_headers_append (SoupMessageHeaders *hdrs,
 	g_array_append_val (hdrs->uncommon_headers, header);
 	if (hdrs->uncommon_concat)
 		g_hash_table_remove (hdrs->uncommon_concat, header.name);
+        return TRUE;
+}
+
+/**
+ * soup_message_headers_append:
+ * @hdrs: a #SoupMessageHeaders
+ * @name: the header name to add
+ * @value: the new value of @name
+ *
+ * Appends a new header with name @name and value @value to @hdrs.
+ *
+ * (If there is an existing header with name @name, then this creates a second
+ * one, which is only allowed for list-valued headers; see also
+ * [method@MessageHeaders.replace].)
+ *
+ * The caller is expected to make sure that @name and @value are
+ * syntactically correct.
+ **/
+void
+soup_message_headers_append (SoupMessageHeaders *hdrs,
+			     const char *name, const char *value)
+{
+	soup_message_headers_append_internal (hdrs, name, value);
 }
 
 /*
- * Appends a header value ensuring that it is valid UTF8.
+ * Appends a header value ensuring that it is valid UTF-8, and also checking the
+ * return value of soup_message_headers_append_internal() to report whether the
+ * headers are invalid for various other reasons.
  */
-void
+gboolean
 soup_message_headers_append_untrusted_data (SoupMessageHeaders *hdrs,
                                             const char         *name,
                                             const char         *value)
 {
         char *safe_value = g_utf8_make_valid (value, -1);
         char *safe_name = g_utf8_make_valid (name, -1);
-        soup_message_headers_append (hdrs, safe_name, safe_value);
+        gboolean result = soup_message_headers_append_internal (hdrs, safe_name, safe_value);
+
         g_free (safe_value);
         g_free (safe_name);
+        return result;
 }
 
 void
diff --git a/tests/header-parsing-test.c b/tests/header-parsing-test.c
index 9490559..98a22a4 100644
--- a/tests/header-parsing-test.c
+++ b/tests/header-parsing-test.c
@@ -24,6 +24,7 @@ static struct RequestTest {
 	const char *method, *path;
 	SoupHTTPVersion version;
 	Header headers[10];
+	GLogLevelFlags log_flags;
 } reqtests[] = {
 	/**********************/
 	/*** VALID REQUESTS ***/
@@ -33,7 +34,7 @@ static struct RequestTest {
 	  "GET / HTTP/1.0\r\n", -1,
 	  SOUP_STATUS_OK,
 	  "GET", "/", SOUP_HTTP_1_0,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Req w/ 1 header", NULL,
@@ -42,7 +43,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header, no leading whitespace", NULL,
@@ -51,7 +52,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header including trailing whitespace", NULL,
@@ -60,7 +61,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header, wrapped", NULL,
@@ -69,7 +70,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header, wrapped with additional whitespace", NULL,
@@ -78,7 +79,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header, wrapped with tab", NULL,
@@ -87,7 +88,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header, wrapped before value", NULL,
@@ -96,7 +97,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 1 header with empty value", NULL,
@@ -105,7 +106,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 2 headers", NULL,
@@ -115,7 +116,7 @@ static struct RequestTest {
 	  { { "Host", "example.com" },
 	    { "Connection", "close" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 3 headers", NULL,
@@ -126,7 +127,7 @@ static struct RequestTest {
 	    { "Connection", "close" },
 	    { "Blah", "blah" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 3 headers, 1st wrapped", NULL,
@@ -137,7 +138,7 @@ static struct RequestTest {
             { "Foo", "bar baz" },
 	    { "Blah", "blah" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 3 headers, 2nd wrapped", NULL,
@@ -148,7 +149,7 @@ static struct RequestTest {
 	    { "Blah", "blah" },
 	    { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ 3 headers, 3rd wrapped", NULL,
@@ -159,7 +160,7 @@ static struct RequestTest {
 	    { "Blah", "blah" },
 	    { "Foo", "bar baz" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ same header multiple times", NULL,
@@ -168,7 +169,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Foo", "bar, baz, quux" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Connection header on HTTP/1.0 message", NULL,
@@ -178,21 +179,21 @@ static struct RequestTest {
 	  { { "Connection", "Bar, Quux" },
             { "Foo", "bar" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "GET with full URI", "667637",
 	  "GET http://example.com HTTP/1.1\r\n", -1,
 	  SOUP_STATUS_OK,
 	  "GET", "http://example.com", SOUP_HTTP_1_1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "GET with full URI in upper-case", "667637",
 	  "GET HTTP://example.com HTTP/1.1\r\n", -1,
 	  SOUP_STATUS_OK,
 	  "GET", "HTTP://example.com", SOUP_HTTP_1_1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	/* It's better for this to be passed through: this means a SoupServer
@@ -202,7 +203,7 @@ static struct RequestTest {
 	  "GET AbOuT: HTTP/1.1\r\n", -1,
 	  SOUP_STATUS_OK,
 	  "GET", "AbOuT:", SOUP_HTTP_1_1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	/****************************/
@@ -217,7 +218,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	/* RFC 2616 section 3.1 says we MUST accept this */
@@ -228,7 +229,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	/* RFC 2616 section 19.3 says we SHOULD accept these */
@@ -240,7 +241,7 @@ static struct RequestTest {
 	  { { "Host", "example.com" },
 	    { "Connection", "close" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "LF instead of CRLF after Request-Line", NULL,
@@ -249,7 +250,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Mixed CRLF/LF", "666316",
@@ -261,7 +262,7 @@ static struct RequestTest {
 	    { "e", "f" },
 	    { "g", "h" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ incorrect whitespace in Request-Line", NULL,
@@ -270,7 +271,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Req w/ incorrect whitespace after Request-Line", "475169",
@@ -279,7 +280,7 @@ static struct RequestTest {
 	  "GET", "/", SOUP_HTTP_1_1,
 	  { { "Host", "example.com" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	/* If the request/status line is parseable, then we
@@ -293,7 +294,7 @@ static struct RequestTest {
 	  { { "Host", "example.com" },
 	    { "Bar", "two" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "First header line is continuation", "666316",
@@ -303,7 +304,7 @@ static struct RequestTest {
 	  { { "Host", "example.com" },
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Zero-length header name", "666316",
@@ -313,7 +314,7 @@ static struct RequestTest {
 	  { { "a", "b" },
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "CR in header name", "666316",
@@ -323,7 +324,7 @@ static struct RequestTest {
 	  { { "a", "b" },
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "CR in header value", "666316",
@@ -336,7 +337,7 @@ static struct RequestTest {
 	    { "s", "t" },		/* CR at end is ignored */
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Tab in header name", "666316",
@@ -351,7 +352,7 @@ static struct RequestTest {
 	    { "p", "q z: w" },
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	{ "Tab in header value", "666316",
@@ -364,7 +365,7 @@ static struct RequestTest {
 	    { "z", "w" },	/* trailing tab ignored */
 	    { "c", "d" },
 	    { NULL }
-	  }
+	  }, 0
 	},
 
 	/************************/
@@ -375,77 +376,77 @@ static struct RequestTest {
 	  "GET /\r\n", -1,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "HTTP 1.2 request (no such thing)", NULL,
 	  "GET / HTTP/1.2\r\n", -1,
 	  SOUP_STATUS_HTTP_VERSION_NOT_SUPPORTED,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "HTTP 2000 request (no such thing)", NULL,
 	  "GET / HTTP/2000.0\r\n", -1,
 	  SOUP_STATUS_HTTP_VERSION_NOT_SUPPORTED,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Long HTTP version terminating at missing minor version", "https://gitlab.gnome.org/GNOME/libsoup/-/issues/404",
 	  unterminated_http_version, sizeof (unterminated_http_version),
 	  SOUP_STATUS_BAD_REQUEST,
            NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Non-HTTP request", NULL,
 	  "GET / SOUP/1.1\r\nHost: example.com\r\n", -1,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Junk after Request-Line", NULL,
 	  "GET / HTTP/1.1 blah\r\nHost: example.com\r\n", -1,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "NUL in Method", NULL,
 	  "G\x00T / HTTP/1.1\r\nHost: example.com\r\n", 37,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "NUL at beginning of Method", "666316",
 	  "\x00 / HTTP/1.1\r\nHost: example.com\r\n", 35,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "NUL in Path", NULL,
 	  "GET /\x00 HTTP/1.1\r\nHost: example.com\r\n", 38,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "No terminating CRLF", NULL,
 	  "GET / HTTP/1.1\r\nHost: example.com", -1,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Unrecognized expectation", NULL,
 	  "GET / HTTP/1.1\r\nHost: example.com\r\nExpect: the-impossible\r\n", -1,
 	  SOUP_STATUS_EXPECTATION_FAILED,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	// https://gitlab.gnome.org/GNOME/libsoup/-/issues/377
@@ -453,21 +454,40 @@ static struct RequestTest {
 	  "GET / HTTP/1.1\r\nHost\x00: example.com\r\n", 36,
 	  SOUP_STATUS_BAD_REQUEST,
 	  NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "NUL in header value", NULL,
 	  "HTTP/1.1 200 OK\r\nFoo: b\x00" "ar\r\n", 28,
 	  SOUP_STATUS_BAD_REQUEST,
            NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
 	},
 
 	{ "Only newlines", NULL,
 	  only_newlines, sizeof (only_newlines),
 	  SOUP_STATUS_BAD_REQUEST,
            NULL, NULL, -1,
-	  { { NULL } }
+	  { { NULL } }, 0
+	},
+	{ "Duplicate Host headers",
+	  "https://gitlab.gnome.org/GNOME/libsoup/-/issues/472",
+	  "GET / HTTP/1.1\r\nHost: example.com\r\nHost: example.org\r\n",
+	  -1,
+	  SOUP_STATUS_BAD_REQUEST,
+	  NULL, NULL, -1,
+	  { { NULL } },
+	  G_LOG_LEVEL_WARNING
+	},
+
+	{ "Duplicate Host headers, case insensitive",
+	  "https://gitlab.gnome.org/GNOME/libsoup/-/issues/472",
+	  "GET / HTTP/1.1\r\nHost: example.com\r\nhost: example.org\r\n",
+	  -1,
+	  SOUP_STATUS_BAD_REQUEST,
+	  NULL, NULL, -1,
+	  { { NULL } },
+	  G_LOG_LEVEL_WARNING
 	}
 };
 static const int num_reqtests = G_N_ELEMENTS (reqtests);
@@ -915,10 +935,17 @@ do_request_tests (void)
 			len = strlen (reqtests[i].request);
 		else
 			len = reqtests[i].length;
+
+		if (reqtests[i].log_flags)
+			g_test_expect_message ("libsoup", reqtests[i].log_flags, "*");
+
 		status = soup_headers_parse_request (reqtests[i].request, len,
 						     headers, &method, &path,
 						     &version);
 		g_assert_cmpint (status, ==, reqtests[i].status);
+		if (reqtests[i].log_flags)
+			g_test_assert_expected_messages ();
+
 		if (SOUP_STATUS_IS_SUCCESSFUL (status)) {
 			g_assert_cmpstr (method, ==, reqtests[i].method);
 			g_assert_cmpstr (path, ==, reqtests[i].path);
@@ -1312,6 +1339,32 @@ do_bad_header_tests (void)
 	soup_message_headers_unref (hdrs);
 }
 
+static void
+do_append_duplicate_host_test (void)
+{
+   SoupMessageHeaders *hdrs;
+   const char *list_value;
+
+   hdrs = soup_message_headers_new (SOUP_MESSAGE_HEADERS_REQUEST);
+   soup_message_headers_append (hdrs, "Host", "a");
+
+   g_test_expect_message ("libsoup", G_LOG_LEVEL_WARNING,
+                      "soup_message_headers_append_common: Rejecting duplicate Host header");
+   soup_message_headers_append (hdrs, "Host", "b");
+   g_test_assert_expected_messages ();
+
+        /* Case insensitive */
+   g_test_expect_message ("libsoup", G_LOG_LEVEL_WARNING,
+                      "soup_message_headers_append_common: Rejecting duplicate Host header");
+   soup_message_headers_append (hdrs, "host", "b");
+   g_test_assert_expected_messages ();
+
+   list_value = soup_message_headers_get_list (hdrs, "Host");
+   g_assert_cmpstr (list_value, ==, "a");
+
+   soup_message_headers_unref (hdrs);
+}
+
 int
 main (int argc, char **argv)
 {
@@ -1327,6 +1380,7 @@ main (int argc, char **argv)
 	g_test_add_func ("/header-parsing/content-type", do_content_type_tests);
 	g_test_add_func ("/header-parsing/append-param", do_append_param_tests);
 	g_test_add_func ("/header-parsing/bad", do_bad_header_tests);
+	g_test_add_func ("/header-parsing/append-duplicate-host", do_append_duplicate_host_test);
 
 	ret = g_test_run ();
 
-- 
2.34.1

