[LEDE-DEV] [PATCH uclient] uclient-http: fix Host: header for literal IPv6 addresses

[Matthias Schiffer]

For literal IPv6 addresses, the host header must have the form

  Host: [...]

including the square brackets, as it may also contain a port. Some
webservers ignore the missing brackets, while others will return error 400.

IPv6 addresses are determined by searching for ':' characters in the host,
as neither IPv4 addresses nor DNS names can contain colons. An alternative
would be to add a flag to the uclient_url struct; but as this struct is
exposed in public headers, such a change could be considered an ABI change,
making a backport difficult.

Signed-off-by: Matthias Schiffer <mschiffer at universe-factory.net>
---

Tested and working fine, but I'd still like some feedback on my approach to
fixing this. Eventually, we might want to move struct uclient_url to an
internal header to avoid exposing it as API/ABI.

 uclient-http.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/uclient-http.c b/uclient-http.c
index ac9d50f..ef8de98 100644
--- a/uclient-http.c
+++ b/uclient-http.c
@@ -20,6 +20,7 @@
 #include <ctype.h>
 #include <unistd.h>
 #include <stdint.h>
+#include <string.h>
 #include <fcntl.h>
 
 #include <libubox/ustream.h>
@@ -562,6 +563,7 @@ uclient_http_send_headers(struct uclient_http *uh)
 	struct uclient_url *url = uh->uc.url;
 	struct blob_attr *cur;
 	enum request_type req_type = uh->req_type;
+	bool literal_ipv6;
 	int rem;
 
 	if (uh->state >= HTTP_STATE_HEADERS_SENT)
@@ -570,11 +572,15 @@ uclient_http_send_headers(struct uclient_http *uh)
 	if (uh->uc.proxy_url)
 		url = uh->uc.proxy_url;
 
+	literal_ipv6 = strchr(url->host, ':');
+
 	ustream_printf(uh->us,
 		"%s %s HTTP/1.1\r\n"
-		"Host: %s%s%s\r\n",
-		request_types[req_type],
-		url->location, url->host,
+		"Host: %s%s%s%s%s\r\n",
+		request_types[req_type], url->location,
+		literal_ipv6 ? "[" : "",
+		url->host,
+		literal_ipv6 ? "]" : "",
 		url->port ? ":" : "",
 		url->port ? url->port : "");
 
-- 
2.14.1