[PATCH] http module is not checking correctly HTTP headers

[Javier Moragon]

According to https://www.ietf.org/rfc/rfc2616.txt 4.2, header names
shall be case insensitive and we are now forced to read headers like
`Content-Length` capitalized.

The problem with that is when a HTTP server responds with a
`content-length` header in lowercase GRUB gets stuck because HTTP
module doesn't know the length of the transmision and the call never
ends. I've been able to reproduce it and after ignoring the text case
it worked perfectly.

Here is it my patch proposal:

diff --git a/grub-core/net/http.c b/grub-core/net/http.c
index b616cf40b..570fa3934 100644
--- a/grub-core/net/http.c
+++ b/grub-core/net/http.c
@@ -130,7 +130,7 @@ parse_line (grub_file_t file, http_data_t data,
char *ptr, grub_size_t len)
       data->first_line_recv = 1;
       return GRUB_ERR_NONE;
     }
-  if (grub_memcmp (ptr, "Content-Length: ", sizeof ("Content-Length: ") - 1)
+  if (grub_strncasecmp (ptr, "Content-Length: ", grub_strlen
("Content-Length: ") )
       == 0 && !data->size_recv)
     {
       ptr += sizeof ("Content-Length: ") - 1;
@@ -138,8 +138,8 @@ parse_line (grub_file_t file, http_data_t data,
char *ptr, grub_size_t len)
       data->size_recv = 1;
       return GRUB_ERR_NONE;
     }
-  if (grub_memcmp (ptr, "Transfer-Encoding: chunked",
-    sizeof ("Transfer-Encoding: chunked") - 1) == 0)
+  if (grub_strncasecmp (ptr, "Transfer-Encoding: chunked",
+    grub_strlen ("Transfer-Encoding: chunked") ) == 0)
     {
       data->chunked = 1;
       return GRUB_ERR_NONE;