httpgce.c File Reference

Google Compute Engine (GCE) metadata retrieval. More...

#include <strings.h>
#include <stdio.h>
#include <ipxe/http.h>

Go to the source code of this file.

Macros
#define	GCE_METADATA_HOST_NAME   "metadata.google.internal"
	Metadata host name. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static int	http_format_metadata_flavor (struct http_transaction *http, char *buf, size_t len)
	Construct HTTP "Metadata-Flavor" header. More...

Variables
struct http_request_header http_request_metadata_flavor	__http_request_header
	HTTP "Metadata-Flavor" header. More...

Detailed Description

Google Compute Engine (GCE) metadata retrieval.

For some unspecified "security" reason, the Google Compute Engine metadata server will refuse any requests that do not include the non-standard HTTP header "Metadata-Flavor: Google".

Definition in file httpgce.c.

Macro Definition Documentation

GCE_METADATA_HOST_NAME

#define GCE_METADATA_HOST_NAME   "metadata.google.internal"

Metadata host name.

This is used to identify metadata requests, in the absence of any more robust mechanism.

Definition at line 45 of file httpgce.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

http_format_metadata_flavor()

static int http_format_metadata_flavor ( struct http_transaction *  http, char *  buf, size_t  len  )

static

Construct HTTP "Metadata-Flavor" header.

Parameters

http	HTTP transaction
buf	Buffer
len	Length of buffer

Return values

len	Length of header value, or negative error

Definition at line 55 of file httpgce.c.

                                                                 {

        /* Do nothing unless this appears to be a Google Compute
         * Engine metadata request.
         */
        if ( strcasecmp ( http->request.host, GCE_METADATA_HOST_NAME ) != 0 )
                return 0;

        /* Construct host URI */
        return snprintf ( buf, len, "Google" );
}

References GCE_METADATA_HOST_NAME, http_request::host, len, http_transaction::request, snprintf(), and strcasecmp().

Variable Documentation

__http_request_header

struct http_request_header http_request_metadata_flavor __http_request_header

Initial value:

={
        .name = "Metadata-Flavor",
        .format = http_format_metadata_flavor,
}

HTTP "Metadata-Flavor" header.

Definition at line 69 of file httpgce.c.