73 lines
2.2 KiB
C
73 lines
2.2 KiB
C
/*
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* Copyright (C) 2017 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/**
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* @file
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*
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* Google Compute Engine (GCE) metadata retrieval
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*
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* For some unspecified "security" reason, the Google Compute Engine
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* metadata server will refuse any requests that do not include the
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* non-standard HTTP header "Metadata-Flavor: Google".
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*/
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#include <strings.h>
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#include <stdio.h>
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#include <ipxe/http.h>
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/** Metadata host name
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*
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* This is used to identify metadata requests, in the absence of any
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* more robust mechanism.
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*/
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#define GCE_METADATA_HOST_NAME "metadata.google.internal"
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/**
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* Construct HTTP "Metadata-Flavor" header
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*
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* @v http HTTP transaction
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* @v buf Buffer
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* @v len Length of buffer
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* @ret len Length of header value, or negative error
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*/
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static int http_format_metadata_flavor ( struct http_transaction *http,
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char *buf, size_t len ) {
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/* Do nothing unless this appears to be a Google Compute
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* Engine metadata request.
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*/
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if ( strcasecmp ( http->request.host, GCE_METADATA_HOST_NAME ) != 0 )
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return 0;
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/* Construct host URI */
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return snprintf ( buf, len, "Google" );
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}
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/** HTTP "Metadata-Flavor" header */
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struct http_request_header http_request_metadata_flavor __http_request_header ={
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.name = "Metadata-Flavor",
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.format = http_format_metadata_flavor,
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};
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