mirror of https://github.com/ipxe/ipxe.git
[peerdist] Add support for constructing and decoding discovery messages
Signed-off-by: Michael Brown <mcb30@ipxe.org>pull/39/head
Michael Brown
parent
f0d594557c
commit
51b99d8bc8
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@ -246,6 +246,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#define ERRFILE_rndis ( ERRFILE_NET | 0x003d0000 )
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#define ERRFILE_rndis ( ERRFILE_NET | 0x003d0000 )
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#define ERRFILE_pccrc ( ERRFILE_NET | 0x003e0000 )
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#define ERRFILE_pccrc ( ERRFILE_NET | 0x003e0000 )
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#define ERRFILE_stp ( ERRFILE_NET | 0x003f0000 )
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#define ERRFILE_stp ( ERRFILE_NET | 0x003f0000 )
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#define ERRFILE_pccrd ( ERRFILE_NET | 0x00400000 )
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#define ERRFILE_image ( ERRFILE_IMAGE | 0x00000000 )
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#define ERRFILE_image ( ERRFILE_IMAGE | 0x00000000 )
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#define ERRFILE_elf ( ERRFILE_IMAGE | 0x00010000 )
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#define ERRFILE_elf ( ERRFILE_IMAGE | 0x00010000 )
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@ -0,0 +1,47 @@
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#ifndef _IPXE_PCCRD_H
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#define _IPXE_PCCRD_H
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/** @file
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*
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* Peer Content Caching and Retrieval: Discovery Protocol [MS-PCCRD]
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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/** PeerDist discovery port */
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#define PEERDIST_DISCOVERY_PORT 3702
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/** PeerDist discovery IPv4 address (239.255.255.250) */
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#define PEERDIST_DISCOVERY_IPV4 \
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( ( 239 << 24 ) | ( 255 << 16 ) | ( 255 << 8 ) | ( 250 << 0 ) )
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/** PeerDist discovery IPv6 address (ff02::c) */
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#define PEERDIST_DISCOVERY_IPV6 \
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{ 0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xc }
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/** A PeerDist discovery reply block count */
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struct peerdist_discovery_block_count {
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/** Count (as an eight-digit hex value) */
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char hex[8];
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} __attribute__ (( packed ));
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/** A PeerDist discovery reply */
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struct peerdist_discovery_reply {
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/** List of segment ID strings
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*
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* The list is terminated with a zero-length string.
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*/
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char *ids;
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/** List of peer locations
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*
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* The list is terminated with a zero-length string.
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*/
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char *locations;
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};
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extern char * peerdist_discovery_request ( const char *uuid, const char *id );
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extern int peerdist_discovery_reply ( char *data, size_t len,
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struct peerdist_discovery_reply *reply );
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#endif /* _IPXE_PCCRD_H */
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@ -0,0 +1,286 @@
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/*
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* Copyright (C) 2015 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 (at your option) 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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#include <stddef.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include <errno.h>
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#include <assert.h>
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#include <ipxe/pccrd.h>
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/** @file
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*
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* Peer Content Caching and Retrieval: Discovery Protocol [MS-PCCRD]
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*
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* This protocol manages to ingeniously combine the excessive
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* verbosity of XML with a paucity of actual information. For
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* example: even in version 2.0 of the protocol it is still not
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* possible to discover which peers hold a specific block within a
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* given segment.
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*
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* For added bonus points, version 1.0 of the protocol is specified to
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* use a case-sensitive string comparison (for SHA2 digest values) but
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* nothing specifies whether the strings in question should be in
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* upper or lower case. There are example strings given in the
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* specification, but the author skilfully manages to leave the issue
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* unresolved by using the somewhat implausible digest value of
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* "0200000000000000000000000000000000000000000000000000000000000000".
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*
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* Just in case you were thinking that the silver lining of the choice
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* to use an XML-based protocol would be the ability to generate and
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* process messages with standard tools, version 2.0 of the protocol
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* places most of the critical information inside a Base64-encoded
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* custom binary data structure. Within an XML element, naturally.
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*
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* I hereby announce this specification to be the 2015 winner of the
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* prestigious "UEFI HII API" award for incompetent design.
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*/
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/** Discovery request format */
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#define PEERDIST_DISCOVERY_REQUEST \
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"<?xml version=\"1.0\" encoding=\"utf-8\"?>" \
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"<soap:Envelope " \
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"xmlns:soap=\"http://www.w3.org/2003/05/soap-envelope\" " \
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"xmlns:wsa=\"http://schemas.xmlsoap.org/ws/2004/08/addressing\" " \
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"xmlns:wsd=\"http://schemas.xmlsoap.org/ws/2005/04/discovery\" " \
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"xmlns:PeerDist=\"http://schemas.microsoft.com/p2p/" \
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"2007/09/PeerDistributionDiscovery\">" \
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"<soap:Header>" \
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"<wsa:To>" \
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"urn:schemas-xmlsoap-org:ws:2005:04:discovery" \
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"</wsa:To>" \
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"<wsa:Action>" \
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"http://schemas.xmlsoap.org/ws/2005/04/discovery/Probe" \
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"</wsa:Action>" \
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"<wsa:MessageID>" \
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"urn:uuid:%s" \
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"</wsa:MessageID>" \
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"</soap:Header>" \
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"<soap:Body>" \
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"<wsd:Probe>" \
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"<wsd:Types>" \
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"PeerDist:PeerDistData" \
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"</wsd:Types>" \
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"<wsd:Scopes MatchBy=\"http://schemas.xmlsoap.org/ws/" \
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"2005/04/discovery/strcmp0\">" \
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"%s" \
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"</wsd:Scopes>" \
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"</wsd:Probe>" \
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"</soap:Body>" \
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"</soap:Envelope>"
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/**
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* Construct discovery request
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*
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* @v uuid Message UUID string
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* @v id Segment identifier string
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* @ret request Discovery request, or NULL on failure
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*
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* The request is dynamically allocated; the caller must eventually
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* free() the request.
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*/
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char * peerdist_discovery_request ( const char *uuid, const char *id ) {
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char *request;
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int len;
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/* Construct request */
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len = asprintf ( &request, PEERDIST_DISCOVERY_REQUEST, uuid, id );
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if ( len < 0 )
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return NULL;
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return request;
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}
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/**
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* Locate discovery reply tag
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*
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* @v data Reply data (not NUL-terminated)
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* @v len Length of reply data
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* @v tag XML tag
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* @ret found Found tag (or NULL if not found)
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*/
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static char * peerdist_discovery_reply_tag ( char *data, size_t len,
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const char *tag ) {
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size_t tag_len = strlen ( tag );
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/* Search, allowing for the fact that the reply data is not
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* cleanly NUL-terminated and may contain embedded NULs due to
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* earlier parsing.
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*/
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for ( ; len >= tag_len ; data++, len-- ) {
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if ( strncmp ( data, tag, tag_len ) == 0 )
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return data;
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}
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return NULL;
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}
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/**
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* Locate discovery reply values
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*
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* @v data Reply data (not NUL-terminated, will be modified)
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* @v len Length of reply data
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* @v name XML tag name
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* @ret values Tag values (or NULL if not found)
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*
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* The reply data is modified by adding NULs and moving characters as
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* needed to produce a NUL-separated list of values, terminated with a
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* zero-length string.
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*
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* This is not supposed to be a full XML parser; it's supposed to
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* include just enough functionality to allow PeerDist discovery to
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* work with existing implementations.
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*/
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static char * peerdist_discovery_reply_values ( char *data, size_t len,
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const char *name ) {
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char buf[ 2 /* "</" */ + strlen ( name ) + 1 /* ">" */ + 1 /* NUL */ ];
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char *open;
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char *close;
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char *start;
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char *end;
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char *in;
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char *out;
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char c;
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/* Locate opening tag */
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snprintf ( buf, sizeof ( buf ), "<%s>", name );
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open = peerdist_discovery_reply_tag ( data, len, buf );
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if ( ! open )
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return NULL;
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start = ( open + strlen ( buf ) );
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len -= ( start - data );
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data = start;
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/* Locate closing tag */
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snprintf ( buf, sizeof ( buf ), "</%s>", name );
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close = peerdist_discovery_reply_tag ( data, len, buf );
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if ( ! close )
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return NULL;
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assert ( close >= open );
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end = close;
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/* Strip initial whitespace, convert other whitespace
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* sequences to single NULs, add terminating pair of NULs.
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* This will probably overwrite part of the closing tag.
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*/
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for ( in = start, out = start ; in < end ; in++ ) {
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c = *in;
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if ( isspace ( c ) ) {
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if ( ( out > start ) && ( out[-1] != '\0' ) )
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*(out++) = '\0';
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} else {
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*(out++) = c;
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}
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}
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*(out++) = '\0';
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*(out++) = '\0';
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assert ( out < ( close + strlen ( buf ) ) );
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return start;
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}
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/**
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* Parse discovery reply
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*
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* @v data Reply data (not NUL-terminated, will be modified)
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* @v len Length of reply data
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* @v reply Discovery reply to fill in
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* @ret rc Return status code
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*
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* The discovery reply includes pointers to strings within the
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* modified reply data.
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*/
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int peerdist_discovery_reply ( char *data, size_t len,
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struct peerdist_discovery_reply *reply ) {
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static const struct peerdist_discovery_block_count zcount = {
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.hex = "00000000",
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};
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struct peerdist_discovery_block_count *count;
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unsigned int max;
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unsigned int i;
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char *scopes;
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char *xaddrs;
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char *blockcount;
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char *in;
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char *out;
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size_t skip;
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/* Find <wsd:Scopes> tag */
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scopes = peerdist_discovery_reply_values ( data, len, "wsd:Scopes" );
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if ( ! scopes ) {
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DBGC ( reply, "PCCRD %p missing <wsd:Scopes> tag\n", reply );
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return -ENOENT;
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}
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/* Find <wsd:XAddrs> tag */
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xaddrs = peerdist_discovery_reply_values ( data, len, "wsd:XAddrs" );
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if ( ! xaddrs ) {
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DBGC ( reply, "PCCRD %p missing <wsd:XAddrs> tag\n", reply );
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return -ENOENT;
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}
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/* Find <PeerDist:BlockCount> tag */
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blockcount = peerdist_discovery_reply_values ( data, len,
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"PeerDist:BlockCount" );
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if ( ! blockcount ) {
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DBGC ( reply, "PCCRD %p missing <PeerDist:BlockCount> tag\n",
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reply );
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return -ENOENT;
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}
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/* Determine maximum number of segments (according to number
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* of entries in the block count list).
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*/
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max = ( strlen ( blockcount ) / sizeof ( *count ) );
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count = container_of ( blockcount,
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struct peerdist_discovery_block_count, hex[0] );
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/* Eliminate any segments with a zero block count */
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for ( i = 0, in = scopes, out = scopes ; *in ; i++, in += skip ) {
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/* Fail if we have overrun the maximum number of segments */
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if ( i >= max ) {
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DBGC ( reply, "PCCRD %p too many segment IDs\n",
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reply );
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return -EPROTO;
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}
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/* Delete segment if block count is zero */
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skip = ( strlen ( in ) + 1 /* NUL */ );
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if ( memcmp ( count[i].hex, zcount.hex,
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sizeof ( zcount.hex ) ) == 0 )
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continue;
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strcpy ( out, in );
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out += skip;
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}
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out[0] = '\0'; /* Ensure list is terminated with a zero-length string */
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/* Fill in discovery reply */
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reply->ids = scopes;
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reply->locations = xaddrs;
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return 0;
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}
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