xref: /freebsd/contrib/unbound/util/data/msgparse.h (revision ddd5b8e9b4d8957fce018c520657cdfa4ecffad3)
1 /*
2  * util/data/msgparse.h - parse wireformat DNS messages.
3  *
4  * Copyright (c) 2007, NLnet Labs. All rights reserved.
5  *
6  * This software is open source.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * Redistributions of source code must retain the above copyright notice,
13  * this list of conditions and the following disclaimer.
14  *
15  * Redistributions in binary form must reproduce the above copyright notice,
16  * this list of conditions and the following disclaimer in the documentation
17  * and/or other materials provided with the distribution.
18  *
19  * Neither the name of the NLNET LABS nor the names of its contributors may
20  * be used to endorse or promote products derived from this software without
21  * specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
27  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33  * POSSIBILITY OF SUCH DAMAGE.
34  */
35 /**
36  * \file
37  * Contains message parsing data structures.
38  * These point back into the packet buffer.
39  *
40  * During parsing RRSIGS are put together with the rrsets they (claim to) sign.
41  * This process works as follows:
42  *	o if RRSIG follows the data rrset, it is added to the rrset rrsig list.
43  *	o if no matching data rrset is found, the RRSIG becomes a new rrset.
44  *	o If the data rrset later follows the RRSIG
45  *		o See if the RRSIG rrset contains multiple types, and needs to
46  *		  have the rrsig(s) for that data type split off.
47  *		o Put the data rr as data type in the rrset and rrsig in list.
48  *	o RRSIGs are allowed to move to a different section. The section of
49  *	  the data item is used for the final rrset.
50  *	o multiple signatures over an RRset are possible.
51  *
52  * For queries of qtype=RRSIG, some special handling is needed, to avoid
53  * splitting the RRSIG in the answer section.
54  *	o duplicate, not split, RRSIGs from the answer section, if qtype=RRSIG.
55  *	o check for doubles in the rrsig list when adding an RRSIG to data,
56  *	  so that a data rrset is signed by RRSIGs with different rdata.
57  *	  when qtype=RRSIG.
58  * This will move the RRSIG from the answer section to sign the data further
59  * in the packet (if possible). If then after that, more RRSIGs are found
60  * that sign the data as well, doubles are removed.
61  */
62 
63 #ifndef UTIL_DATA_MSGPARSE_H
64 #define UTIL_DATA_MSGPARSE_H
65 #include "util/storage/lruhash.h"
66 #include <ldns/packet.h>
67 struct rrset_parse;
68 struct rr_parse;
69 struct regional;
70 
71 /** number of buckets in parse rrset hash table. Must be power of 2. */
72 #define PARSE_TABLE_SIZE 32
73 /** Maximum TTL that is allowed. */
74 extern uint32_t MAX_TTL;
75 /** Minimum TTL that is allowed. */
76 extern uint32_t MIN_TTL;
77 /** Negative cache time (for entries without any RRs.) */
78 #define NORR_TTL 5 /* seconds */
79 
80 /**
81  * Data stored in scratch pad memory during parsing.
82  * Stores the data that will enter into the msgreply and packet result.
83  */
84 struct msg_parse {
85 	/** id from message, network format. */
86 	uint16_t id;
87 	/** flags from message, host format. */
88 	uint16_t flags;
89 	/** count of RRs, host format */
90 	uint16_t qdcount;
91 	/** count of RRs, host format */
92 	uint16_t ancount;
93 	/** count of RRs, host format */
94 	uint16_t nscount;
95 	/** count of RRs, host format */
96 	uint16_t arcount;
97 	/** count of RRsets per section. */
98 	size_t an_rrsets;
99 	/** count of RRsets per section. */
100 	size_t ns_rrsets;
101 	/** count of RRsets per section. */
102 	size_t ar_rrsets;
103 	/** total number of rrsets found. */
104 	size_t rrset_count;
105 
106 	/** query dname (pointer to start location in packet, NULL if none */
107 	uint8_t* qname;
108 	/** length of query dname in octets, 0 if none */
109 	size_t qname_len;
110 	/** query type, host order. 0 if qdcount=0 */
111 	uint16_t qtype;
112 	/** query class, host order. 0 if qdcount=0 */
113 	uint16_t qclass;
114 
115 	/**
116 	 * Hash table array used during parsing to lookup rrset types.
117 	 * Based on name, type, class.  Same hash value as in rrset cache.
118 	 */
119 	struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
120 
121 	/** linked list of rrsets that have been found (in order). */
122 	struct rrset_parse* rrset_first;
123 	/** last element of rrset list. */
124 	struct rrset_parse* rrset_last;
125 };
126 
127 /**
128  * Data stored for an rrset during parsing.
129  */
130 struct rrset_parse {
131 	/** next in hash bucket */
132 	struct rrset_parse* rrset_bucket_next;
133 	/** next in list of all rrsets */
134 	struct rrset_parse* rrset_all_next;
135 	/** hash value of rrset */
136 	hashvalue_t hash;
137 	/** which section was it found in: one of
138 	 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
139 	 */
140 	ldns_pkt_section section;
141 	/** start of (possibly compressed) dname in packet */
142 	uint8_t* dname;
143 	/** length of the dname uncompressed wireformat */
144 	size_t dname_len;
145 	/** type, host order. */
146 	uint16_t type;
147 	/** class, network order. var name so that it is not a c++ keyword. */
148 	uint16_t rrset_class;
149 	/** the flags for the rrset, like for packedrrset */
150 	uint32_t flags;
151 	/** number of RRs in the rr list */
152 	size_t rr_count;
153 	/** sum of RR rdata sizes */
154 	size_t size;
155 	/** linked list of RRs in this rrset. */
156 	struct rr_parse* rr_first;
157 	/** last in list of RRs in this rrset. */
158 	struct rr_parse* rr_last;
159 	/** number of RRSIGs over this rrset. */
160 	size_t rrsig_count;
161 	/** linked list of RRsig RRs over this rrset. */
162 	struct rr_parse* rrsig_first;
163 	/** last in list of RRSIG RRs over this rrset. */
164 	struct rr_parse* rrsig_last;
165 };
166 
167 /**
168  * Data stored for an RR during parsing.
169  */
170 struct rr_parse {
171 	/**
172 	 * Pointer to the RR. Points to start of TTL value in the packet.
173 	 * Rdata length and rdata follow it.
174 	 * its dname, type and class are the same and stored for the rrset.
175 	 */
176 	uint8_t* ttl_data;
177 	/** true if ttl_data is not part of the packet, but elsewhere in mem.
178 	 * Set for generated CNAMEs for DNAMEs. */
179 	int outside_packet;
180 	/** the length of the rdata if allocated (with no dname compression)*/
181 	size_t size;
182 	/** next in list of RRs. */
183 	struct rr_parse* next;
184 };
185 
186 /** Check if label length is first octet of a compression pointer, pass u8. */
187 #define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 )
188 /** Calculate destination offset of a compression pointer. pass first and
189  * second octets of the compression pointer. */
190 #define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) )
191 /** create a compression pointer to the given offset. */
192 #define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset)))
193 
194 /** error codes, extended with EDNS, so > 15. */
195 #define EDNS_RCODE_BADVERS	16	/** bad EDNS version */
196 /** largest valid compression offset */
197 #define PTR_MAX_OFFSET 	0x3fff
198 
199 /**
200  * EDNS data storage
201  * EDNS rdata is ignored.
202  */
203 struct edns_data {
204 	/** if EDNS OPT record was present */
205 	int edns_present;
206 	/** Extended RCODE */
207 	uint8_t ext_rcode;
208 	/** The EDNS version number */
209 	uint8_t edns_version;
210 	/** the EDNS bits field from ttl (host order): Z */
211 	uint16_t bits;
212 	/** UDP reassembly size. */
213 	uint16_t udp_size;
214 };
215 
216 /**
217  * Obtain size in the packet of an rr type, that is before dname type.
218  * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types.
219  * @param rdf: the rdf type from the descriptor.
220  * @return: size in octets. 0 on failure.
221  */
222 size_t get_rdf_size(ldns_rdf_type rdf);
223 
224 /**
225  * Parse the packet.
226  * @param pkt: packet, position at call must be at start of packet.
227  *	at end position is after packet.
228  * @param msg: where to store results.
229  * @param region: how to alloc results.
230  * @return: 0 if OK, or rcode on error.
231  */
232 int parse_packet(ldns_buffer* pkt, struct msg_parse* msg,
233 	struct regional* region);
234 
235 /**
236  * After parsing the packet, extract EDNS data from packet.
237  * If not present this is noted in the data structure.
238  * If a parse error happens, an error code is returned.
239  *
240  * Quirks:
241  *	o ignores OPT rdata.
242  *	o ignores OPT owner name.
243  *	o ignores extra OPT records, except the last one in the packet.
244  *
245  * @param msg: parsed message structure. Modified on exit, if EDNS was present
246  * 	it is removed from the additional section.
247  * @param edns: the edns data is stored here. Does not have to be initialised.
248  * @return: 0 on success. or an RCODE on an error.
249  *	RCODE formerr if OPT in wrong section, and so on.
250  */
251 int parse_extract_edns(struct msg_parse* msg, struct edns_data* edns);
252 
253 /**
254  * If EDNS data follows a query section, extract it and initialize edns struct.
255  * @param pkt: the packet. position at start must be right after the query
256  *	section. At end, right after EDNS data or no movement if failed.
257  * @param edns: the edns data allocated by the caller. Does not have to be
258  *	initialised.
259  * @return: 0 on success, or an RCODE on error.
260  *	RCODE formerr if OPT is badly formatted and so on.
261  */
262 int parse_edns_from_pkt(ldns_buffer* pkt, struct edns_data* edns);
263 
264 /**
265  * Calculate hash value for rrset in packet.
266  * @param pkt: the packet.
267  * @param dname: pointer to uncompressed dname, or compressed dname in packet.
268  * @param type: rrset type in host order.
269  * @param dclass: rrset class in network order.
270  * @param rrset_flags: rrset flags (same as packed_rrset flags).
271  * @return hash value
272  */
273 hashvalue_t pkt_hash_rrset(ldns_buffer* pkt, uint8_t* dname, uint16_t type,
274         uint16_t dclass, uint32_t rrset_flags);
275 
276 /**
277  * Lookup in msg hashtable to find a rrset.
278  * @param msg: with the hashtable.
279  * @param pkt: packet for compressed names.
280  * @param h: hash value
281  * @param rrset_flags: flags of rrset sought for.
282  * @param dname: name of rrset sought for.
283  * @param dnamelen: len of dname.
284  * @param type: rrset type, host order.
285  * @param dclass: rrset class, network order.
286  * @return NULL or the rrset_parse if found.
287  */
288 struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg,
289 	ldns_buffer* pkt, hashvalue_t h, uint32_t rrset_flags,
290 	uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass);
291 
292 /**
293  * Remove rrset from hash table.
294  * @param msg: with hashtable.
295  * @param rrset: with hash value and id info.
296  */
297 void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset);
298 
299 #endif /* UTIL_DATA_MSGPARSE_H */
300