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
25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33  * SOFTWARE, EVEN IF ADVISED OF THE 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 "sldns/pkthdr.h"
67 #include "sldns/rrdef.h"
68 struct sldns_buffer;
69 struct rrset_parse;
70 struct rr_parse;
71 struct regional;
72 struct edns_option;
73 struct config_file;
74 struct comm_point;
75 
76 /** number of buckets in parse rrset hash table. Must be power of 2. */
77 #define PARSE_TABLE_SIZE 32
78 /** Maximum TTL that is allowed. */
79 extern time_t MAX_TTL;
80 /** Minimum TTL that is allowed. */
81 extern time_t MIN_TTL;
82 /** Maximum Negative TTL that is allowed */
83 extern time_t MAX_NEG_TTL;
84 /** If we serve expired entries and prefetch them */
85 extern int SERVE_EXPIRED;
86 /** Time to serve records after expiration */
87 extern time_t SERVE_EXPIRED_TTL;
88 /** TTL to use for expired records */
89 extern time_t SERVE_EXPIRED_REPLY_TTL;
90 /** Negative cache time (for entries without any RRs.) */
91 #define NORR_TTL 5 /* seconds */
92 /** If we serve the original TTL or decrementing TTLs */
93 extern int SERVE_ORIGINAL_TTL;
94 
95 /**
96  * Data stored in scratch pad memory during parsing.
97  * Stores the data that will enter into the msgreply and packet result.
98  */
99 struct msg_parse {
100 	/** id from message, network format. */
101 	uint16_t id;
102 	/** flags from message, host format. */
103 	uint16_t flags;
104 	/** count of RRs, host format */
105 	uint16_t qdcount;
106 	/** count of RRs, host format */
107 	uint16_t ancount;
108 	/** count of RRs, host format */
109 	uint16_t nscount;
110 	/** count of RRs, host format */
111 	uint16_t arcount;
112 	/** count of RRsets per section. */
113 	size_t an_rrsets;
114 	/** count of RRsets per section. */
115 	size_t ns_rrsets;
116 	/** count of RRsets per section. */
117 	size_t ar_rrsets;
118 	/** total number of rrsets found. */
119 	size_t rrset_count;
120 
121 	/** query dname (pointer to start location in packet, NULL if none */
122 	uint8_t* qname;
123 	/** length of query dname in octets, 0 if none */
124 	size_t qname_len;
125 	/** query type, host order. 0 if qdcount=0 */
126 	uint16_t qtype;
127 	/** query class, host order. 0 if qdcount=0 */
128 	uint16_t qclass;
129 
130 	/**
131 	 * Hash table array used during parsing to lookup rrset types.
132 	 * Based on name, type, class.  Same hash value as in rrset cache.
133 	 */
134 	struct rrset_parse* hashtable[PARSE_TABLE_SIZE];
135 
136 	/** linked list of rrsets that have been found (in order). */
137 	struct rrset_parse* rrset_first;
138 	/** last element of rrset list. */
139 	struct rrset_parse* rrset_last;
140 };
141 
142 /**
143  * Data stored for an rrset during parsing.
144  */
145 struct rrset_parse {
146 	/** next in hash bucket */
147 	struct rrset_parse* rrset_bucket_next;
148 	/** next in list of all rrsets */
149 	struct rrset_parse* rrset_all_next;
150 	/** hash value of rrset */
151 	hashvalue_type hash;
152 	/** which section was it found in: one of
153 	 * LDNS_SECTION_ANSWER, LDNS_SECTION_AUTHORITY, LDNS_SECTION_ADDITIONAL
154 	 */
155 	sldns_pkt_section section;
156 	/** start of (possibly compressed) dname in packet */
157 	uint8_t* dname;
158 	/** length of the dname uncompressed wireformat */
159 	size_t dname_len;
160 	/** type, host order. */
161 	uint16_t type;
162 	/** class, network order. var name so that it is not a c++ keyword. */
163 	uint16_t rrset_class;
164 	/** the flags for the rrset, like for packedrrset */
165 	uint32_t flags;
166 	/** number of RRs in the rr list */
167 	size_t rr_count;
168 	/** sum of RR rdata sizes */
169 	size_t size;
170 	/** linked list of RRs in this rrset. */
171 	struct rr_parse* rr_first;
172 	/** last in list of RRs in this rrset. */
173 	struct rr_parse* rr_last;
174 	/** number of RRSIGs over this rrset. */
175 	size_t rrsig_count;
176 	/** linked list of RRsig RRs over this rrset. */
177 	struct rr_parse* rrsig_first;
178 	/** last in list of RRSIG RRs over this rrset. */
179 	struct rr_parse* rrsig_last;
180 };
181 
182 /**
183  * Data stored for an RR during parsing.
184  */
185 struct rr_parse {
186 	/**
187 	 * Pointer to the RR. Points to start of TTL value in the packet.
188 	 * Rdata length and rdata follow it.
189 	 * its dname, type and class are the same and stored for the rrset.
190 	 */
191 	uint8_t* ttl_data;
192 	/** true if ttl_data is not part of the packet, but elsewhere in mem.
193 	 * Set for generated CNAMEs for DNAMEs. */
194 	int outside_packet;
195 	/** the length of the rdata if allocated (with no dname compression)*/
196 	size_t size;
197 	/** next in list of RRs. */
198 	struct rr_parse* next;
199 };
200 
201 /** Check if label length is first octet of a compression pointer, pass u8. */
202 #define LABEL_IS_PTR(x) ( ((x)&0xc0) == 0xc0 )
203 /** Calculate destination offset of a compression pointer. pass first and
204  * second octets of the compression pointer. */
205 #define PTR_OFFSET(x, y) ( ((x)&0x3f)<<8 | (y) )
206 /** create a compression pointer to the given offset. */
207 #define PTR_CREATE(offset) ((uint16_t)(0xc000 | (offset)))
208 
209 /** error codes, extended with EDNS, so > 15. */
210 #define EDNS_RCODE_BADVERS	16	/** bad EDNS version */
211 /** largest valid compression offset */
212 #define PTR_MAX_OFFSET 	0x3fff
213 
214 /**
215  * EDNS data storage
216  * rdata is parsed in a list (has accessor functions). allocated in a
217  * region.
218  */
219 struct edns_data {
220 	/** if EDNS OPT record was present */
221 	int edns_present;
222 	/** Extended RCODE */
223 	uint8_t ext_rcode;
224 	/** The EDNS version number */
225 	uint8_t edns_version;
226 	/** the EDNS bits field from ttl (host order): Z */
227 	uint16_t bits;
228 	/** UDP reassembly size. */
229 	uint16_t udp_size;
230 	/** rdata element list of options of an incoming packet created at
231 	 * parse time, or NULL if none */
232 	struct edns_option* opt_list_in;
233 	/** rdata element list of options to encode for outgoing packets,
234 	 * or NULL if none */
235 	struct edns_option* opt_list_out;
236 	/** rdata element list of outgoing edns options from modules
237 	 * or NULL if none */
238 	struct edns_option* opt_list_inplace_cb_out;
239 	/** block size to pad */
240 	uint16_t padding_block_size;
241 };
242 
243 /**
244  * EDNS option
245  */
246 struct edns_option {
247 	/** next item in list */
248 	struct edns_option* next;
249 	/** type of this edns option */
250 	uint16_t opt_code;
251 	/** length of this edns option (cannot exceed uint16 in encoding) */
252 	size_t opt_len;
253 	/** data of this edns option; allocated in region, or NULL if len=0 */
254 	uint8_t* opt_data;
255 };
256 
257 /**
258  * Obtain size in the packet of an rr type, that is before dname type.
259  * Do TYPE_DNAME, and type STR, yourself. Gives size for most regular types.
260  * @param rdf: the rdf type from the descriptor.
261  * @return: size in octets. 0 on failure.
262  */
263 size_t get_rdf_size(sldns_rdf_type rdf);
264 
265 /**
266  * Parse the packet.
267  * @param pkt: packet, position at call must be at start of packet.
268  *	at end position is after packet.
269  * @param msg: where to store results.
270  * @param region: how to alloc results.
271  * @return: 0 if OK, or rcode on error.
272  */
273 int parse_packet(struct sldns_buffer* pkt, struct msg_parse* msg,
274 	struct regional* region);
275 
276 /**
277  * After parsing the packet, extract EDNS data from packet.
278  * If not present this is noted in the data structure.
279  * If a parse error happens, an error code is returned.
280  *
281  * Quirks:
282  *	o ignores OPT rdata.
283  *	o ignores OPT owner name.
284  *	o ignores extra OPT records, except the last one in the packet.
285  *
286  * @param msg: parsed message structure. Modified on exit, if EDNS was present
287  * 	it is removed from the additional section.
288  * @param edns: the edns data is stored here. Does not have to be initialised.
289  * @param region: region to alloc results in (edns option contents)
290  * @return: 0 on success. or an RCODE on an error.
291  *	RCODE formerr if OPT in wrong section, and so on.
292  */
293 int parse_extract_edns_from_response_msg(struct msg_parse* msg,
294 	struct edns_data* edns, struct regional* region);
295 
296 /**
297  * Skip RRs from packet
298  * @param pkt: the packet. position at start must be right after the query
299  *	section. At end, right after EDNS data or no movement if failed.
300  * @param num: Limit of the number of records we want to parse.
301  * @return: 0 on success, 1 on failure.
302  */
303 int skip_pkt_rrs(struct sldns_buffer* pkt, int num);
304 
305 /**
306  * If EDNS data follows a query section, extract it and initialize edns struct.
307  * @param pkt: the packet. position at start must be right after the query
308  *	section. At end, right after EDNS data or no movement if failed.
309  * @param edns: the edns data allocated by the caller. Does not have to be
310  *	initialised.
311  * @param cfg: the configuration (with nsid value etc.)
312  * @param c: commpoint to determine transport (if needed)
313  * @param region: region to alloc results in (edns option contents)
314  * @return: 0 on success, or an RCODE on error.
315  *	RCODE formerr if OPT is badly formatted and so on.
316  */
317 int parse_edns_from_query_pkt(struct sldns_buffer* pkt, struct edns_data* edns,
318 	struct config_file* cfg, struct comm_point* c, struct regional* region);
319 
320 /**
321  * Calculate hash value for rrset in packet.
322  * @param pkt: the packet.
323  * @param dname: pointer to uncompressed dname, or compressed dname in packet.
324  * @param type: rrset type in host order.
325  * @param dclass: rrset class in network order.
326  * @param rrset_flags: rrset flags (same as packed_rrset flags).
327  * @return hash value
328  */
329 hashvalue_type pkt_hash_rrset(struct sldns_buffer* pkt, uint8_t* dname,
330 	uint16_t type, uint16_t dclass, uint32_t rrset_flags);
331 
332 /**
333  * Lookup in msg hashtable to find a rrset.
334  * @param msg: with the hashtable.
335  * @param pkt: packet for compressed names.
336  * @param h: hash value
337  * @param rrset_flags: flags of rrset sought for.
338  * @param dname: name of rrset sought for.
339  * @param dnamelen: len of dname.
340  * @param type: rrset type, host order.
341  * @param dclass: rrset class, network order.
342  * @return NULL or the rrset_parse if found.
343  */
344 struct rrset_parse* msgparse_hashtable_lookup(struct msg_parse* msg,
345 	struct sldns_buffer* pkt, hashvalue_type h, uint32_t rrset_flags,
346 	uint8_t* dname, size_t dnamelen, uint16_t type, uint16_t dclass);
347 
348 /**
349  * Remove rrset from hash table.
350  * @param msg: with hashtable.
351  * @param rrset: with hash value and id info.
352  */
353 void msgparse_bucket_remove(struct msg_parse* msg, struct rrset_parse* rrset);
354 
355 /**
356  * Log the edns options in the edns option list.
357  * @param level: the verbosity level.
358  * @param info_str: the informational string to be printed before the options.
359  * @param list: the edns option list.
360  */
361 void log_edns_opt_list(enum verbosity_value level, const char* info_str,
362 	struct edns_option* list);
363 
364 #endif /* UTIL_DATA_MSGPARSE_H */
365