Line No. | Rev | Author | Line |
---|---|---|---|
1 | 32 | kaklik | /********************************************************************* |
2 | * |
||
3 | * Domain Name System (DNS) Client |
||
4 | * Module for Microchip TCP/IP Stack |
||
5 | * -Provides hostname to IP address translation |
||
6 | * -Reference: RFC 1035 |
||
7 | * |
||
8 | ********************************************************************* |
||
9 | * FileName: DNS.c |
||
10 | * Dependencies: UDP, ARP, Tick |
||
11 | * Processor: PIC18, PIC24F, PIC24H, dsPIC30F, dsPIC33F, PIC32 |
||
12 | * Compiler: Microchip C32 v1.05 or higher |
||
13 | * Microchip C30 v3.12 or higher |
||
14 | * Microchip C18 v3.30 or higher |
||
15 | * HI-TECH PICC-18 PRO 9.63PL2 or higher |
||
16 | * Company: Microchip Technology, Inc. |
||
17 | * |
||
18 | * Software License Agreement |
||
19 | * |
||
20 | * Copyright (C) 2002-2009 Microchip Technology Inc. All rights |
||
21 | * reserved. |
||
22 | * |
||
23 | * Microchip licenses to you the right to use, modify, copy, and |
||
24 | * distribute: |
||
25 | * (i) the Software when embedded on a Microchip microcontroller or |
||
26 | * digital signal controller product ("Device") which is |
||
27 | * integrated into Licensee's product; or |
||
28 | * (ii) ONLY the Software driver source files ENC28J60.c, ENC28J60.h, |
||
29 | * ENCX24J600.c and ENCX24J600.h ported to a non-Microchip device |
||
30 | * used in conjunction with a Microchip ethernet controller for |
||
31 | * the sole purpose of interfacing with the ethernet controller. |
||
32 | * |
||
33 | * You should refer to the license agreement accompanying this |
||
34 | * Software for additional information regarding your rights and |
||
35 | * obligations. |
||
36 | * |
||
37 | * THE SOFTWARE AND DOCUMENTATION ARE PROVIDED "AS IS" WITHOUT |
||
38 | * WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT |
||
39 | * LIMITATION, ANY WARRANTY OF MERCHANTABILITY, FITNESS FOR A |
||
40 | * PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL |
||
41 | * MICROCHIP BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR |
||
42 | * CONSEQUENTIAL DAMAGES, LOST PROFITS OR LOST DATA, COST OF |
||
43 | * PROCUREMENT OF SUBSTITUTE GOODS, TECHNOLOGY OR SERVICES, ANY CLAIMS |
||
44 | * BY THIRD PARTIES (INCLUDING BUT NOT LIMITED TO ANY DEFENSE |
||
45 | * THEREOF), ANY CLAIMS FOR INDEMNITY OR CONTRIBUTION, OR OTHER |
||
46 | * SIMILAR COSTS, WHETHER ASSERTED ON THE BASIS OF CONTRACT, TORT |
||
47 | * (INCLUDING NEGLIGENCE), BREACH OF WARRANTY, OR OTHERWISE. |
||
48 | * |
||
49 | * |
||
50 | * Author Date Comment |
||
51 | *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
||
52 | * Howard Schlunder 7/31/06 Original |
||
53 | * Howard Schlunder 10/09/06 Added DNSBeginUsage(), DNSEndUsage() |
||
54 | * module ownership semaphore |
||
55 | * Howard Schlunder 08/28/09 Fixed name compression parsing bug |
||
56 | ********************************************************************/ |
||
57 | #define __DNS_C |
||
58 | |||
59 | #include "TCPIP Stack/TCPIP.h" |
||
60 | |||
61 | #if defined(STACK_USE_DNS) |
||
62 | |||
63 | /**************************************************************************** |
||
64 | Section: |
||
65 | Constants and Global Variables |
||
66 | ***************************************************************************/ |
||
67 | |||
68 | #define DNS_PORT 53u // Default port for DNS resolutions |
||
69 | #define DNS_TIMEOUT (TICK_SECOND*1) // Elapsed time after which a DNS resolution is considered to have timed out |
||
70 | |||
71 | static UDP_SOCKET MySocket = INVALID_UDP_SOCKET; // UDP socket to use for DNS queries |
||
72 | static BYTE *DNSHostName; // Host name in RAM to look up |
||
73 | static ROM BYTE *DNSHostNameROM; // Host name in ROM to look up |
||
74 | static BYTE RecordType; // Record type being queried |
||
75 | static NODE_INFO ResolvedInfo; // Node information about the resolved node |
||
76 | |||
77 | // Semaphore flags for the DNS module |
||
78 | static union |
||
79 | { |
||
80 | BYTE Val; |
||
81 | struct |
||
82 | { |
||
83 | unsigned char DNSInUse : 1; // Indicates the DNS module is in use |
||
84 | unsigned char AddressValid : 1; // Indicates that the address resolution is valid and complete |
||
85 | unsigned char filler : 6; |
||
86 | } bits; |
||
87 | } Flags = {0x00}; |
||
88 | |||
89 | // State machine for a DNS query |
||
90 | static enum |
||
91 | { |
||
92 | DNS_START = 0, // Initial state to reset client state variables |
||
93 | DNS_ARP_START_RESOLVE, // Send ARP resolution of DNS server or gateway MAC address |
||
94 | DNS_ARP_RESOLVE, // Wait for response to ARP request |
||
95 | DNS_OPEN_SOCKET, // Open UDP socket |
||
96 | DNS_QUERY, // Send DNS query to DNS server |
||
97 | DNS_GET_RESULT, // Wait for response from DNS server |
||
98 | DNS_FAIL, // ARP or DNS server not responding |
||
99 | DNS_DONE // DNS query is finished |
||
100 | } smDNS = DNS_DONE; |
||
101 | |||
102 | // Structure for the DNS header |
||
103 | typedef struct |
||
104 | { |
||
105 | WORD_VAL TransactionID; |
||
106 | WORD_VAL Flags; |
||
107 | WORD_VAL Questions; |
||
108 | WORD_VAL Answers; |
||
109 | WORD_VAL AuthoritativeRecords; |
||
110 | WORD_VAL AdditionalRecords; |
||
111 | } DNS_HEADER; |
||
112 | |||
113 | typedef struct |
||
114 | { |
||
115 | // Response name is first, but it is variable length and must be retrieved using the DNSDiscardName() function |
||
116 | WORD_VAL ResponseType; |
||
117 | WORD_VAL ResponseClass; |
||
118 | DWORD_VAL ResponseTTL; |
||
119 | WORD_VAL ResponseLen; |
||
120 | } DNS_ANSWER_HEADER; |
||
121 | |||
122 | |||
123 | /**************************************************************************** |
||
124 | Section: |
||
125 | Function Prototypes |
||
126 | ***************************************************************************/ |
||
127 | |||
128 | static void DNSPutString(BYTE* String); |
||
129 | static void DNSDiscardName(void); |
||
130 | |||
131 | #if defined(__18CXX) |
||
132 | static void DNSPutROMString(ROM BYTE* String); |
||
133 | #else |
||
134 | // Non-ROM alias for C30/C32 |
||
135 | #define DNSPutROMString(a) DNSPutString((BYTE*)a) |
||
136 | #endif |
||
137 | |||
138 | |||
139 | /***************************************************************************** |
||
140 | Function: |
||
141 | BOOL DNSBeginUsage(void) |
||
142 | |||
143 | Summary: |
||
144 | Claims access to the DNS module. |
||
145 | |||
146 | Description: |
||
147 | This function acts as a semaphore to obtain usage of the DNS module. |
||
148 | Call this function and ensure that it returns TRUE before calling any |
||
149 | other DNS APIs. Call DNSEndUsage when this application no longer |
||
150 | needs the DNS module so that other applications may make use of it. |
||
151 | |||
152 | Precondition: |
||
153 | Stack is initialized. |
||
154 | |||
155 | Parameters: |
||
156 | None |
||
157 | |||
158 | Return Values: |
||
159 | TRUE - No other DNS resolutions are in progress and the calling |
||
160 | application has sucessfully taken ownership of the DNS module |
||
161 | FALSE - The DNS module is currently in use. Yield to the stack and |
||
162 | attempt this call again later. |
||
163 | |||
164 | Remarks: |
||
165 | Ensure that DNSEndUsage is always called once your application has |
||
166 | obtained control of the DNS module. If this is not done, the stack |
||
167 | will hang for all future applications requiring DNS access. |
||
168 | ***************************************************************************/ |
||
169 | BOOL DNSBeginUsage(void) |
||
170 | { |
||
171 | if(Flags.bits.DNSInUse) |
||
172 | return FALSE; |
||
173 | |||
174 | Flags.bits.DNSInUse = TRUE; |
||
175 | return TRUE; |
||
176 | } |
||
177 | |||
178 | |||
179 | /***************************************************************************** |
||
180 | Function: |
||
181 | BOOL DNSEndUsage(void) |
||
182 | |||
183 | Summary: |
||
184 | Releases control of the DNS module. |
||
185 | |||
186 | Description: |
||
187 | This function acts as a semaphore to obtain usage of the DNS module. |
||
188 | Call this function when this application no longer needs the DNS |
||
189 | module so that other applications may make use of it. |
||
190 | |||
191 | Precondition: |
||
192 | DNSBeginUsage returned TRUE on a previous call. |
||
193 | |||
194 | Parameters: |
||
195 | None |
||
196 | |||
197 | Return Values: |
||
198 | TRUE - The address to the host name was successfully resolved. |
||
199 | FALSE - The DNS failed or the address does not exist. |
||
200 | |||
201 | Remarks: |
||
202 | Ensure that DNSEndUsage is always called once your application has |
||
203 | obtained control of the DNS module. If this is not done, the stack |
||
204 | will hang for all future applications requiring DNS access. |
||
205 | ***************************************************************************/ |
||
206 | BOOL DNSEndUsage(void) |
||
207 | { |
||
208 | if(MySocket != INVALID_UDP_SOCKET) |
||
209 | { |
||
210 | UDPClose(MySocket); |
||
211 | MySocket = INVALID_UDP_SOCKET; |
||
212 | } |
||
213 | smDNS = DNS_DONE; |
||
214 | Flags.bits.DNSInUse = FALSE; |
||
215 | |||
216 | return Flags.bits.AddressValid; |
||
217 | } |
||
218 | |||
219 | |||
220 | /***************************************************************************** |
||
221 | Function: |
||
222 | void DNSResolve(BYTE* Hostname, BYTE Type) |
||
223 | |||
224 | Summary: |
||
225 | Begins resolution of an address. |
||
226 | |||
227 | Description: |
||
228 | This function attempts to resolve a host name to an IP address. When |
||
229 | called, it starts the DNS state machine. Call DNSIsResolved repeatedly |
||
230 | to determine if the resolution is complete. |
||
231 | |||
232 | Only one DNS resoultion may be executed at a time. The Hostname must |
||
233 | not be modified in memory until the resolution is complete. |
||
234 | |||
235 | Precondition: |
||
236 | DNSBeginUsage returned TRUE on a previous call. |
||
237 | |||
238 | Parameters: |
||
239 | Hostname - A pointer to the null terminated string specifiying the |
||
240 | host for which to resolve an IP. |
||
241 | RecordType - DNS_TYPE_A or DNS_TYPE_MX depending on what type of |
||
242 | record resolution is desired. |
||
243 | |||
244 | Returns: |
||
245 | None |
||
246 | |||
247 | Remarks: |
||
248 | This function requires access to one UDP socket. If none are available, |
||
249 | MAX_UDP_SOCKETS may need to be increased. |
||
250 | ***************************************************************************/ |
||
251 | void DNSResolve(BYTE* Hostname, BYTE Type) |
||
252 | { |
||
253 | if(StringToIPAddress(Hostname, &ResolvedInfo.IPAddr)) |
||
254 | { |
||
255 | Flags.bits.AddressValid = TRUE; |
||
256 | smDNS = DNS_DONE; |
||
257 | } |
||
258 | else |
||
259 | { |
||
260 | DNSHostName = Hostname; |
||
261 | DNSHostNameROM = NULL; |
||
262 | smDNS = DNS_START; |
||
263 | RecordType = Type; |
||
264 | Flags.bits.AddressValid = FALSE; |
||
265 | } |
||
266 | } |
||
267 | |||
268 | |||
269 | /***************************************************************************** |
||
270 | Function: |
||
271 | void DNSResolveROM(ROM BYTE* Hostname, BYTE Type) |
||
272 | |||
273 | Summary: |
||
274 | Begins resolution of an address. |
||
275 | |||
276 | Description: |
||
277 | This function attempts to resolve a host name to an IP address. When |
||
278 | called, it starts the DNS state machine. Call DNSIsResolved repeatedly |
||
279 | to determine if the resolution is complete. |
||
280 | |||
281 | Only one DNS resoultion may be executed at a time. The Hostname must |
||
282 | not be modified in memory until the resolution is complete. |
||
283 | |||
284 | Precondition: |
||
285 | DNSBeginUsage returned TRUE on a previous call. |
||
286 | |||
287 | Parameters: |
||
288 | Hostname - A pointer to the null terminated string specifiying the |
||
289 | host for which to resolve an IP. |
||
290 | RecordType - DNS_TYPE_A or DNS_TYPE_MX depending on what type of |
||
291 | record resolution is desired. |
||
292 | |||
293 | Returns: |
||
294 | None |
||
295 | |||
296 | Remarks: |
||
297 | This function requires access to one UDP socket. If none are available, |
||
298 | MAX_UDP_SOCKETS may need to be increased. |
||
299 | |||
300 | This function is aliased to DNSResolve on non-PIC18 platforms. |
||
301 | ***************************************************************************/ |
||
302 | #if defined(__18CXX) |
||
303 | void DNSResolveROM(ROM BYTE* Hostname, BYTE Type) |
||
304 | { |
||
305 | if(ROMStringToIPAddress(Hostname, &ResolvedInfo.IPAddr)) |
||
306 | { |
||
307 | Flags.bits.AddressValid = TRUE; |
||
308 | smDNS = DNS_DONE; |
||
309 | } |
||
310 | else |
||
311 | { |
||
312 | DNSHostName = NULL; |
||
313 | DNSHostNameROM = Hostname; |
||
314 | smDNS = DNS_START; |
||
315 | RecordType = Type; |
||
316 | Flags.bits.AddressValid = FALSE; |
||
317 | } |
||
318 | } |
||
319 | #endif |
||
320 | |||
321 | |||
322 | /***************************************************************************** |
||
323 | Function: |
||
324 | BOOL DNSIsResolved(IP_ADDR* HostIP) |
||
325 | |||
326 | Summary: |
||
327 | Determines if the DNS resolution is complete and provides the IP. |
||
328 | |||
329 | Description: |
||
330 | Call this function to determine if the DNS resolution of an address has |
||
331 | been completed. If so, the resolved address will be provided in HostIP. |
||
332 | |||
333 | Precondition: |
||
334 | DNSResolve or DNSResolveROM has been called. |
||
335 | |||
336 | Parameters: |
||
337 | HostIP - A pointer to an IP_ADDR structure in which to store the |
||
338 | resolved IP address once resolution is complete. |
||
339 | |||
340 | Return Values: |
||
341 | TRUE - The DNS client has obtained an IP, or the DNS process |
||
342 | has encountered an error. HostIP will be 0.0.0.0 on error. Possible |
||
343 | errors include server timeout (i.e. DNS server not available), hostname |
||
344 | not in the DNS, or DNS server errors. |
||
345 | FALSE - The resolution process is still in progress. |
||
346 | ***************************************************************************/ |
||
347 | BOOL DNSIsResolved(IP_ADDR* HostIP) |
||
348 | { |
||
349 | static DWORD StartTime; |
||
350 | static WORD_VAL SentTransactionID __attribute__((persistent)); |
||
351 | static BYTE vARPAttemptCount; |
||
352 | static BYTE vDNSAttemptCount; |
||
353 | BYTE i; |
||
354 | WORD_VAL w; |
||
355 | DNS_HEADER DNSHeader; |
||
356 | DNS_ANSWER_HEADER DNSAnswerHeader; |
||
357 | |||
358 | switch(smDNS) |
||
359 | { |
||
360 | case DNS_START: |
||
361 | vARPAttemptCount = 0; |
||
362 | vDNSAttemptCount = 0; |
||
363 | // No break; |
||
364 | |||
365 | case DNS_ARP_START_RESOLVE: |
||
366 | ARPResolve(&AppConfig.PrimaryDNSServer); |
||
367 | vARPAttemptCount++; |
||
368 | StartTime = TickGet(); |
||
369 | smDNS = DNS_ARP_RESOLVE; |
||
370 | break; |
||
371 | |||
372 | case DNS_ARP_RESOLVE: |
||
373 | if(!ARPIsResolved(&AppConfig.PrimaryDNSServer, &ResolvedInfo.MACAddr)) |
||
374 | { |
||
375 | if(TickGet() - StartTime > DNS_TIMEOUT) |
||
376 | smDNS = (vARPAttemptCount >= 3u) ? DNS_FAIL : DNS_ARP_START_RESOLVE; |
||
377 | break; |
||
378 | } |
||
379 | ResolvedInfo.IPAddr.Val = AppConfig.PrimaryDNSServer.Val; |
||
380 | smDNS = DNS_OPEN_SOCKET; |
||
381 | // No break: DNS_OPEN_SOCKET is the correct next state |
||
382 | |||
383 | case DNS_OPEN_SOCKET: |
||
384 | MySocket = UDPOpen(0, &ResolvedInfo, DNS_PORT); |
||
385 | if(MySocket == INVALID_UDP_SOCKET) |
||
386 | break; |
||
387 | |||
388 | smDNS = DNS_QUERY; |
||
389 | // No need to break, we can immediately start resolution |
||
390 | |||
391 | case DNS_QUERY: |
||
392 | if(!UDPIsPutReady(MySocket)) |
||
393 | break; |
||
394 | |||
395 | // Put DNS query here |
||
396 | SentTransactionID.Val++; |
||
397 | UDPPut(SentTransactionID.v[1]);// User chosen transaction ID |
||
398 | UDPPut(SentTransactionID.v[0]); |
||
399 | UDPPut(0x01); // Standard query with recursion |
||
400 | UDPPut(0x00); |
||
401 | UDPPut(0x00); // 0x0001 questions |
||
402 | UDPPut(0x01); |
||
403 | UDPPut(0x00); // 0x0000 answers |
||
404 | UDPPut(0x00); |
||
405 | UDPPut(0x00); // 0x0000 name server resource records |
||
406 | UDPPut(0x00); |
||
407 | UDPPut(0x00); // 0x0000 additional records |
||
408 | UDPPut(0x00); |
||
409 | |||
410 | // Put hostname string to resolve |
||
411 | if(DNSHostName) |
||
412 | DNSPutString(DNSHostName); |
||
413 | else |
||
414 | DNSPutROMString(DNSHostNameROM); |
||
415 | |||
416 | UDPPut(0x00); // Type: DNS_TYPE_A A (host address) or DNS_TYPE_MX for mail exchange |
||
417 | UDPPut(RecordType); |
||
418 | UDPPut(0x00); // Class: IN (Internet) |
||
419 | UDPPut(0x01); |
||
420 | |||
421 | UDPFlush(); |
||
422 | StartTime = TickGet(); |
||
423 | smDNS = DNS_GET_RESULT; |
||
424 | break; |
||
425 | |||
426 | case DNS_GET_RESULT: |
||
427 | if(!UDPIsGetReady(MySocket)) |
||
428 | { |
||
429 | if(TickGet() - StartTime > DNS_TIMEOUT) |
||
430 | smDNS = DNS_FAIL; |
||
431 | break; |
||
432 | } |
||
433 | |||
434 | // Retrieve the DNS header and de-big-endian it |
||
435 | UDPGet(&DNSHeader.TransactionID.v[1]); |
||
436 | UDPGet(&DNSHeader.TransactionID.v[0]); |
||
437 | |||
438 | // Throw this packet away if it isn't in response to our last query |
||
439 | if(DNSHeader.TransactionID.Val != SentTransactionID.Val) |
||
440 | { |
||
441 | UDPDiscard(); |
||
442 | break; |
||
443 | } |
||
444 | |||
445 | UDPGet(&DNSHeader.Flags.v[1]); |
||
446 | UDPGet(&DNSHeader.Flags.v[0]); |
||
447 | UDPGet(&DNSHeader.Questions.v[1]); |
||
448 | UDPGet(&DNSHeader.Questions.v[0]); |
||
449 | UDPGet(&DNSHeader.Answers.v[1]); |
||
450 | UDPGet(&DNSHeader.Answers.v[0]); |
||
451 | UDPGet(&DNSHeader.AuthoritativeRecords.v[1]); |
||
452 | UDPGet(&DNSHeader.AuthoritativeRecords.v[0]); |
||
453 | UDPGet(&DNSHeader.AdditionalRecords.v[1]); |
||
454 | UDPGet(&DNSHeader.AdditionalRecords.v[0]); |
||
455 | |||
456 | // Remove all questions (queries) |
||
457 | while(DNSHeader.Questions.Val--) |
||
458 | { |
||
459 | DNSDiscardName(); |
||
460 | UDPGet(&w.v[1]); // Question type |
||
461 | UDPGet(&w.v[0]); |
||
462 | UDPGet(&w.v[1]); // Question class |
||
463 | UDPGet(&w.v[0]); |
||
464 | } |
||
465 | |||
466 | // Scan through answers |
||
467 | while(DNSHeader.Answers.Val--) |
||
468 | { |
||
469 | DNSDiscardName(); // Throw away response name |
||
470 | UDPGet(&DNSAnswerHeader.ResponseType.v[1]); // Response type |
||
471 | UDPGet(&DNSAnswerHeader.ResponseType.v[0]); |
||
472 | UDPGet(&DNSAnswerHeader.ResponseClass.v[1]); // Response class |
||
473 | UDPGet(&DNSAnswerHeader.ResponseClass.v[0]); |
||
474 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[3]); // Time to live |
||
475 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[2]); |
||
476 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[1]); |
||
477 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[0]); |
||
478 | UDPGet(&DNSAnswerHeader.ResponseLen.v[1]); // Response length |
||
479 | UDPGet(&DNSAnswerHeader.ResponseLen.v[0]); |
||
480 | |||
481 | // Make sure that this is a 4 byte IP address, response type A or MX, class 1 |
||
482 | // Check if this is Type A or MX |
||
483 | if( DNSAnswerHeader.ResponseType.Val == 0x0001u && |
||
484 | DNSAnswerHeader.ResponseClass.Val == 0x0001u && // Internet class |
||
485 | DNSAnswerHeader.ResponseLen.Val == 0x0004u) |
||
486 | { |
||
487 | Flags.bits.AddressValid = TRUE; |
||
488 | UDPGet(&ResolvedInfo.IPAddr.v[0]); |
||
489 | UDPGet(&ResolvedInfo.IPAddr.v[1]); |
||
490 | UDPGet(&ResolvedInfo.IPAddr.v[2]); |
||
491 | UDPGet(&ResolvedInfo.IPAddr.v[3]); |
||
492 | goto DoneSearchingRecords; |
||
493 | } |
||
494 | else |
||
495 | { |
||
496 | while(DNSAnswerHeader.ResponseLen.Val--) |
||
497 | { |
||
498 | UDPGet(&i); |
||
499 | } |
||
500 | } |
||
501 | } |
||
502 | |||
503 | // Remove all Authoritative Records |
||
504 | while(DNSHeader.AuthoritativeRecords.Val--) |
||
505 | { |
||
506 | DNSDiscardName(); // Throw away response name |
||
507 | UDPGet(&DNSAnswerHeader.ResponseType.v[1]); // Response type |
||
508 | UDPGet(&DNSAnswerHeader.ResponseType.v[0]); |
||
509 | UDPGet(&DNSAnswerHeader.ResponseClass.v[1]); // Response class |
||
510 | UDPGet(&DNSAnswerHeader.ResponseClass.v[0]); |
||
511 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[3]); // Time to live |
||
512 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[2]); |
||
513 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[1]); |
||
514 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[0]); |
||
515 | UDPGet(&DNSAnswerHeader.ResponseLen.v[1]); // Response length |
||
516 | UDPGet(&DNSAnswerHeader.ResponseLen.v[0]); |
||
517 | |||
518 | // Make sure that this is a 4 byte IP address, response type A or MX, class 1 |
||
519 | // Check if this is Type A |
||
520 | if( DNSAnswerHeader.ResponseType.Val == 0x0001u && |
||
521 | DNSAnswerHeader.ResponseClass.Val == 0x0001u && // Internet class |
||
522 | DNSAnswerHeader.ResponseLen.Val == 0x0004u) |
||
523 | { |
||
524 | Flags.bits.AddressValid = TRUE; |
||
525 | UDPGet(&ResolvedInfo.IPAddr.v[0]); |
||
526 | UDPGet(&ResolvedInfo.IPAddr.v[1]); |
||
527 | UDPGet(&ResolvedInfo.IPAddr.v[2]); |
||
528 | UDPGet(&ResolvedInfo.IPAddr.v[3]); |
||
529 | goto DoneSearchingRecords; |
||
530 | } |
||
531 | else |
||
532 | { |
||
533 | while(DNSAnswerHeader.ResponseLen.Val--) |
||
534 | { |
||
535 | UDPGet(&i); |
||
536 | } |
||
537 | } |
||
538 | } |
||
539 | |||
540 | // Remove all Additional Records |
||
541 | while(DNSHeader.AdditionalRecords.Val--) |
||
542 | { |
||
543 | DNSDiscardName(); // Throw away response name |
||
544 | UDPGet(&DNSAnswerHeader.ResponseType.v[1]); // Response type |
||
545 | UDPGet(&DNSAnswerHeader.ResponseType.v[0]); |
||
546 | UDPGet(&DNSAnswerHeader.ResponseClass.v[1]); // Response class |
||
547 | UDPGet(&DNSAnswerHeader.ResponseClass.v[0]); |
||
548 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[3]); // Time to live |
||
549 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[2]); |
||
550 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[1]); |
||
551 | UDPGet(&DNSAnswerHeader.ResponseTTL.v[0]); |
||
552 | UDPGet(&DNSAnswerHeader.ResponseLen.v[1]); // Response length |
||
553 | UDPGet(&DNSAnswerHeader.ResponseLen.v[0]); |
||
554 | |||
555 | // Make sure that this is a 4 byte IP address, response type A or MX, class 1 |
||
556 | // Check if this is Type A |
||
557 | if( DNSAnswerHeader.ResponseType.Val == 0x0001u && |
||
558 | DNSAnswerHeader.ResponseClass.Val == 0x0001u && // Internet class |
||
559 | DNSAnswerHeader.ResponseLen.Val == 0x0004u) |
||
560 | { |
||
561 | Flags.bits.AddressValid = TRUE; |
||
562 | UDPGet(&ResolvedInfo.IPAddr.v[0]); |
||
563 | UDPGet(&ResolvedInfo.IPAddr.v[1]); |
||
564 | UDPGet(&ResolvedInfo.IPAddr.v[2]); |
||
565 | UDPGet(&ResolvedInfo.IPAddr.v[3]); |
||
566 | goto DoneSearchingRecords; |
||
567 | } |
||
568 | else |
||
569 | { |
||
570 | while(DNSAnswerHeader.ResponseLen.Val--) |
||
571 | { |
||
572 | UDPGet(&i); |
||
573 | } |
||
574 | } |
||
575 | } |
||
576 | |||
577 | DoneSearchingRecords: |
||
578 | |||
579 | UDPDiscard(); |
||
580 | UDPClose(MySocket); |
||
581 | MySocket = INVALID_UDP_SOCKET; |
||
582 | smDNS = DNS_DONE; |
||
583 | // No break, DNS_DONE is the correct step |
||
584 | |||
585 | case DNS_DONE: |
||
586 | // Return 0.0.0.0 if DNS resolution failed, otherwise return the |
||
587 | // resolved IP address |
||
588 | if(!Flags.bits.AddressValid) |
||
589 | ResolvedInfo.IPAddr.Val = 0; |
||
590 | HostIP->Val = ResolvedInfo.IPAddr.Val; |
||
591 | return TRUE; |
||
592 | |||
593 | case DNS_FAIL: |
||
594 | // If 3 attempts or more, quit |
||
595 | if(vDNSAttemptCount >= 2u) |
||
596 | { |
||
597 | // Return an invalid IP address 0.0.0.0 if we can't finish ARP or DNS query step |
||
598 | HostIP->Val = 0x00000000; |
||
599 | return TRUE; |
||
600 | } |
||
601 | vDNSAttemptCount++; |
||
602 | |||
603 | // Swap primary and secondary DNS servers if there is a secondary DNS server programmed |
||
604 | if(AppConfig.SecondaryDNSServer.Val) |
||
605 | { |
||
606 | AppConfig.PrimaryDNSServer.Val ^= AppConfig.SecondaryDNSServer.Val; |
||
607 | AppConfig.SecondaryDNSServer.Val ^= AppConfig.PrimaryDNSServer.Val; |
||
608 | AppConfig.PrimaryDNSServer.Val ^= AppConfig.SecondaryDNSServer.Val; |
||
609 | |||
610 | // Start another ARP resolution for the secondary server (now primary) |
||
611 | vARPAttemptCount = 0; |
||
612 | if(MySocket != INVALID_UDP_SOCKET) |
||
613 | { |
||
614 | UDPClose(MySocket); |
||
615 | MySocket = INVALID_UDP_SOCKET; |
||
616 | } |
||
617 | smDNS = DNS_ARP_START_RESOLVE; |
||
618 | } |
||
619 | |||
620 | break; |
||
621 | |||
622 | } |
||
623 | |||
624 | return FALSE; |
||
625 | } |
||
626 | |||
627 | /***************************************************************************** |
||
628 | Function: |
||
629 | static void DNSPutString(BYTE* String) |
||
630 | |||
631 | Summary: |
||
632 | Writes a string to the DNS socket. |
||
633 | |||
634 | Description: |
||
635 | This function writes a string to the DNS socket, ensuring that it is |
||
636 | properly formatted. |
||
637 | |||
638 | Precondition: |
||
639 | UDP socket is obtained and ready for writing. |
||
640 | |||
641 | Parameters: |
||
642 | String - the string to write to the UDP socket. |
||
643 | |||
644 | Returns: |
||
645 | None |
||
646 | ***************************************************************************/ |
||
647 | static void DNSPutString(BYTE* String) |
||
648 | { |
||
649 | BYTE *RightPtr; |
||
650 | BYTE i; |
||
651 | BYTE Len; |
||
652 | |||
653 | RightPtr = String; |
||
654 | |||
655 | while(1) |
||
656 | { |
||
657 | do |
||
658 | { |
||
659 | i = *RightPtr++; |
||
660 | } while((i != 0x00u) && (i != '.') && (i != '/') && (i != ',') && (i != '>')); |
||
661 | |||
662 | // Put the length and data |
||
663 | // Also, skip over the '.' in the input string |
||
664 | Len = (BYTE)(RightPtr-String-1); |
||
665 | UDPPut(Len); |
||
666 | String += UDPPutArray(String, Len) + 1; |
||
667 | |||
668 | if(i == 0x00u || i == '/' || i == ',' || i == '>') |
||
669 | break; |
||
670 | } |
||
671 | |||
672 | // Put the string null terminator character (zero length label) |
||
673 | UDPPut(0x00); |
||
674 | } |
||
675 | |||
676 | /***************************************************************************** |
||
677 | Function: |
||
678 | static void DNSPutROMString(ROM BYTE* String) |
||
679 | |||
680 | Summary: |
||
681 | Writes a ROM string to the DNS socket. |
||
682 | |||
683 | Description: |
||
684 | This function writes a string to the DNS socket, ensuring that it is |
||
685 | properly formatted. |
||
686 | |||
687 | Precondition: |
||
688 | UDP socket is obtained and ready for writing. |
||
689 | |||
690 | Parameters: |
||
691 | String - the string to write to the UDP socket. |
||
692 | |||
693 | Returns: |
||
694 | None |
||
695 | |||
696 | Remarks: |
||
697 | This function is aliased to DNSPutString on non-PIC18 platforms. |
||
698 | ***************************************************************************/ |
||
699 | #if defined(__18CXX) |
||
700 | static void DNSPutROMString(ROM BYTE* String) |
||
701 | { |
||
702 | ROM BYTE *RightPtr; |
||
703 | BYTE i; |
||
704 | BYTE Len; |
||
705 | |||
706 | RightPtr = String; |
||
707 | |||
708 | while(1) |
||
709 | { |
||
710 | do |
||
711 | { |
||
712 | i = *RightPtr++; |
||
713 | } while((i != 0x00u) && (i != '.') && (i != '/') && (i != ',') && (i != '>')); |
||
714 | |||
715 | // Put the length and data |
||
716 | // Also, skip over the '.' in the input string |
||
717 | Len = (BYTE)(RightPtr-String-1); |
||
718 | UDPPut(Len); |
||
719 | String += UDPPutROMArray(String, Len) + 1; |
||
720 | |||
721 | if(i == 0x00u || i == '/' || i == ',' || i == '>') |
||
722 | break; |
||
723 | } |
||
724 | |||
725 | // Put the string terminator character (zero length label) |
||
726 | UDPPut(0x00); |
||
727 | } |
||
728 | #endif |
||
729 | |||
730 | |||
731 | /***************************************************************************** |
||
732 | Function: |
||
733 | static void DNSDiscardName(void) |
||
734 | |||
735 | Summary: |
||
736 | Reads a name string or string pointer from the DNS socket and discards it. |
||
737 | |||
738 | Description: |
||
739 | This function reads a name string from the DNS socket. Each string |
||
740 | consists of a series of labels. Each label consists of a length prefix |
||
741 | byte, followed by the label bytes. At the end of the string, a zero length |
||
742 | label is found as termination. If name compression is used, this function |
||
743 | will automatically detect the pointer and discard it. |
||
744 | |||
745 | Precondition: |
||
746 | UDP socket is obtained and ready for reading a DNS name |
||
747 | |||
748 | Parameters: |
||
749 | None |
||
750 | |||
751 | Returns: |
||
752 | None |
||
753 | ***************************************************************************/ |
||
754 | static void DNSDiscardName(void) |
||
755 | { |
||
756 | BYTE i; |
||
757 | |||
758 | while(1) |
||
759 | { |
||
760 | // Get first byte which will tell us if this is a 16-bit pointer or the |
||
761 | // length of the first of a series of labels |
||
762 | if(!UDPGet(&i)) |
||
763 | return; |
||
764 | |||
765 | // Check if this is a pointer, if so, get the reminaing 8 bits and return |
||
766 | if((i & 0xC0u) == 0xC0u) |
||
767 | { |
||
768 | UDPGet(&i); |
||
769 | return; |
||
770 | } |
||
771 | |||
772 | // Exit once we reach a zero length label |
||
773 | if(i == 0u) |
||
774 | return; |
||
775 | |||
776 | // Discard complete label |
||
777 | UDPGetArray(NULL, i); |
||
778 | } |
||
779 | } |
||
780 | |||
781 | |||
782 | #endif //#if defined(STACK_USE_DNS) |
Powered by WebSVN v2.8.3