📄 dns_8c-source.html
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00223 <span class="keywordflow">switch</span>(event){00224 <span class="keywordflow">case</span> <a class="code" href="tcp__ip_8h.html#a31">UDP_EVENT_DATA</a>:00225 <span class="comment">/* only process data while not in ready state */</span>00226 <span class="keywordflow">if</span>(<a class="code" href="dns_8c.html#a3">dns_state</a>==DNS_STATE_READY){00227 DEBUGOUT(<span class="stringliteral">"DNS: Received answer in wrong state\r\n"</span>);00228 <span class="keywordflow">return</span> (-1);00229 }00230 00231 <span class="comment">/* inital size checking. Every DNS reply will be bigger</span>00232 <span class="comment"> than 16 bytes */</span>00233 <span class="keywordflow">if</span>(datalen<16){00234 DEBUGOUT(<span class="stringliteral">"DNS: UDP packet way to short for DNS!\r\n"</span>);00235 <span class="keywordflow">return</span> (-1);00236 }00237 00238 <span class="comment">/* some data received, check if it's what we're waiting for */</span>00239 tmp_int=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00240 tmp_int=(tmp_int<<8)+<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00241 <span class="keywordflow">if</span>(tmp_int!=0xaaaa){00242 DEBUGOUT(<span class="stringliteral">"DNS: ERROR: ID wrong!\r\n"</span>);00243 <span class="keywordflow">return</span> (-1);00244 }00245 00246 tmp_byte=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00247 00248 <span class="keywordflow">if</span>(!(tmp_byte&0x80)){00249 DEBUGOUT(<span class="stringliteral">"DNS: THIS IS NOT AN ANSWER! WE'RE NOT A DNS SERVER!\r\n"</span>);00250 <span class="keywordflow">return</span> (-1);00251 }00252 00253 <span class="comment">/* opcode or truncated ? */</span>00254 <span class="keywordflow">if</span>(tmp_byte&0x7a){00255 DEBUGOUT(<span class="stringliteral">"DNS: Opcode not zero or message truncated. \r\n"</span>);00256 dns_event_listener(<a class="code" href="dns_8h.html#a4">DNS_EVENT_ERROR</a>,<a class="code" href="dns_8h.html#a12">DNS_ERROR_GENERAL</a>);00257 <span class="keywordflow">return</span> (-1);00258 }00259 00260 tmp_byte=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00261 00262 <span class="comment">/* check RCODE */</span>00263 <span class="keywordflow">if</span>((tmp_byte&0x7f)&&(tmp_byte&0x80)){00264 <span class="comment">/* RCODE not zero, and recursion is available */</span>00265 <span class="comment">/* There was an error. Inform listener */</span>00266 DEBUGOUT(<span class="stringliteral">"DNS: RCODE not zero and recursion available! \r\n"</span>);00267 dns_event_listener(<a class="code" href="dns_8h.html#a4">DNS_EVENT_ERROR</a>,tmp_byte&0x7f);00268 <span class="keywordflow">return</span> (-1);00269 }00270 00271 <span class="comment">/* question count == 1 ? */</span>00272 tmp_int=(((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00273 tmp_int+=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00274 <span class="keywordflow">if</span>(tmp_int != 1){00275 DEBUGOUT(<span class="stringliteral">"DNS: we only sent one question and received a couple of answers!!\r\n"</span>);00276 dns_event_listener(<a class="code" href="dns_8h.html#a4">DNS_EVENT_ERROR</a>,<a class="code" href="dns_8h.html#a12">DNS_ERROR_GENERAL</a>);00277 <span class="keywordflow">return</span> (-1);00278 }00279 00280 dns_ancount=(((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00281 dns_ancount+=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00282 00283 dns_nscount=(((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00284 dns_nscount+=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00285 00286 <span class="comment">/* skip ARCOUNT */</span>00287 <a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00288 <a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00289 00290 <span class="comment">/* got to the data, let's process it */</span>00291 <span class="comment">/* check if question section is appropriate (QNAME the same</span>00292 <span class="comment"> and QTYPE=QCLASS=1</span>00293 <span class="comment"> */</span>00294 tmp_ptr=<a class="code" href="dns_8c.html#a8">dns_hostptr</a>;00295 <span class="keywordflow">while</span>((tmp_byte=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())!=0){00296 <span class="keywordflow">while</span>((tmp_byte--)!=0){00297 <span class="keywordflow">if</span>(*tmp_ptr++!=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>()){00298 DEBUGOUT(<span class="stringliteral">"DNS: QNAME not the same!!!! \r\n"</span>);00299 <span class="comment">/* we'll assume that this was from some previous</span>00300 <span class="comment"> query and just exit here */</span>00301 <span class="keywordflow">return</span> (-1);00302 }00303 }00304 <span class="comment">/* reached the end of the label. Is it dot or end of string? */</span>00305 00306 <span class="keywordflow">if</span>(*tmp_ptr==<span class="charliteral">'\0'</span>){00307 <span class="keywordflow">continue</span>;00308 }00309 00310 <span class="keywordflow">if</span>(*tmp_ptr++!=<span class="charliteral">'.'</span>){00311 DEBUGOUT(<span class="stringliteral">"DNS: DOT not where it's supposed to be!\r\n"</span>);00312 <span class="keywordflow">return</span> (-1);00313 }00314 }00315 00316 00317 <span class="comment">/* qtype and qclass */</span>00318 tmp_int=(((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00319 tmp_int+=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00320 00321 tmp_int|=((UINT16)(<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00322 tmp_int|=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00323 00324 <span class="keywordflow">if</span>(tmp_int!=0x0001){00325 DEBUGOUT(<span class="stringliteral">"DNS: Question section QTYPE and/or QCLASS not ok!\r\n"</span>);00326 dns_event_listener(<a class="code" href="dns_8h.html#a4">DNS_EVENT_ERROR</a>,<a class="code" href="dns_8h.html#a12">DNS_ERROR_GENERAL</a>);00327 <span class="keywordflow">return</span> (-1);00328 }00329 00330 <span class="comment">/* process all answer RRs and try to find answer */</span>00331 00332 <span class="comment">/* simply try to find INET class RR. It is</span>00333 <span class="comment"> _PROBABLY_ what we're after. More extensive checking</span>00334 <span class="comment"> would demand buffering the reply which may not be</span>00335 <span class="comment"> desireable.</span>00336 <span class="comment"> */</span>00337 <span class="keywordflow">while</span>(dns_ancount||dns_nscount){00338 <span class="keywordflow">do</span>{00339 tmp_byte=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00340 }<span class="keywordflow">while</span>((tmp_byte!=0)&&((tmp_byte&0xc0)!=0xc0));00341 00342 <span class="keywordflow">if</span>(tmp_byte!=0) <span class="comment">/*second offset byte used in compression*/</span>00343 <a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00344 00345 <span class="comment">/* TYPE */</span>00346 tmp_int=((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8;00347 tmp_int|=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00348 00349 <span class="comment">/* CLASS */</span>00350 tmp_int|=(((UINT16)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8);00351 tmp_int|=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00352 00353 <span class="comment">/* CLASS==INET and TYPE=A ? */</span>00354 <span class="keywordflow">if</span>(tmp_int==0x0001){00355 00356 <span class="comment">/* got it. Skip TTL and read RDLENGTH */</span>00357 <span class="keywordflow">for</span>(tmp_byte=0;tmp_byte<6;tmp_byte++){00358 tmp_int=(tmp_int<<8)+<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00359 }00360 00361 <span class="keywordflow">if</span>(tmp_int==0x0004){00362 <span class="comment">/* great, read IP address*/</span>00363 <a class="code" href="dns_8c.html#a7">dns_tmp_ip</a>=((UINT32)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<24;00364 <a class="code" href="dns_8c.html#a7">dns_tmp_ip</a>+=((UINT32)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<16;00365 <a class="code" href="dns_8c.html#a7">dns_tmp_ip</a>+=((UINT32)<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>())<<8;00366 <a class="code" href="dns_8c.html#a7">dns_tmp_ip</a>+=<a class="code" href="system_8h.html#a9">RECEIVE_NETWORK_B</a>();00367 00368 <span class="comment">/* we got some IP address. Is it what we asked for</span>00369 <span class="comment"> or a NS IP addr*/</span>00370 <span class="keywordflow">if</span>(dns_ancount){00371 DEBUGOUT(<span class="stringliteral">"DNS: Got IP address!\r\n"</span>);00372 dns_event_listener(<a class="code" href="dns_8h.html#a5">DNS_EVENT_SUCCESS</a>,<a class="code" href="dns_8c.html#a7">dns_tmp_ip</a>);00373 <a class="code" href="dns_8c.html#a3">dns_state</a>=DNS_STATE_READY;00374 }<span class="keywordflow">else</span>{00375 DEBUGOUT(<span class="stringliteral">"DNS: Got auth DNS IP addr!\r\n"</span>);00376 <span class="comment">/* invoke another query to the authority */</span>00377 <a class="code" href="dns_8c.html#a11">dns_retransmit</a>();⌨️ 快捷键说明
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