fetchdns.html

用JAVA编写的,在做实验的时候留下来的,本来想删的,但是传上来,大家分享吧

<a name="155" href="#155">155</a>                     address = InetAddress.getByName(dnsName);
<a name="156" href="#156">156</a>                 } <strong>catch</strong> (UnknownHostException e1) {
<a name="157" href="#157">157</a>                     address = <strong>null</strong>;
<a name="158" href="#158">158</a>                 }
<a name="159" href="#159">159</a>                 <strong>if</strong> (address != <strong>null</strong>) {
<a name="160" href="#160">160</a>                     targetHost.setIP(address, DEFAULT_TTL_FOR_NON_DNS_RESOLVES);
<a name="161" href="#161">161</a>                     curi.setFetchStatus(S_GETBYNAME_SUCCESS);
<a name="162" href="#162">162</a>                     <strong>if</strong> (logger.isLoggable(Level.FINE)) {
<a name="163" href="#163">163</a>                         logger.fine(<span class="string">"Found address for "</span> + dnsName +
<a name="164" href="#164">164</a>                             <span class="string">" using native dns."</span>);
<a name="165" href="#165">165</a>                     }
<a name="166" href="#166">166</a>                 } <strong>else</strong> {
<a name="167" href="#167">167</a>                     <strong>if</strong> (logger.isLoggable(Level.FINE)) {
<a name="168" href="#168">168</a>                         logger.fine(<span class="string">"Failed find of address for "</span> + dnsName +
<a name="169" href="#169">169</a>                             <span class="string">" using native dns."</span>);
<a name="170" href="#170">170</a>                     }
<a name="171" href="#171">171</a>                     setUnresolvable(curi, targetHost);
<a name="172" href="#172">172</a>                 }
<a name="173" href="#173">173</a>             } <strong>else</strong> {
<a name="174" href="#174">174</a>                 setUnresolvable(curi, targetHost);
<a name="175" href="#175">175</a>             }
<a name="176" href="#176">176</a>         }
<a name="177" href="#177">177</a>         curi.putLong(A_FETCH_COMPLETED_TIME, System.currentTimeMillis());
<a name="178" href="#178">178</a>     }
<a name="179" href="#179">179</a>     
<a name="180" href="#180">180</a>     <strong>protected</strong> <strong>void</strong> storeDNSRecord(<strong>final</strong> <a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> curi, <strong>final</strong> String dnsName,
<a name="181" href="#181">181</a>     		<strong>final</strong> <a href="../../../../org/archive/crawler/datamodel/CrawlHost.html">CrawlHost</a> targetHost, <strong>final</strong> Record[] rrecordSet) {
<a name="182" href="#182">182</a>         <em class="comment">// Get TTL and IP info from the first A record (there may be</em>
<a name="183" href="#183">183</a>         <em class="comment">// multiple, e.g. www.washington.edu) then update the CrawlServer</em>
<a name="184" href="#184">184</a>         ARecord arecord = getFirstARecord(rrecordSet);
<a name="185" href="#185">185</a>         <strong>if</strong> (arecord == <strong>null</strong>) {
<a name="186" href="#186">186</a>             <strong>throw</strong> <strong>new</strong> NullPointerException(<span class="string">"Got null arecord for "</span> +
<a name="187" href="#187">187</a>                 dnsName);
<a name="188" href="#188">188</a>         }
<a name="189" href="#189">189</a>         targetHost.setIP(arecord.getAddress(), arecord.getTTL());
<a name="190" href="#190">190</a>         <strong>try</strong> {
<a name="191" href="#191">191</a>         	recordDNS(curi, rrecordSet);
<a name="192" href="#192">192</a>             curi.setFetchStatus(S_DNS_SUCCESS);
<a name="193" href="#193">193</a>             curi.putString(A_DNS_SERVER_IP_LABEL, FindServer.server());
<a name="194" href="#194">194</a>         } <strong>catch</strong> (IOException e) {
<a name="195" href="#195">195</a>         	logger.log(Level.SEVERE, <span class="string">"Failed store of DNS Record for "</span> +
<a name="196" href="#196">196</a>         		curi.toString(), e);
<a name="197" href="#197">197</a>         	setUnresolvable(curi, targetHost);
<a name="198" href="#198">198</a>         }
<a name="199" href="#199">199</a>     }
<a name="200" href="#200">200</a>     
<a name="201" href="#201">201</a>     <strong>protected</strong> <strong>boolean</strong> isQuadAddress(<strong>final</strong> <a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> curi, <strong>final</strong> String dnsName,
<a name="202" href="#202">202</a> 			<strong>final</strong> <a href="../../../../org/archive/crawler/datamodel/CrawlHost.html">CrawlHost</a> targetHost) {
<a name="203" href="#203">203</a> 		<strong>boolean</strong> result = false;
<a name="204" href="#204">204</a> 		Matcher matcher = InetAddressUtil.IPV4_QUADS.matcher(dnsName);
<a name="205" href="#205">205</a> 		<em class="comment">// If it's an ip no need to do a lookup</em>
<a name="206" href="#206">206</a> 		<strong>if</strong> (matcher == <strong>null</strong> || !matcher.matches()) {
<a name="207" href="#207">207</a> 			<strong>return</strong> result;
<a name="208" href="#208">208</a> 		}
<a name="209" href="#209">209</a> 		
<a name="210" href="#210">210</a> 		result = <strong>true</strong>;
<a name="211" href="#211">211</a> 		<em class="comment">// Ideally this branch would never be reached: no CrawlURI</em>
<a name="212" href="#212">212</a> 		<em class="comment">// would be created for numerical IPs</em>
<a name="213" href="#213">213</a> 		<strong>if</strong> (logger.isLoggable(Level.WARNING)) {
<a name="214" href="#214">214</a> 			logger.warning(<span class="string">"Unnecessary DNS CrawlURI created: "</span> + curi);
<a name="215" href="#215">215</a> 		}
<a name="216" href="#216">216</a> 		<strong>try</strong> {
<a name="217" href="#217">217</a> 			targetHost.setIP(InetAddress.getByAddress(dnsName, <strong>new</strong> byte[] {
<a name="218" href="#218">218</a> 					(byte) (<strong>new</strong> Integer(matcher.group(1)).intValue()),
<a name="219" href="#219">219</a> 					(byte) (<strong>new</strong> Integer(matcher.group(2)).intValue()),
<a name="220" href="#220">220</a> 					(byte) (<strong>new</strong> Integer(matcher.group(3)).intValue()),
<a name="221" href="#221">221</a> 					(byte) (<strong>new</strong> Integer(matcher.group(4)).intValue()) }),
<a name="222" href="#222">222</a> 					CrawlHost.IP_NEVER_EXPIRES); <em class="comment">// Never expire numeric IPs</em>
<a name="223" href="#223">223</a> 			curi.setFetchStatus(S_DNS_SUCCESS);
<a name="224" href="#224">224</a> 		} <strong>catch</strong> (UnknownHostException e) {
<a name="225" href="#225">225</a> 			logger.log(Level.SEVERE, <span class="string">"Should never be "</span> + e.getMessage(), e);
<a name="226" href="#226">226</a> 			setUnresolvable(curi, targetHost);
<a name="227" href="#227">227</a> 		}
<a name="228" href="#228">228</a> 		<strong>return</strong> result;
<a name="229" href="#229">229</a> 	}
<a name="230" href="#230">230</a>     
<a name="231" href="#231">231</a>     <strong>protected</strong> <strong>void</strong> recordDNS(<strong>final</strong> <a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> curi, <strong>final</strong> Record[] rrecordSet)
<a name="232" href="#232">232</a> 	throws IOException {
<a name="233" href="#233">233</a> 		<strong>final</strong> byte[] dnsRecord =
<a name="234" href="#234">234</a> 			getDNSRecord(curi.getLong(A_FETCH_BEGAN_TIME), rrecordSet);
<a name="235" href="#235">235</a> 		HttpRecorder rec = HttpRecorder.getHttpRecorder();
<a name="236" href="#236">236</a>         <em class="comment">// Shall we get a digest on the content downloaded?</em>
<a name="237" href="#237">237</a>         <strong>boolean</strong> sha1Content = ((Boolean)getUncheckedAttribute(curi,
<a name="238" href="#238">238</a>             FetchHTTP.ATTR_SHA1_CONTENT)).booleanValue();
<a name="239" href="#239">239</a>         <strong>if</strong>(sha1Content) {
<a name="240" href="#240">240</a>             rec.getRecordedInput().setSha1Digest();
<a name="241" href="#241">241</a>         } <strong>else</strong> {
<a name="242" href="#242">242</a>             rec.getRecordedInput().setDigest(<strong>null</strong>);
<a name="243" href="#243">243</a>         }
<a name="244" href="#244">244</a> 		curi.setHttpRecorder(rec);
<a name="245" href="#245">245</a> 		InputStream is = curi.getHttpRecorder().inputWrap(
<a name="246" href="#246">246</a> 				<strong>new</strong> ByteArrayInputStream(dnsRecord));
<a name="247" href="#247">247</a> 		<em class="comment">// Reading from the wrapped stream, behind the scenes, will write</em>
<a name="248" href="#248">248</a> 		<em class="comment">// files into scratch space</em>
<a name="249" href="#249">249</a> 		<strong>try</strong> {
<a name="250" href="#250">250</a> 			<strong>while</strong> (is.read(<strong>this</strong>.reusableBuffer) != -1) {
<a name="251" href="#251">251</a> 				<strong>continue</strong>;
<a name="252" href="#252">252</a> 			}
<a name="253" href="#253">253</a> 		} <strong>finally</strong> {
<a name="254" href="#254">254</a> 			is.close();
<a name="255" href="#255">255</a> 			rec.closeRecorders();
<a name="256" href="#256">256</a> 		}
<a name="257" href="#257">257</a> 		curi.setContentSize(dnsRecord.length);
<a name="258" href="#258">258</a>         curi.setContentDigest(FetchHTTP.SHA1,
<a name="259" href="#259">259</a>             rec.getRecordedInput().getDigestValue());
<a name="260" href="#260">260</a> 	}
<a name="261" href="#261">261</a>     
<a name="262" href="#262">262</a>     <strong>protected</strong> byte [] getDNSRecord(<strong>final</strong> <strong>long</strong> fetchStart,
<a name="263" href="#263">263</a>     		<strong>final</strong> Record[] rrecordSet)
<a name="264" href="#264">264</a>     throws IOException {
<a name="265" href="#265">265</a>         ByteArrayOutputStream baos = <strong>new</strong> ByteArrayOutputStream();
<a name="266" href="#266">266</a>         <em class="comment">// Start the record with a 14-digit date per RFC 2540</em>
<a name="267" href="#267">267</a>         byte[] fetchDate = ArchiveUtils.get14DigitDate(fetchStart).getBytes();
<a name="268" href="#268">268</a>         baos.write(fetchDate);
<a name="269" href="#269">269</a>         <em class="comment">// Don't forget the newline</em>
<a name="270" href="#270">270</a>         baos.write(<span class="string">"\n"</span>.getBytes());
<a name="271" href="#271">271</a>         <strong>int</strong> recordLength = fetchDate.length + 1;
<a name="272" href="#272">272</a>         <strong>if</strong> (rrecordSet != <strong>null</strong>) {
<a name="273" href="#273">273</a>             <strong>for</strong> (<strong>int</strong> i = 0; i &lt; rrecordSet.length; i++) {
<a name="274" href="#274">274</a>                 byte[] record = rrecordSet[i].toString().getBytes();
<a name="275" href="#275">275</a>                 recordLength += record.length;
<a name="276" href="#276">276</a>                 baos.write(record);
<a name="277" href="#277">277</a>                 <em class="comment">// Add the newline between records back in</em>
<a name="278" href="#278">278</a>                 baos.write(<span class="string">"\n"</span>.getBytes());
<a name="279" href="#279">279</a>                 recordLength += 1;
<a name="280" href="#280">280</a>             }
<a name="281" href="#281">281</a>         }
<a name="282" href="#282">282</a>         <strong>return</strong> baos.toByteArray();
<a name="283" href="#283">283</a>     }
<a name="284" href="#284">284</a>     
<a name="285" href="#285">285</a>     <strong>protected</strong> <strong>void</strong> setUnresolvable(<a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> curi, <a href="../../../../org/archive/crawler/datamodel/CrawlHost.html">CrawlHost</a> host) {
<a name="286" href="#286">286</a>         host.setIP(<strong>null</strong>, 0);
<a name="287" href="#287">287</a>         curi.setFetchStatus(S_DOMAIN_UNRESOLVABLE); 
<a name="288" href="#288">288</a>     }
<a name="289" href="#289">289</a>     
<a name="290" href="#290">290</a>     <strong>protected</strong> ARecord getFirstARecord(Record[] rrecordSet) {
<a name="291" href="#291">291</a>         ARecord arecord = <strong>null</strong>;
<a name="292" href="#292">292</a>         <strong>if</strong> (rrecordSet == <strong>null</strong> || rrecordSet.length == 0) {
<a name="293" href="#293">293</a>             <strong>if</strong> (logger.isLoggable(Level.FINEST)) {
<a name="294" href="#294">294</a>                 logger.finest(<span class="string">"rrecordSet is null or zero length: "</span> +
<a name="295" href="#295">295</a>                     rrecordSet);
<a name="296" href="#296">296</a>             }
<a name="297" href="#297">297</a>             <strong>return</strong> arecord;
<a name="298" href="#298">298</a>         }
<a name="299" href="#299">299</a>         <strong>for</strong> (<strong>int</strong> i = 0; i &lt; rrecordSet.length; i++) {
<a name="300" href="#300">300</a>             <strong>if</strong> (rrecordSet[i].getType() != Type.A) {
<a name="301" href="#301">301</a>                 <strong>if</strong> (logger.isLoggable(Level.FINEST)) {
<a name="302" href="#302">302</a>                     logger.finest(<span class="string">"Record "</span> + Integer.toString(i) +
<a name="303" href="#303">303</a>                         <span class="string">" is not A type but "</span> + rrecordSet[i].getType());
<a name="304" href="#304">304</a>                 }
<a name="305" href="#305">305</a>                 <strong>continue</strong>;
<a name="306" href="#306">306</a>             }
<a name="307" href="#307">307</a>             arecord = (ARecord) rrecordSet[i];
<a name="308" href="#308">308</a>             <strong>break</strong>;
<a name="309" href="#309">309</a>         }
<a name="310" href="#310">310</a>         <strong>return</strong> arecord;
<a name="311" href="#311">311</a>     }
<a name="312" href="#312">312</a> }
</pre>
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