Configuring Stub Solver (#600)

* testing new method

* implementing solver

* testing stub solver

* tested

* configured new solver

* fixing bug

* implementing ip version check

* setup the docs

* add ref

* english

* updating the docs

* [Gradle Release Plugin] - new version commit:  '3.32.1-snapshot'.

RELEASE-NOTES.md

@@ -1,3 +1,6 @@
+## 3.32.1
+* Configuring Stub Solver. #545
+
 ## 3.32.0
 * Implementing Stub Solver but not exposing. #545
 

docs/content/2-features/stub-solver/_index.en.md

@@ -0,0 +1,48 @@
+---
+title: Stub Solver
+---
+
+You can use stub solver to transform IPs into hostnames without need to create a 
+configuration file as in Local DB Solver. Stub Solver was inspired in `nip.io` and `sslip.io`.
+
+## Examples:
+
+**Without a name:**
+
+* `10.0.0.1.stub` => `10.0.0.1`
+* `192-168-1-250.stub` => `192.168.1.250`
+* `0a000803.stub` => `10.0.8.3`
+
+**With a name:**
+
+* `app.10.8.0.1.stub` => `10.8.0.1`
+* `app-116-203-255-68.stub` => `116.203.255.68`
+* `app-c0a801fc.stub` => `192.168.1.252`
+* `customer1.app.10.0.0.1.stub` => `10.0.0.1`
+* `customer2-app-127-0-0-1.stub` => `127.0.0.1`
+* `customer3-app-7f000101.stub` => `127.0.1.1`
+* `app.2a01-4f8-c17-b8f--2.stub` => `2a01:4f8:c17:b8f::2`
+
+### Format Reference
+
+```
+${name}[.-]${ip_address}.stub
+```
+
+* `${name}` (optional): you can set a name to make it easier to recognize the IP
+* `${ip_address}`: The ip address which the DNS will answer it can be in 4 formats
+  * dot notation: magic.127.0.0.1.stub
+  * dash notation: magic-127-0-0-1.stub
+  * hexadecimal notation: magic-7f000001.stub
+  * Ipv6 notation: magic.2a01-4f8-c17-b8f--2.stub
+
+### Customize the domain name
+
+<tbd>
+
+## Refs
+
+* [Stub Solver #545][1]
+
+
+[1]: https://github.com/mageddo/dns-proxy-server/issues/545

docs/content/3-configuration/_index.en.md

@@ -192,15 +192,17 @@ __Version 2__
   "dockerSolverHostMachineFallbackActive": true,
   "solverRemote" : {
     "circuitBreaker" : { 
-      "failureThreshold" : 3, // how many attempts before open the circuit?
-      "failureThresholdCapacity" : 10, // how many attempts store to the stack?
-      "successThreshold" : 5, // how many attempts before close the circuit?
-      "testDelay" : "PT20S" // how many time to wait before test the circuit again?, see https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html#toString-- for format explanation
+      "failureThreshold" : 3, 
+      "failureThresholdCapacity" : 10,
+      "successThreshold" : 5, 
+      "testDelay" : "PT20S"
     }
   }
 }
 ```
 
+* [Solver remote circuit breaker configuration][3] 
+
 ## Environment variable configuration
 
 Boolean values
@@ -221,3 +223,4 @@ $ docker run defreitas/dns-proxy-server --help
 
 [1]: {{%relref "2-features/auto-configuration-as-default-dns/_index.md" %}}
 [2]: {{%relref "2-features/local-entries/_index.md" %}}
+[3]: {{%relref "2-features/remote-solver-circuitbreaker/_index.en.md" %}}

gradle.properties

@@ -1 +1 @@
-version=3.32.0-snapshot
+version=3.32.1-snapshot

src/main/java/com/mageddo/dns/Hostname.java

@@ -44,4 +44,8 @@ public String toString() {
   public static Hostname of(String hostname) {
     return new Hostname(hostname);
   }
+
+  public boolean endsWith(String name) {
+    return this.value.endsWith(StringUtils.lowerCase(name));
+  }
 }

src/main/java/com/mageddo/dns/utils/Messages.java

@@ -269,7 +269,11 @@ public static Message withResponseCode(Message res, int rRode) {
     return res;
   }
 
-  static Message withDefaultResponseHeaders(Message res) {
+  public static int getRCode(Message m){
+    return m.getRcode();
+  }
+
+  public static Message withDefaultResponseHeaders(Message res) {
     final var header = res.getHeader();
     header.setFlag(Flags.QR);
     header.setFlag(Flags.RA);
@@ -305,4 +309,8 @@ public static boolean isSuccess(Message res) {
   public static String findAnswerRawIP(Message res) {
     return findFirstAnswerRecord(res).rdataToString();
   }
+
+  public static boolean isNxDomain(Message m) {
+    return m.getRcode() == Rcode.NXDOMAIN;
+  }
 }

src/main/java/com/mageddo/dnsproxyserver/di/module/ModuleSolver.java

@@ -9,6 +9,7 @@
 import com.mageddo.dnsproxyserver.solver.SolverDocker;
 import com.mageddo.dnsproxyserver.solver.SolverLocalDB;
 import com.mageddo.dnsproxyserver.solver.SolverSystem;
+import com.mageddo.dnsproxyserver.solver.stub.SolverStub;
 import dagger.Module;
 import dagger.Provides;
 import dagger.multibindings.ElementsIntoSet;
@@ -24,9 +25,9 @@ public interface ModuleSolver {
   @Singleton
   @ElementsIntoSet
   static Set<Solver> solvers(
-    SolverSystem o1, SolverDocker o2, SolverLocalDB o3, SolverCachedRemote o4
+    SolverSystem o1, SolverDocker o2, SolverLocalDB o3, SolverCachedRemote o4, SolverStub o5
   ) {
-    return Set.of(o1, o2, o3, o4);
+    return Set.of(o1, o2, o3, o4, o5);
   }
 
   @Provides

src/main/java/com/mageddo/dnsproxyserver/solver/Response.java

@@ -5,6 +5,7 @@
 import lombok.NonNull;
 import lombok.Value;
 import org.xbill.DNS.Message;
+import org.xbill.DNS.Rcode;
 
 import java.time.Duration;
 import java.time.LocalDateTime;
@@ -50,6 +51,9 @@ public static Response of(Message message, Duration dpsTtl) {
   }
 
   public static Response nxDomain(Message message) {
+    if (!Messages.isNxDomain(message)) {
+      Messages.withResponseCode(message, Rcode.NXDOMAIN);
+    }
     return of(message, DEFAULT_NXDOMAIN_TTL);
   }
 
@@ -74,4 +78,8 @@ public Response withTTL(Duration ttl) {
       .dpsTtl(ttl)
       .build();
   }
+
+  public int getRCode() {
+    return this.message.getRcode();
+  }
 }

src/main/java/com/mageddo/dnsproxyserver/solver/ResponseMapper.java

@@ -0,0 +1,15 @@
+package com.mageddo.dnsproxyserver.solver;
+
+import com.mageddo.commons.lang.Objects;
+import com.mageddo.dns.utils.Messages;
+import com.mageddo.net.IP;
+import org.xbill.DNS.Message;
+
+public class ResponseMapper {
+  public static Response toDefaultSuccessAnswer(Message query, IP ip, IP.Version version) {
+    return Response.of(
+      Messages.answer(query, Objects.mapOrNull(ip, IP::toText), version),
+      Messages.DEFAULT_TTL_DURATION
+    );
+  }
+}

src/main/java/com/mageddo/dnsproxyserver/solver/SolverProvider.java

@@ -17,6 +17,7 @@ public class SolverProvider {
 
   static final String[] solversOrder = {
     "SolverSystem",
+    "SolverStub",
     "SolverDocker",
     SolverLocalDB.NAME,
     SolverCachedRemote.NAME

src/main/java/com/mageddo/dnsproxyserver/solver/SolverSystem.java

@@ -1,12 +1,10 @@
 package com.mageddo.dnsproxyserver.solver;
 
-import com.mageddo.commons.lang.Objects;
+import com.mageddo.dns.utils.Messages;
 import com.mageddo.dnsproxyserver.config.Config.Entry.Type;
-import com.mageddo.dnsproxyserver.config.application.Configs;
 import com.mageddo.dnsproxyserver.config.ConfigEntryTypes;
-import com.mageddo.dns.utils.Messages;
+import com.mageddo.dnsproxyserver.config.application.Configs;
 import com.mageddo.dnsproxyserver.usecase.HostMachineService;
-import com.mageddo.net.IP;
 import lombok.AllArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.xbill.DNS.Message;
@@ -36,10 +34,7 @@ public Response handle(Message query) {
     if (hostname.isEqualTo(config.getHostMachineHostname())) { // fixme fazer case com hostname + search domain
       final var ip = this.machineService.findHostMachineIP(questionType.toVersion());
       log.debug("status=solvingHostMachineName, host={}, ip={}", hostname, ip);
-      return Response.of(
-        Messages.answer(query, Objects.mapOrNull(ip, IP::toText), questionType.toVersion()),
-        Messages.DEFAULT_TTL_DURATION
-      );
+      return ResponseMapper.toDefaultSuccessAnswer(query, ip, questionType.toVersion());
     }
     return null;
   }

src/main/java/com/mageddo/dnsproxyserver/solver/stub/HostnameIpExtractor.java

@@ -1,12 +1,28 @@
 package com.mageddo.dnsproxyserver.solver.stub;
 
+import com.mageddo.dns.Hostname;
 import com.mageddo.dnsproxyserver.solver.stub.addressexpression.AddressExpressions;
 import com.mageddo.dnsproxyserver.solver.stub.addressexpression.ParseException;
 import com.mageddo.net.IP;
+import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.lang3.Validate;
 
+@Slf4j
 public class HostnameIpExtractor {
 
+  public static IP safeExtract(Hostname hostname, String domain) {
+    try {
+      return extract(hostname, domain);
+    } catch (Exception e) {
+      log.info("status=failedToExtractIpFromHostname, hostname={}, msg={}", hostname, e.getMessage(), e);
+      return null;
+    }
+  }
+
+  public static IP extract(Hostname hostname, String domain) {
+    return extract(hostname.getCanonicalValue(), domain);
+  }
+
   public static IP extract(String hostname, String domain) {
 
     hostname = removeDomainFrom(hostname, domain);

src/main/java/com/mageddo/dnsproxyserver/solver/stub/SolverStub.java

@@ -1,16 +1,56 @@
 package com.mageddo.dnsproxyserver.solver.stub;
 
+import com.mageddo.dns.utils.Messages;
+import com.mageddo.dnsproxyserver.config.Config;
+import com.mageddo.dnsproxyserver.config.ConfigEntryTypes;
 import com.mageddo.dnsproxyserver.solver.Response;
+import com.mageddo.dnsproxyserver.solver.ResponseMapper;
 import com.mageddo.dnsproxyserver.solver.Solver;
+import lombok.AllArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 import org.xbill.DNS.Message;
 
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import static com.mageddo.dns.utils.Messages.findQuestionTypeCode;
+
 /**
  * Extract the address from the hostname then answer.
  * Inspired at nip.io and sslip.io, see #545.
  */
+
+@Slf4j
+@Singleton
+@AllArgsConstructor(onConstructor = @__({@Inject}))
 public class SolverStub implements Solver {
+
+  public static final String DOMAIN_NAME = "stub";
+
   @Override
   public Response handle(Message query) {
-    return null;
+    final var questionType = Messages.findQuestionType(query);
+    if (ConfigEntryTypes.isNot(questionType, Config.Entry.Type.A, Config.Entry.Type.AAAA)) {
+      log.debug("status=unsupportedType, type={}, query={}", findQuestionTypeCode(query), Messages.simplePrint(query));
+      return null;
+    }
+
+    final var hostname = Messages.findQuestionHostname(query);
+    if (!hostname.endsWith(DOMAIN_NAME)) {
+      log.debug("status=hostnameDoesntMatchRequiredDomain, hostname={}", hostname);
+      return null;
+    }
+
+    final var foundIp = HostnameIpExtractor.safeExtract(hostname, DOMAIN_NAME);
+    if (foundIp == null) {
+      log.debug("status=notSolved, hostname={}", hostname);
+      return null;
+    }
+    if (!foundIp.isVersionEqualsTo(questionType.toVersion())) {
+      log.debug("status=incompatibleIpAndQueryType, hostname={}, questionType={}", hostname, questionType);
+      return Response.nxDomain(query);
+    }
+    log.debug("status=solved, host={}, ip={}", hostname, foundIp);
+    return ResponseMapper.toDefaultSuccessAnswer(query, foundIp, questionType.toVersion());
   }
 }

src/main/java/com/mageddo/net/IP.java

@@ -37,6 +37,10 @@ static List<IP> listOf(String ... ips) {
 
   boolean notEqualTo(String ip);
 
+  default boolean isVersionEqualsTo(Version version){
+    return this.version().equals(version);
+  }
+
   enum Version {
 
     IPV4,

src/test/java/com/mageddo/dns/HostnameTest.java

@@ -0,0 +1,21 @@
+package com.mageddo.dns;
+
+import org.junit.jupiter.api.Test;
+import testing.templates.HostnameTemplates;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class HostnameTest {
+
+  @Test
+  void mustEndsWith(){
+    final var hostname = Hostname.of(HostnameTemplates.NGINX_COM_BR);
+    assertTrue(hostname.endsWith(".com.br"));
+  }
+
+  @Test
+  void mustNotEndsWith(){
+    final var hostname = Hostname.of(HostnameTemplates.NGINX_COM_BR);
+    assertFalse(hostname.endsWith(".com"));
+  }
+}