onExpectedResponse() — netty Function Reference

Architecture documentation for the onExpectedResponse() function in DnsResolveContext.java from the netty codebase.

Function java NativeResolver JavaResolver calls 7 called by 1

Entity Profile

NativeResolver→ JavaResolver→ onExpectedResponse() — netty Function Reference

Dependency Diagram

graph TD
  1ff8f220_55f4_0cc5_b454_65682e36be5e["onExpectedResponse()"]
  3bc002ec_f54e_a55f_0b37_77eac88c60db["DnsResolveContext"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|defined in| 3bc002ec_f54e_a55f_0b37_77eac88c60db
  6b22df1c_91b5_21bf_29f9_518f692074d4["onResponse()"]
  6b22df1c_91b5_21bf_29f9_518f692074d4 -->|calls| 1ff8f220_55f4_0cc5_b454_65682e36be5e
  e8e0f39e_4c0b_4101_2c4b_e74b1af9a114["buildAliasMap()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| e8e0f39e_4c0b_4101_2c4b_e74b1af9a114
  836e4609_6a00_0ab5_76ae_511f287c23c9["isEmpty()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| 836e4609_6a00_0ab5_76ae_511f287c23c9
  62ab1144_69c1_0204_37b8_4eea34d6eac3["isCompleteEarly()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| 62ab1144_69c1_0204_37b8_4eea34d6eac3
  161fe130_19c1_016b_ea22_8d91937c6452["add()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| 161fe130_19c1_016b_ea22_8d91937c6452
  ef806d7b_af94_59ce_ffc1_c767faa5b6f5["isDuplicateAllowed()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| ef806d7b_af94_59ce_ffc1_c767faa5b6f5
  83b5f3ee_8078_cb8b_b707_9c1f58a2c6cb["onResponseCNAME()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| 83b5f3ee_8078_cb8b_b707_9c1f58a2c6cb
  e1a10468_2ab8_17c7_5dfe_66d356b0d510["cache()"]
  1ff8f220_55f4_0cc5_b454_65682e36be5e -->|calls| e1a10468_2ab8_17c7_5dfe_66d356b0d510
  style 1ff8f220_55f4_0cc5_b454_65682e36be5e fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

resolver-dns/src/main/java/io/netty/resolver/dns/DnsResolveContext.java lines 810–946

    private void onExpectedResponse(
            DnsQuestion question, AddressedEnvelope<DnsResponse, InetSocketAddress> envelope,
            final DnsQueryLifecycleObserver queryLifecycleObserver, Promise<List<T>> promise) {

        // We often get a bunch of CNAMES as well when we asked for A/AAAA.
        final DnsResponse response = envelope.content();
        final Map<String, String> cnames = buildAliasMap(response, cnameCache(), parent.executor());
        final int answerCount = response.count(DnsSection.ANSWER);

        boolean found = false;
        boolean completeEarly = this.completeEarly;
        boolean cnameNeedsFollow = !cnames.isEmpty();
        for (int i = 0; i < answerCount; i ++) {
            final DnsRecord r = response.recordAt(DnsSection.ANSWER, i);
            final DnsRecordType type = r.type();
            boolean matches = false;
            for (DnsRecordType expectedType : expectedTypes) {
                if (type == expectedType) {
                    matches = true;
                    break;
                }
            }

            if (!matches) {
                continue;
            }

            final String questionName = question.name().toLowerCase(Locale.US);
            final String recordName = r.name().toLowerCase(Locale.US);

            // Make sure the record is for the questioned domain.
            if (!recordName.equals(questionName)) {
                Map<String, String> cnamesCopy = new HashMap<String, String>(cnames);
                // Even if the record's name is not exactly same, it might be an alias defined in the CNAME records.
                String resolved = questionName;
                do {
                    resolved = cnamesCopy.remove(resolved);
                    if (recordName.equals(resolved)) {
                        // We followed a CNAME chain that was part of the response without any extra queries.
                        cnameNeedsFollow = false;
                        break;
                    }
                } while (resolved != null);

                if (resolved == null) {
                    assert questionName.isEmpty() || questionName.charAt(questionName.length() - 1) == '.';

                    for (String searchDomain : parent.searchDomains()) {
                        if (searchDomain.isEmpty()) {
                            continue;
                        }

                        final String fqdn;
                        if (searchDomain.charAt(searchDomain.length() - 1) == '.') {
                            fqdn = questionName + searchDomain;
                        } else {
                            fqdn = questionName + searchDomain + '.';
                        }
                        if (recordName.equals(fqdn)) {
                            resolved = recordName;
                            break;
                        }
                    }
                    if (resolved == null) {
                        if (logger.isDebugEnabled()) {
                            logger.debug("{} Ignoring record {} for [{}: {}] as it contains a different name than " +
                                            "the question name [{}]. Cnames: {}, Search domains: {}",
                                    channel, r.toString(), response.id(), envelope.sender(),
                                    questionName, cnames, parent.searchDomains());
                        }
                        continue;
                    }
                }
            }

            final T converted = convertRecord(r, hostname, additionals, parent.executor());
            if (converted == null) {
                if (logger.isDebugEnabled()) {
                    logger.debug("{} Ignoring record {} for [{}: {}] as the converted record is null. "
                                    + "Hostname [{}], Additionals: {}",
                            channel, r.toString(), response.id(),