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Commit a26cc2a2 authored by nuccachen's avatar nuccachen Committed by Hungming Chen
Browse files

Synthesize DNS64 prefix in netd 

Synthesize DNS64 prefix with IPv4 dns query result in the following
conditions:
1. If specify address family to IPv6 and no IPv6 addresses result is
   obtained, then if IPv4 addresses result could be obtained
2. If address family is unspecified and query results are all IPv4
   addresses

Test: built, flashed, booted
      system/netd/tests/runtests.sh passes
Bug: 78545619

Change-Id: Ia7c5963c054772f8c95b95849282e9d9d5761515
parent 727544c0

dns_responder/dns_responder.cpp

+32 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <vector>



#define LOG_TAG "DNSResponder"

#include <android-base/strings.h>

#include <log/log.h>

#include <netdutils/SocketOption.h>
@@ -848,6 +849,37 @@ bool DNSResponder::addAnswerRecords(const DNSQuestion& question, 
            ALOGI("inet_pton(AF_INET6, %s) failed", it->second.c_str());

            return false;

        }

    } else if (question.qtype == ns_type::ns_t_ptr) {

        constexpr char delimiter = '.';

        std::string name = it->second;

        std::vector<char> rdata;



        // PTRDNAME field

        // The "name" should be an absolute domain name which ends in a dot.

        if (name.back() != delimiter) {

            ALOGI("invalid absolute domain name");

            return false;

        }

        name.pop_back();  // remove the dot in tail



        for (const std::string& label : android::base::Split(name, {delimiter})) {

            // The length of label is limited to 63 octets or less. See RFC 1035 section 3.1.

            if (label.length() == 0 || label.length() > 63) {

                ALOGI("invalid label length");

                return false;

            }



            rdata.push_back(label.length());

            rdata.insert(rdata.end(), label.begin(), label.end());

        }

        rdata.push_back(0);  // Length byte of zero terminates the label list



        // The length of domain name is limited to 255 octets or less. See RFC 1035 section 3.1.

        if (rdata.size() > 255) {

            ALOGI("invalid name length");

            return false;

        }

        record.rdata = move(rdata);

    } else {

        ALOGI("unhandled qtype %s", dnstype2str(question.qtype));

        return false;

resolver_test.cpp

+841 −0

File changed.

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