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Commit 9a057c71 authored by Pabba Prakash's avatar Pabba Prakash Committed by Automerger Merge Worker
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DnsResolver: Support case-insensitive domain name hash am: 66707820 

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/1202636

Change-Id: I84f04ecdd900ae5f77f409c8b325f9a447afb8a3
parents aec20b43 66707820

res_cache.cpp

+25 −10
Original line number Diff line number Diff line
@@ -264,6 +264,22 @@ struct DnsPacket { 
    const uint8_t* cursor;

};



static uint8_t res_tolower(uint8_t c) {

    return (c >= 'A' && c <= 'Z') ? (c | 0x20) : c;

}



static int res_memcasecmp(const unsigned char *s1, const unsigned char *s2, size_t len) {

    for (size_t i = 0; i < len; i++) {

        int ch1 = *s1++;

        int ch2 = *s2++;

        int d = res_tolower(ch1) - res_tolower(ch2);

        if (d != 0) {

            return d;

        }

    }

    return 0;

}



static void _dnsPacket_init(DnsPacket* packet, const uint8_t* buff, int bufflen) {

    packet->base = buff;

    packet->end = buff + bufflen;
@@ -451,14 +467,12 @@ static unsigned _dnsPacket_hashQName(DnsPacket* packet, unsigned hash) { 
    const uint8_t* end = packet->end;



    for (;;) {

        int c;



        if (p >= end) { /* should not happen */

            LOG(INFO) << __func__ << ": INTERNAL_ERROR: read-overflow";

            break;

        }



        c = *p++;

        int c = *p++;



        if (c == 0) break;
@@ -470,9 +484,12 @@ static unsigned _dnsPacket_hashQName(DnsPacket* packet, unsigned hash) { 
            LOG(INFO) << __func__ << ": INTERNAL_ERROR: simple label read-overflow";

            break;

        }



        while (c > 0) {

            hash = hash * FNV_MULT ^ *p++;

            c -= 1;

            uint8_t ch = *p++;

            ch = res_tolower(ch);

            hash = hash * FNV_MULT ^ ch;

            c--;

        }

    }

    packet->cursor = p;
@@ -548,14 +565,12 @@ static int _dnsPacket_isEqualDomainName(DnsPacket* pack1, DnsPacket* pack2) { 
    const uint8_t* end2 = pack2->end;



    for (;;) {

        int c1, c2;



        if (p1 >= end1 || p2 >= end2) {

            LOG(INFO) << __func__ << ": INTERNAL_ERROR: read-overflow";

            break;

        }

        c1 = *p1++;

        c2 = *p2++;

        int c1 = *p1++;

        int c2 = *p2++;

        if (c1 != c2) break;



        if (c1 == 0) {
@@ -571,7 +586,7 @@ static int _dnsPacket_isEqualDomainName(DnsPacket* pack1, DnsPacket* pack2) { 
            LOG(INFO) << __func__ << ": INTERNAL_ERROR: simple label read-overflow";

            break;

        }

        if (memcmp(p1, p2, c1) != 0) break;

        if (res_memcasecmp(p1, p2, c1) != 0) break;

        p1 += c1;

        p2 += c1;

        /* we rely on the bound checks at the start of the loop */

tests/resolv_integration_test.cpp

+45 −0
Original line number Diff line number Diff line
@@ -893,6 +893,51 @@ TEST_F(ResolverTest, GetAddrInfo_cnamesIllegalRdata) { 
    EXPECT_TRUE(result == nullptr);

}



TEST_F(ResolverTest, GetAddrInfoForCaseInSensitiveDomains) {

    test::DNSResponder dns;

    const char* host_name = "howdy.example.com.";

    const char* host_name2 = "HOWDY.example.com.";

    const std::vector<DnsRecord> records = {

            {host_name, ns_type::ns_t_a, "1.2.3.4"},

            {host_name, ns_type::ns_t_aaaa, "::1.2.3.4"},

            {host_name2, ns_type::ns_t_a, "1.2.3.5"},

            {host_name2, ns_type::ns_t_aaaa, "::1.2.3.5"},

    };

    StartDns(dns, records);

    ASSERT_TRUE(mDnsClient.SetResolversForNetwork());



    ScopedAddrinfo hostname_result = safe_getaddrinfo("howdy", nullptr, nullptr);

    EXPECT_TRUE(hostname_result != nullptr);

    const size_t hostname1_count_after_first_query = GetNumQueries(dns, host_name);

    EXPECT_LE(1U, hostname1_count_after_first_query);

    // Could be A or AAAA

    std::string hostname_result_str = ToString(hostname_result);

    EXPECT_TRUE(hostname_result_str == "1.2.3.4" || hostname_result_str == "::1.2.3.4");



    // Verify that the name is cached.

    ScopedAddrinfo hostname2_result = safe_getaddrinfo("HOWDY", nullptr, nullptr);

    EXPECT_TRUE(hostname2_result != nullptr);

    const size_t hostname1_count_after_second_query = GetNumQueries(dns, host_name);

    EXPECT_LE(1U, hostname1_count_after_second_query);



    // verify that there is no change in num of queries for howdy.example.com

    EXPECT_EQ(hostname1_count_after_first_query, hostname1_count_after_second_query);



    // Number of queries for HOWDY.example.com would be >= 1 if domain names

    // are considered case-sensitive, else number of queries should be 0.

    const size_t hostname2_count = GetNumQueries(dns, host_name2);

    EXPECT_EQ(0U,hostname2_count);

    std::string hostname2_result_str = ToString(hostname2_result);

    EXPECT_TRUE(hostname2_result_str == "1.2.3.4" || hostname2_result_str == "::1.2.3.4");



    // verify that the result is still the same address even though

    // mixed-case string is not in the DNS

    ScopedAddrinfo result = safe_getaddrinfo("HowDY", nullptr, nullptr);

    EXPECT_TRUE(result != nullptr);

    std::string result_str = ToString(result);

    EXPECT_TRUE(result_str == "1.2.3.4" || result_str == "::1.2.3.4");

}



TEST_F(ResolverTest, MultidomainResolution) {

    constexpr char host_name[] = "nihao.example2.com.";

    std::vector<std::string> searchDomains = {"example1.com", "example2.com", "example3.com"};