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Commit 05adc5bf authored by Ken Chen's avatar Ken Chen Committed by Automerger Merge Worker
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Don't use 5353 source port for mDNS queries am: f3c42075 am: 4e552607 am:... 

Don't use 5353 source port for mDNS queries am: f3c42075 am: 4e552607 am: c8e63898 am: 486cd8de

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2049146



Change-Id: I03c06856c981631502d8f37bc08210f108dc04fc
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents 01eb5e75 486cd8de

res_send.cpp

+9 −3
Original line number Diff line number Diff line
@@ -253,7 +253,7 @@ static struct timespec evNowTime(void) { 
// END: Code copied from ISC eventlib



/* BIONIC-BEGIN: implement source port randomization */

static int random_bind(int s, int family) {

static int random_bind(int s, int family, bool isMdns) {

    sockaddr_union u;

    int j;

    socklen_t slen;
@@ -279,6 +279,10 @@ static int random_bind(int s, int family) { 
    for (j = 0; j < 10; j++) {

        /* find a random port between 1025 .. 65534 */

        int port = 1025 + (arc4random_uniform(65535 - 1025));

        // RFC 6762 section 5.1: Don't use 5353 source port on one-shot Multicast DNS queries. DNS

        // resolver does not fully compliant mDNS.

        if (isMdns && port == 5353) continue;



        if (family == AF_INET)

            u.sin.sin_port = htons(port);

        else
@@ -775,7 +779,7 @@ same_ns: 
            }

        }

        errno = 0;

        if (random_bind(statp->tcp_nssock, nsap->sa_family) < 0) {

        if (random_bind(statp->tcp_nssock, nsap->sa_family, false /* isMdns */) < 0) {

            *terrno = errno;

            dump_error("bind/vc", nsap);

            statp->closeSockets();
@@ -1078,7 +1082,9 @@ static int setupUdpSocket(ResState* statp, const sockaddr* sockap, unique_fd* fd 
        }

    }



    if (random_bind(*fd_out, sockap->sa_family) < 0) {

    const auto addr = IPSockAddr::toIPSockAddr(*sockap);

    const bool isMdns = (addr == mdns_addrs[0] || addr == mdns_addrs[1]);

    if (random_bind(*fd_out, sockap->sa_family, isMdns) < 0) {

        *terrno = errno;

        dump_error("bind", sockap);

        return 0;