Retry binding sockets in DNSResponder if errno is EADDRNOTAVAIL am: db04a2bd

#define LOG_TAG "DNSResponder"

#include <android-base/logging.h>

#include <android-base/strings.h>

#include <netdutils/BackoffSequence.h>

#include <netdutils/InternetAddresses.h>

#include <netdutils/Slice.h>

#include <netdutils/SocketOption.h>

using android::netdutils::BackoffSequence;

using android::netdutils::enableSockopt;

using android::netdutils::ScopedAddrinfo;

using android::netdutils::Slice;

using std::chrono::milliseconds;

namespace test {

    return std::string();

}

// Because The address might still being set up (b/186181084), This is a wrapper function

// that retries bind() if errno is EADDRNOTAVAIL

int bindSocket(int socket, const sockaddr* address, socklen_t address_len) {

    // Set the wrapper to try bind() at most 6 times with backoff time

    // (100 ms, 200 ms, ..., 1600 ms).

    auto backoff = BackoffSequence<milliseconds>::Builder()

                           .withInitialRetransmissionTime(milliseconds(100))

                           .withMaximumRetransmissionCount(5)

                           .build();

    while (true) {

        int ret = bind(socket, address, address_len);

        if (ret == 0 || errno != EADDRNOTAVAIL) {

            return ret;

        }

        if (!backoff.hasNextTimeout()) break;

        LOG(WARNING) << "Retry to bind " << addr2str(address, address_len);

        std::this_thread::sleep_for(backoff.getNextTimeout());

    }

    // Set errno before return since it might have been changed somewhere.

    errno = EADDRNOTAVAIL;

    return -1;

}

/* DNS struct helpers */

const char* dnstype2str(unsigned dnstype) {

        const std::string host_str = addr2str(ai->ai_addr, ai->ai_addrlen);

        const char* socket_str = (socket_type == SOCK_STREAM) ? "TCP" : "UDP";

        if (bind(fd.get(), ai->ai_addr, ai->ai_addrlen)) {

        if (bindSocket(fd.get(), ai->ai_addr, ai->ai_addrlen)) {

            PLOG(ERROR) << "failed to bind " << socket_str << " " << host_str << ":"

                        << listen_service_;

            continue;