tests/binder_test.cpp

/*
 * Copyright 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * binder_test.cpp - unit tests for netd binder RPCs.
 */

#include <cerrno>
#include <cinttypes>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <set>
#include <vector>

#include <fcntl.h>
#include <ifaddrs.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <openssl/base64.h>

#include <android-base/macros.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <bpf/BpfUtils.h>
#include <cutils/multiuser.h>
#include <gtest/gtest.h>
#include <logwrap/logwrap.h>
#include <netutils/ifc.h>

#include "InterfaceController.h"
#include "NetdConstants.h"
#include "Stopwatch.h"
#include "XfrmController.h"
#include "tun_interface.h"
#include "android/net/INetd.h"
#include "android/net/UidRange.h"
#include "binder/IServiceManager.h"
#include "netdutils/Syscalls.h"

#define IP_PATH "/system/bin/ip"
#define IP6TABLES_PATH "/system/bin/ip6tables"
#define IPTABLES_PATH "/system/bin/iptables"
#define TUN_DEV "/dev/tun"

using namespace android;
using namespace android::base;
using namespace android::binder;
using android::base::StartsWith;
using android::bpf::hasBpfSupport;
using android::net::INetd;
using android::net::TunInterface;
using android::net::UidRange;
using android::net::XfrmController;
using android::netdutils::sSyscalls;
using android::os::PersistableBundle;

#define SKIP_IF_BPF_SUPPORTED         \
    do {                              \
        if (hasBpfSupport()) return;  \
    } while (0);

static const char* IP_RULE_V4 = "-4";
static const char* IP_RULE_V6 = "-6";
static const int TEST_NETID1 = 65501;
static const int TEST_NETID2 = 65502;
constexpr int BASE_UID = AID_USER_OFFSET * 5;

static const std::string NO_SOCKET_ALLOW_RULE("! owner UID match 0-4294967294");
static const std::string ESP_ALLOW_RULE("esp");

class BinderTest : public ::testing::Test {

public:
    BinderTest() {
        sp<IServiceManager> sm = defaultServiceManager();
        sp<IBinder> binder = sm->getService(String16("netd"));
        if (binder != nullptr) {
            mNetd = interface_cast<INetd>(binder);
        }
    }

    void SetUp() override {
        ASSERT_NE(nullptr, mNetd.get());
    }

    void TearDown() override {
        mNetd->networkDestroy(TEST_NETID1);
        mNetd->networkDestroy(TEST_NETID2);
    }

    bool allocateIpSecResources(bool expectOk, int32_t *spi);

    // Static because setting up the tun interface takes about 40ms.
    static void SetUpTestCase() {
        ASSERT_EQ(0, sTun.init());
        ASSERT_LE(sTun.name().size(), static_cast<size_t>(IFNAMSIZ));
    }

    static void TearDownTestCase() {
        // Closing the socket removes the interface and IP addresses.
        sTun.destroy();
    }

    static void fakeRemoteSocketPair(int *clientSocket, int *serverSocket, int *acceptedSocket);

protected:
    sp<INetd> mNetd;
    static TunInterface sTun;
};

TunInterface BinderTest::sTun;

class TimedOperation : public Stopwatch {
public:
    explicit TimedOperation(const std::string &name): mName(name) {}
    virtual ~TimedOperation() {
        fprintf(stderr, "    %s: %6.1f ms\n", mName.c_str(), timeTaken());
    }

private:
    std::string mName;
};

TEST_F(BinderTest, TestIsAlive) {
    TimedOperation t("isAlive RPC");
    bool isAlive = false;
    mNetd->isAlive(&isAlive);
    ASSERT_TRUE(isAlive);
}

static int randomUid() {
    return 100000 * arc4random_uniform(7) + 10000 + arc4random_uniform(5000);
}

static std::vector<std::string> runCommand(const std::string& command) {
    std::vector<std::string> lines;

    FILE *f = popen(command.c_str(), "r");  // NOLINT(cert-env33-c)
    if (f == nullptr) {
        perror("popen");
        return lines;
    }

    char *line = nullptr;
    size_t bufsize = 0;
    ssize_t linelen = 0;
    while ((linelen = getline(&line, &bufsize, f)) >= 0) {
        lines.push_back(std::string(line, linelen));
        free(line);
        line = nullptr;
    }

    pclose(f);
    return lines;
}

static std::vector<std::string> listIpRules(const char *ipVersion) {
    std::string command = StringPrintf("%s %s rule list", IP_PATH, ipVersion);
    return runCommand(command);
}

static std::vector<std::string> listIptablesRule(const char *binary, const char *chainName) {
    std::string command = StringPrintf("%s -w -n -L %s", binary, chainName);
    return runCommand(command);
}

static int iptablesRuleLineLength(const char *binary, const char *chainName) {
    return listIptablesRule(binary, chainName).size();
}

static bool iptablesRuleExists(const char *binary,
                               const char *chainName,
                               const std::string& expectedRule) {
    std::vector<std::string> rules = listIptablesRule(binary, chainName);
    for (const auto& rule : rules) {
        if(rule.find(expectedRule) != std::string::npos) {
            return true;
        }
    }
    return false;
}

static bool iptablesNoSocketAllowRuleExists(const char *chainName){
    return iptablesRuleExists(IPTABLES_PATH, chainName, NO_SOCKET_ALLOW_RULE) &&
           iptablesRuleExists(IP6TABLES_PATH, chainName, NO_SOCKET_ALLOW_RULE);
}

static bool iptablesEspAllowRuleExists(const char *chainName){
    return iptablesRuleExists(IPTABLES_PATH, chainName, ESP_ALLOW_RULE) &&
           iptablesRuleExists(IP6TABLES_PATH, chainName, ESP_ALLOW_RULE);
}

TEST_F(BinderTest, TestFirewallReplaceUidChain) {
    SKIP_IF_BPF_SUPPORTED;

    std::string chainName = StringPrintf("netd_binder_test_%u", arc4random_uniform(10000));
    const int kNumUids = 500;
    std::vector<int32_t> noUids(0);
    std::vector<int32_t> uids(kNumUids);
    for (int i = 0; i < kNumUids; i++) {
        uids[i] = randomUid();
    }

    bool ret;
    {
        TimedOperation op(StringPrintf("Programming %d-UID whitelist chain", kNumUids));
        mNetd->firewallReplaceUidChain(chainName, true, uids, &ret);
    }
    EXPECT_EQ(true, ret);
    EXPECT_EQ((int) uids.size() + 9, iptablesRuleLineLength(IPTABLES_PATH, chainName.c_str()));
    EXPECT_EQ((int) uids.size() + 15, iptablesRuleLineLength(IP6TABLES_PATH, chainName.c_str()));
    EXPECT_EQ(true, iptablesNoSocketAllowRuleExists(chainName.c_str()));
    EXPECT_EQ(true, iptablesEspAllowRuleExists(chainName.c_str()));
    {
        TimedOperation op("Clearing whitelist chain");
        mNetd->firewallReplaceUidChain(chainName, false, noUids, &ret);
    }
    EXPECT_EQ(true, ret);
    EXPECT_EQ(5, iptablesRuleLineLength(IPTABLES_PATH, chainName.c_str()));
    EXPECT_EQ(5, iptablesRuleLineLength(IP6TABLES_PATH, chainName.c_str()));

    {
        TimedOperation op(StringPrintf("Programming %d-UID blacklist chain", kNumUids));
        mNetd->firewallReplaceUidChain(chainName, false, uids, &ret);
    }
    EXPECT_EQ(true, ret);
    EXPECT_EQ((int) uids.size() + 5, iptablesRuleLineLength(IPTABLES_PATH, chainName.c_str()));
    EXPECT_EQ((int) uids.size() + 5, iptablesRuleLineLength(IP6TABLES_PATH, chainName.c_str()));
    EXPECT_EQ(false, iptablesNoSocketAllowRuleExists(chainName.c_str()));
    EXPECT_EQ(false, iptablesEspAllowRuleExists(chainName.c_str()));

    {
        TimedOperation op("Clearing blacklist chain");
        mNetd->firewallReplaceUidChain(chainName, false, noUids, &ret);
    }
    EXPECT_EQ(true, ret);
    EXPECT_EQ(5, iptablesRuleLineLength(IPTABLES_PATH, chainName.c_str()));
    EXPECT_EQ(5, iptablesRuleLineLength(IP6TABLES_PATH, chainName.c_str()));

    // Check that the call fails if iptables returns an error.
    std::string veryLongStringName = "netd_binder_test_UnacceptablyLongIptablesChainName";
    mNetd->firewallReplaceUidChain(veryLongStringName, true, noUids, &ret);
    EXPECT_EQ(false, ret);
}

TEST_F(BinderTest, TestVirtualTunnelInterface) {
    const struct TestData {
        const std::string family;
        const std::string deviceName;
        const std::string localAddress;
        const std::string remoteAddress;
        int32_t iKey;
        int32_t oKey;
    } kTestData[] = {
        {"IPV4", "test_vti", "127.0.0.1", "8.8.8.8", 0x1234 + 53, 0x1234 + 53},
        {"IPV6", "test_vti6", "::1", "2001:4860:4860::8888", 0x1234 + 50, 0x1234 + 50},
    };

    for (unsigned int i = 0; i < arraysize(kTestData); i++) {
        const auto& td = kTestData[i];

        binder::Status status;

        // Create Virtual Tunnel Interface.
        status = mNetd->addVirtualTunnelInterface(td.deviceName, td.localAddress, td.remoteAddress,
                                                  td.iKey, td.oKey);
        EXPECT_TRUE(status.isOk()) << td.family << status.exceptionMessage();

        // Update Virtual Tunnel Interface.
        status = mNetd->updateVirtualTunnelInterface(td.deviceName, td.localAddress,
                                                     td.remoteAddress, td.iKey, td.oKey);
        EXPECT_TRUE(status.isOk()) << td.family << status.exceptionMessage();

        // Remove Virtual Tunnel Interface.
        status = mNetd->removeVirtualTunnelInterface(td.deviceName);
        EXPECT_TRUE(status.isOk()) << td.family << status.exceptionMessage();
    }
}

// IPsec tests are not run in 32 bit mode; both 32-bit kernels and
// mismatched ABIs (64-bit kernel with 32-bit userspace) are unsupported.
#if INTPTR_MAX != INT32_MAX
#define RETURN_FALSE_IF_NEQ(_expect_, _ret_) \
        do { if ((_expect_) != (_ret_)) return false; } while(false)
bool BinderTest::allocateIpSecResources(bool expectOk, int32_t *spi) {
    netdutils::Status status = XfrmController::ipSecAllocateSpi(0, "::", "::1", 123, spi);
    SCOPED_TRACE(status);
    RETURN_FALSE_IF_NEQ(status.ok(), expectOk);

    // Add a policy
    status = XfrmController::ipSecAddSecurityPolicy(0, 0, "::", "::1", 123, 0, 0);
    SCOPED_TRACE(status);
    RETURN_FALSE_IF_NEQ(status.ok(), expectOk);

    // Add an ipsec interface
    status = netdutils::statusFromErrno(
            XfrmController::addVirtualTunnelInterface(
                    "ipsec_test", "::", "::1", 0xF00D, 0xD00D, false),
            "addVirtualTunnelInterface");
    return (status.ok() == expectOk);
}

TEST_F(BinderTest, TestXfrmControllerInit) {
    netdutils::Status status;
    status = XfrmController::Init();
    SCOPED_TRACE(status);

    // Older devices or devices with mismatched Kernel/User ABI cannot support the IPsec
    // feature.
    if (status.code() == EOPNOTSUPP) return;

    ASSERT_TRUE(status.ok());

    int32_t spi = 0;

    ASSERT_TRUE(allocateIpSecResources(true, &spi));
    ASSERT_TRUE(allocateIpSecResources(false, &spi));

    status = XfrmController::Init();
    ASSERT_TRUE(status.ok());
    ASSERT_TRUE(allocateIpSecResources(true, &spi));

    // Clean up
    status = XfrmController::ipSecDeleteSecurityAssociation(0, "::", "::1", 123, spi, 0);
    SCOPED_TRACE(status);
    ASSERT_TRUE(status.ok());

    status = XfrmController::ipSecDeleteSecurityPolicy(0, 0, "::", "::1", 0, 0);
    SCOPED_TRACE(status);
    ASSERT_TRUE(status.ok());

    // Remove Virtual Tunnel Interface.
    status = netdutils::statusFromErrno(
            XfrmController::removeVirtualTunnelInterface("ipsec_test"),
            "removeVirtualTunnelInterface");

    ASSERT_TRUE(status.ok());
}
#endif

static int bandwidthDataSaverEnabled(const char *binary) {
    std::vector<std::string> lines = listIptablesRule(binary, "bw_data_saver");

    // Output looks like this:
    //
    // Chain bw_data_saver (1 references)
    // target     prot opt source               destination
    // RETURN     all  --  0.0.0.0/0            0.0.0.0/0
    //
    // or:
    //
    // Chain bw_data_saver (1 references)
    // target     prot opt source               destination
    // ... possibly connectivity critical packet rules here ...
    // REJECT     all  --  ::/0            ::/0

    EXPECT_GE(lines.size(), 3U);

    if (lines.size() == 3 && StartsWith(lines[2], "RETURN ")) {
        // Data saver disabled.
        return 0;
    }

    size_t minSize = (std::string(binary) == IPTABLES_PATH) ? 3 : 9;

    if (lines.size() >= minSize && StartsWith(lines[lines.size() -1], "REJECT ")) {
        // Data saver enabled.
        return 1;
    }

    return -1;
}

bool enableDataSaver(sp<INetd>& netd, bool enable) {
    TimedOperation op(enable ? " Enabling data saver" : "Disabling data saver");
    bool ret;
    netd->bandwidthEnableDataSaver(enable, &ret);
    return ret;
}

int getDataSaverState() {
    const int enabled4 = bandwidthDataSaverEnabled(IPTABLES_PATH);
    const int enabled6 = bandwidthDataSaverEnabled(IP6TABLES_PATH);
    EXPECT_EQ(enabled4, enabled6);
    EXPECT_NE(-1, enabled4);
    EXPECT_NE(-1, enabled6);
    if (enabled4 != enabled6 || (enabled6 != 0 && enabled6 != 1)) {
        return -1;
    }
    return enabled6;
}

TEST_F(BinderTest, TestBandwidthEnableDataSaver) {
    const int wasEnabled = getDataSaverState();
    ASSERT_NE(-1, wasEnabled);

    if (wasEnabled) {
        ASSERT_TRUE(enableDataSaver(mNetd, false));
        EXPECT_EQ(0, getDataSaverState());
    }

    ASSERT_TRUE(enableDataSaver(mNetd, false));
    EXPECT_EQ(0, getDataSaverState());

    ASSERT_TRUE(enableDataSaver(mNetd, true));
    EXPECT_EQ(1, getDataSaverState());

    ASSERT_TRUE(enableDataSaver(mNetd, true));
    EXPECT_EQ(1, getDataSaverState());

    if (!wasEnabled) {
        ASSERT_TRUE(enableDataSaver(mNetd, false));
        EXPECT_EQ(0, getDataSaverState());
    }
}

static bool ipRuleExistsForRange(const uint32_t priority, const UidRange& range,
        const std::string& action, const char* ipVersion) {
    // Output looks like this:
    //   "12500:\tfrom all fwmark 0x0/0x20000 iif lo uidrange 1000-2000 prohibit"
    std::vector<std::string> rules = listIpRules(ipVersion);

    std::string prefix = StringPrintf("%" PRIu32 ":", priority);
    std::string suffix = StringPrintf(" iif lo uidrange %d-%d %s\n",
            range.getStart(), range.getStop(), action.c_str());
    for (const auto& line : rules) {
        if (android::base::StartsWith(line, prefix) && android::base::EndsWith(line, suffix)) {
            return true;
        }
    }
    return false;
}

static bool ipRuleExistsForRange(const uint32_t priority, const UidRange& range,
        const std::string& action) {
    bool existsIp4 = ipRuleExistsForRange(priority, range, action, IP_RULE_V4);
    bool existsIp6 = ipRuleExistsForRange(priority, range, action, IP_RULE_V6);
    EXPECT_EQ(existsIp4, existsIp6);
    return existsIp4;
}

TEST_F(BinderTest, TestNetworkInterfaces) {
    EXPECT_TRUE(mNetd->networkCreatePhysical(TEST_NETID1, "").isOk());
    EXPECT_EQ(EEXIST, mNetd->networkCreatePhysical(TEST_NETID1, "").serviceSpecificErrorCode());
    EXPECT_EQ(EEXIST, mNetd->networkCreateVpn(TEST_NETID1, false, true).serviceSpecificErrorCode());
    EXPECT_TRUE(mNetd->networkCreateVpn(TEST_NETID2, false, true).isOk());

    EXPECT_TRUE(mNetd->networkAddInterface(TEST_NETID1, sTun.name()).isOk());
    EXPECT_EQ(EBUSY,
              mNetd->networkAddInterface(TEST_NETID2, sTun.name()).serviceSpecificErrorCode());

    EXPECT_TRUE(mNetd->networkDestroy(TEST_NETID1).isOk());
    EXPECT_TRUE(mNetd->networkAddInterface(TEST_NETID2, sTun.name()).isOk());
    EXPECT_TRUE(mNetd->networkDestroy(TEST_NETID2).isOk());
}

TEST_F(BinderTest, TestNetworkUidRules) {
    const uint32_t RULE_PRIORITY_SECURE_VPN = 12000;

    EXPECT_TRUE(mNetd->networkCreateVpn(TEST_NETID1, false, true).isOk());
    EXPECT_EQ(EEXIST, mNetd->networkCreateVpn(TEST_NETID1, false, true).serviceSpecificErrorCode());
    EXPECT_TRUE(mNetd->networkAddInterface(TEST_NETID1, sTun.name()).isOk());

    std::vector<UidRange> uidRanges = {
        {BASE_UID + 8005, BASE_UID + 8012},
        {BASE_UID + 8090, BASE_UID + 8099}
    };
    UidRange otherRange(BASE_UID + 8190, BASE_UID + 8299);
    std::string suffix = StringPrintf("lookup %s ", sTun.name().c_str());

    EXPECT_TRUE(mNetd->networkAddUidRanges(TEST_NETID1, uidRanges).isOk());

    EXPECT_TRUE(ipRuleExistsForRange(RULE_PRIORITY_SECURE_VPN, uidRanges[0], suffix));
    EXPECT_FALSE(ipRuleExistsForRange(RULE_PRIORITY_SECURE_VPN, otherRange, suffix));
    EXPECT_TRUE(mNetd->networkRemoveUidRanges(TEST_NETID1, uidRanges).isOk());
    EXPECT_FALSE(ipRuleExistsForRange(RULE_PRIORITY_SECURE_VPN, uidRanges[0], suffix));

    EXPECT_TRUE(mNetd->networkAddUidRanges(TEST_NETID1, uidRanges).isOk());
    EXPECT_TRUE(ipRuleExistsForRange(RULE_PRIORITY_SECURE_VPN, uidRanges[1], suffix));
    EXPECT_TRUE(mNetd->networkDestroy(TEST_NETID1).isOk());
    EXPECT_FALSE(ipRuleExistsForRange(RULE_PRIORITY_SECURE_VPN, uidRanges[1], suffix));

    EXPECT_EQ(ENONET, mNetd->networkDestroy(TEST_NETID1).serviceSpecificErrorCode());
}

TEST_F(BinderTest, TestNetworkRejectNonSecureVpn) {
    constexpr uint32_t RULE_PRIORITY = 12500;

    std::vector<UidRange> uidRanges = {
        {BASE_UID + 150, BASE_UID + 224},
        {BASE_UID + 226, BASE_UID + 300}
    };

    const std::vector<std::string> initialRulesV4 = listIpRules(IP_RULE_V4);
    const std::vector<std::string> initialRulesV6 = listIpRules(IP_RULE_V6);

    // Create two valid rules.
    ASSERT_TRUE(mNetd->networkRejectNonSecureVpn(true, uidRanges).isOk());
    EXPECT_EQ(initialRulesV4.size() + 2, listIpRules(IP_RULE_V4).size());
    EXPECT_EQ(initialRulesV6.size() + 2, listIpRules(IP_RULE_V6).size());
    for (auto const& range : uidRanges) {
        EXPECT_TRUE(ipRuleExistsForRange(RULE_PRIORITY, range, "prohibit"));
    }

    // Remove the rules.
    ASSERT_TRUE(mNetd->networkRejectNonSecureVpn(false, uidRanges).isOk());
    EXPECT_EQ(initialRulesV4.size(), listIpRules(IP_RULE_V4).size());
    EXPECT_EQ(initialRulesV6.size(), listIpRules(IP_RULE_V6).size());
    for (auto const& range : uidRanges) {
        EXPECT_FALSE(ipRuleExistsForRange(RULE_PRIORITY, range, "prohibit"));
    }

    // Fail to remove the rules a second time after they are already deleted.
    binder::Status status = mNetd->networkRejectNonSecureVpn(false, uidRanges);
    ASSERT_EQ(binder::Status::EX_SERVICE_SPECIFIC, status.exceptionCode());
    EXPECT_EQ(ENOENT, status.serviceSpecificErrorCode());

    // All rules should be the same as before.
    EXPECT_EQ(initialRulesV4, listIpRules(IP_RULE_V4));
    EXPECT_EQ(initialRulesV6, listIpRules(IP_RULE_V6));
}

// Create a socket pair that isLoopbackSocket won't think is local.
void BinderTest::fakeRemoteSocketPair(int *clientSocket, int *serverSocket, int *acceptedSocket) {
    *serverSocket = socket(AF_INET6, SOCK_STREAM | SOCK_CLOEXEC, 0);
    struct sockaddr_in6 server6 = { .sin6_family = AF_INET6, .sin6_addr = sTun.dstAddr() };
    ASSERT_EQ(0, bind(*serverSocket, (struct sockaddr *) &server6, sizeof(server6)));

    socklen_t addrlen = sizeof(server6);
    ASSERT_EQ(0, getsockname(*serverSocket, (struct sockaddr *) &server6, &addrlen));
    ASSERT_EQ(0, listen(*serverSocket, 10));

    *clientSocket = socket(AF_INET6, SOCK_STREAM | SOCK_CLOEXEC, 0);
    struct sockaddr_in6 client6 = { .sin6_family = AF_INET6, .sin6_addr = sTun.srcAddr() };
    ASSERT_EQ(0, bind(*clientSocket, (struct sockaddr *) &client6, sizeof(client6)));
    ASSERT_EQ(0, connect(*clientSocket, (struct sockaddr *) &server6, sizeof(server6)));
    ASSERT_EQ(0, getsockname(*clientSocket, (struct sockaddr *) &client6, &addrlen));

    *acceptedSocket = accept4(*serverSocket, (struct sockaddr *) &server6, &addrlen, SOCK_CLOEXEC);
    ASSERT_NE(-1, *acceptedSocket);

    ASSERT_EQ(0, memcmp(&client6, &server6, sizeof(client6)));
}

void checkSocketpairOpen(int clientSocket, int acceptedSocket) {
    char buf[4096];
    EXPECT_EQ(4, write(clientSocket, "foo", sizeof("foo")));
    EXPECT_EQ(4, read(acceptedSocket, buf, sizeof(buf)));
    EXPECT_EQ(0, memcmp(buf, "foo", sizeof("foo")));
}

void checkSocketpairClosed(int clientSocket, int acceptedSocket) {
    // Check that the client socket was closed with ECONNABORTED.
    int ret = write(clientSocket, "foo", sizeof("foo"));
    int err = errno;
    EXPECT_EQ(-1, ret);
    EXPECT_EQ(ECONNABORTED, err);

    // Check that it sent a RST to the server.
    ret = write(acceptedSocket, "foo", sizeof("foo"));
    err = errno;
    EXPECT_EQ(-1, ret);
    EXPECT_EQ(ECONNRESET, err);
}

TEST_F(BinderTest, TestSocketDestroy) {
    int clientSocket, serverSocket, acceptedSocket;
    ASSERT_NO_FATAL_FAILURE(fakeRemoteSocketPair(&clientSocket, &serverSocket, &acceptedSocket));

    // Pick a random UID in the system UID range.
    constexpr int baseUid = AID_APP - 2000;
    static_assert(baseUid > 0, "Not enough UIDs? Please fix this test.");
    int uid = baseUid + 500 + arc4random_uniform(1000);
    EXPECT_EQ(0, fchown(clientSocket, uid, -1));

    // UID ranges that don't contain uid.
    std::vector<UidRange> uidRanges = {
        {baseUid + 42, baseUid + 449},
        {baseUid + 1536, AID_APP - 4},
        {baseUid + 498, uid - 1},
        {uid + 1, baseUid + 1520},
    };
    // A skip list that doesn't contain UID.
    std::vector<int32_t> skipUids { baseUid + 123, baseUid + 1600 };

    // Close sockets. Our test socket should be intact.
    EXPECT_TRUE(mNetd->socketDestroy(uidRanges, skipUids).isOk());
    checkSocketpairOpen(clientSocket, acceptedSocket);

    // UID ranges that do contain uid.
    uidRanges = {
        {baseUid + 42, baseUid + 449},
        {baseUid + 1536, AID_APP - 4},
        {baseUid + 498, baseUid + 1520},
    };
    // Add uid to the skip list.
    skipUids.push_back(uid);

    // Close sockets. Our test socket should still be intact because it's in the skip list.
    EXPECT_TRUE(mNetd->socketDestroy(uidRanges, skipUids).isOk());
    checkSocketpairOpen(clientSocket, acceptedSocket);

    // Now remove uid from skipUids, and close sockets. Our test socket should have been closed.
    skipUids.resize(skipUids.size() - 1);
    EXPECT_TRUE(mNetd->socketDestroy(uidRanges, skipUids).isOk());
    checkSocketpairClosed(clientSocket, acceptedSocket);

    close(clientSocket);
    close(serverSocket);
    close(acceptedSocket);
}

namespace {

int netmaskToPrefixLength(const uint8_t *buf, size_t buflen) {
    if (buf == nullptr) return -1;

    int prefixLength = 0;
    bool endOfContiguousBits = false;
    for (unsigned int i = 0; i < buflen; i++) {
        const uint8_t value = buf[i];

        // Bad bit sequence: check for a contiguous set of bits from the high
        // end by verifying that the inverted value + 1 is a power of 2
        // (power of 2 iff. (v & (v - 1)) == 0).
        const uint8_t inverse = ~value + 1;
        if ((inverse & (inverse - 1)) != 0) return -1;

        prefixLength += (value == 0) ? 0 : CHAR_BIT - ffs(value) + 1;

        // Bogus netmask.
        if (endOfContiguousBits && value != 0) return -1;

        if (value != 0xff) endOfContiguousBits = true;
    }

    return prefixLength;
}

template<typename T>
int netmaskToPrefixLength(const T *p) {
    return netmaskToPrefixLength(reinterpret_cast<const uint8_t*>(p), sizeof(T));
}


static bool interfaceHasAddress(
        const std::string &ifname, const char *addrString, int prefixLength) {
    struct addrinfo *addrinfoList = nullptr;
    ScopedAddrinfo addrinfoCleanup(addrinfoList);

    const struct addrinfo hints = {
        .ai_flags    = AI_NUMERICHOST,
        .ai_family   = AF_UNSPEC,
        .ai_socktype = SOCK_DGRAM,
    };
    if (getaddrinfo(addrString, nullptr, &hints, &addrinfoList) != 0 ||
        addrinfoList == nullptr || addrinfoList->ai_addr == nullptr) {
        return false;
    }

    struct ifaddrs *ifaddrsList = nullptr;
    ScopedIfaddrs ifaddrsCleanup(ifaddrsList);

    if (getifaddrs(&ifaddrsList) != 0) {
        return false;
    }

    for (struct ifaddrs *addr = ifaddrsList; addr != nullptr; addr = addr->ifa_next) {
        if (std::string(addr->ifa_name) != ifname ||
            addr->ifa_addr == nullptr ||
            addr->ifa_addr->sa_family != addrinfoList->ai_addr->sa_family) {
            continue;
        }

        switch (addr->ifa_addr->sa_family) {
        case AF_INET: {
            auto *addr4 = reinterpret_cast<const struct sockaddr_in*>(addr->ifa_addr);
            auto *want = reinterpret_cast<const struct sockaddr_in*>(addrinfoList->ai_addr);
            if (memcmp(&addr4->sin_addr, &want->sin_addr, sizeof(want->sin_addr)) != 0) {
                continue;
            }

            if (prefixLength < 0) return true;  // not checking prefix lengths

            if (addr->ifa_netmask == nullptr) return false;
            auto *nm = reinterpret_cast<const struct sockaddr_in*>(addr->ifa_netmask);
            EXPECT_EQ(prefixLength, netmaskToPrefixLength(&nm->sin_addr));
            return (prefixLength == netmaskToPrefixLength(&nm->sin_addr));
        }
        case AF_INET6: {
            auto *addr6 = reinterpret_cast<const struct sockaddr_in6*>(addr->ifa_addr);
            auto *want = reinterpret_cast<const struct sockaddr_in6*>(addrinfoList->ai_addr);
            if (memcmp(&addr6->sin6_addr, &want->sin6_addr, sizeof(want->sin6_addr)) != 0) {
                continue;
            }

            if (prefixLength < 0) return true;  // not checking prefix lengths

            if (addr->ifa_netmask == nullptr) return false;
            auto *nm = reinterpret_cast<const struct sockaddr_in6*>(addr->ifa_netmask);
            EXPECT_EQ(prefixLength, netmaskToPrefixLength(&nm->sin6_addr));
            return (prefixLength == netmaskToPrefixLength(&nm->sin6_addr));
        }
        default:
            // Cannot happen because we have already screened for matching
            // address families at the top of each iteration.
            continue;
        }
    }

    return false;
}

}  // namespace

TEST_F(BinderTest, TestInterfaceAddRemoveAddress) {
    static const struct TestData {
        const char *addrString;
        const int   prefixLength;
        const bool  expectSuccess;
    } kTestData[] = {
        { "192.0.2.1", 24, true },
        { "192.0.2.2", 25, true },
        { "192.0.2.3", 32, true },
        { "192.0.2.4", 33, false },
        { "192.not.an.ip", 24, false },
        { "2001:db8::1", 64, true },
        { "2001:db8::2", 65, true },
        { "2001:db8::3", 128, true },
        { "2001:db8::4", 129, false },
        { "foo:bar::bad", 64, false },
    };

    for (unsigned int i = 0; i < arraysize(kTestData); i++) {
        const auto &td = kTestData[i];

        // [1.a] Add the address.
        binder::Status status = mNetd->interfaceAddAddress(
                sTun.name(), td.addrString, td.prefixLength);
        if (td.expectSuccess) {
            EXPECT_TRUE(status.isOk()) << status.exceptionMessage();
        } else {
            ASSERT_EQ(binder::Status::EX_SERVICE_SPECIFIC, status.exceptionCode());
            ASSERT_NE(0, status.serviceSpecificErrorCode());
        }

        // [1.b] Verify the addition meets the expectation.
        if (td.expectSuccess) {
            EXPECT_TRUE(interfaceHasAddress(sTun.name(), td.addrString, td.prefixLength));
        } else {
            EXPECT_FALSE(interfaceHasAddress(sTun.name(), td.addrString, -1));
        }

        // [2.a] Try to remove the address.  If it was not previously added, removing it fails.
        status = mNetd->interfaceDelAddress(sTun.name(), td.addrString, td.prefixLength);
        if (td.expectSuccess) {
            EXPECT_TRUE(status.isOk()) << status.exceptionMessage();
        } else {
            ASSERT_EQ(binder::Status::EX_SERVICE_SPECIFIC, status.exceptionCode());
            ASSERT_NE(0, status.serviceSpecificErrorCode());
        }

        // [2.b] No matter what, the address should not be present.
        EXPECT_FALSE(interfaceHasAddress(sTun.name(), td.addrString, -1));
    }
}

TEST_F(BinderTest, TestSetProcSysNet) {
    static const struct TestData {
        const int family;
        const int which;
        const char *ifname;
        const char *parameter;
        const char *value;
        const int expectedReturnCode;
    } kTestData[] = {
        { INetd::IPV4, INetd::CONF, sTun.name().c_str(), "arp_ignore", "1", 0 },
        { -1, INetd::CONF, sTun.name().c_str(), "arp_ignore", "1", EAFNOSUPPORT },
        { INetd::IPV4, -1, sTun.name().c_str(), "arp_ignore", "1", EINVAL },
        { INetd::IPV4, INetd::CONF, "..", "conf/lo/arp_ignore", "1", EINVAL },
        { INetd::IPV4, INetd::CONF, ".", "lo/arp_ignore", "1", EINVAL },
        { INetd::IPV4, INetd::CONF, sTun.name().c_str(), "../all/arp_ignore", "1", EINVAL },
        { INetd::IPV6, INetd::NEIGH, sTun.name().c_str(), "ucast_solicit", "7", 0 },
    };

    for (unsigned int i = 0; i < arraysize(kTestData); i++) {
        const auto &td = kTestData[i];

        const binder::Status status = mNetd->setProcSysNet(
                    td.family, td.which, td.ifname, td.parameter,
                    td.value);

        if (td.expectedReturnCode == 0) {
            SCOPED_TRACE(String8::format("test case %d should have passed", i));
            EXPECT_EQ(0, status.exceptionCode());
            EXPECT_EQ(0, status.serviceSpecificErrorCode());
        } else {
            SCOPED_TRACE(String8::format("test case %d should have failed", i));
            EXPECT_EQ(binder::Status::EX_SERVICE_SPECIFIC, status.exceptionCode());
            EXPECT_EQ(td.expectedReturnCode, status.serviceSpecificErrorCode());
        }
    }
}

static std::string base64Encode(const std::vector<uint8_t>& input) {
    size_t out_len;
    EXPECT_EQ(1, EVP_EncodedLength(&out_len, input.size()));
    // out_len includes the trailing NULL.
    uint8_t output_bytes[out_len];
    EXPECT_EQ(out_len - 1, EVP_EncodeBlock(output_bytes, input.data(), input.size()));
    return std::string(reinterpret_cast<char*>(output_bytes));
}

TEST_F(BinderTest, TestSetResolverConfiguration_Tls) {
    const std::vector<std::string> LOCALLY_ASSIGNED_DNS{"8.8.8.8", "2001:4860:4860::8888"};
    std::vector<uint8_t> fp(SHA256_SIZE);
    std::vector<uint8_t> short_fp(1);
    std::vector<uint8_t> long_fp(SHA256_SIZE + 1);
    std::vector<std::string> test_domains;
    std::vector<int> test_params = { 300, 25, 8, 8 };
    unsigned test_netid = 0;
    static const struct TestData {
        const std::vector<std::string> servers;
        const std::string tlsName;
        const std::vector<std::vector<uint8_t>> tlsFingerprints;
        const int expectedReturnCode;
    } kTlsTestData[] = {
        { {"192.0.2.1"}, "", {}, 0 },
        { {"2001:db8::2"}, "host.name", {}, 0 },
        { {"192.0.2.3"}, "@@@@", { fp }, 0 },
        { {"2001:db8::4"}, "", { fp }, 0 },
        { {}, "", {}, 0 },
        { {""}, "", {}, EINVAL },
        { {"192.0.*.5"}, "", {}, EINVAL },
        { {"2001:dg8::6"}, "", {}, EINVAL },
        { {"2001:db8::c"}, "", { short_fp }, EINVAL },
        { {"192.0.2.12"}, "", { long_fp }, EINVAL },
        { {"2001:db8::e"}, "", { fp, fp, fp }, 0 },
        { {"192.0.2.14"}, "", { fp, short_fp }, EINVAL },
    };

    for (unsigned int i = 0; i < arraysize(kTlsTestData); i++) {
        const auto &td = kTlsTestData[i];

        std::vector<std::string> fingerprints;
        for (const auto& fingerprint : td.tlsFingerprints) {
            fingerprints.push_back(base64Encode(fingerprint));
        }
        binder::Status status = mNetd->setResolverConfiguration(
                test_netid, LOCALLY_ASSIGNED_DNS, test_domains, test_params,
                td.tlsName, td.servers, fingerprints);

        if (td.expectedReturnCode == 0) {
            SCOPED_TRACE(String8::format("test case %d should have passed", i));
            SCOPED_TRACE(status.toString8());
            EXPECT_EQ(0, status.exceptionCode());
        } else {
            SCOPED_TRACE(String8::format("test case %d should have failed", i));
            EXPECT_EQ(binder::Status::EX_SERVICE_SPECIFIC, status.exceptionCode());
            EXPECT_EQ(td.expectedReturnCode, status.serviceSpecificErrorCode());
        }
    }
    // Ensure TLS is disabled before the start of the next test.
    mNetd->setResolverConfiguration(
        test_netid, kTlsTestData[0].servers, test_domains, test_params,
        "", {}, {});
}

void expectNoTestCounterRules() {
    for (const auto& binary : { IPTABLES_PATH, IP6TABLES_PATH }) {
        std::string command = StringPrintf("%s -w -nvL tetherctrl_counters", binary);
        std::string allRules = Join(runCommand(command), "\n");
        EXPECT_EQ(std::string::npos, allRules.find("netdtest_"));
    }
}

void addTetherCounterValues(const char* path, const std::string& if1, const std::string& if2,
                            int byte, int pkt) {
    runCommand(StringPrintf("%s -w -A tetherctrl_counters -i %s -o %s -j RETURN -c %d %d",
                            path, if1.c_str(), if2.c_str(), pkt, byte));
}

void delTetherCounterValues(const char* path, const std::string& if1, const std::string& if2) {
    runCommand(StringPrintf("%s -w -D tetherctrl_counters -i %s -o %s -j RETURN",
                            path, if1.c_str(), if2.c_str()));
    runCommand(StringPrintf("%s -w -D tetherctrl_counters -i %s -o %s -j RETURN",
                            path, if2.c_str(), if1.c_str()));
}

TEST_F(BinderTest, TestTetherGetStats) {
    expectNoTestCounterRules();

    // TODO: fold this into more comprehensive tests once we have binder RPCs for enabling and
    // disabling tethering. We don't check the return value because these commands will fail if
    // tethering is already enabled.
    runCommand(StringPrintf("%s -w -N tetherctrl_counters", IPTABLES_PATH));
    runCommand(StringPrintf("%s -w -N tetherctrl_counters", IP6TABLES_PATH));

    std::string intIface1 = StringPrintf("netdtest_%u", arc4random_uniform(10000));
    std::string intIface2 = StringPrintf("netdtest_%u", arc4random_uniform(10000));
    std::string intIface3 = StringPrintf("netdtest_%u", arc4random_uniform(10000));
    std::string extIface1 = StringPrintf("netdtest_%u", arc4random_uniform(10000));
    std::string extIface2 = StringPrintf("netdtest_%u", arc4random_uniform(10000));

    addTetherCounterValues(IPTABLES_PATH,  intIface1, extIface1, 123, 111);
    addTetherCounterValues(IP6TABLES_PATH, intIface1, extIface1, 456,  10);
    addTetherCounterValues(IPTABLES_PATH,  extIface1, intIface1, 321, 222);
    addTetherCounterValues(IP6TABLES_PATH, extIface1, intIface1, 654,  20);
    // RX is from external to internal, and TX is from internal to external.
    // So rxBytes is 321 + 654  = 975, txBytes is 123 + 456 = 579, etc.
    std::vector<int64_t> expected1 = { 975, 242, 579, 121 };

    addTetherCounterValues(IPTABLES_PATH,  intIface2, extIface2, 1000, 333);
    addTetherCounterValues(IP6TABLES_PATH, intIface2, extIface2, 3000,  30);

    addTetherCounterValues(IPTABLES_PATH,  extIface2, intIface2, 2000, 444);
    addTetherCounterValues(IP6TABLES_PATH, extIface2, intIface2, 4000,  40);

    addTetherCounterValues(IP6TABLES_PATH, intIface3, extIface2, 1000,  25);
    addTetherCounterValues(IP6TABLES_PATH, extIface2, intIface3, 2000,  35);
    std::vector<int64_t> expected2 = { 8000, 519, 5000, 388 };

    PersistableBundle stats;
    binder::Status status = mNetd->tetherGetStats(&stats);
    EXPECT_TRUE(status.isOk()) << "Getting tethering stats failed: " << status;

    std::vector<int64_t> actual1;
    EXPECT_TRUE(stats.getLongVector(String16(extIface1.c_str()), &actual1));
    EXPECT_EQ(expected1, actual1);

    std::vector<int64_t> actual2;
    EXPECT_TRUE(stats.getLongVector(String16(extIface2.c_str()), &actual2));
    EXPECT_EQ(expected2, actual2);

    for (const auto& path : { IPTABLES_PATH, IP6TABLES_PATH }) {
        delTetherCounterValues(path, intIface1, extIface1);
        delTetherCounterValues(path, intIface2, extIface2);
        if (path == IP6TABLES_PATH) {
            delTetherCounterValues(path, intIface3, extIface2);
        }
    }

    expectNoTestCounterRules();
}