server/InterfaceController.cpp - platform/system/netd - Gitiles

 /*
  * Copyright (C) 2012 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.
  */

 #include <dirent.h>
 #include <errno.h>
 #include <malloc.h>
 #include <net/if.h>
 #include <net/if_arp.h>
 #include <sys/socket.h>

 #include <functional>

 #define LOG_TAG "InterfaceController"
 #include <android-base/file.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <linux/if_ether.h>
 #include <log/log.h>
 #include <netutils/ifc.h>

 #include <android/net/INetd.h>
 #include <netdutils/Misc.h>
 #include <netdutils/Slice.h>
 #include <netdutils/Syscalls.h>

 #include "InterfaceController.h"
 #include "RouteController.h"

 using android::base::ReadFileToString;
 using android::base::StringPrintf;
 using android::base::Trim;
 using android::base::WriteStringToFile;
 using android::net::INetd;
 using android::net::RouteController;
 using android::netdutils::isOk;
 using android::netdutils::makeSlice;
 using android::netdutils::sSyscalls;
 using android::netdutils::Status;
 using android::netdutils::statusFromErrno;
 using android::netdutils::StatusOr;
 using android::netdutils::toString;
 using android::netdutils::status::ok;

 namespace {

 const char ipv4_proc_path[] = "/proc/sys/net/ipv4/conf";
 const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";

 const char ipv4_neigh_conf_dir[] = "/proc/sys/net/ipv4/neigh";
 const char ipv6_neigh_conf_dir[] = "/proc/sys/net/ipv6/neigh";

 const char proc_net_path[] = "/proc/sys/net";
 const char sys_net_path[] = "/sys/class/net";

 constexpr int kRouteInfoMinPrefixLen = 48;

 // RFC 7421 prefix length.
 constexpr int kRouteInfoMaxPrefixLen = 64;

 // Property used to persist RFC 7217 stable secret. Protected by SELinux policy.
 const char kStableSecretProperty[] = "persist.netd.stable_secret";

 // RFC 7217 stable secret on linux is formatted as an IPv6 address.
 // This function uses 128 bits of high quality entropy to generate an
 // address for this purpose. This function should be not be called
 // frequently.
 StatusOr<std::string> randomIPv6Address() {
     in6_addr addr = {};
     const auto& sys = sSyscalls.get();
     ASSIGN_OR_RETURN(auto fd, sys.open("/dev/random", O_RDONLY));
     RETURN_IF_NOT_OK(sys.read(fd, makeSlice(addr)));
     return toString(addr);
 }

 inline bool isNormalPathComponent(const char *component) {
     return (strcmp(component, ".") != 0) &&
            (strcmp(component, "..") != 0) &&
            (strchr(component, '/') == nullptr);
 }

 inline bool isAddressFamilyPathComponent(const char *component) {
     return strcmp(component, "ipv4") == 0 || strcmp(component, "ipv6") == 0;
 }

 inline bool isInterfaceName(const char *name) {
     return isNormalPathComponent(name) &&
            (strcmp(name, "default") != 0) &&
            (strcmp(name, "all") != 0);
 }

 int writeValueToPath(
         const char* dirname, const char* subdirname, const char* basename,
         const char* value) {
     std::string path(StringPrintf("%s/%s/%s", dirname, subdirname, basename));
     return WriteStringToFile(value, path) ? 0 : -EREMOTEIO;
 }

 // Run @fn on each interface as well as 'default' in the path @dirname.
 void forEachInterface(
         const std::string& dirname,
         const std::function<void(const std::string& path, const std::string& iface)>& fn) {
     // Run on default, which controls the behavior of any interfaces that are created in the future.
     fn(dirname, "default");
     DIR* dir = opendir(dirname.c_str());
     if (!dir) {
         ALOGE("Can't list %s: %s", dirname.c_str(), strerror(errno));
         return;
     }
     while (true) {
         const dirent *ent = readdir(dir);
         if (!ent) {
             break;
         }
         if ((ent->d_type != DT_DIR) || !isInterfaceName(ent->d_name)) {
             continue;
         }
         fn(dirname, ent->d_name);
     }
     closedir(dir);
 }

 void setOnAllInterfaces(const char* dirname, const char* basename, const char* value) {
     auto fn = [basename, value](const std::string& path, const std::string& iface) {
         writeValueToPath(path.c_str(), iface.c_str(), basename, value);
     };
     forEachInterface(dirname, fn);
 }

 void setIPv6UseOutgoingInterfaceAddrsOnly(const char *value) {
     setOnAllInterfaces(ipv6_proc_path, "use_oif_addrs_only", value);
 }

 std::string getParameterPathname(
         const char *family, const char *which, const char *interface, const char *parameter) {
     if (!isAddressFamilyPathComponent(family)) {
         errno = EAFNOSUPPORT;
         return "";
     } else if (!isNormalPathComponent(which) ||
                !isInterfaceName(interface) ||
                !isNormalPathComponent(parameter)) {
         errno = EINVAL;
         return "";
     }

     return StringPrintf("%s/%s/%s/%s/%s", proc_net_path, family, which, interface, parameter);
 }

 void setAcceptIPv6RIO(int min, int max) {
     auto fn = [min, max](const std::string& prefix, const std::string& iface) {
         int rv = writeValueToPath(prefix.c_str(), iface.c_str(), "accept_ra_rt_info_min_plen",
                                   std::to_string(min).c_str());
         if (rv != 0) {
             // Only update max_plen if the write to min_plen succeeded. This ordering will prevent
             // RIOs from being accepted unless both min and max are written successfully.
             return;
         }
         writeValueToPath(prefix.c_str(), iface.c_str(), "accept_ra_rt_info_max_plen",
                          std::to_string(max).c_str());
     };
     forEachInterface(ipv6_proc_path, fn);
 }

 // Ideally this function would return StatusOr<std::string>, however
 // there is no safe value for dflt that will always differ from the
 // stored property. Bugs code could conceivably end up persisting the
 // reserved value resulting in surprising behavior.
 std::string getProperty(const std::string& key, const std::string& dflt) {
     return android::base::GetProperty(key, dflt);
 };

 Status setProperty(const std::string& key, const std::string& val) {
     // SetProperty does not dependably set errno to a meaningful value. Use our own error code so
     // callers don't get confused.
     return android::base::SetProperty(key, val)
         ? ok
         : statusFromErrno(EREMOTEIO, "SetProperty failed, see libc logs");
 };


 }  // namespace

 namespace android {
 namespace net {
 std::mutex InterfaceController::mutex;

 android::netdutils::Status InterfaceController::enableStablePrivacyAddresses(
         const std::string& iface,
         const GetPropertyFn& getProperty,
         const SetPropertyFn& setProperty) {
     const auto& sys = sSyscalls.get();
     const std::string procTarget = std::string(ipv6_proc_path) + "/" + iface + "/stable_secret";
     auto procFd = sys.open(procTarget, O_CLOEXEC | O_WRONLY);

     // Devices with old kernels (typically < 4.4) don't support
     // RFC 7217 stable privacy addresses.
     if (equalToErrno(procFd, ENOENT)) {
         return statusFromErrno(EOPNOTSUPP,
                                "Failed to open stable_secret. Assuming unsupported kernel version");
     }

     // If stable_secret exists but we can't open it, something strange is going on.
     RETURN_IF_NOT_OK(procFd);

     const char kUninitialized[] = "uninitialized";
     const auto oldSecret = getProperty(kStableSecretProperty, kUninitialized);
     std::string secret = oldSecret;

     // Generate a new secret if no persistent property existed.
     if (oldSecret == kUninitialized) {
         ASSIGN_OR_RETURN(secret, randomIPv6Address());
     }

     // Ask the OS to generate SLAAC addresses on iface using secret.
     RETURN_IF_NOT_OK(sys.write(procFd.value(), makeSlice(secret)));

     // Don't persist an existing secret.
     if (oldSecret != kUninitialized) {
         return ok;
     }

     return setProperty(kStableSecretProperty, secret);
 }

 void InterfaceController::initializeAll() {
     // Initial IPv6 settings.
     // By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
     // This causes RAs to work or not work based on whether forwarding is on, and causes routes
     // learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
     // by always setting accept_ra to 2.
     setAcceptRA("2");

     // Accept RIOs with prefix length in the closed interval [48, 64].
     setAcceptIPv6RIO(kRouteInfoMinPrefixLen, kRouteInfoMaxPrefixLen);

     setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);

     // Enable optimistic DAD for IPv6 addresses on all interfaces.
     setIPv6OptimisticMode("1");

     // Reduce the ARP/ND base reachable time from the default (30sec) to 15sec.
     setBaseReachableTimeMs(15 * 1000);

     // When sending traffic via a given interface use only addresses configured
     // on that interface as possible source addresses.
     setIPv6UseOutgoingInterfaceAddrsOnly("1");

     // Ensure that ICMP redirects are rejected globally on all interfaces.
     disableIcmpRedirects();
 }

 int InterfaceController::setEnableIPv6(const char *interface, const int on) {
     if (!isIfaceName(interface)) {
         return -ENOENT;
     }
     // When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
     // When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
     // addresses and routes and disables IPv6 on the interface.
     const char *disable_ipv6 = on ? "0" : "1";
     return writeValueToPath(ipv6_proc_path, interface, "disable_ipv6", disable_ipv6);
 }

 // Changes to addrGenMode will not fully take effect until the next
 // time disable_ipv6 transitions from 1 to 0.
 Status InterfaceController::setIPv6AddrGenMode(const std::string& interface, int mode) {
     if (!isIfaceName(interface)) {
         return statusFromErrno(ENOENT, "invalid iface name: " + interface);
     }

     switch (mode) {
         case INetd::IPV6_ADDR_GEN_MODE_EUI64:
             // Ignore return value. If /proc/.../addr_gen_mode is
             // missing we're probably in EUI64 mode already.
             writeValueToPath(ipv6_proc_path, interface.c_str(), "addr_gen_mode", "0");
             break;
         case INetd::IPV6_ADDR_GEN_MODE_STABLE_PRIVACY: {
             return enableStablePrivacyAddresses(interface, getProperty, setProperty);
         }
         case INetd::IPV6_ADDR_GEN_MODE_NONE:
         case INetd::IPV6_ADDR_GEN_MODE_RANDOM:
         default:
             return statusFromErrno(EOPNOTSUPP, "unsupported addrGenMode");
     }

     return ok;
 }

 int InterfaceController::setAcceptIPv6Ra(const char *interface, const int on) {
     if (!isIfaceName(interface)) {
         errno = ENOENT;
         return -1;
     }
     // Because forwarding can be enabled even when tethering is off, we always
     // use mode "2" (accept RAs, even if forwarding is enabled).
     const char *accept_ra = on ? "2" : "0";
     return writeValueToPath(ipv6_proc_path, interface, "accept_ra", accept_ra);
 }

 int InterfaceController::setAcceptIPv6Dad(const char *interface, const int on) {
     if (!isIfaceName(interface)) {
         errno = ENOENT;
         return -1;
     }
     const char *accept_dad = on ? "1" : "0";
     return writeValueToPath(ipv6_proc_path, interface, "accept_dad", accept_dad);
 }

 int InterfaceController::setIPv6DadTransmits(const char *interface, const char *value) {
     if (!isIfaceName(interface)) {
         errno = ENOENT;
         return -1;
     }
     return writeValueToPath(ipv6_proc_path, interface, "dad_transmits", value);
 }

 int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
     if (!isIfaceName(interface)) {
         errno = ENOENT;
         return -errno;
     }
     // 0: disable IPv6 privacy addresses
     // 2: enable IPv6 privacy addresses and prefer them over non-privacy ones.
     return writeValueToPath(ipv6_proc_path, interface, "use_tempaddr", on ? "2" : "0");
 }

 void InterfaceController::setAcceptRA(const char *value) {
     setOnAllInterfaces(ipv6_proc_path, "accept_ra", value);
 }

 // |tableOrOffset| is interpreted as:
 //     If == 0: default. Routes go into RT6_TABLE_MAIN.
 //     If > 0: user set. Routes go into the specified table.
 //     If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
 //             ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
 //             table 1005, etc.
 void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
     std::string value(StringPrintf("%d", tableOrOffset));
     setOnAllInterfaces(ipv6_proc_path, "accept_ra_rt_table", value.c_str());
 }

 int InterfaceController::setMtu(const char *interface, const char *mtu)
 {
     if (!isIfaceName(interface)) {
         errno = ENOENT;
         return -errno;
     }
     return writeValueToPath(sys_net_path, interface, "mtu", mtu);
 }

 // Returns zero on success and negative errno on failure.
 int InterfaceController::addAddress(const char *interface,
         const char *addrString, int prefixLength) {
     return ifc_add_address(interface, addrString, prefixLength);
 }

 // Returns zero on success and negative errno on failure.
 int InterfaceController::delAddress(const char *interface,
         const char *addrString, int prefixLength) {
     return ifc_del_address(interface, addrString, prefixLength);
 }

 int InterfaceController::disableIcmpRedirects() {
     int rv = 0;
     rv |= writeValueToPath(ipv4_proc_path, "all", "accept_redirects", "0");
     rv |= writeValueToPath(ipv6_proc_path, "all", "accept_redirects", "0");
     setOnAllInterfaces(ipv4_proc_path, "accept_redirects", "0");
     setOnAllInterfaces(ipv6_proc_path, "accept_redirects", "0");
     return rv;
 }

 int InterfaceController::getParameter(
         const char *family, const char *which, const char *interface, const char *parameter,
         std::string *value) {
     const std::string path(getParameterPathname(family, which, interface, parameter));
     if (path.empty()) {
         return -errno;
     }
     if (ReadFileToString(path, value)) {
         *value = Trim(*value);
         return 0;
     }
     return -errno;
 }

 int InterfaceController::setParameter(
         const char *family, const char *which, const char *interface, const char *parameter,
         const char *value) {
     const std::string path(getParameterPathname(family, which, interface, parameter));
     if (path.empty()) {
         return -errno;
     }
     return WriteStringToFile(value, path) ? 0 : -errno;
 }

 void InterfaceController::setBaseReachableTimeMs(unsigned int millis) {
     std::string value(StringPrintf("%u", millis));
     setOnAllInterfaces(ipv4_neigh_conf_dir, "base_reachable_time_ms", value.c_str());
     setOnAllInterfaces(ipv6_neigh_conf_dir, "base_reachable_time_ms", value.c_str());
 }

 void InterfaceController::setIPv6OptimisticMode(const char *value) {
     setOnAllInterfaces(ipv6_proc_path, "optimistic_dad", value);
     setOnAllInterfaces(ipv6_proc_path, "use_optimistic", value);
 }

 StatusOr<std::vector<std::string>> InterfaceController::getIfaceNames() {
     std::vector<std::string> ifaceNames;
     DIR* d;
     struct dirent* de;

     if (!(d = opendir("/sys/class/net"))) {
         return statusFromErrno(errno, "Cannot open iface directory");
     }
     while ((de = readdir(d))) {
         if ((de->d_type != DT_DIR) && (de->d_type != DT_LNK)) continue;
         if (de->d_name[0] == '.') continue;
         ifaceNames.push_back(std::string(de->d_name));
     }
     closedir(d);
     return ifaceNames;
 }

 StatusOr<std::map<std::string, uint32_t>> InterfaceController::getIfaceList() {
     std::map<std::string, uint32_t> ifacePairs;

     ASSIGN_OR_RETURN(auto ifaceNames, getIfaceNames());

     for (const auto& name : ifaceNames) {
         uint32_t ifaceIndex = if_nametoindex(name.c_str());
         if (ifaceIndex) {
             ifacePairs.insert(std::pair<std::string, uint32_t>(name, ifaceIndex));
         }
     }
     return ifacePairs;
 }

 namespace {

 std::string hwAddrToStr(unsigned char* hwaddr) {
     return StringPrintf("%02x:%02x:%02x:%02x:%02x:%02x", hwaddr[0], hwaddr[1], hwaddr[2], hwaddr[3],
                         hwaddr[4], hwaddr[5]);
 }

 int ipv4NetmaskToPrefixLength(in_addr_t mask) {
     int prefixLength = 0;
     uint32_t m = ntohl(mask);
     while (m & (1 << 31)) {
         prefixLength++;
         m = m << 1;
     }
     return prefixLength;
 }

 std::string toStdString(const String16& s) {
     return std::string(String8(s.string()));
 }

 }  // namespace

 Status InterfaceController::setCfg(const InterfaceConfigurationParcel& cfg) {
     const auto& sys = sSyscalls.get();
     ASSIGN_OR_RETURN(auto fd, sys.socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0));
     struct ifreq ifr = {
             .ifr_addr = {.sa_family = AF_INET},  // Clear the IPv4 address.
     };
     strlcpy(ifr.ifr_name, cfg.ifName.c_str(), IFNAMSIZ);

     // Make sure that clear IPv4 address before set flag
     // SIOCGIFFLAGS might override ifr and caused clear IPv4 addr ioctl error
     RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCSIFADDR, &ifr));

     if (!cfg.flags.empty()) {
         RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCGIFFLAGS, &ifr));
         uint16_t flags = ifr.ifr_flags;

         for (const auto& flag : cfg.flags) {
             if (flag == toStdString(INetd::IF_STATE_UP())) {
                 ifr.ifr_flags = ifr.ifr_flags | IFF_UP;
             } else if (flag == toStdString(INetd::IF_STATE_DOWN())) {
                 ifr.ifr_flags = (ifr.ifr_flags & (~IFF_UP));
             }
         }

         if (ifr.ifr_flags != flags) {
             RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCSIFFLAGS, &ifr));
         }
     }

     if (int ret = ifc_add_address(cfg.ifName.c_str(), cfg.ipv4Addr.c_str(), cfg.prefixLength)) {
         return statusFromErrno(-ret, "Failed to add addr");
     }

     return ok;
 }

 StatusOr<InterfaceConfigurationParcel> InterfaceController::getCfg(const std::string& ifName) {
     struct in_addr addr = {};
     int prefixLength = 0;
     unsigned char hwaddr[ETH_ALEN] = {};
     unsigned flags = 0;
     InterfaceConfigurationParcel cfgResult;

     const auto& sys = sSyscalls.get();
     ASSIGN_OR_RETURN(auto fd, sys.socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0));

     struct ifreq ifr = {};
     strlcpy(ifr.ifr_name, ifName.c_str(), IFNAMSIZ);

     if (isOk(sys.ioctl(fd, SIOCGIFADDR, &ifr))) {
         addr.s_addr = ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr;
     }

     if (isOk(sys.ioctl(fd, SIOCGIFNETMASK, &ifr))) {
         prefixLength =
                 ipv4NetmaskToPrefixLength(((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr);
     }

     if (isOk(sys.ioctl(fd, SIOCGIFFLAGS, &ifr))) {
         flags = ifr.ifr_flags;
     }

     // ETH_ALEN is for ARPHRD_ETHER, it is better to check the sa_family.
     // However, we keep old design for the consistency.
     if (isOk(sys.ioctl(fd, SIOCGIFHWADDR, &ifr))) {
         memcpy((void*) hwaddr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
     } else {
         ALOGW("Failed to retrieve HW addr for %s (%s)", ifName.c_str(), strerror(errno));
     }

     cfgResult.ifName = ifName;
     cfgResult.hwAddr = hwAddrToStr(hwaddr);
     cfgResult.ipv4Addr = std::string(inet_ntoa(addr));
     cfgResult.prefixLength = prefixLength;
     cfgResult.flags.push_back(flags & IFF_UP ? toStdString(INetd::IF_STATE_UP())
                                              : toStdString(INetd::IF_STATE_DOWN()));

     if (flags & IFF_BROADCAST) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_BROADCAST()));
     if (flags & IFF_LOOPBACK) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_LOOPBACK()));
     if (flags & IFF_POINTOPOINT)
         cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_POINTOPOINT()));
     if (flags & IFF_RUNNING) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_RUNNING()));
     if (flags & IFF_MULTICAST) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_MULTICAST()));

     return cfgResult;
 }

 int InterfaceController::clearAddrs(const std::string& ifName) {
     return ifc_clear_addresses(ifName.c_str());
 }

 }  // namespace net
 }  // namespace android
	/*
	* Copyright (C) 2012 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.
	*/

	#include <dirent.h>
	#include <errno.h>
	#include <malloc.h>
	#include <net/if.h>
	#include <net/if_arp.h>
	#include <sys/socket.h>

	#include <functional>

	#define LOG_TAG "InterfaceController"
	#include <android-base/file.h>
	#include <android-base/properties.h>
	#include <android-base/stringprintf.h>
	#include <android-base/strings.h>
	#include <linux/if_ether.h>
	#include <log/log.h>
	#include <netutils/ifc.h>

	#include <android/net/INetd.h>
	#include <netdutils/Misc.h>
	#include <netdutils/Slice.h>
	#include <netdutils/Syscalls.h>

	#include "InterfaceController.h"
	#include "RouteController.h"

	using android::base::ReadFileToString;
	using android::base::StringPrintf;
	using android::base::Trim;
	using android::base::WriteStringToFile;
	using android::net::INetd;
	using android::net::RouteController;
	using android::netdutils::isOk;
	using android::netdutils::makeSlice;
	using android::netdutils::sSyscalls;
	using android::netdutils::Status;
	using android::netdutils::statusFromErrno;
	using android::netdutils::StatusOr;
	using android::netdutils::toString;
	using android::netdutils::status::ok;

	namespace {

	const char ipv4_proc_path[] = "/proc/sys/net/ipv4/conf";
	const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";

	const char ipv4_neigh_conf_dir[] = "/proc/sys/net/ipv4/neigh";
	const char ipv6_neigh_conf_dir[] = "/proc/sys/net/ipv6/neigh";

	const char proc_net_path[] = "/proc/sys/net";
	const char sys_net_path[] = "/sys/class/net";

	constexpr int kRouteInfoMinPrefixLen = 48;

	// RFC 7421 prefix length.
	constexpr int kRouteInfoMaxPrefixLen = 64;

	// Property used to persist RFC 7217 stable secret. Protected by SELinux policy.
	const char kStableSecretProperty[] = "persist.netd.stable_secret";

	// RFC 7217 stable secret on linux is formatted as an IPv6 address.
	// This function uses 128 bits of high quality entropy to generate an
	// address for this purpose. This function should be not be called
	// frequently.
	StatusOr<std::string> randomIPv6Address() {
	in6_addr addr = {};
	const auto& sys = sSyscalls.get();
	ASSIGN_OR_RETURN(auto fd, sys.open("/dev/random", O_RDONLY));
	RETURN_IF_NOT_OK(sys.read(fd, makeSlice(addr)));
	return toString(addr);
	}

	inline bool isNormalPathComponent(const char *component) {
	return (strcmp(component, ".") != 0) &&
	(strcmp(component, "..") != 0) &&
	(strchr(component, '/') == nullptr);
	}

	inline bool isAddressFamilyPathComponent(const char *component) {
	return strcmp(component, "ipv4") == 0 \|\| strcmp(component, "ipv6") == 0;
	}

	inline bool isInterfaceName(const char *name) {
	return isNormalPathComponent(name) &&
	(strcmp(name, "default") != 0) &&
	(strcmp(name, "all") != 0);
	}

	int writeValueToPath(
	const char* dirname, const char* subdirname, const char* basename,
	const char* value) {
	std::string path(StringPrintf("%s/%s/%s", dirname, subdirname, basename));
	return WriteStringToFile(value, path) ? 0 : -EREMOTEIO;
	}

	// Run @fn on each interface as well as 'default' in the path @dirname.
	void forEachInterface(
	const std::string& dirname,
	const std::function<void(const std::string& path, const std::string& iface)>& fn) {
	// Run on default, which controls the behavior of any interfaces that are created in the future.
	fn(dirname, "default");
	DIR* dir = opendir(dirname.c_str());
	if (!dir) {
	ALOGE("Can't list %s: %s", dirname.c_str(), strerror(errno));
	return;
	}
	while (true) {
	const dirent *ent = readdir(dir);
	if (!ent) {
	break;
	}
	if ((ent->d_type != DT_DIR) \|\| !isInterfaceName(ent->d_name)) {
	continue;
	}
	fn(dirname, ent->d_name);
	}
	closedir(dir);
	}

	void setOnAllInterfaces(const char* dirname, const char* basename, const char* value) {
	auto fn = [basename, value](const std::string& path, const std::string& iface) {
	writeValueToPath(path.c_str(), iface.c_str(), basename, value);
	};
	forEachInterface(dirname, fn);
	}

	void setIPv6UseOutgoingInterfaceAddrsOnly(const char *value) {
	setOnAllInterfaces(ipv6_proc_path, "use_oif_addrs_only", value);
	}

	std::string getParameterPathname(
	const char family, const char which, const char interface, const char parameter) {
	if (!isAddressFamilyPathComponent(family)) {
	errno = EAFNOSUPPORT;
	return "";
	} else if (!isNormalPathComponent(which) \|\|
	!isInterfaceName(interface) \|\|
	!isNormalPathComponent(parameter)) {
	errno = EINVAL;
	return "";
	}

	return StringPrintf("%s/%s/%s/%s/%s", proc_net_path, family, which, interface, parameter);
	}

	void setAcceptIPv6RIO(int min, int max) {
	auto fn = [min, max](const std::string& prefix, const std::string& iface) {
	int rv = writeValueToPath(prefix.c_str(), iface.c_str(), "accept_ra_rt_info_min_plen",
	std::to_string(min).c_str());
	if (rv != 0) {
	// Only update max_plen if the write to min_plen succeeded. This ordering will prevent
	// RIOs from being accepted unless both min and max are written successfully.
	return;
	}
	writeValueToPath(prefix.c_str(), iface.c_str(), "accept_ra_rt_info_max_plen",
	std::to_string(max).c_str());
	};
	forEachInterface(ipv6_proc_path, fn);
	}

	// Ideally this function would return StatusOr<std::string>, however
	// there is no safe value for dflt that will always differ from the
	// stored property. Bugs code could conceivably end up persisting the
	// reserved value resulting in surprising behavior.
	std::string getProperty(const std::string& key, const std::string& dflt) {
	return android::base::GetProperty(key, dflt);
	};

	Status setProperty(const std::string& key, const std::string& val) {
	// SetProperty does not dependably set errno to a meaningful value. Use our own error code so
	// callers don't get confused.
	return android::base::SetProperty(key, val)
	? ok
	: statusFromErrno(EREMOTEIO, "SetProperty failed, see libc logs");
	};


	} // namespace

	namespace android {
	namespace net {
	std::mutex InterfaceController::mutex;

	android::netdutils::Status InterfaceController::enableStablePrivacyAddresses(
	const std::string& iface,
	const GetPropertyFn& getProperty,
	const SetPropertyFn& setProperty) {
	const auto& sys = sSyscalls.get();
	const std::string procTarget = std::string(ipv6_proc_path) + "/" + iface + "/stable_secret";
	auto procFd = sys.open(procTarget, O_CLOEXEC \| O_WRONLY);

	// Devices with old kernels (typically < 4.4) don't support
	// RFC 7217 stable privacy addresses.
	if (equalToErrno(procFd, ENOENT)) {
	return statusFromErrno(EOPNOTSUPP,
	"Failed to open stable_secret. Assuming unsupported kernel version");
	}

	// If stable_secret exists but we can't open it, something strange is going on.
	RETURN_IF_NOT_OK(procFd);

	const char kUninitialized[] = "uninitialized";
	const auto oldSecret = getProperty(kStableSecretProperty, kUninitialized);
	std::string secret = oldSecret;

	// Generate a new secret if no persistent property existed.
	if (oldSecret == kUninitialized) {
	ASSIGN_OR_RETURN(secret, randomIPv6Address());
	}

	// Ask the OS to generate SLAAC addresses on iface using secret.
	RETURN_IF_NOT_OK(sys.write(procFd.value(), makeSlice(secret)));

	// Don't persist an existing secret.
	if (oldSecret != kUninitialized) {
	return ok;
	}

	return setProperty(kStableSecretProperty, secret);
	}

	void InterfaceController::initializeAll() {
	// Initial IPv6 settings.
	// By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
	// This causes RAs to work or not work based on whether forwarding is on, and causes routes
	// learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
	// by always setting accept_ra to 2.
	setAcceptRA("2");

	// Accept RIOs with prefix length in the closed interval [48, 64].
	setAcceptIPv6RIO(kRouteInfoMinPrefixLen, kRouteInfoMaxPrefixLen);

	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);

	// Enable optimistic DAD for IPv6 addresses on all interfaces.
	setIPv6OptimisticMode("1");

	// Reduce the ARP/ND base reachable time from the default (30sec) to 15sec.
	setBaseReachableTimeMs(15 * 1000);

	// When sending traffic via a given interface use only addresses configured
	// on that interface as possible source addresses.
	setIPv6UseOutgoingInterfaceAddrsOnly("1");

	// Ensure that ICMP redirects are rejected globally on all interfaces.
	disableIcmpRedirects();
	}

	int InterfaceController::setEnableIPv6(const char *interface, const int on) {
	if (!isIfaceName(interface)) {
	return -ENOENT;
	}
	// When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
	// When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
	// addresses and routes and disables IPv6 on the interface.
	const char *disable_ipv6 = on ? "0" : "1";
	return writeValueToPath(ipv6_proc_path, interface, "disable_ipv6", disable_ipv6);
	}

	// Changes to addrGenMode will not fully take effect until the next
	// time disable_ipv6 transitions from 1 to 0.
	Status InterfaceController::setIPv6AddrGenMode(const std::string& interface, int mode) {
	if (!isIfaceName(interface)) {
	return statusFromErrno(ENOENT, "invalid iface name: " + interface);
	}

	switch (mode) {
	case INetd::IPV6_ADDR_GEN_MODE_EUI64:
	// Ignore return value. If /proc/.../addr_gen_mode is
	// missing we're probably in EUI64 mode already.
	writeValueToPath(ipv6_proc_path, interface.c_str(), "addr_gen_mode", "0");
	break;
	case INetd::IPV6_ADDR_GEN_MODE_STABLE_PRIVACY: {
	return enableStablePrivacyAddresses(interface, getProperty, setProperty);
	}
	case INetd::IPV6_ADDR_GEN_MODE_NONE:
	case INetd::IPV6_ADDR_GEN_MODE_RANDOM:
	default:
	return statusFromErrno(EOPNOTSUPP, "unsupported addrGenMode");
	}

	return ok;
	}

	int InterfaceController::setAcceptIPv6Ra(const char *interface, const int on) {
	if (!isIfaceName(interface)) {
	errno = ENOENT;
	return -1;
	}
	// Because forwarding can be enabled even when tethering is off, we always
	// use mode "2" (accept RAs, even if forwarding is enabled).
	const char *accept_ra = on ? "2" : "0";
	return writeValueToPath(ipv6_proc_path, interface, "accept_ra", accept_ra);
	}

	int InterfaceController::setAcceptIPv6Dad(const char *interface, const int on) {
	if (!isIfaceName(interface)) {
	errno = ENOENT;
	return -1;
	}
	const char *accept_dad = on ? "1" : "0";
	return writeValueToPath(ipv6_proc_path, interface, "accept_dad", accept_dad);
	}

	int InterfaceController::setIPv6DadTransmits(const char interface, const char value) {
	if (!isIfaceName(interface)) {
	errno = ENOENT;
	return -1;
	}
	return writeValueToPath(ipv6_proc_path, interface, "dad_transmits", value);
	}

	int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
	if (!isIfaceName(interface)) {
	errno = ENOENT;
	return -errno;
	}
	// 0: disable IPv6 privacy addresses
	// 2: enable IPv6 privacy addresses and prefer them over non-privacy ones.
	return writeValueToPath(ipv6_proc_path, interface, "use_tempaddr", on ? "2" : "0");
	}

	void InterfaceController::setAcceptRA(const char *value) {
	setOnAllInterfaces(ipv6_proc_path, "accept_ra", value);
	}

	// \|tableOrOffset\| is interpreted as:
	// If == 0: default. Routes go into RT6_TABLE_MAIN.
	// If > 0: user set. Routes go into the specified table.
	// If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
	// ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
	// table 1005, etc.
	void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
	std::string value(StringPrintf("%d", tableOrOffset));
	setOnAllInterfaces(ipv6_proc_path, "accept_ra_rt_table", value.c_str());
	}

	int InterfaceController::setMtu(const char interface, const char mtu)
	{
	if (!isIfaceName(interface)) {
	errno = ENOENT;
	return -errno;
	}
	return writeValueToPath(sys_net_path, interface, "mtu", mtu);
	}

	// Returns zero on success and negative errno on failure.
	int InterfaceController::addAddress(const char *interface,
	const char *addrString, int prefixLength) {
	return ifc_add_address(interface, addrString, prefixLength);
	}

	// Returns zero on success and negative errno on failure.
	int InterfaceController::delAddress(const char *interface,
	const char *addrString, int prefixLength) {
	return ifc_del_address(interface, addrString, prefixLength);
	}

	int InterfaceController::disableIcmpRedirects() {
	int rv = 0;
	rv \|= writeValueToPath(ipv4_proc_path, "all", "accept_redirects", "0");
	rv \|= writeValueToPath(ipv6_proc_path, "all", "accept_redirects", "0");
	setOnAllInterfaces(ipv4_proc_path, "accept_redirects", "0");
	setOnAllInterfaces(ipv6_proc_path, "accept_redirects", "0");
	return rv;
	}

	int InterfaceController::getParameter(
	const char family, const char which, const char interface, const char parameter,
	std::string *value) {
	const std::string path(getParameterPathname(family, which, interface, parameter));
	if (path.empty()) {
	return -errno;
	}
	if (ReadFileToString(path, value)) {
	value = Trim(value);
	return 0;
	}
	return -errno;
	}

	int InterfaceController::setParameter(
	const char family, const char which, const char interface, const char parameter,
	const char *value) {
	const std::string path(getParameterPathname(family, which, interface, parameter));
	if (path.empty()) {
	return -errno;
	}
	return WriteStringToFile(value, path) ? 0 : -errno;
	}

	void InterfaceController::setBaseReachableTimeMs(unsigned int millis) {
	std::string value(StringPrintf("%u", millis));
	setOnAllInterfaces(ipv4_neigh_conf_dir, "base_reachable_time_ms", value.c_str());
	setOnAllInterfaces(ipv6_neigh_conf_dir, "base_reachable_time_ms", value.c_str());
	}

	void InterfaceController::setIPv6OptimisticMode(const char *value) {
	setOnAllInterfaces(ipv6_proc_path, "optimistic_dad", value);
	setOnAllInterfaces(ipv6_proc_path, "use_optimistic", value);
	}

	StatusOr<std::vector<std::string>> InterfaceController::getIfaceNames() {
	std::vector<std::string> ifaceNames;
	DIR* d;
	struct dirent* de;

	if (!(d = opendir("/sys/class/net"))) {
	return statusFromErrno(errno, "Cannot open iface directory");
	}
	while ((de = readdir(d))) {
	if ((de->d_type != DT_DIR) && (de->d_type != DT_LNK)) continue;
	if (de->d_name[0] == '.') continue;
	ifaceNames.push_back(std::string(de->d_name));
	}
	closedir(d);
	return ifaceNames;
	}

	StatusOr<std::map<std::string, uint32_t>> InterfaceController::getIfaceList() {
	std::map<std::string, uint32_t> ifacePairs;

	ASSIGN_OR_RETURN(auto ifaceNames, getIfaceNames());

	for (const auto& name : ifaceNames) {
	uint32_t ifaceIndex = if_nametoindex(name.c_str());
	if (ifaceIndex) {
	ifacePairs.insert(std::pair<std::string, uint32_t>(name, ifaceIndex));
	}
	}
	return ifacePairs;
	}

	namespace {

	std::string hwAddrToStr(unsigned char* hwaddr) {
	return StringPrintf("%02x:%02x:%02x:%02x:%02x:%02x", hwaddr[0], hwaddr[1], hwaddr[2], hwaddr[3],
	hwaddr[4], hwaddr[5]);
	}

	int ipv4NetmaskToPrefixLength(in_addr_t mask) {
	int prefixLength = 0;
	uint32_t m = ntohl(mask);
	while (m & (1 << 31)) {
	prefixLength++;
	m = m << 1;
	}
	return prefixLength;
	}

	std::string toStdString(const String16& s) {
	return std::string(String8(s.string()));
	}

	} // namespace

	Status InterfaceController::setCfg(const InterfaceConfigurationParcel& cfg) {
	const auto& sys = sSyscalls.get();
	ASSIGN_OR_RETURN(auto fd, sys.socket(AF_INET, SOCK_DGRAM \| SOCK_CLOEXEC, 0));
	struct ifreq ifr = {
	.ifr_addr = {.sa_family = AF_INET}, // Clear the IPv4 address.
	};
	strlcpy(ifr.ifr_name, cfg.ifName.c_str(), IFNAMSIZ);

	// Make sure that clear IPv4 address before set flag
	// SIOCGIFFLAGS might override ifr and caused clear IPv4 addr ioctl error
	RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCSIFADDR, &ifr));

	if (!cfg.flags.empty()) {
	RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCGIFFLAGS, &ifr));
	uint16_t flags = ifr.ifr_flags;

	for (const auto& flag : cfg.flags) {
	if (flag == toStdString(INetd::IF_STATE_UP())) {
	ifr.ifr_flags = ifr.ifr_flags \| IFF_UP;
	} else if (flag == toStdString(INetd::IF_STATE_DOWN())) {
	ifr.ifr_flags = (ifr.ifr_flags & (~IFF_UP));
	}
	}

	if (ifr.ifr_flags != flags) {
	RETURN_IF_NOT_OK(sys.ioctl(fd, SIOCSIFFLAGS, &ifr));
	}
	}

	if (int ret = ifc_add_address(cfg.ifName.c_str(), cfg.ipv4Addr.c_str(), cfg.prefixLength)) {
	return statusFromErrno(-ret, "Failed to add addr");
	}

	return ok;
	}

	StatusOr<InterfaceConfigurationParcel> InterfaceController::getCfg(const std::string& ifName) {
	struct in_addr addr = {};
	int prefixLength = 0;
	unsigned char hwaddr[ETH_ALEN] = {};
	unsigned flags = 0;
	InterfaceConfigurationParcel cfgResult;

	const auto& sys = sSyscalls.get();
	ASSIGN_OR_RETURN(auto fd, sys.socket(AF_INET, SOCK_DGRAM \| SOCK_CLOEXEC, 0));

	struct ifreq ifr = {};
	strlcpy(ifr.ifr_name, ifName.c_str(), IFNAMSIZ);

	if (isOk(sys.ioctl(fd, SIOCGIFADDR, &ifr))) {
	addr.s_addr = ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr;
	}

	if (isOk(sys.ioctl(fd, SIOCGIFNETMASK, &ifr))) {
	prefixLength =
	ipv4NetmaskToPrefixLength(((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr);
	}

	if (isOk(sys.ioctl(fd, SIOCGIFFLAGS, &ifr))) {
	flags = ifr.ifr_flags;
	}

	// ETH_ALEN is for ARPHRD_ETHER, it is better to check the sa_family.
	// However, we keep old design for the consistency.
	if (isOk(sys.ioctl(fd, SIOCGIFHWADDR, &ifr))) {
	memcpy((void*) hwaddr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
	} else {
	ALOGW("Failed to retrieve HW addr for %s (%s)", ifName.c_str(), strerror(errno));
	}

	cfgResult.ifName = ifName;
	cfgResult.hwAddr = hwAddrToStr(hwaddr);
	cfgResult.ipv4Addr = std::string(inet_ntoa(addr));
	cfgResult.prefixLength = prefixLength;
	cfgResult.flags.push_back(flags & IFF_UP ? toStdString(INetd::IF_STATE_UP())
	: toStdString(INetd::IF_STATE_DOWN()));

	if (flags & IFF_BROADCAST) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_BROADCAST()));
	if (flags & IFF_LOOPBACK) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_LOOPBACK()));
	if (flags & IFF_POINTOPOINT)
	cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_POINTOPOINT()));
	if (flags & IFF_RUNNING) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_RUNNING()));
	if (flags & IFF_MULTICAST) cfgResult.flags.push_back(toStdString(INetd::IF_FLAG_MULTICAST()));

	return cfgResult;
	}

	int InterfaceController::clearAddrs(const std::string& ifName) {
	return ifc_clear_addresses(ifName.c_str());
	}

	} // namespace net
	} // namespace android