[posix] add otSysSetInfraNetif API (openthread#9528)

This commit adds a new API `otSysSetInfraNetif` to support specifying
the infrastructure network interface for the platform. This can be
useful in following cases:
- The infra link cannot be determined at the start up of
  `otbr-agent`. We can call this API to specify the infra link without
  specifying it in the command line arguments.
- Let Thread Border Router switch to another infra link without
  restarting the whole OpenThread stack.

src/core/border_router/infra_if.cpp

@@ -60,7 +60,6 @@ Error InfraIf::Init(uint32_t aIfIndex)
  Error error = kErrorNone;
 
  VerifyOrExit(!mInitialized, error = kErrorInvalidState);
- VerifyOrExit(aIfIndex > 0, error = kErrorInvalidArgs);
 
  mIfIndex = aIfIndex;
  mInitialized = true;

src/lib/platform/exit_code.h

@@ -82,6 +82,12 @@ enum
  * No response from radio spinel.
  */
  OT_EXIT_RADIO_SPINEL_NO_RESPONSE = 6,
+
+ /**
+ * Invalid state.
+ */
+ OT_EXIT_INVALID_STATE = 7,
+
 };
 
 /**

src/posix/platform/include/openthread/openthread-system.h

@@ -226,6 +226,18 @@ typedef struct otSysInfraNetIfAddressCounters
  */
 void otSysCountInfraNetifAddresses(otSysInfraNetIfAddressCounters *aAddressCounters);
 
+/**
+ * Sets the infrastructure network interface and the ICMPv6 socket.
+ *
+ * This function specifies the network interface name and the ICMPv6 socket on that interface. After calling this
+ * function, the caller can call otBorderRoutingInit() to let Border Routing work on that interface.
+ *
+ * @param[in] aInfraNetifName The name of the infrastructure network interface.
+ * @param[in] aIcmp6Socket A SOCK_RAW socket running on the infrastructure network interface.
+ *
+ */
+void otSysSetInfraNetif(const char *aInfraNetifName, int aIcmp6Socket);
+
 #ifdef __cplusplus
 } // end of extern "C"
 #endif

src/posix/platform/infra_if.cpp

@@ -123,9 +123,8 @@ void otSysCountInfraNetifAddresses(otSysInfraNetIfAddressCounters *aAddressCount
 
 namespace ot {
 namespace Posix {
-namespace {
 
-int CreateIcmp6Socket(void)
+int InfraNetif::CreateIcmp6Socket(const char *aInfraIfName)
 {
  int sock;
  int rval;
@@ -168,6 +167,13 @@ int CreateIcmp6Socket(void)
  rval = setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &kHopLimit, sizeof(kHopLimit));
  VerifyOrDie(rval == 0, OT_EXIT_ERROR_ERRNO);
 
+#ifdef __linux__
+ rval = setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, aInfraIfName, strlen(aInfraIfName));
+#else // __NetBSD__ || __FreeBSD__ || __APPLE__
+ rval = setsockopt(mInfraIfIcmp6Socket, IPPROTO_IPV6, IPV6_BOUND_IF, &mInfraIfIndex, sizeof(mInfraIfIndex));
+#endif // __linux__
+ VerifyOrDie(rval == 0, OT_EXIT_ERROR_ERRNO);
+
  return sock;
 }
 
@@ -200,8 +206,6 @@ int CreateNetLinkSocket(void)
  return sock;
 }
 
-} // namespace
-
 otError InfraNetif::SendIcmp6Nd(uint32_t aInfraIfIndex,
  const otIp6Address &aDestAddress,
  const uint8_t *aBuffer,
@@ -276,7 +280,10 @@ otError InfraNetif::SendIcmp6Nd(uint32_t aInfraIfIndex,
  return error;
 }
 
-bool InfraNetif::IsRunning(void) const { return (GetFlags() & IFF_RUNNING) && HasLinkLocalAddress(); }
+bool InfraNetif::IsRunning(void) const
+{
+ return mInfraIfIndex ? ((GetFlags() & IFF_RUNNING) && HasLinkLocalAddress()) : false;
+}
 
 uint32_t InfraNetif::GetFlags(void) const
 {
@@ -368,10 +375,18 @@ bool InfraNetif::HasLinkLocalAddress(void) const
  return hasLla;
 }
 
-void InfraNetif::Init(const char *aIfName)
+void InfraNetif::Init(void) { mNetLinkSocket = CreateNetLinkSocket(); }
+
+void InfraNetif::SetInfraNetif(const char *aIfName, int aIcmp6Socket)
 {
- ssize_t rval;
- uint32_t ifIndex = 0;
+ uint32_t ifIndex = 0;
+ otBorderRoutingState state = otBorderRoutingGetState(gInstance);
+
+ OT_ASSERT(gInstance != nullptr);
+
+ VerifyOrDie(mNetLinkSocket != -1, OT_EXIT_INVALID_STATE);
+ VerifyOrDie(state == OT_BORDER_ROUTING_STATE_UNINITIALIZED || state == OT_BORDER_ROUTING_STATE_DISABLED,
+ OT_EXIT_INVALID_STATE);
 
  if (aIfName == nullptr || aIfName[0] == '\0')
  {
@@ -389,17 +404,14 @@ void InfraNetif::Init(const char *aIfName)
  otLogCritPlat("Failed to get the index for infra interface %s", aIfName);
  DieNow(OT_EXIT_INVALID_ARGUMENTS);
  }
- mInfraIfIndex = ifIndex;
 
- mInfraIfIcmp6Socket = CreateIcmp6Socket();
-#ifdef __linux__
- rval = setsockopt(mInfraIfIcmp6Socket, SOL_SOCKET, SO_BINDTODEVICE, mInfraIfName, strlen(mInfraIfName));
-#else // __NetBSD__ || __FreeBSD__ || __APPLE__
- rval = setsockopt(mInfraIfIcmp6Socket, IPPROTO_IPV6, IPV6_BOUND_IF, &mInfraIfIndex, sizeof(mInfraIfIndex));
-#endif // __linux__
- VerifyOrDie(rval == 0, OT_EXIT_ERROR_ERRNO);
+ mInfraIfIndex = ifIndex;
 
- mNetLinkSocket = CreateNetLinkSocket();
+ if (mInfraIfIcmp6Socket != -1)
+ {
+ close(mInfraIfIcmp6Socket);
+ }
+ mInfraIfIcmp6Socket = aIcmp6Socket;
 
 exit:
  return;
@@ -408,7 +420,7 @@ void InfraNetif::Init(const char *aIfName)
 void InfraNetif::SetUp(void)
 {
  OT_ASSERT(gInstance != nullptr);
- VerifyOrExit(mInfraIfIndex != 0);
+ VerifyOrExit(mNetLinkSocket != -1);
 
  SuccessOrDie(otBorderRoutingInit(gInstance, mInfraIfIndex, platformInfraIfIsRunning()));
  SuccessOrDie(otBorderRoutingSetEnabled(gInstance, /* aEnabled */ true));
@@ -419,12 +431,8 @@ void InfraNetif::SetUp(void)
 
 void InfraNetif::TearDown(void)
 {
- VerifyOrExit(mInfraIfIndex != 0);
-
+ IgnoreError(otBorderRoutingSetEnabled(gInstance, false));
  Mainloop::Manager::Get().Remove(*this);
-
-exit:
- return;
 }
 
 void InfraNetif::Deinit(void)

src/posix/platform/infra_if.hpp

@@ -71,12 +71,21 @@ class InfraNetif : public Mainloop::Source, private NonCopyable
  /**
  * Initializes the infrastructure network interface.
  *
+ * To specify the infrastructure network interface, you need to call SetInfraNetif() after Init().
+ *
  * @note This method is called before OpenThread instance is created.
  *
- * @param[in] aIfName A pointer to infrastructure network interface name.
+ */
+ void Init(void);
+
+ /**
+ * Sets the infrastructure network interface.
+ *
+ * @param[in] aIfName A pointer to infrastructure network interface name.
+ * @param[in] aIcmp6Socket A SOCK_RAW socket for sending/receiving ICMPv6 messages.
  *
  */
- void Init(const char *aIfName);
+ void SetInfraNetif(const char *aIfName, int aIcmp6Socket);
 
  /**
  * Sets up the infrastructure network interface.
@@ -175,6 +184,16 @@ class InfraNetif : public Mainloop::Source, private NonCopyable
  */
  static InfraNetif &Get(void);
 
+ /**
+ * Creates a socket for sending/receiving ICMPv6 messages.
+ *
+ * @param[in] aInfraIfName The infrastructure network interface name.
+ *
+ * @returns The file descriptor of the socket.
+ *
+ */
+ static int CreateIcmp6Socket(const char *aInfraIfName);
+
 private:
  static const char kWellKnownIpv4OnlyName[]; // "ipv4only.arpa"
  static const otIp4Address kWellKnownIpv4OnlyAddress1; // 192.0.0.170

src/posix/platform/system.cpp

@@ -121,6 +121,13 @@ static const char *getTrelRadioUrl(otPlatformConfig *aPlatformConfig)
 }
 #endif
 
+#if OPENTHREAD_POSIX_CONFIG_INFRA_IF_ENABLE
+void otSysSetInfraNetif(const char *aInfraNetifName, int aIcmp6Socket)
+{
+ ot::Posix::InfraNetif::Get().SetInfraNetif(aInfraNetifName, aIcmp6Socket);
+}
+#endif
+
 void platformInit(otPlatformConfig *aPlatformConfig)
 {
 #if OPENTHREAD_POSIX_CONFIG_BACKTRACE_ENABLE
@@ -143,7 +150,8 @@ void platformInit(otPlatformConfig *aPlatformConfig)
 #endif
 
 #if OPENTHREAD_POSIX_CONFIG_INFRA_IF_ENABLE
- ot::Posix::InfraNetif::Get().Init(aPlatformConfig->mBackboneInterfaceName);
+ ot::Posix::InfraNetif::Get().Init();
+
 #endif
 
  gNetifName[0] = '\0';
@@ -164,15 +172,22 @@ void platformInit(otPlatformConfig *aPlatformConfig)
  return;
 }
 
-void platformSetUp(void)
+void platformSetUp(otPlatformConfig *aPlatformConfig)
 {
+ OT_UNUSED_VARIABLE(aPlatformConfig);
+
  VerifyOrExit(!gDryRun);
 
 #if OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
  platformBackboneSetUp();
 #endif
 
 #if OPENTHREAD_POSIX_CONFIG_INFRA_IF_ENABLE
+ if (aPlatformConfig->mBackboneInterfaceName != nullptr && strlen(aPlatformConfig->mBackboneInterfaceName) > 0)
+ {
+ otSysSetInfraNetif(aPlatformConfig->mBackboneInterfaceName,
+ ot::Posix::InfraNetif::CreateIcmp6Socket(aPlatformConfig->mBackboneInterfaceName));
+ }
  ot::Posix::InfraNetif::Get().SetUp();
 #endif
 
@@ -206,7 +221,7 @@ otInstance *otSysInit(otPlatformConfig *aPlatformConfig)
  gInstance = otInstanceInitSingle();
  OT_ASSERT(gInstance != nullptr);
 
- platformSetUp();
+ platformSetUp(aPlatformConfig);
 
  return gInstance;
 }