From 086be076ee66411f21b5004696f452309479b13e Mon Sep 17 00:00:00 2001
From: Yakun Xu <xyk@google.com>
Date: Wed, 24 Mar 2021 03:47:11 +0800
Subject: [PATCH] [udp] bind to an interface when sending/connecting (#6332)

---
 src/core/api/udp_api.cpp |  2 +-
 src/core/net/udp6.cpp    | 39 +++++++++++++++++----------------------
 src/core/net/udp6.hpp    |  3 ++-
 3 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/src/core/api/udp_api.cpp b/src/core/api/udp_api.cpp
index bd907e721..7bd961b28 100644
--- a/src/core/api/udp_api.cpp
+++ b/src/core/api/udp_api.cpp
@@ -68,7 +68,7 @@ otError otUdpBind(otInstance *aInstance, otUdpSocket *aSocket, const otSockAddr
     Instance &instance = *static_cast<Instance *>(aInstance);
 
     return instance.Get<Ip6::Udp>().Bind(*static_cast<Ip6::Udp::SocketHandle *>(aSocket),
-                                         *static_cast<const Ip6::SockAddr *>(aSockName));
+                                         *static_cast<const Ip6::SockAddr *>(aSockName), OT_NETIF_THREAD);
 }
 
 otError otUdpConnect(otInstance *aInstance, otUdpSocket *aSocket, const otSockAddr *aSockName)
diff --git a/src/core/net/udp6.cpp b/src/core/net/udp6.cpp
index f97e5c623..a01504151 100644
--- a/src/core/net/udp6.cpp
+++ b/src/core/net/udp6.cpp
@@ -89,25 +89,7 @@ Error Udp::Socket::Open(otUdpReceive aHandler, void *aContext)
 
 Error Udp::Socket::Bind(const SockAddr &aSockAddr, otNetifIdentifier aNetifIdentifier)
 {
-    OT_UNUSED_VARIABLE(aNetifIdentifier);
-
-    Error error = kErrorNone;
-
-#if OPENTHREAD_CONFIG_PLATFORM_UDP_ENABLE
-    SuccessOrExit(error = otPlatUdpBindToNetif(this, aNetifIdentifier));
-#endif
-
-#if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
-    if (aNetifIdentifier == OT_NETIF_BACKBONE)
-    {
-        Get<Udp>().SetBackboneSocket(*this);
-    }
-#endif
-
-    SuccessOrExit(error = Get<Udp>().Bind(*this, aSockAddr));
-
-exit:
-    return error;
+    return Get<Udp>().Bind(*this, aSockAddr, aNetifIdentifier);
 }
 
 Error Udp::Socket::Bind(uint16_t aPort, otNetifIdentifier aNetifIdentifier)
@@ -220,10 +202,23 @@ exit:
     return error;
 }
 
-Error Udp::Bind(SocketHandle &aSocket, const SockAddr &aSockAddr)
+Error Udp::Bind(SocketHandle &aSocket, const SockAddr &aSockAddr, otNetifIdentifier aNetifIdentifier)
 {
+    OT_UNUSED_VARIABLE(aNetifIdentifier);
+
     Error error = kErrorNone;
 
+#if OPENTHREAD_CONFIG_PLATFORM_UDP_ENABLE
+    SuccessOrExit(error = otPlatUdpBindToNetif(&aSocket, aNetifIdentifier));
+#endif
+
+#if OPENTHREAD_FTD && OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
+    if (aNetifIdentifier == OT_NETIF_BACKBONE)
+    {
+        SetBackboneSocket(aSocket);
+    }
+#endif
+
     VerifyOrExit(aSockAddr.GetAddress().IsUnspecified() || Get<ThreadNetif>().HasUnicastAddress(aSockAddr.GetAddress()),
                  error = kErrorInvalidArgs);
 
@@ -295,7 +290,7 @@ Error Udp::Connect(SocketHandle &aSocket, const SockAddr &aSockAddr)
 
     if (!aSocket.IsBound())
     {
-        SuccessOrExit(error = Bind(aSocket, aSocket.GetSockName()));
+        SuccessOrExit(error = Bind(aSocket, aSocket.GetSockName(), OT_NETIF_THREAD));
     }
 
 #if OPENTHREAD_CONFIG_PLATFORM_UDP_ENABLE
@@ -356,7 +351,7 @@ Error Udp::SendTo(SocketHandle &aSocket, Message &aMessage, const MessageInfo &a
 
     if (!aSocket.IsBound())
     {
-        SuccessOrExit(error = Bind(aSocket, aSocket.GetSockName()));
+        SuccessOrExit(error = Bind(aSocket, aSocket.GetSockName(), OT_NETIF_THREAD));
     }
 
     messageInfoLocal.SetSockPort(aSocket.GetSockName().mPort);
diff --git a/src/core/net/udp6.hpp b/src/core/net/udp6.hpp
index 04d53affa..1992cb415 100644
--- a/src/core/net/udp6.hpp
+++ b/src/core/net/udp6.hpp
@@ -451,13 +451,14 @@ public:
      *
      * @param[in]  aSocket          A reference to the socket.
      * @param[in]  aSockAddr        A reference to the socket address.
+     * @param[in]  aNetifIdentifier The network interface identifier.
      *
      * @retval kErrorNone            Successfully bound the socket.
      * @retval kErrorInvalidArgs     Unable to bind to Thread network interface with the given address.
      * @retval kErrorFailed          Failed to bind UDP Socket.
      *
      */
-    Error Bind(SocketHandle &aSocket, const SockAddr &aSockAddr);
+    Error Bind(SocketHandle &aSocket, const SockAddr &aSockAddr, otNetifIdentifier aNetifIdentifier);
 
     /**
      * This method connects a UDP socket.