[cli] update br scan to allow network interface selection for mDNS binding

include/commissioner/error.hpp

@@ -161,6 +161,11 @@ enum class ErrorCode : int
      * The error is out of the address space of OT Commissioner.
      */
     kUnknown = 19,
+
+    /**
+     * The error occurs when attempting to bind a network interface to an mDNS socket."
+     */
+    kSocketBindError = 20,
 };
 
 /**

src/app/cli/README.md

@@ -743,7 +743,7 @@ Each advanced command always sends associative `MGMT_*_(GET|SET).req` requests.
 ```shell
 > help br
 usage:
-br scan [--nwk <network-alias-list> | --dom <domain-name>] [--export <json-file-path>] [--timeout <ms>]
+br scan [--nwk <network-alias-list> | --dom <domain-name>] [--export <json-file-path>] [--timeout <ms>] [--netif <network-interface>]
 br add <json-file-path>
 br list [--nwk <network-alias-list> | --dom <domain-name>]
 br delete (<br-record-id> | --nwk <network-alias-list> | --dom <domain-name>)

src/app/cli/interpreter.cpp

@@ -45,6 +45,7 @@
 #include <vector>
 
 #include <fcntl.h>
+#include <sys/socket.h>
 #include <sys/types.h>
 #include <unistd.h>
 
@@ -111,6 +112,8 @@
 #define WARN_NETWORK_SELECTION_DROPPED "Network selection was dropped by the command"
 #define WARN_NETWORK_SELECTION_CHANGED "Network selection was changed by the command"
 
+#define SO_BINDTODEVICE 25
+
 #define COLOR_ALIAS_FAILED Console::Color::kYellow
 
 namespace ot {
@@ -213,7 +216,8 @@ const std::map<std::string, std::string> &Interpreter::mUsageMap = *new std::map
     {"br", "br list [--nwk <network-alias-list> | --dom <domain-name>]\n"
            "br add <json-file-path>\n"
            "br delete (<br-record-id> | --nwk <network-alias-list> | --dom <domain-name>)\n"
-           "br scan [--nwk <network-alias-list> | --dom <domain-name>] [--export <json-file-path>] [--timeout <ms>]\n"},
+           "br scan [--nwk <network-alias-list> | --dom <domain-name>] [--export <json-file-path>] [--timeout <ms>] "
+           "[--netif <network-interface>]\n"},
     {"domain", "domain list [--dom <domain-name>]"},
     {"network", "network save <network-data-file>\n"
                 "network sync\n"
@@ -1421,6 +1425,7 @@ Interpreter::Value Interpreter::ProcessBr(const Expression &aExpr)
         const std::string                  kServiceName    = "_meshcop._udp.local";
 
         uint32_t                                  scanTimeout = 10000;
+        std::string                               netIf       = "";
         int                                       mdnsSocket  = -1;
         FDGuard                                   fdgMdnsSocket;
         std::thread                               selectThread;
@@ -1432,20 +1437,47 @@ Interpreter::Value Interpreter::ProcessBr(const Expression &aExpr)
         nlohmann::json                            baJson;
         char                                      mdnsSendBuffer[kMdnsBufferSize];
 
-        if (mContext.mCommandKeys.size() == 2 && mContext.mCommandKeys[0] == "--timeout")
+        for (auto it = mContext.mCommandKeys.begin(); it != mContext.mCommandKeys.end(); ++it)
         {
-            try
+            if (*it == "--timeout")
             {
-                scanTimeout = stol(mContext.mCommandKeys[1]);
-            } catch (...)
+                if (++it != mContext.mCommandKeys.end())
+                {
+                    try
+                    {
+                        scanTimeout = stol(*it);
+                    } catch (...)
+                    {
+                        ExitNow(value = ERROR_INVALID_ARGS("Imparsable timeout value '{}'", *it));
+                    }
+                }
+                else
+                {
+                    ExitNow(value = ERROR_INVALID_ARGS("Missing {} value", *--it));
+                }
+            }
+            else if (*it == "--netif")
             {
-                ExitNow(value = ERROR_INVALID_ARGS("Imparsable timeout value '{}'", aExpr[3]));
+                if (++it != mContext.mCommandKeys.end())
+                {
+                    netIf = *it;
+                }
+                else
+                {
+                    ExitNow(value = ERROR_INVALID_ARGS("Missing {} value", *--it));
+                }
             }
         }
 
         // Open IPv4 mDNS socket
         mdnsSocket = mdns_socket_open_ipv4();
         VerifyOrExit(mdnsSocket >= 0, value = ERROR_IO_ERROR("failed to open mDNS IPv4 socket"));
+
+        if (!netIf.empty() && setsockopt(mdnsSocket, SOL_SOCKET, SO_BINDTODEVICE, netIf.c_str(), netIf.size()) < 0)
+        {
+            ExitNow(value = ERROR_SOCKET_BIND_ERROR("failed to bind network interface {}: {}", netIf, strerror(errno)));
+        }
+
         fdgMdnsSocket.mFD = mdnsSocket;
 
         //  Initialize event library

src/common/error.cpp

@@ -86,6 +86,8 @@ static std::string ErrorCodeToString(ErrorCode code)
         return "REGISTRY_ERROR";
     case ErrorCode::kUnknown:
         return "UNKNOWN";
+    case ErrorCode::kSocketBindError:
+        return "SOCKET_BIND_ERROR";
 
     default:
         VerifyOrDie(false);

src/common/error_macros.hpp

@@ -137,5 +137,10 @@
     {                                                                          \
         ErrorCode::kUnknown, fmt::format(FMT_STRING((aFormat)), ##__VA_ARGS__) \
     }
+#define ERROR_SOCKET_BIND_ERROR(aFormat, ...)                                          \
+    Error                                                                              \
+    {                                                                                  \
+        ErrorCode::kSocketBindError, fmt::format(FMT_STRING((aFormat)), ##__VA_ARGS__) \
+    }
 
 #endif // ERROR_MACROS_HPP_