mirror of https://github.com/ARMmbed/mbed-os.git
0d2badf42c
RFC3315 specifies the following: "The relay agent MAY send the Interface-id option to identify the interface on which the client message was received. If a relay agent receives a Relay-reply message with an Interface-id option, the relay agent relays the message to the client through the interface identified by the option." The current implementation of the DHCP relay reply handling, the interface ID field from the server response is ignored. Managing the interface ID is very important especially as DHCP requests/replies use link-local addresses. The consequence of this is that the interface must always be specified because the routing layer cannot guess the correct interface. Moreover, Mbed provides a mechanism to enable/disable the interface ID option on a DHCP relay instance, so it is important to fully support it. The reason why this issue has not been discoverd until now is that the DHCP relay is mainly used on systems that use only one interface (such as Wi-SUN routers). By default, when no interface ID is specified for the socket, the latter will choose 6loWPAN interface by default. This means that if two interfaces are used on the same device, the 6loWPAN interface is always selected. The commit adds code to retrieve the interface-id value contained within the DHCP relay reply message and write it to a control message header that is added to the socket message. This tells the socket which interface to choose. If the interface-id option is not enabled on the relay, this procedure is simply ignored. |
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|---|---|---|
| .. | ||
| 6LoWPAN | ||
| BorderRouter | ||
| Common_Protocols | ||
| Core | ||
| DHCPv6_Server | ||
| DHCPv6_client | ||
| MAC | ||
| MLE | ||
| MPL | ||
| NWK_INTERFACE | ||
| RPL | ||
| Security | ||
| Service_Libs | ||
| configs | ||
| ipv6_stack | ||
| libDHCPv6 | ||
| libNET | ||
| nsconfig.h | ||