Commit 1224c5a4 authored by Jukka Rissanen's avatar Jukka Rissanen Committed by Henrik Brix Andersen
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net: dhcpv4: Honor network interface for DNS servers 



Bind the network interface to the network interface we
have received the DNS servers from. This is now the default.
The previous behavior can be restored by disabling the
CONFIG_NET_DHCPV4_DNS_SERVER_VIA_INTERFACE option.

Signed-off-by: default avatarJukka Rissanen <jukka.rissanen@nordicsemi.no>
parent 2af5dba9

subsys/net/lib/dhcpv4/Kconfig

+17 −0
Original line number Diff line number Diff line
@@ -96,6 +96,23 @@ config NET_DHCPV4_OPTION_PRINT_IGNORED 
	  received and ignored. If this is not set, then we print these as unknown

	  options.



config NET_DHCPV4_DNS_SERVER_VIA_INTERFACE

	bool "Make DNS servers specific to the network interface"

	depends on NET_DHCPV4_OPTION_DNS_ADDRESS

	default y

	help

	  If this is set, then if the system has multiple network interfaces

	  and each has DHCP enabled, then assign DNS servers received from that

	  network interface, to that specific interface.

	  If this option is not set, then any interface can be used for all

	  the configured DNS server addresses when doing DNS queries.

	  Example: We receive DNS server 192.0.2.53 DHCPv4 option from Wi-Fi

	  interface and DNS server 198.51.100.53 from Ethernet interface.

	  When this option is set, the DNS resolver will use DNS server

	  192.0.2.53 when sending DNS query to the Wi-Fi interface and DNS

	  server 198.51.100.53 when sending DNS query to the Ethernet

	  interface.



endif # NET_DHCPV4



config NET_DHCPV4_SERVER

subsys/net/lib/dhcpv4/dhcpv4.c

+19 −1
Original line number Diff line number Diff line
@@ -1171,7 +1171,25 @@ static bool dhcpv4_parse_options(struct net_pkt *pkt, 
			for (uint8_t i = 0; i < dns_servers_cnt; i++) {

				dnses[i].sin_family = AF_INET;

			}



			if (IS_ENABLED(CONFIG_NET_DHCPV4_DNS_SERVER_VIA_INTERFACE)) {

				/* If we are using the interface to resolve DNS servers,

				 * we need to save the interface index.

				 */

				int ifindex = net_if_get_by_iface(iface);

				int interfaces[MAX_DNS_SERVERS];



				for (uint8_t i = 0; i < dns_servers_cnt; i++) {

					interfaces[i] = ifindex;

				}



				status = dns_resolve_reconfigure_with_interfaces(ctx, NULL,

										 dns_servers,

										 interfaces);

			} else {

				status = dns_resolve_reconfigure(ctx, NULL, dns_servers);

			}



			if (status < 0) {

				NET_DBG("options_dns, failed to set "

					"resolve address: %d", status);

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