From: Nick Porter <nick@portercomputing.co.uk>
Date: Mon, 24 Jun 2024 13:46:06 +0000 (+0100)
Subject: Add client_port to proto_dhcpv4_udp
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fdaadd62f01fed107b3ddb12bb5ac6008fdbd0e9;p=thirdparty%2Ffreeradius-server.git

Add client_port to proto_dhcpv4_udp
---

diff --git a/raddb/sites-available/dhcp b/raddb/sites-available/dhcp
index d1c16a0321b..58e03654068 100644
--- a/raddb/sites-available/dhcp
+++ b/raddb/sites-available/dhcp
@@ -56,6 +56,14 @@ listen {
 		#  This is also the destination port when sending to a giaddr.
 		port = 6700
 
+		#  The port to which server -> client messages should be sent.
+		#  This should be 68 on a production network, though other ports
+		#  can be useful for testing.
+		#
+		#  If this is not set then server -> client replies will be sent
+		#  to the source port of the client -> server request.
+		client_port = 68
+
 		#  Interface name we are listening on. See comments above.
 #		interface = lo0
 
diff --git a/src/listen/dhcpv4/proto_dhcpv4_udp.c b/src/listen/dhcpv4/proto_dhcpv4_udp.c
index 8492b065bbf..8364c89ba69 100644
--- a/src/listen/dhcpv4/proto_dhcpv4_udp.c
+++ b/src/listen/dhcpv4/proto_dhcpv4_udp.c
@@ -61,6 +61,7 @@ typedef struct {
 	uint32_t			max_attributes;		//!< Limit maximum decodable attributes.
 
 	uint16_t			port;			//!< Port to listen on.
+	uint16_t			client_port;		//!< Client port to reply to.
 
 	bool				broadcast;		//!< whether we listen for broadcast packets
 
@@ -95,6 +96,7 @@ static const conf_parser_t udp_listen_config[] = {
 	{ FR_CONF_OFFSET("port_name", proto_dhcpv4_udp_t, port_name) },
 
 	{ FR_CONF_OFFSET("port", proto_dhcpv4_udp_t, port) },
+	{ FR_CONF_OFFSET("client_port", proto_dhcpv4_udp_t, client_port) },
 	{ FR_CONF_OFFSET_IS_SET("recv_buff", FR_TYPE_UINT32, 0, proto_dhcpv4_udp_t, recv_buff) },
 
 	{ FR_CONF_OFFSET("broadcast", proto_dhcpv4_udp_t, broadcast) } ,
@@ -319,6 +321,16 @@ static ssize_t mod_write(fr_listen_t *li, void *packet_ctx, UNUSED fr_time_t req
 
 		packet->opcode = 2; /* server message */
 
+		/*
+		 *	If the client port is specified, use it.
+		 *
+		 *	RFC 2131 page 23.
+		 *
+		 *	"DHCP messages from a server to a client are sent
+		 *	to the 'DHCP client' port (68)"
+		 */
+		if (inst->client_port) socket.inet.dst_port = inst->client_port;
+
 		/*
 		 *	NAKs are broadcast when there's no giaddr.
 		 *