add "original" to proto_dhcpv4_encode()

and then use it to set giaddr, if it wasn't already set
along with other fields such as hwtype, hwlen, hops, and chaddr

src/modules/proto_dhcpv4/proto_dhcpv4.c

@@ -397,7 +397,7 @@ static ssize_t mod_encode(void const *instance, REQUEST *request, uint8_t *buffe
 		if (data_len > 0) return data_len;
 	}
 
-	data_len = fr_dhcpv4_encode(buffer, buffer_len,
+	data_len = fr_dhcpv4_encode(buffer, buffer_len, original,
 				    request->reply->code, ntohl(original->xid), request->reply->vps);
 	if (data_len < 0) {
 		RPEDEBUG("Failed encoding DHCPV4 reply");

src/protocols/dhcpv4/base.c

@@ -268,7 +268,7 @@ bool fr_dhcpv4_ok(uint8_t const *data, ssize_t data_len, uint8_t *message_type,
 	return true;
 }
 
-ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, uint32_t xid, VALUE_PAIR *vps)
+ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, dhcp_packet_t *original, uint32_t xid, VALUE_PAIR *vps)
 {
 	uint8_t		*p;
 	fr_cursor_t	cursor;
@@ -312,17 +312,35 @@ ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, uint32_t xid,
 
 	/* DHCP-Hardware-Type */
 	vp = fr_pair_find_by_da(vps, attr_dhcp_hardware_type, TAG_ANY);
-	if (vp) *p = vp->vp_uint8;
+	if (vp) {
+		*p = vp->vp_uint8;
+
+	} else if (original) {
+		*p = original->htype;
+
+	} /* else leave it unset */
 	p += 1;
 
 	/* DHCP-Hardware-Address-len */
 	vp = fr_pair_find_by_da(vps, attr_dhcp_hardware_address_length, TAG_ANY);
-	if (vp) *p = vp->vp_uint8;
+	if (vp) {
+		*p = vp->vp_uint8;
+
+	} else if (original) {
+		*p = original->hlen;
+
+	} /* else leave it unset */
 	p += 1;
 
 	/* DHCP-Hop-Count */
 	vp = fr_pair_find_by_da(vps, attr_dhcp_hop_count, TAG_ANY);
-	if (vp) *p = vp->vp_uint8;
+	if (vp) {
+		*p = vp->vp_uint8;
+
+	} else if (original) {
+		*p = original->hops;
+
+	} /* else leave it unset */
 	p++;
 
 	/* DHCP-Transaction-Id */
@@ -377,10 +395,15 @@ ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, uint32_t xid,
 	vp = fr_pair_find_by_da(vps, attr_dhcp_gateway_ip_address, TAG_ANY);
 	if (vp) {
 		lvalue = vp->vp_ipv4addr;
+		memcpy(p, &lvalue, 4);
+
+	} else if (original) {	/* copy whatever value was in the original */
+		memcpy(p, original->giaddr, sizeof(original->giaddr));
+
 	} else {
 		lvalue = htonl(INADDR_ANY);
+		memcpy(p, &lvalue, 4);
 	}
-	memcpy(p, &lvalue, 4);
 	p += 4;
 
 	/* DHCP-Client-Hardware-Address */
@@ -394,6 +417,10 @@ ssize_t fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, uint32_t xid,
 
 			memcpy(p, vp->vp_ether, sizeof(vp->vp_ether));
 		} /* else ignore it */
+
+	} else if (original) {	/* copy whatever value was in the original */
+		memcpy(p, original->chaddr, sizeof(original->chaddr));
+
 	}
 	p += DHCP_CHADDR_LEN;
 

src/protocols/dhcpv4/dhcpv4.h

@@ -141,7 +141,7 @@ int8_t		fr_dhcpv4_attr_cmp(void const *a, void const *b);
 
 bool		fr_dhcpv4_ok(uint8_t const *data, ssize_t data_len, uint8_t *message_type, uint32_t *xid);
 RADIUS_PACKET	*fr_dhcpv4_packet_alloc(uint8_t const *data, ssize_t data_len);
-ssize_t		fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, uint32_t xid, VALUE_PAIR *vps);
+ssize_t		fr_dhcpv4_encode(uint8_t *buffer, size_t buflen, int code, dhcp_packet_t *original, uint32_t xid, VALUE_PAIR *vps);
 int		fr_dhcpv4_global_init(void);
 void		fr_dhcpv4_global_free(void);
 void		fr_dhcpv4_print_hex(FILE *fp, uint8_t const *packet, size_t packet_len);

src/protocols/dhcpv4/packet.c

@@ -348,7 +348,7 @@ int fr_dhcpv4_packet_encode(RADIUS_PACKET *packet)
 		packet->id = fr_rand();
 	}
 
-	len = fr_dhcpv4_encode(packet->data, packet->data_len, packet->code, packet->id, packet->vps);
+	len = fr_dhcpv4_encode(packet->data, packet->data_len, packet->code, NULL, packet->id, packet->vps);
 	if (len < 0) return -1;
 
 	packet->data_len = len;