set src/dst IP for packets appropriately

diff --git a/src/modules/proto_dhcpv4/proto_dhcpv4_udp.c b/src/modules/proto_dhcpv4/proto_dhcpv4_udp.c
index bea5dcf628e28c68c432a13182bacb540927ecd2..9ae11e0e9ee326500eb82b9bda0a06802ef6d77a 100644 (file)
--- a/src/modules/proto_dhcpv4/proto_dhcpv4_udp.c
+++ b/src/modules/proto_dhcpv4/proto_dhcpv4_udp.c
@@ -158,7 +158,7 @@ static ssize_t mod_read(void *instance, void **packet_ctx, fr_time_t **recv_time
                             &address->dst_ipaddr, &address->dst_port,
                             &address->if_index, &timestamp);
        if (data_size < 0) {
-               DEBUG2("proto_dhcpv4_udp got read error %zd: %s", data_size, fr_strerror());
+               DEBUG2("proto_dhvpv4_udp got read error %zd: %s", data_size, fr_strerror());
                return data_size;
        }
 
@@ -214,7 +214,7 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
 {
        proto_dhcpv4_udp_t              *inst = talloc_get_type_abort(instance, proto_dhcpv4_udp_t);
        fr_io_track_t                   *track = talloc_get_type_abort(packet_ctx, fr_io_track_t);
-       fr_io_address_t                 address = *track->address;
+       fr_io_address_t                 address;
 
        int                             flags;
        ssize_t                         data_size;
@@ -230,14 +230,26 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
 
        rad_assert(track->reply_len == 0);
 
+       /*
+        *      Swap src/dst IP/port
+        */
+       address.src_ipaddr = track->address->dst_ipaddr;
+       address.src_port = track->address->dst_port;
+       address.dst_ipaddr = track->address->src_ipaddr;
+       address.dst_port = track->address->src_port;
+       address.if_index = track->address->if_index;
+
        /*
         *      Figure out which kind of packet we're sending.
         */
        if (!inst->connection) {
-               uint8_t const *code;
+               uint8_t const *code, *sid;
                uint32_t ipaddr;
                dhcp_packet_t *packet = (dhcp_packet_t *) buffer;
                dhcp_packet_t *request = (dhcp_packet_t *) track->packet; /* only 20 bytes tho! */
+#ifdef WITH_IFINDEX_IPADDR_RESOLUTION
+               fr_ipaddr_t primary;
+#endif
 
                /*
                 *      This isn't available in the packet header.
@@ -248,6 +260,33 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                        return 0;
                }
 
+               /*
+                *      Set the source IP of the packet.
+                *
+                *      - if src_ipaddr is unicast, use that
+                *      - else if socket wasn't bound to *, then use that
+                *      - else if we have if_index, get main IP from that interface and use that.
+                *      - else for offer/ack, look at option 54, for Server Identification and use that
+                *      - else leave source IP as whatever is already in "address.src_ipaddr".
+                */
+               if (inst->src_ipaddr.addr.v4.s_addr != INADDR_ANY) {
+                       address.src_ipaddr = inst->src_ipaddr;
+
+               } else if (inst->ipaddr.addr.v4.s_addr != INADDR_ANY) {
+                       address.src_ipaddr = inst->ipaddr;
+
+#ifdef WITH_IFINDEX_IPADDR_RESOLUTION
+               } else if ((address->if_index > 0) &&
+                          (fr_ipaddr_from_ifindex(&primary, inst->sockfd, &address.dst_ipaddr.af,
+                                                  &address.if_index) == 0)) {
+                       address.src_ipaddr = primary;
+#endif
+               } else if (((code[2] == FR_DHCP_OFFER) || (code[2] == FR_DHCP_ACK)) &&
+                          ((sid = fr_dhcpv4_packet_get_option(packet, buffer_len, FR_DHCP_DHCP_SERVER_IDENTIFIER)) != NULL) &&
+                          (sid[1] == 4)) {
+                       memcpy(&address.src_ipaddr.addr.v4.s_addr, sid + 2, 4);
+               }
+
                /*
                 *      We have GIADDR in the packet, so send it
                 *      there.  The packet is FROM our IP address and
@@ -258,8 +297,7 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                if (ipaddr != INADDR_ANY) {
                        address.dst_ipaddr.addr.v4.s_addr = ipaddr;
                        address.dst_port = inst->port;
-                       address.src_ipaddr = inst->src_ipaddr;
-                       address.dst_port = inst->port;
+                       address.src_port = inst->port;
 
                        /*
                         *      Increase the hop count for client
@@ -294,7 +332,7 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                 */
                if (((request->flags & FR_DHCP_FLAGS_VALUE_BROADCAST) != 0) &&
                    (request->ciaddr == INADDR_ANY)) {
-                       DEBUG("Reply will be broadcast");
+                       DEBUG("Reply will be broadcast due to client request.");
                        address.dst_ipaddr.addr.v4.s_addr = INADDR_BROADCAST;
                        goto send_reply;
                }
@@ -309,6 +347,17 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                        goto send_reply;
                }
 
+               /*
+                *      The original packet was unicast to us, such as
+                *      via a relay.  We have a unicast destination
+                *      address, so we just use that.
+                */
+               if ((packet->yiaddr == htonl(INADDR_ANY)) &&
+                   (address.dst_ipaddr.addr.v4.s_addr != htonl(INADDR_BROADCAST))) {
+                       DEBUG("Reply will be unicast to source IP from original packet.");
+                       goto send_reply;
+               }
+
                switch (code[2]) {
                        /*
                         *      Offers are sent to YIADDR if we
@@ -319,11 +368,8 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                         */
                case FR_DHCP_OFFER:
                        /*
-                        *      The master_io automatically swaps
-                        *      src/dst ip/port before calling us.  So
-                        *      if we received the request from
-                        *      YIADDR, then the reply will
-                        *      automatically be sent there as well.
+                        *      If the packet was unicast from the
+                        *      client, unicast it back.
                         */
                        if (memcmp(&address.dst_ipaddr.addr.v4.s_addr, &packet->yiaddr, 4) == 0) {
                                DEBUG("Reply will be unicast to YIADDR.");
@@ -340,7 +386,7 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
 
 #endif
                        } else {
-                               DEBUG("Reply will be broadcast.");
+                               DEBUG("Reply will be broadcast due to OFFER.");
                                address.dst_ipaddr.addr.v4.s_addr = INADDR_BROADCAST;
                        }
                        break;
@@ -357,7 +403,7 @@ static ssize_t mod_write(void *instance, void *packet_ctx,
                         *      NAKs are broadcast.
                         */
                case FR_DHCP_NAK:
-                       DEBUG("Reply will be broadcast.");
+                       DEBUG("Reply will be broadcast due to NAK.");
                        address.dst_ipaddr.addr.v4.s_addr = INADDR_BROADCAST;
                        break;
 
@@ -372,9 +418,9 @@ send_reply:
         *      proto_radius_dhcpv4 takes care of suppressing do-not-respond, etc.
         */
        data_size = udp_send(inst->sockfd, buffer, buffer_len, flags,
-                            &address.dst_ipaddr, address.dst_port,
+                            &address.src_ipaddr, address.src_port,
                             address.if_index,
-                            &address.src_ipaddr, address.src_port);
+                            &address.dst_ipaddr, address.dst_port);
 
        /*
         *      This socket is dead.  That's an error...
@@ -575,6 +621,11 @@ static int mod_bootstrap(void *instance, CONF_SECTION *cs)
                return -1;
        }
 
+       if (inst->ipaddr.af != AF_INET) {
+               cf_log_err(cs, "DHCPv4 transport cannot use IPv6 for 'ipaddr'");
+               return -1;
+       }
+
        /*
         *      If src_ipaddr is defined, it must be of the same address family as "ipaddr"
         */
@@ -584,6 +635,14 @@ static int mod_bootstrap(void *instance, CONF_SECTION *cs)
                return -1;
        }
 
+       /*
+        *      Set src_ipaddr to INADDR_NONE if not otherwise specified
+        */
+       if (inst->src_ipaddr.af == AF_UNSPEC) {
+               memset(&inst->src_ipaddr, 0, sizeof(inst->src_ipaddr));
+               inst->src_ipaddr.af = AF_INET;
+       }
+
        if (inst->recv_buff_is_set) {
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, >=, 32);
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, <=, INT_MAX);