dhcpcd-discuss

I don't maintain dhcpcd-7 anymore - many bugs have been fixed since.
Anyway the attached patch should work - let me know.

Roy

On 20/08/2020 17:10, Shyamlee Badole wrote:
> Hi,
>
> Thank You for sending the patch.
> Since we are using dhcpcd 7.0.0 if you have, can you please share the patch for 
> this version?
>
> Thanks,
> Shyamlee
>
> On Thu, Aug 20, 2020 at 8:43 PM Roy Marples <roy@xxxxxxxxxxxx 
> <mailto:roy@xxxxxxxxxxxx>> wrote:
>
>     On 20/08/2020 11:57, Shyamlee Badole wrote:
>      > Hi,
>      >
>      > I am attaching the pcap file to give you a better idea of the issue.
>      >
>      > As seen from the pcap, when the link is detected on the interface (eth1),
>      > initially the client tried to contact the dhcp server after which it
>     broadcasted
>      > the request asking for previous lease. After that a timeout occurs (eth1:
>     timed
>      > out contacting a DHCP server, using last lease)
>      >
>      > After timeout(since that router is down), the client has sent a Broadcast
>      > DISCOVER, to which a dhcp server belonging to another network has offered
>     an ip.
>      > (eth1: offered 192.168.44.6 from 192.168.44.1)
>      > The client is now sending REQUEST to the server(192.168.44.1) using the
>     previous
>      > IP(66.170.65.115).
>      > This REQUEST is sent unicast to the old router gateway and the client is not
>      > able to accept the offered ip and continuously sends the unicast REQUEST.
>      > Since the client has already entered the Discover phase, it should
>     broadcast the
>      > request instead of unicasting to the old gateway (which is no longer valid).
>      > If this request to accept the offer was broadcasted, it will be able to
>     receive
>      > the reply from the new server.
>
>     Thanks, makes it simple to fix I hope!
>     Comitted this to fix:
>     https://roy.marples.name/cgit/dhcpcd.git/commit/?id=f021b552b5c53cfa785bc5f8df1c97fa8ffa9b86
>
>     Can you test it please?
>
>     Roy
diff --git a/src/dhcp.c b/src/dhcp.c
index ed1b0a6d..f99b3834 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -778,7 +778,7 @@ make_message(struct bootp **bootpm, const struct interface *ifp, uint8_t type)
 	    (type == DHCP_REQUEST &&
 	    state->addr->mask.s_addr == lease->mask.s_addr &&
 	    (state->new == NULL || IS_DHCP(state->new)) &&
-	    !(state->added & STATE_FAKE))))
+	    !(state->added & (STATE_FAKE | STATE_EXPIRED)))))
 		bootp->ciaddr = state->addr->addr.s_addr;
 
 	bootp->op = BOOTREQUEST;
@@ -1968,6 +1968,9 @@ dhcp_expire(void *arg)
 
 	logerrx("%s: DHCP lease expired", ifp->name);
 	if (ifp->options->options & DHCPCD_LASTLEASE_EXTEND) {
+		struct dhcp_state *state = D_STATE(ifp);
+
+		state->added |= STATE_EXPIRED;
 		if (dhcp_leaseextend(ifp) == 0)
 			return;
 		logerr(__func__);
diff --git a/src/ipv4.h b/src/ipv4.h
index bcd0031f..03b9ac61 100644
--- a/src/ipv4.h
+++ b/src/ipv4.h
@@ -117,6 +117,7 @@ bool inet_getroutes(struct dhcpcd_ctx *, struct rt_head *);
 
 #define STATE_ADDED		0x01
 #define STATE_FAKE		0x02
+#define STATE_EXPIRED		0x04
 
 int ipv4_deladdr(struct ipv4_addr *, int);
 struct ipv4_addr *ipv4_addaddr(struct interface *,