dhcpv4: Replace the DiscoveryTimeout timer when discovery done

We should replace `DiscoveryTimeout` timer with `RequestTimeout` when
the discovery is done and entering request phase.

Manually tested by checking debug logs of
`cargo run --example mozim_dhcpv4_async`.

DHCPv6 part does not have this problem as it only single retry timer
`DhcpV6Event::TransmitWait`.

Signed-off-by: Gris Ge <[email protected]>

src/dhcpv4/client.rs

@@ -169,8 +169,14 @@ impl DhcpV4Client {
                     return Ok(None);
                 }
             };
-        self.phase = DhcpV4Phase::Request;
         socket.send(&self.gen_request_pkg(&lease).to_eth_pkg_broadcast()?)?;
+        self.event_pool.add_timer(
+            Duration::from_secs(gen_dhcp_request_delay(0).into()),
+            DhcpV4Event::RequestTimeout,
+        )?;
+        self.retry_count = 0;
+        self.event_pool.del_timer(DhcpV4Event::DiscoveryTimeout)?;
+        self.phase = DhcpV4Phase::Request;
         Ok(None)
     }
 
@@ -221,6 +227,7 @@ impl DhcpV4Client {
             };
         self.clean_up();
         self.lease = Some(lease.clone());
+        self.event_pool.del_timer(DhcpV4Event::RequestTimeout)?;
         self.set_renew_rebind_timer(&lease)?;
         Ok(Some(lease))
     }

src/event.rs

@@ -196,6 +196,7 @@ impl<T: DhcpEvent> DhcpEventPool<T> {
         if let Some(timer_fd) = self.timer_fds.remove(&event) {
             self.epoll.del_fd(timer_fd.as_raw_fd())?;
         }
+        log::debug!("Deleted timer {event} from event pool");
         Ok(())
     }