Merge pull request #22 from mehlis/log-dhcp4-events

dhcpv4: log requests and replies to syslog

diff --combined src/dhcpv4.c
index d978da8c7fa003416e951efdb65b68c2390e684c,7fe5bd8d4eb6971cfe5f6f354d9c4bca5723e6e2..9b9b528d852cffceb9855310b9703ac440e012df
--- 1/src/dhcpv4.c
--- 2/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@@ -45,6 -45,29 +45,29 @@@ int init_dhcpv4(void
        return 0;
  }
  
+ char *dhcpv4_msg_to_string(uint8_t reqmsg)
+ {
+       switch (reqmsg) {
+       case (DHCPV4_MSG_DISCOVER):
+               return "DHCPV4_MSG_DISCOVER";
+       case (DHCPV4_MSG_OFFER):
+               return "DHCPV4_MSG_OFFER";
+       case (DHCPV4_MSG_REQUEST):
+               return "DHCPV4_MSG_REQUEST";
+       case (DHCPV4_MSG_DECLINE):
+               return "DHCPV4_MSG_DECLINE";
+       case (DHCPV4_MSG_ACK):
+               return "DHCPV4_MSG_ACK";
+       case (DHCPV4_MSG_NAK):
+               return "DHCPV4_MSG_NAK";
+       case (DHCPV4_MSG_RELEASE):
+               return "DHCPV4_MSG_RELEASE";
+       case (DHCPV4_MSG_INFORM):
+               return "DHCPV4_MSG_INFORM";
+       default:
+               return "UNKNOWN";
+       }
+ }
  
  int setup_dhcpv4_interface(struct interface *iface, bool enable)
  {
@@@ -334,18 -357,14 +357,23 @@@ static void handle_dhcpv4(void *addr, v
        } else if (reqmsg == DHCPV4_MSG_REQUEST && reqaddr.s_addr &&
                        reqaddr.s_addr != htonl(lease->addr)) {
                msg = DHCPV4_MSG_NAK;
 -              lease = NULL;
 +              /*
 +               * DHCP client requested an IP which we can't offer to him. Probably the
 +               * client changed the network. The reply type is set to DHCPV4_MSG_NAK,
 +               * because the client should not use that IP.
 +               *
 +               * For modern devices we build an answer that includes a valid IP, like
 +               * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
 +               * perform additional DHCP round trips.
 +               *
 +               */
        }
  
+       syslog(LOG_WARNING, "received %s from %x:%x:%x:%x:%x:%x",
+                       dhcpv4_msg_to_string(reqmsg),
+                       req->chaddr[0],req->chaddr[1],req->chaddr[2],
+                       req->chaddr[3],req->chaddr[4],req->chaddr[5]);
+ 
        if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
                return;
  
@@@ -393,11 -412,8 +421,11 @@@
                                        len, search_buf);
        }
  
 -      dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
 -
 +      if (iface->dhcpv4_router_cnt == 0)
 +              dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
 +      else
 +              dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
 +                              4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
  
  
        if (iface->dhcpv4_dns_cnt == 0)
@@@ -431,6 -447,11 +459,11 @@@
                ioctl(sock, SIOCSARP, &arp);
        }
  
+       syslog(LOG_WARNING, "sending %s to %x:%x:%x:%x:%x:%x",
+                       dhcpv4_msg_to_string(msg),
+                       req->chaddr[0],req->chaddr[1],req->chaddr[2],
+                       req->chaddr[3],req->chaddr[4],req->chaddr[5]);
+ 
        sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
                        (struct sockaddr*)&dest, sizeof(dest));
  }