netutils/dhcpd: fix incorrect OFFER packet handling

This commit fixes incorrect OFFER packet handling of DHCPD. When DHCP
server sends an OFFER packet, the broadcast address in subnet should be
specified instead of the global broadcast address, so that we can avoid
the packet forwarding issue among loopback and user network interfaces.

Change-Id: Ib69ab1b2d17c0f89a56a955c6ac68ee6405267bf
Signed-off-by: Jin-Seong Kim <jseong82.kim@samsung.com>

diff --git a/apps/netutils/dhcpd/dhcpd.c b/apps/netutils/dhcpd/dhcpd.c
index 89aa672..b062dc5 100755 (executable)
--- a/apps/netutils/dhcpd/dhcpd.c
+++ b/apps/netutils/dhcpd/dhcpd.c
@@ -974,12 +974,60 @@ static int dhcpd_sendpacket(int bbroadcast)
                nvdbg("sendto %08lx:%04x len=%d\n", (long)ntohl(addr.sin_addr.s_addr), ntohs(addr.sin_port), len);
                ret = sendto(sockfd, &g_state.ds_outpacket, len, 0, (struct sockaddr *)&addr, sizeof(struct sockaddr_in));
                close(sockfd);
+       } else {
+               ndbg("create socket failed : %d\n", sockfd);
        }
 
        return ret;
 }
 
 /****************************************************************************
+ * Name: dhcpd_send_offerpacket
+ ****************************************************************************/
+
+static int dhcpd_send_offerpacket(void)
+{
+       struct sockaddr_in addr;
+       in_addr_t ipaddr;
+       int sockfd;
+       int len;
+       int ret = ERROR;
+
+       memcpy(&ipaddr, g_state.ds_outpacket.yiaddr, 4);
+
+#if HAVE_NETMASK
+       /* A dhcp offer message should be sent as broadcast message
+        *  Some platform might discard 255.255.255.255 broadcast message, so replace it to subnet broadcast message
+        */
+       ipaddr |= (~htonl(CONFIG_NETUTILS_DHCPD_NETMASK));
+#else
+       ipaddr = htonl(IPADDR_BROADCAST);
+#endif
+
+       sockfd = dhcpd_openresponder();
+       if (sockfd >= 0) {
+               /* Then send the reponse to the DHCP client port at that address */
+
+               memset(&addr, 0, sizeof(struct sockaddr_in));
+               addr.sin_family = AF_INET;
+               addr.sin_port = HTONS(DHCP_CLIENT_PORT);
+               addr.sin_addr.s_addr = ipaddr;
+
+               /* Send the minimum sized packet that includes the END option */
+
+               len = (g_state.ds_optend - (uint8_t *)&g_state.ds_outpacket) + 1;
+               nvdbg("dhcp offer sendto %08lx:%04x len=%d\n", (long)ntohl(addr.sin_addr.s_addr), ntohs(addr.sin_port), len);
+               ret = sendto(sockfd, &g_state.ds_outpacket, len, 0, (struct sockaddr *)&addr, sizeof(struct sockaddr_in));
+               close(sockfd);
+       } else {
+               ndbg("create socket failed : %d\n", sockfd);
+       }
+
+       return ret;
+}
+
+
+/****************************************************************************
  * Name: dhcpd_sendoffer
  ****************************************************************************/
 
@@ -1017,7 +1065,7 @@ static inline int dhcpd_sendoffer(in_addr_t ipaddr, uint32_t leasetime)
 #endif
 
        /* Send the offer response */
-       return dhcpd_sendpacket(true);
+       return dhcpd_send_offerpacket();
 }
 
 /****************************************************************************