[5003] Minor improvements in the PktFilterInet code.

src/lib/dhcp/pkt_filter_inet.cc

@@ -84,8 +84,8 @@ PktFilterInet::openSocket(Iface& iface,
                   << "/port=" << port);
     }
 
-    // if there is no support for IP_PKTINFO, we are really out of luck
-    // it will be difficult to undersand, where this packet came from
+    // On Linux systems IP_PKTINFO socket option is supported. This
+    // option is used to retrieve destination address of the packet.
 #if defined (IP_PKTINFO) && defined (OS_LINUX)
     int flag = 1;
     if (setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &flag, sizeof(flag)) != 0) {
@@ -93,6 +93,7 @@ PktFilterInet::openSocket(Iface& iface,
         isc_throw(SocketConfigError, "setsockopt: IP_PKTINFO: failed.");
     }
 
+    // On BSD systems IP_RECVDSTADDR is used instead of IP_PKTINFO.
 #elif defined (IP_RECVDSTADDR) && defined (OS_BSD)
     int flag = 1;
     if (setsockopt(sock, IPPROTO_IP, IP_RECVDSTADDR, &flag, sizeof(flag)) != 0) {
@@ -164,19 +165,15 @@ PktFilterInet::receive(Iface& iface, const SocketInfo& socket_info) {
     struct cmsghdr* cmsg;
     cmsg = CMSG_FIRSTHDR(&m);
 
-// In the future the OS-specific code may be abstracted to a different
-// file but for now we keep it here because there is no code yet, which
-// is specific to non-Linux systems.
+// Linux systems support IP_PKTINFO option which is used to retrieve the
+// destination address of the received packet. On BSD systems IP_RECVDSTADDR
+// is used instead.
 #if defined (IP_PKTINFO) && defined (OS_LINUX)
     struct in_pktinfo* pktinfo;
-    struct in_addr to_addr;
-
-    memset(&to_addr, 0, sizeof(to_addr));
-
     while (cmsg != NULL) {
         if ((cmsg->cmsg_level == IPPROTO_IP) &&
             (cmsg->cmsg_type == IP_PKTINFO)) {
-            pktinfo = (struct in_pktinfo*)CMSG_DATA(cmsg);
+            pktinfo = reinterpret_cast<struct in_pktinfo*>(CMSG_DATA(cmsg));
 
             pkt->setIndex(pktinfo->ipi_ifindex);
             pkt->setLocalAddr(IOAddress(htonl(pktinfo->ipi_addr.s_addr)));
@@ -199,7 +196,7 @@ PktFilterInet::receive(Iface& iface, const SocketInfo& socket_info) {
     while (cmsg != NULL) {
         if ((cmsg->cmsg_level == IPPROTO_IP) &&
             (cmsg->cmsg_type == IP_RECVDSTADDR)) {
-            to_addr = (struct in_addr*)CMSG_DATA(cmsg);
+            to_addr = reinterpret_cast<struct in_addr*>(CMSG_DATA(cmsg));
             pkt->setLocalAddr(IOAddress(htonl(to_addr->s_addr)));
             break;
         }
@@ -261,23 +258,6 @@ PktFilterInet::send(const Iface&, uint16_t sockfd,
     pktinfo->ipi_ifindex = pkt->getIndex();
     pktinfo->ipi_spec_dst.s_addr = htonl(pkt->getLocalAddr()); // set the source IP address
     m.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
-
-#elif defined (IP_RECVDSTADDR) && defined (OS_BSD)
-/*    // Setting the interface is a bit more involved.
-    //
-    // We have to create a "control message", and set that to
-    // define the IPv4 packet information. We set the source address
-    // to handle correctly interfaces with multiple addresses.
-    m.msg_control = &control_buf_[0];
-    m.msg_controllen = control_buf_len_;
-    struct cmsghdr* cmsg = CMSG_FIRSTHDR(&m);
-    cmsg->cmsg_level = IPPROTO_IP;
-    cmsg->cmsg_type = IP_RECVDSTADDR;
-    cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
-    struct in_addr* pktinfo =(struct in_addr *)CMSG_DATA(cmsg);
-    memset(pktinfo, 0, sizeof(struct in_addr));
-    pktinfo->s_addr = htonl(pkt->getLocalAddr());
-    m.msg_controllen = CMSG_SPACE(sizeof(struct in_addr)); */
 #endif
 
     pkt->updateTimestamp();