dhcpv4: remove comment code lines
[project/odhcpd.git] / src / dhcpv4.c
index 7b200cd..0f613b2 100644 (file)
@@ -45,6 +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)
 {
@@ -96,26 +119,19 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                }
 
                // Create a range if not specified
-               struct ifreq ifreq;
-               strncpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
-
-               struct sockaddr_in *saddr = (struct sockaddr_in*)&ifreq.ifr_addr;
-               struct sockaddr_in *smask = (struct sockaddr_in*)&ifreq.ifr_netmask;
                if (!(iface->dhcpv4_start.s_addr & htonl(0xffff0000)) &&
-                               !(iface->dhcpv4_end.s_addr & htonl(0xffff0000)) &&
-                               !ioctl(sock, SIOCGIFADDR, &ifreq)) {
-                       struct in_addr addr = saddr->sin_addr;
+                               !(iface->dhcpv4_end.s_addr & htonl(0xffff0000))) {
+                       struct in_addr addr = ubus_get_address4(iface->ifname);
 
-                       ioctl(sock, SIOCGIFNETMASK, &ifreq);
-                       struct in_addr mask = smask->sin_addr;
+                       struct in_addr mask = ubus_get_mask4(iface->ifname);
 
                        uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
                        uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
 
                        if (start && end && start < end &&
                                        start > ntohl(addr.s_addr & ~mask.s_addr) &&
-                                       (start & ntohl(mask.s_addr)) == start &&
-                                       (end & ntohl(mask.s_addr)) == end) {
+                                       (start & ntohl(~mask.s_addr)) == start &&
+                                       (end & ntohl(~mask.s_addr)) == end) {
                                iface->dhcpv4_start.s_addr = htonl(start) |
                                                (addr.s_addr & mask.s_addr);
                                iface->dhcpv4_end.s_addr = htonl(end) |
@@ -199,7 +215,6 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                        struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
                                        struct dhcpv4_assignment, head);
                        list_del(&a->head);
-                       free(a->hostname);
                        free(a);
                }
 
@@ -334,9 +349,23 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
        } 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;
 
@@ -402,16 +431,36 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 
        struct sockaddr_in dest = *((struct sockaddr_in*)addr);
        if (req->giaddr.s_addr) {
+               /*
+                * relay agent is configured, send reply to the agent
+                */
                dest.sin_addr = req->giaddr;
                dest.sin_port = htons(DHCPV4_SERVER_PORT);
        } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
+               /*
+                * client has existing configuration (ciaddr is set) AND this address is
+                * not the address it used for the dhcp message
+                */
                dest.sin_addr = req->ciaddr;
                dest.sin_port = htons(DHCPV4_CLIENT_PORT);
        } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
                        req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
+               /*
+                * client requests a broadcast reply OR we can't offer an IP
+                */
+               dest.sin_addr.s_addr = INADDR_BROADCAST;
+               dest.sin_port = htons(DHCPV4_CLIENT_PORT);
+       } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
+               /*
+                * client has no previous configuration -> no IP, so we need to reply
+                * with a broadcast packet
+                */
                dest.sin_addr.s_addr = INADDR_BROADCAST;
                dest.sin_port = htons(DHCPV4_CLIENT_PORT);
        } else {
+               /*
+                * send reply to the newly (in this proccess) allocated IP
+                */
                dest.sin_addr = reply.yiaddr;
                dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 
@@ -422,54 +471,97 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
                ioctl(sock, SIOCSARP, &arp);
        }
 
+       if (dest.sin_addr.s_addr == INADDR_BROADCAST) {
+               /*
+                * reply goes to IP broadcast -> MAC broadcast
+                */
+               syslog(LOG_WARNING, "sending %s to ff:ff:ff:ff:ff:ff - %s",
+                               dhcpv4_msg_to_string(msg),
+                               inet_ntoa(dest.sin_addr));
+       } else {
+               /*
+                * reply is send directly to IP,
+                * MAC is assumed to be the same as the request
+                */
+               syslog(LOG_WARNING, "sending %s to %x:%x:%x:%x:%x:%x - %s",
+                               dhcpv4_msg_to_string(msg),
+                               req->chaddr[0],req->chaddr[1],req->chaddr[2],
+                               req->chaddr[3],req->chaddr[4],req->chaddr[5],
+                               inet_ntoa(dest.sin_addr));
+       }
+
        sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
                        (struct sockaddr*)&dest, sizeof(dest));
 }
 
+static bool dhcpv4_test(struct interface *iface, uint32_t try)
+{
+       struct dhcpv4_assignment *c;
+       list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
+               if (c->addr == try) {
+                       return false;
+               }
+       }
+       return true;
+}
 
 static bool dhcpv4_assign(struct interface *iface,
                struct dhcpv4_assignment *assign, uint32_t raddr)
 {
-       const unsigned tries = 10;
        uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
        uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
        uint32_t count = end - start + 1;
 
-       // Seed RNG with checksum of DUID
+       // try to assign the IP the client asked for
+       if (start <= raddr && raddr <= end && dhcpv4_test(iface, raddr)) {
+               assign->addr = raddr;
+               list_add(&assign->head, &iface->dhcpv4_assignments);
+               syslog(LOG_DEBUG, "assigning the IP the client asked for: %u.%u.%u.%u",
+                               (assign->addr & 0xff000000) >> 24,
+                               (assign->addr & 0x00ff0000) >> 16,
+                               (assign->addr & 0x0000ff00) >> 8,
+                               (assign->addr & 0x000000ff));
+               return true;
+       }
+
+       // Seed RNG with checksum of hwaddress
        uint32_t seed = 0;
-       for (size_t i = 0; i < sizeof(assign->hwaddr); ++i)
-               seed += assign->hwaddr[i];
+       for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) {
+               // Knuth's multiplicative method
+               uint8_t o = assign->hwaddr[i];
+               seed += (o*2654435761) % UINT32_MAX;
+       }
        srand(seed);
 
-       // Try to assign up to 100x
-       for (unsigned i = 0; i < tries; ++i) {
-               uint32_t try = (((uint32_t)rand()) % count) + start;
-               if (i == 0 && raddr >= start && raddr <= end)
-                       try = raddr;
-               else if (i == tries - 1)
-                       try = start;
+       uint32_t try = (((uint32_t)rand()) % count) + start;
+
+       if (list_empty(&iface->dhcpv4_assignments)) {
+               assign->addr = try;
+               list_add(&assign->head, &iface->dhcpv4_assignments);
+               syslog(LOG_DEBUG, "assigning mapped IP (empty list): %u.%u.%u.%u",
+                               (assign->addr & 0xff000000) >> 24,
+                               (assign->addr & 0x00ff0000) >> 16,
+                               (assign->addr & 0x0000ff00) >> 8,
+                               (assign->addr & 0x000000ff));
+               return true;
+       }
 
-               if (list_empty(&iface->dhcpv4_assignments)) {
+       for (uint32_t i = 0; i < count; ++i) {
+               if (dhcpv4_test(iface, try)) {
+                       /* test was successful: IP address is not assigned, assign it */
                        assign->addr = try;
                        list_add(&assign->head, &iface->dhcpv4_assignments);
+                       syslog(LOG_DEBUG, "assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
+                                       (assign->addr & 0xff000000) >> 24,
+                                       (assign->addr & 0x00ff0000) >> 16,
+                                       (assign->addr & 0x0000ff00) >> 8,
+                                       (assign->addr & 0x000000ff), i, count);
                        return true;
                }
-
-               struct dhcpv4_assignment *c;
-               list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
-                       if (c->addr > try) {
-                               assign->addr = try;
-                               list_add_tail(&assign->head, &c->head);
-                               return true;
-                       } else if (c->addr == try) {
-                               if (i < tries - 1)
-                                       break;
-                               else
-                                       ++try;
-                       }
-               }
+               try = (((try - start) + 1) % count) + start;
        }
 
+       syslog(LOG_DEBUG, "can't assign any IP address -> address space is full");
        return false;
 }
 
@@ -535,10 +627,9 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                if (assigned && a)
                        lease = a;
        } else if (msg == DHCPV4_MSG_RELEASE) {
-               if (a) {
+               if (a && a->valid_until != LONG_MAX)
                        a->valid_until = 0;
-               }
-       } else if (msg == DHCPV4_MSG_DECLINE) {
+       } else if (msg == DHCPV4_MSG_DECLINE && a && a->valid_until != LONG_MAX) {
                memset(a->hwaddr, 0, sizeof(a->hwaddr));
                a->valid_until = now + 3600; // Block address for 1h
        }