Limit lifetime of non-static leases in case of release and decline
[project/odhcpd.git] / src / dhcpv4.c
index f277a67..509b092 100644 (file)
@@ -37,7 +37,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
                struct interface *iface, void *dest_addr);
 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
-               const char *hostname);
+               uint32_t *leasetime, const char *hostname);
 
 // Create socket and register events
 int init_dhcpv4(void)
@@ -181,7 +181,10 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                        a->addr = ntohl(lease->ipaddr.s_addr);
                        memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
                        memcpy(a->hostname, lease->hostname, hostlen);
-                       a->valid_until = LONG_MAX;
+                       /* Static assignment */
+                       a->flags |= OAF_STATIC;
+                       /* Infinite valid */
+                       a->valid_until = 0;
 
                        // Assign to all interfaces
                        struct dhcpv4_assignment *c;
@@ -246,8 +249,7 @@ static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
        *cookie = c + len;
 }
 
-
-// Simple DHCPv6-server for information requests
+// Handler for DHCPv4 messages
 static void handle_dhcpv4(void *addr, void *data, size_t len,
                struct interface *iface, _unused void *dest_addr)
 {
@@ -312,6 +314,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
        uint8_t msg = DHCPV4_MSG_ACK;
 
        struct in_addr reqaddr = {INADDR_ANY};
+       uint32_t leasetime = 0;
        char hostname[256];
        hostname[0] = 0;
 
@@ -336,7 +339,8 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
                                if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
                                        return; // Ignore from homenet
                        }
-               }
+               } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4)
+                       memcpy(&leasetime, opt->data, 4);
        }
 
        if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
@@ -346,7 +350,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 
        struct dhcpv4_assignment *lease = NULL;
        if (reqmsg != DHCPV4_MSG_INFORM)
-               lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, hostname);
+               lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, &leasetime, hostname);
 
        if (!lease) {
                if (reqmsg == DHCPV4_MSG_REQUEST)
@@ -382,25 +386,20 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
        dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &ifaddr.sin_addr);
 
        if (lease) {
-               reply.yiaddr.s_addr = htonl(lease->addr);
-
                uint32_t val;
-               uint32_t leasetime;
 
-               if (lease->leasetime >= 60) {
-                       leasetime = lease->leasetime;
-               } else {
-                       leasetime = iface->dhcpv4_leasetime;
-               }
+               reply.yiaddr.s_addr = htonl(lease->addr);
 
                val = htonl(leasetime);
                dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
 
-               val = htonl(500 * leasetime / 1000);
-               dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
+               if (leasetime != UINT32_MAX) {
+                       val = htonl(500 * leasetime / 1000);
+                       dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
 
-               val = htonl(875 * leasetime / 1000);
-               dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
+                       val = htonl(875 * leasetime / 1000);
+                       dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
+               }
 
                dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr);
 
@@ -586,7 +585,7 @@ static bool dhcpv4_assign(struct interface *iface,
 
 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
-               const char *hostname)
+               uint32_t *leasetime, const char *hostname)
 {
        struct dhcpv4_assignment *lease = NULL;
        uint32_t raddr = ntohl(reqaddr.s_addr);
@@ -598,7 +597,7 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                        a = c;
                        if (c->addr == raddr)
                                break;
-               } else if (c->valid_until < now) {
+               } else if (!INFINITE_VALID(c->valid_until) && c->valid_until < now) {
                        list_del(&c->head);
                        free(c);
                }
@@ -607,6 +606,7 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
        if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
                bool assigned = !!a;
                size_t hostlen = strlen(hostname) + 1;
+               uint32_t my_leasetime;
 
                if (!a && !iface->no_dynamic_dhcp) { // Create new binding
                        a = calloc(1, sizeof(*a) + hostlen);
@@ -616,6 +616,8 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                        }
                        memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
                        memcpy(a->hostname, hostname, hostlen);
+                       // Don't consider new assignment as infinite
+                       a->valid_until = now;
 
                        assigned = dhcpv4_assign(iface, a, raddr);
                }
@@ -633,17 +635,27 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                        a->head.prev->next = &a->head;
                }
 
-               uint32_t leasetime;
-               if (a->leasetime) {
-                       leasetime = a->leasetime;
+               if (a->leasetime >= 60) {
+                       my_leasetime = a->leasetime;
                } else {
-                       leasetime = iface->dhcpv4_leasetime;
+                       my_leasetime = iface->dhcpv4_leasetime;
                }
 
-               // Was only a solicitation: mark binding for removal
-               if (assigned && a->valid_until < now) {
-                       a->valid_until = (msg == DHCPV4_MSG_DISCOVER) ? 0 :
-                                       (now + leasetime);
+               if ((*leasetime == 0) || (my_leasetime < *leasetime))
+                       *leasetime = my_leasetime;
+
+               if (assigned) {
+                       if (msg == DHCPV4_MSG_DISCOVER) {
+                               a->flags &= ~OAF_BOUND;
+
+                               if (!(a->flags & OAF_STATIC))
+                                       a->valid_until = now;
+                       } else {
+                               a->flags |= OAF_BOUND;
+
+                               if (!(a->flags & OAF_STATIC))
+                                       a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime));
+                       }
                } else if (!assigned && a) { // Cleanup failed assignment
                        free(a);
                        a = NULL;
@@ -651,12 +663,19 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
 
                if (assigned && a)
                        lease = a;
-       } else if (msg == DHCPV4_MSG_RELEASE) {
-               if (a && a->valid_until != LONG_MAX)
-                       a->valid_until = 0;
-       } 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
+       } else if (msg == DHCPV4_MSG_RELEASE && a) {
+               a->flags &= ~OAF_BOUND;
+
+               if (!(a->flags & OAF_STATIC))
+                       a->valid_until = now - 1;
+
+       } else if (msg == DHCPV4_MSG_DECLINE && a) {
+               a->flags &= ~OAF_BOUND;
+
+               if (!(a->flags & OAF_STATIC)) {
+                       memset(a->hwaddr, 0, sizeof(a->hwaddr));
+                       a->valid_until = now + 3600; // Block address for 1h
+               }
        }
 
        dhcpv6_write_statefile();