udhcp: add PXELINUX config file option (code 209) definition

[oweals/busybox.git] / networking / udhcp / leases.c

diff --git a/networking/udhcp/leases.c b/networking/udhcp/leases.c
index 81acb9910b8f5e58b25785c2d12b27bdc33c36cb..c5b60b1083ad8efd363de53b656a965ad31ff889 100644 (file)
--- a/networking/udhcp/leases.c
+++ b/networking/udhcp/leases.c
@@ -1,15 +1,12 @@
 /* vi: set sw=4 ts=4: */
 /*
- * leases.c -- tools to manage DHCP leases
  * Russ Dill <Russ.Dill@asu.edu> July 2001
  *
- * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
-
 #include "common.h"
 #include "dhcpd.h"
 
-
 /* Find the oldest expired lease, NULL if there are no expired leases */
 static struct dyn_lease *oldest_expired_lease(void)
 {
@@ -28,7 +25,6 @@ static struct dyn_lease *oldest_expired_lease(void)
        return oldest_lease;
 }
 
-
 /* Clear out all leases with matching nonzero chaddr OR yiaddr.
  * If chaddr == NULL, this is a conflict lease.
  */
@@ -45,8 +41,7 @@ static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
        }
 }
 
-
-/* Add a lease into the table, clearing out any old ones
+/* Add a lease into the table, clearing out any old ones.
  * If chaddr == NULL, this is a conflict lease.
  */
 struct dyn_lease* FAST_FUNC add_lease(
@@ -65,6 +60,8 @@ struct dyn_lease* FAST_FUNC add_lease(
                memset(oldest, 0, sizeof(*oldest));
                if (hostname) {
                        char *p;
+
+                       hostname_len++; /* include NUL */
                        if (hostname_len > sizeof(oldest->hostname))
                                hostname_len = sizeof(oldest->hostname);
                        p = safe_strncpy(oldest->hostname, hostname, hostname_len);
@@ -84,14 +81,12 @@ struct dyn_lease* FAST_FUNC add_lease(
        return oldest;
 }
 
-
 /* True if a lease has expired */
 int FAST_FUNC is_expired_lease(struct dyn_lease *lease)
 {
        return (lease->expires < (leasetime_t) time(NULL));
 }
 
-
 /* Find the first lease that matches MAC, NULL if no match */
 struct dyn_lease* FAST_FUNC find_lease_by_mac(const uint8_t *mac)
 {
@@ -104,7 +99,6 @@ struct dyn_lease* FAST_FUNC find_lease_by_mac(const uint8_t *mac)
        return NULL;
 }
 
-
 /* Find the first lease that matches IP, NULL is no match */
 struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
 {
@@ -117,7 +111,6 @@ struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
        return NULL;
 }
 
-
 /* Check if the IP is taken; if it is, add it to the lease table */
 static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
 {
@@ -138,28 +131,48 @@ static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
        return 0;
 }
 
-
 /* Find a new usable (we think) address */
 uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
 {
        uint32_t addr;
        struct dyn_lease *oldest_lease = NULL;
 
-       addr = server_config.start_ip; /* addr is in host order here */
-       for (; addr <= server_config.end_ip; addr++) {
+#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
+       uint32_t stop;
+       unsigned i, hash;
+
+       /* hash hwaddr: use the SDBM hashing algorithm.  Seems to give good
+        * dispersal even with similarly-valued "strings".
+        */
+       hash = 0;
+       for (i = 0; i < 6; i++)
+               hash += safe_mac[i] + (hash << 6) + (hash << 16) - hash;
+
+       /* pick a seed based on hwaddr then iterate until we find a free address. */
+       addr = server_config.start_ip
+               + (hash % (1 + server_config.end_ip - server_config.start_ip));
+       stop = addr;
+#else
+       addr = server_config.start_ip;
+#define stop (server_config.end_ip + 1)
+#endif
+       do {
                uint32_t nip;
                struct dyn_lease *lease;
 
                /* ie, 192.168.55.0 */
                if ((addr & 0xff) == 0)
-                       continue;
+                       goto next_addr;
                /* ie, 192.168.55.255 */
                if ((addr & 0xff) == 0xff)
-                       continue;
+                       goto next_addr;
                nip = htonl(addr);
+               /* skip our own address */
+               if (nip == server_config.server_nip)
+                       goto next_addr;
                /* is this a static lease addr? */
                if (is_nip_reserved(server_config.static_leases, nip))
-                       continue;
+                       goto next_addr;
 
                lease = find_lease_by_nip(nip);
                if (!lease) {
@@ -170,7 +183,14 @@ uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
                        if (!oldest_lease || lease->expires < oldest_lease->expires)
                                oldest_lease = lease;
                }
-       }
+
+ next_addr:
+               addr++;
+#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
+               if (addr > server_config.end_ip)
+                       addr = server_config.start_ip;
+#endif
+       } while (addr != stop);
 
        if (oldest_lease
         && is_expired_lease(oldest_lease)