dhcpv4: fix DHCPv4 hostname handling

Fix hostname not being reported as "-" in the DHCP statefile in case
no hostname is reported by the DHCPv4 client
(https://:wqgithub.com/openwrt/odhcpd/issues/94)

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 509b09230c5431d8582d1debc3415c082ccddd13..9d9ed92a5135461c18e9ecf0871123d079053886 100644 (file)
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -1,5 +1,6 @@
 /**
  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
+ * Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License v2 as published by
@@ -32,12 +33,12 @@
 #include "dhcpv4.h"
 #include "dhcpv6.h"
 
-
+static void free_dhcpv4_assignment(struct dhcpv4_assignment *a);
 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,
-               uint32_t *leasetime, const char *hostname);
+               uint32_t *leasetime, const char *hostname, const size_t hostname_len);
 
 // Create socket and register events
 int init_dhcpv4(void)
@@ -169,8 +170,7 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                struct lease *lease;
                list_for_each_entry(lease, &leases, head) {
                        // Construct entry
-                       size_t hostlen = strlen(lease->hostname) + 1;
-                       struct dhcpv4_assignment *a = calloc(1, sizeof(*a) + hostlen);
+                       struct dhcpv4_assignment *a = calloc(1, sizeof(*a));
                        if (!a) {
                                syslog(LOG_ERR, "Calloc failed for static lease on interface %s",
                                        iface->ifname);
@@ -178,9 +178,9 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                        }
                        if (lease->dhcpv4_leasetime >= 60)
                                a->leasetime = lease->dhcpv4_leasetime;
+
                        a->addr = ntohl(lease->ipaddr.s_addr);
                        memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
-                       memcpy(a->hostname, lease->hostname, hostlen);
                        /* Static assignment */
                        a->flags |= OAF_STATIC;
                        /* Infinite valid */
@@ -201,18 +201,21 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                                list_add(&a->head, &iface->dhcpv4_assignments);
                        }
 
-                       if (!a->head.next)
-                               free(a);
+                       if (a->head.next) {
+                               if (lease->hostname[0]) {
+                                       free(a->hostname);
+                                       a->hostname = strdup(lease->hostname);
+                               }
+                       } else
+                               free_dhcpv4_assignment(a);
                }
 
                // Clean invalid assignments
                struct dhcpv4_assignment *a, *n;
                list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
                        if ((htonl(a->addr) & smask->sin_addr.s_addr) !=
-                                       (iface->dhcpv4_start.s_addr & smask->sin_addr.s_addr)) {
-                               list_del(&a->head);
-                               free(a);
-                       }
+                                       (iface->dhcpv4_start.s_addr & smask->sin_addr.s_addr))
+                               free_dhcpv4_assignment(a);
                }
 
 
@@ -223,17 +226,21 @@ int setup_dhcpv4_interface(struct interface *iface, bool enable)
                iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
                odhcpd_register(&iface->dhcpv4_event);
        } else if (iface->dhcpv4_assignments.next) {
-               while (!list_empty(&iface->dhcpv4_assignments)) {
-                       struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
-                                       struct dhcpv4_assignment, head);
-                       list_del(&a->head);
-                       free(a);
-               }
-
+               while (!list_empty(&iface->dhcpv4_assignments))
+                       free_dhcpv4_assignment(list_first_entry(&iface->dhcpv4_assignments,
+                                                       struct dhcpv4_assignment, head));
        }
        return 0;
 }
 
+static void free_dhcpv4_assignment(struct dhcpv4_assignment *a)
+{
+       if (a->head.next)
+               list_del(&a->head);
+
+       free(a->hostname);
+       free(a);
+}
 
 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
                uint8_t type, uint8_t len, const void *data)
@@ -315,8 +322,8 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 
        struct in_addr reqaddr = {INADDR_ANY};
        uint32_t leasetime = 0;
+       size_t hostname_len = 0;
        char hostname[256];
-       hostname[0] = 0;
 
        uint8_t *start = &req->options[4];
        uint8_t *end = ((uint8_t*)data) + len;
@@ -325,8 +332,9 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
                if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1) {
                        reqmsg = opt->data[0];
                } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
-                       memcpy(hostname, opt->data, opt->len);
-                       hostname[opt->len] = 0;
+                       hostname_len = opt->len;
+                       memcpy(hostname, opt->data, hostname_len);
+                       hostname[hostname_len] = 0;
                } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4) {
                        memcpy(&reqaddr, opt->data, 4);
                } else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
@@ -350,7 +358,8 @@ 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, &leasetime, hostname);
+               lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
+                                       &leasetime, hostname, hostname_len);
 
        if (!lease) {
                if (reqmsg == DHCPV4_MSG_REQUEST)
@@ -403,7 +412,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 
                dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr);
 
-               if (lease->hostname[0])
+               if (lease->hostname)
                        dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
                                        strlen(lease->hostname), lease->hostname);
 
@@ -585,7 +594,7 @@ 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,
-               uint32_t *leasetime, const char *hostname)
+               uint32_t *leasetime, const char *hostname, const size_t hostname_len)
 {
        struct dhcpv4_assignment *lease = NULL;
        uint32_t raddr = ntohl(reqaddr.s_addr);
@@ -597,44 +606,27 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                        a = c;
                        if (c->addr == raddr)
                                break;
-               } else if (!INFINITE_VALID(c->valid_until) && c->valid_until < now) {
-                       list_del(&c->head);
-                       free(c);
-               }
+               } else if (!INFINITE_VALID(c->valid_until) && c->valid_until < now)
+                       free_dhcpv4_assignment(c);
        }
 
        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);
+                       a = calloc(1, sizeof(*a));
                        if (!a) {
                                syslog(LOG_ERR, "Failed to calloc binding on interface %s", iface->ifname);
                                return NULL;
                        }
                        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);
                }
 
-               if (assigned && !a->hostname[0] && hostname) {
-                       a = realloc(a, sizeof(*a) + hostlen);
-                       if (!a) {
-                               syslog(LOG_ERR, "Failed to realloc binding on interface %s", iface->ifname);
-                               return NULL;
-                       }
-                       memcpy(a->hostname, hostname, hostlen);
-
-                       // Fixup list
-                       a->head.next->prev = &a->head;
-                       a->head.prev->next = &a->head;
-               }
-
                if (a->leasetime >= 60) {
                        my_leasetime = a->leasetime;
                } else {
@@ -651,13 +643,21 @@ static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
                                if (!(a->flags & OAF_STATIC))
                                        a->valid_until = now;
                        } else {
+                               if (hostname_len > 0) {
+                                       a->hostname = realloc(a->hostname, hostname_len + 1);
+                                       if (a->hostname) {
+                                               memcpy(a->hostname, hostname, hostname_len);
+                                               a->hostname[hostname_len] = 0;
+                                       }
+                               }
+
                                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);
+                       free_dhcpv4_assignment(a);
                        a = NULL;
                }
 

diff --git a/src/dhcpv4.h b/src/dhcpv4.h
index cd6c978431e54e4c4245a0ca1c751dc48d16bc7d..4d14f094cc5848d0e7feb26e8573f4df9cd5daca 100644 (file)
--- a/src/dhcpv4.h
+++ b/src/dhcpv4.h
@@ -1,5 +1,6 @@
 /**
  *   Copyright (C) 2012 Steven Barth <steven@midlink.org>
+ *   Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License version 2
@@ -80,7 +81,7 @@ struct dhcpv4_assignment {
        uint8_t hwaddr[6];
        uint32_t leasetime;
        unsigned int flags;
-       char hostname[];
+       char *hostname;
 };
 
 struct dhcpv4_option {

diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
index a7146a767960cde012f1962a5e014f64e6a4c272..b0a0adadf32630b66f730bd7fe550f170ae06899 100644 (file)
--- a/src/dhcpv6-ia.c
+++ b/src/dhcpv6-ia.c
@@ -1,5 +1,6 @@
 /**
  * Copyright (C) 2013 Steven Barth <steven@midlink.org>
+ * Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License v2 as published by
@@ -324,7 +325,7 @@ void dhcpv6_write_statefile(void)
                                        struct in_addr addr = {htonl(c->addr)};
                                        inet_ntop(AF_INET, &addr, ipbuf, sizeof(ipbuf) - 1);
 
-                                       if (c->hostname[0]) {
+                                       if (c->hostname) {
                                                fputs(ipbuf, fp);
 
                                                char b[256];