import of dnsmasq-2.0.tar.gz

src/rfc2131.c

@@ -0,0 +1,499 @@
+/* dnsmasq is Copyright (c) 2000-2003 Simon Kelley
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 dated June, 1991.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+*/
+
+/* Author's email: simon@thekelleys.org.uk */
+
+#include "dnsmasq.h"
+
+#define BOOTREQUEST              1
+#define BOOTREPLY                2
+#define DHCP_COOKIE              0x63825363
+
+#define OPTION_PAD               0
+#define OPTION_NETMASK           1
+#define OPTION_ROUTER            3
+#define OPTION_DNSSERVER         6
+#define OPTION_HOSTNAME          12
+#define OPTION_DOMAINNAME        15
+#define OPTION_BROADCAST         28
+#define OPTION_CLIENT_ID         61
+#define OPTION_REQUESTED_IP      50 
+#define OPTION_LEASE_TIME        51
+#define OPTION_OVERLOAD          52
+#define OPTION_MESSAGE_TYPE      53
+#define OPTION_SERVER_IDENTIFIER 54
+#define OPTION_REQUESTED_OPTIONS 55
+#define OPTION_MAXMESSAGE        57
+#define OPTION_END               255
+
+#define DHCPDISCOVER             1
+#define DHCPOFFER                2
+#define DHCPREQUEST              3
+#define DHCPDECLINE              4
+#define DHCPACK                  5
+#define DHCPNAK                  6
+#define DHCPRELEASE              7
+#define DHCPINFORM               8
+
+static unsigned char *option_put(unsigned char *p, unsigned char *end, int opt, int len, unsigned int val);
+static void bootp_option_put(struct dhcp_packet *mess, char *filename, char *sname);
+static int option_len(unsigned char *opt);
+static void *option_ptr(unsigned char *opt);
+static struct in_addr option_addr(unsigned char *opt);
+static unsigned int option_uint(unsigned char *opt);
+static void log_packet(char *type, struct in_addr *addr, unsigned char *hwaddr, char *interface);
+static unsigned char *option_find(struct dhcp_packet *mess, int size, int opt_type);
+static unsigned char *do_req_options(struct dhcp_context *context,
+				     unsigned char *p, unsigned char *end, 
+				     unsigned char *req_options, 
+				     struct dhcp_opt *config_opts,
+				     char *domainname, char *hostname);
+
+
+int dhcp_reply(struct dhcp_context *context, struct dhcp_packet *mess,
+	       unsigned int sz, time_t now, char *namebuff, 
+	       struct dhcp_opt *dhcp_opts, struct dhcp_config *dhcp_configs, 
+	       char *domain_suffix, char *dhcp_file, char *dhcp_sname, 
+	       struct in_addr dhcp_next_server)
+{
+  unsigned char *opt, *clid;
+  struct dhcp_lease *lease;
+  int clid_len;
+  unsigned char *p = mess->options;
+  char *hostname = NULL;
+  char *req_options = NULL;
+  unsigned int renewal_time, expires_time, def_time;
+  struct dhcp_config *config;
+ 
+  if (mess->op != BOOTREQUEST || 
+      mess->htype != ARPHRD_ETHER || 
+      mess->hlen != ETHER_ADDR_LEN ||
+      mess->cookie != htonl(DHCP_COOKIE))
+    return 0;	
+  
+  mess->op = BOOTREPLY;
+
+  /* If there is no client identifier option, use the hardware address */
+  if ((opt = option_find(mess, sz, OPTION_CLIENT_ID)))
+    {
+      clid = option_ptr(opt);
+      clid_len = option_len(opt);
+    }
+  else
+    {
+      clid =  mess->chaddr;
+      clid_len = 0;
+    }
+  
+  /* do we have a lease in store? */
+  lease = lease_find_by_client(clid, clid_len);
+  
+  if ((opt = option_find(mess, sz, OPTION_REQUESTED_OPTIONS)))
+    {
+      int len = option_len(opt);
+      req_options = namebuff;
+      memcpy(req_options, option_ptr(opt), len);
+      req_options[len] = OPTION_END;
+    }
+
+  if ((config = find_config(dhcp_configs, context, clid, clid_len, mess->chaddr, NULL)) && 
+      config->hostname)
+    hostname = config->hostname;
+  else if ((opt = option_find(mess, sz, OPTION_HOSTNAME)))
+    {
+      int len = option_len(opt);
+      /* namebuff is 1K long, use half for requested options and half for hostname */
+      /* len < 256 by definition */
+      hostname = namebuff + 500;
+      memcpy(hostname, option_ptr(opt), len);
+      /* May not be zero terminated */
+      hostname[len] = 0;
+      /* ensure there are no strange chars in there */
+      if (!canonicalise(hostname))
+	hostname = NULL;
+    }
+
+  if (hostname)
+    {
+      char *dot = strchr(hostname, '.');
+      if (dot)
+	{
+	  if (!domain_suffix || !hostname_isequal(dot+1, domain_suffix))
+	    {
+	      syslog(LOG_WARNING, "Ignoring DHCP host name %s because it has an illegal domain part", hostname);
+	      hostname = NULL;
+	    }
+	  else
+	    *dot = 0; /* truncate */
+	}
+    }
+     
+  /* search again now we have a hostname */
+  config = find_config(dhcp_configs, context, clid, clid_len, mess->chaddr, hostname);
+  def_time = config ? config->lease_time : context->lease_time;
+  
+  if ((opt = option_find(mess, sz, OPTION_LEASE_TIME)))
+    {
+      unsigned int req_time = option_uint(opt);
+        
+      if (def_time == 0xffffffff || 
+	  (req_time != 0xffffffff && req_time < def_time))
+	expires_time = renewal_time = req_time;
+      else
+	expires_time = renewal_time = def_time;
+    }
+  else
+    {
+      renewal_time = def_time;
+      if (lease)
+	expires_time = (unsigned int)difftime(lease->expires, now);
+      else 
+	expires_time = def_time;
+    }
+ 
+  if (!(opt = option_find(mess, sz, OPTION_MESSAGE_TYPE)))
+    return 0;
+  
+  switch (opt[2])
+    {
+    case DHCPRELEASE:
+      if (lease)
+	{
+	  log_packet("RELEASE", &lease->addr, mess->chaddr, context->iface);
+	  lease_prune(lease, now);
+	}
+      return 0;
+      
+    case DHCPDISCOVER:
+            
+      if ((opt = option_find(mess, sz, OPTION_REQUESTED_IP)))	 
+	mess->yiaddr = option_addr(opt);
+      
+      log_packet("DISCOVER", opt ? &mess->yiaddr : NULL, mess->chaddr, context->iface);
+      
+      if (lease)
+	mess->yiaddr = lease->addr;
+      else if (config && config->addr.s_addr && !lease_find_by_addr(config->addr))
+	mess->yiaddr = config->addr;
+      else if ((!opt || !address_available(context, mess->yiaddr)) &&
+	       !address_allocate(context, dhcp_configs, &mess->yiaddr))
+	{
+	  syslog(LOG_WARNING, "address pool exhausted");
+	  return 0;
+	}
+	            
+      bootp_option_put(mess, dhcp_file, dhcp_sname);
+      mess->siaddr = dhcp_next_server;
+      p = option_put(p, &mess->options[308], OPTION_MESSAGE_TYPE, 1, DHCPOFFER);
+      p = option_put(p, &mess->options[308], OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->serv_addr.s_addr));
+      p = option_put(p, &mess->options[308], OPTION_LEASE_TIME, 4, expires_time);
+      p = do_req_options(context, p, &mess->options[308], req_options, dhcp_opts, domain_suffix, NULL);
+      p = option_put(p, &mess->options[308], OPTION_END, 0, 0);
+      
+      log_packet("OFFER" , &mess->yiaddr, mess->chaddr, context->iface);
+      return p - (unsigned char *)mess;
+
+      
+    case DHCPREQUEST:
+      if (mess->ciaddr.s_addr)
+	{
+	  /* RENEWING or REBINDING */ 
+	  /* Must exist a lease for this address */
+	  log_packet("REQUEST", &mess->ciaddr, mess->chaddr, context->iface);
+	  
+	  if (!lease || mess->ciaddr.s_addr != lease->addr.s_addr)
+	    {
+	      log_packet("NAK", &mess->ciaddr, mess->chaddr, context->iface);
+	      
+	      mess->siaddr.s_addr = mess->yiaddr.s_addr = mess->ciaddr.s_addr = 0;
+	      bootp_option_put(mess, NULL, NULL);
+	      p = option_put(p, &mess->options[308], OPTION_MESSAGE_TYPE, 1, DHCPNAK);
+	      p = option_put(p, &mess->options[308], OPTION_END, 0, 0);
+	      
+	      return (unsigned char *)mess - p; /* -ve to force bcast */
+	    }
+	  
+	  mess->yiaddr = mess->ciaddr;
+	}
+      else
+	{
+	  /* SELECTING  or INIT_REBOOT */
+	  if ((opt = option_find(mess, sz, OPTION_SERVER_IDENTIFIER)) &&
+	      (context->serv_addr.s_addr != option_addr(opt).s_addr))
+	    return 0;
+	  
+	  if (!(opt = option_find(mess, sz, OPTION_REQUESTED_IP)))
+	    return 0;
+	  
+	  mess->yiaddr = option_addr(opt);
+	  log_packet("REQUEST", &mess->yiaddr, mess->chaddr, context->iface);
+	  
+	  /* If a lease exists for this host and another address, squash it. */
+	  if (lease && lease->addr.s_addr != mess->yiaddr.s_addr)
+	    {
+	      lease_prune(lease, now);
+	      lease = NULL;
+	    }
+	  
+	  /* accept addresses in the dynamic range or ones allocated statically to
+	     particular hosts or an address which the host already has. */
+	  if (!lease &&
+	      !address_available(context, mess->yiaddr) && 
+	      (!config || config->addr.s_addr == 0 || config->addr.s_addr != mess->yiaddr.s_addr))
+	    {
+	      log_packet("NAK", &mess->yiaddr, mess->chaddr, context->iface);
+	      
+	      mess->siaddr.s_addr = mess->yiaddr.s_addr = mess->ciaddr.s_addr = 0;
+	      bootp_option_put(mess, NULL, NULL);
+	      p = option_put(p, &mess->options[308], OPTION_MESSAGE_TYPE, 1, DHCPNAK);
+	      p = option_put(p, &mess->options[308], OPTION_END, 0, 0);
+	      
+	      return (unsigned char *)mess - p; /* -ve to force bcast */
+	    }
+	  
+	  if (!lease && 
+	      !(lease = lease_allocate(clid, clid_len, mess->yiaddr)))
+	    return 0;
+	}	    
+      
+      lease_set_hwaddr(lease, mess->chaddr);
+      lease_set_hostname(lease, hostname, domain_suffix);
+      lease_set_expires(lease, renewal_time == 0xffffffff ? 0 : now + (time_t)renewal_time);
+      
+      bootp_option_put(mess, dhcp_file, dhcp_sname);
+      mess->siaddr = dhcp_next_server;
+      p = option_put(p, &mess->options[308], OPTION_MESSAGE_TYPE, 1, DHCPACK);
+      p = option_put(p, &mess->options[308], OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->serv_addr.s_addr));
+      p = option_put(p, &mess->options[308], OPTION_LEASE_TIME, 4, renewal_time);
+      p = do_req_options(context, p, &mess->options[308], req_options, dhcp_opts, domain_suffix, hostname);
+      p = option_put(p, &mess->options[308], OPTION_END, 0, 0);
+      
+      log_packet("ACK", &mess->yiaddr, mess->chaddr, context->iface);
+      return p - (unsigned char *)mess; 
+      
+    case DHCPINFORM:
+      log_packet("INFORM", &mess->ciaddr, mess->chaddr, context->iface);
+      
+      p = option_put(p, &mess->options[308], OPTION_MESSAGE_TYPE, 1, DHCPACK);
+      p = option_put(p, &mess->options[308], OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(context->serv_addr.s_addr));
+      p = do_req_options(context, p, &mess->options[308], req_options, dhcp_opts, domain_suffix, hostname);
+      p = option_put(p, &mess->options[308], OPTION_END, 0, 0);
+      
+      log_packet("ACK", &mess->ciaddr, mess->chaddr, context->iface);
+      return p - (unsigned char *)mess; 
+    }
+  
+  return 0;
+}
+
+static void log_packet(char *type, struct in_addr *addr, unsigned char *hwaddr, char *interface)
+{
+  syslog(LOG_INFO, "DHCP%s(%s)%s%s hwaddr=%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
+	 type,
+	 interface, 
+	 addr ? " " : "",
+	 addr ? inet_ntoa(*addr) : "",
+	 hwaddr[0], hwaddr[1], hwaddr[2], hwaddr[3], hwaddr[4], hwaddr[5]);
+}
+
+static int option_len(unsigned char *opt)
+{
+  return opt[1];
+}
+
+static void *option_ptr(unsigned char *opt)
+{
+  return &opt[2];
+}
+
+static struct in_addr option_addr(unsigned char *opt)
+{
+  /* this worries about unaligned data in the option. */
+  /* struct in_addr is network byte order */
+  struct in_addr ret;
+
+  memcpy(&ret, option_ptr(opt), INADDRSZ);
+
+  return ret;
+}
+
+static unsigned int option_uint(unsigned char *opt)
+{
+  /* this worries about unaligned data and byte order */
+  unsigned int ret;
+
+  memcpy(&ret, option_ptr(opt), sizeof(unsigned int));
+  
+  return ntohl(ret);
+}
+
+static void bootp_option_put(struct dhcp_packet *mess, char *filename, char *sname)
+{
+  memset(mess->sname, 0, sizeof(mess->sname));
+  memset(mess->file, 0, sizeof(mess->file));
+  if (sname)
+    strncpy(mess->sname, sname, sizeof(mess->sname)-1);
+  if (filename)
+    strncpy(mess->file, filename, sizeof(mess->file)-1);
+}
+
+static unsigned char *option_put(unsigned char *p, unsigned char *end, int opt, int len, unsigned int val)
+{
+  int i;
+
+  if (p + len + 2 < end)
+    {
+      *(p++) = opt;
+      *(p++) = len;
+      
+      for (i = 0; i < len; i++)
+	*(p++) = val >> (8 * (len - (i + 1)));
+    }
+  return p;
+}
+
+static unsigned char *option_find1(unsigned char *p, unsigned char *end, int opt, int *overload)
+{
+  
+  if (!p)
+    return NULL;
+  
+  while (*p != OPTION_END) 
+    {
+      if (end && (p >= end))
+	return 0; /* malformed packet */
+      else if (*p == OPTION_PAD)
+	p++;
+      else if (*p == OPTION_OVERLOAD)
+	{
+	  if (end && (p >= end - 3))
+	    return 0; /* malformed packet */
+	  if (overload) 
+	    *overload = *(p+2);
+	  p += 3;
+	}
+      else 
+	{ 
+	  int opt_len;;
+	  if (end && (p >= end - 2))
+	    return 0; /* malformed packet */
+	  opt_len = option_len(p);
+	  if (end && (p >= end - (2 + opt_len)))
+	    return 0; /* malformed packet */
+	  if (*p == opt)
+	    return p;
+	  p += opt_len + 2;
+	}
+    }
+  
+  return NULL;
+}
+ 
+static unsigned char *option_find(struct dhcp_packet *mess, int size, int opt_type)
+{
+  int overload = 0; 
+  unsigned char *ret;
+  
+  ret = option_find1(&mess->options[0], ((unsigned char *)mess) + size, opt_type, &overload);
+  
+  if (!ret && (overload & 1)) 
+    ret = option_find1(&mess->file[0], &mess->file[128], opt_type, &overload);
+
+  if (!ret && (overload & 2))
+    ret = option_find1(&mess->sname[0], &mess->file[64], opt_type, &overload);
+
+  return ret;
+}
+
+static int in_list(unsigned char *list, int opt)
+{
+  int i;
+  
+  for (i = 0; list[i] != OPTION_END; i++)
+    if (opt == list[i])
+      return 1;
+
+  return 0;
+}
+
+static struct dhcp_opt *option_find2(struct dhcp_opt *opts, int opt)
+{
+  for (; opts; opts = opts->next)
+    if (opts->opt == opt)
+      return opts;
+  return NULL;
+}
+
+static unsigned char *do_req_options(struct dhcp_context *context,
+				     unsigned char *p, unsigned char *end, 
+				     unsigned char *req_options,
+				     struct dhcp_opt *config_opts,
+				     char *domainname, char *hostname)
+{
+  int i;
+  
+  if (!req_options)
+    return p;
+
+  if (in_list(req_options, OPTION_NETMASK) &&
+      !option_find2(config_opts, OPTION_NETMASK))
+    p = option_put(p, end, OPTION_NETMASK, INADDRSZ, ntohl(context->netmask.s_addr));
+  
+  if (in_list(req_options, OPTION_BROADCAST) &&
+      !option_find2(config_opts, OPTION_BROADCAST))
+    p = option_put(p, end, OPTION_BROADCAST, INADDRSZ, ntohl(context->broadcast.s_addr));
+  
+  if (in_list(req_options, OPTION_ROUTER) &&
+      !option_find2(config_opts, OPTION_ROUTER))
+    p = option_put(p, end, OPTION_ROUTER, INADDRSZ, ntohl(context->serv_addr.s_addr));
+
+  if (in_list(req_options, OPTION_DNSSERVER) &&
+      !option_find2(config_opts, OPTION_DNSSERVER))
+    p = option_put(p, end, OPTION_DNSSERVER, INADDRSZ, ntohl(context->serv_addr.s_addr));
+  
+  if (in_list(req_options, OPTION_DOMAINNAME) && 
+      !option_find2(config_opts, OPTION_DOMAINNAME) &&
+      domainname && (p + strlen(domainname) + 2 < end))
+    {
+      *(p++) = OPTION_DOMAINNAME;
+      *(p++) = strlen(domainname);
+      memcpy(p, domainname, strlen(domainname));
+      p += strlen(domainname);
+    }
+ 
+  /* Note that we ignore attempts to set the hostname using 
+     --dhcp-option=12,<name> */
+  if (in_list(req_options, OPTION_HOSTNAME) && 
+       hostname && (p + strlen(hostname) + 2 < end))
+    {
+      *(p++) = OPTION_HOSTNAME;
+      *(p++) = strlen(hostname);
+      memcpy(p, hostname, strlen(hostname));
+      p += strlen(hostname);
+    }
+  
+  for (i = 0; req_options[i] != OPTION_END; i++)
+    {
+      struct dhcp_opt *opt = option_find2(config_opts, req_options[i]);
+      if (req_options[i] != OPTION_HOSTNAME && opt && (p + opt->len + 2 < end))
+	{
+	  *(p++) = opt->opt;
+	  *(p++) = opt->len;
+	  memcpy(p, opt->val, opt->len);
+	  p += opt->len;
+	}
+    }
+     
+  return p;
+}
+
+