/* dnsmasq is Copyright (c) 2000-2007 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.
*/

#define COPYRIGHT "Copyright (C) 2000-2007 Simon Kelley" 

/* get these before config.h  for IPv6 stuff... */
#include <sys/types.h> 
#include <netinet/in.h>

#ifdef __APPLE__
/* need this before arpa/nameser.h */
#  define BIND_8_COMPAT
#endif
#include <arpa/nameser.h>

/* and this. */
#include <getopt.h>

#include "config.h"

#define gettext_noop(S) (S)
#ifdef NO_GETTEXT
#  define _(S) (S)
#else
#  include <libintl.h>
#  include <locale.h>   
#  define _(S) gettext(S)
#endif

#include <arpa/inet.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <limits.h>
#include <net/if.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <ctype.h>
#include <signal.h>
#include <time.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <stdarg.h>
#if defined(__OpenBSD__) || defined(__NetBSD__)
#  include <netinet/if_ether.h>
#else
#  include <net/ethernet.h>
#endif
#include <net/if_arp.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <sys/uio.h>
#include <syslog.h>
#include <dirent.h>
#ifndef HAVE_LINUX_NETWORK
#  include <net/if_dl.h>
#endif

#ifdef HAVE_LINUX_NETWORK
#include <linux/capability.h>
/* There doesn't seem to be a universally-available 
   userpace header for this. */
extern int capset(cap_user_header_t header, cap_user_data_t data);
#include <sys/prctl.h>
#endif

/* Min buffer size: we check after adding each record, so there must be 
   memory for the largest packet, and the largest record so the
   min for DNS is PACKETSZ+MAXDNAME+RRFIXEDSZ which is < 1000.
   This might be increased is EDNS packet size if greater than the minimum.
*/
#define DNSMASQ_PACKETSZ PACKETSZ+MAXDNAME+RRFIXEDSZ

#define OPT_BOGUSPRIV      (1<<0)
#define OPT_FILTER         (1<<1)
#define OPT_LOG            (1<<2)
#define OPT_SELFMX         (1<<3)
#define OPT_NO_HOSTS       (1<<4)
#define OPT_NO_POLL        (1<<5)
#define OPT_DEBUG          (1<<6)
#define OPT_ORDER          (1<<7)
#define OPT_NO_RESOLV      (1<<8)
#define OPT_EXPAND         (1<<9)
#define OPT_LOCALMX        (1<<10)
#define OPT_NO_NEG         (1<<11)
#define OPT_NODOTS_LOCAL   (1<<12)
#define OPT_NOWILD         (1<<13)
#define OPT_ETHERS         (1<<14)
#define OPT_RESOLV_DOMAIN  (1<<15)
#define OPT_NO_FORK        (1<<16)
#define OPT_AUTHORITATIVE  (1<<17)
#define OPT_LOCALISE       (1<<18)
#define OPT_DBUS           (1<<19)
#define OPT_BOOTP_DYNAMIC  (1<<20)
#define OPT_NO_PING        (1<<21)
#define OPT_LEASE_RO       (1<<22)
#define OPT_RELOAD         (1<<24)
#define OPT_TFTP           (1<<25)
#define OPT_TFTP_SECURE    (1<<26)

struct all_addr {
  union {
    struct in_addr addr4;
#ifdef HAVE_IPV6
    struct in6_addr addr6;
#endif
  } addr;
};

struct bogus_addr {
  struct in_addr addr;
  struct bogus_addr *next;
};

/* dns doctor param */
struct doctor {
  struct in_addr in, out, mask;
  struct doctor *next;
};

struct mx_srv_record {
  char *name, *target;
  int issrv, srvport, priority, weight;
  unsigned int offset;
  struct mx_srv_record *next;
};

struct txt_record {
  char *name, *txt;
  unsigned short class, len;
  struct txt_record *next;
};

struct ptr_record {
  char *name, *ptr;
  struct ptr_record *next;
};

union bigname {
  char name[MAXDNAME];
  union bigname *next; /* freelist */
};

struct crec { 
  struct crec *next, *prev, *hash_next;
  time_t ttd; /* time to die */
  int uid; 
  union {
    struct all_addr addr;
    struct {
      struct crec *cache;
      int uid;
    } cname;
  } addr;
  unsigned short flags;
  union {
    char sname[SMALLDNAME];
    union bigname *bname;
    char *namep;
  } name;
};

#define F_IMMORTAL  1
#define F_CONFIG    2
#define F_REVERSE   4
#define F_FORWARD   8
#define F_DHCP      16 
#define F_NEG       32       
#define F_HOSTS     64
#define F_IPV4      128
#define F_IPV6      256
#define F_BIGNAME   512
#define F_UPSTREAM  1024
#define F_SERVER    2048
#define F_NXDOMAIN  4096
#define F_QUERY     8192
#define F_CNAME     16384
#define F_NOERR     32768

/* struct sockaddr is not large enough to hold any address,
   and specifically not big enough to hold an IPv6 address.
   Blech. Roll our own. */
union mysockaddr {
  struct sockaddr sa;
  struct sockaddr_in in;
#ifdef HAVE_BROKEN_SOCKADDR_IN6
  /* early versions of glibc don't include sin6_scope_id in sockaddr_in6
     but latest kernels _require_ it to be set. The choice is to have
     dnsmasq fail to compile on back-level libc or fail to run
     on latest kernels with IPv6. Or to do this: sorry that it's so gross. */
  struct my_sockaddr_in6 {
    sa_family_t     sin6_family;    /* AF_INET6 */
    uint16_t        sin6_port;      /* transport layer port # */
    uint32_t        sin6_flowinfo;  /* IPv6 traffic class & flow info */
    struct in6_addr sin6_addr;      /* IPv6 address */
    uint32_t        sin6_scope_id;  /* set of interfaces for a scope */
  } in6;
#elif defined(HAVE_IPV6)
  struct sockaddr_in6 in6;
#endif
};

#define SERV_FROM_RESOLV       1  /* 1 for servers from resolv, 0 for command line. */
#define SERV_NO_ADDR           2  /* no server, this domain is local only */
#define SERV_LITERAL_ADDRESS   4  /* addr is the answer, not the server */ 
#define SERV_HAS_SOURCE        8  /* source address specified */
#define SERV_HAS_DOMAIN       16  /* server for one domain only */
#define SERV_FOR_NODOTS       32  /* server for names with no domain part only */
#define SERV_WARNED_RECURSIVE 64  /* avoid warning spam */
#define SERV_FROM_DBUS       128  /* 1 if source is DBus */
#define SERV_MARK            256  /* for mark-and-delete */
#define SERV_TYPE    (SERV_HAS_DOMAIN | SERV_FOR_NODOTS)


struct serverfd {
  int fd;
  union mysockaddr source_addr;
  struct serverfd *next;
};

struct server {
  union mysockaddr addr, source_addr;
  struct serverfd *sfd; 
  char *domain; /* set if this server only handles a domain. */ 
  int flags, tcpfd;
  struct server *next; 
};

struct irec {
  union mysockaddr addr;
  struct in_addr netmask; /* only valid for IPv4 */
  int dhcp_ok;
  struct irec *next;
};

struct listener {
  int fd, tcpfd, tftpfd, family;
  struct irec *iface; /* only valid for non-wildcard */
  struct listener *next;
};

/* interface and address parms from command line. */
struct iname {
  char *name;
  union mysockaddr addr;
  int isloop, used;
  struct iname *next;
};

/* resolv-file parms from command-line */
struct resolvc {
  struct resolvc *next;
  int is_default, logged;
  time_t mtime;
  char *name;
};

/* adn-hosts parms from command-line */
struct hostsfile {
  struct hostsfile *next;
  char *fname;
  int index; /* matches to cache entries for logging */
};

struct frec {
  union mysockaddr source;
  struct all_addr dest;
  struct server *sentto; /* NULL means free */
  unsigned int iface;
  unsigned short orig_id, new_id;
  int fd, forwardall;
  unsigned int crc;
  time_t time;
  struct frec *next;
};

/* actions in the daemon->helper RPC */
#define ACTION_DEL           1
#define ACTION_OLD_HOSTNAME  2
#define ACTION_OLD           3
#define ACTION_ADD           4

#define DHCP_CHADDR_MAX 16

struct dhcp_lease {
  int clid_len;          /* length of client identifier */
  unsigned char *clid;   /* clientid */
  char *hostname, *fqdn; /* name from client-hostname option or config */
  char *old_hostname;    /* hostname before it moved to another lease */
  char auth_name;        /* hostname came from config, not from client */
  char new;              /* newly created */
  char changed;          /* modified */
  char aux_changed;      /* CLID or expiry changed */
  time_t expires;        /* lease expiry */
#ifdef HAVE_BROKEN_RTC
  unsigned int length;
#endif
  int hwaddr_len, hwaddr_type;
  unsigned char hwaddr[DHCP_CHADDR_MAX]; 
  struct in_addr addr;
  unsigned char *vendorclass, *userclass;
  unsigned int vendorclass_len, userclass_len;
  struct dhcp_lease *next;
};

struct dhcp_netid {
  char *net;
  struct dhcp_netid *next;
};

struct dhcp_netid_list {
  struct dhcp_netid *list;
  struct dhcp_netid_list *next;
};

struct dhcp_config {
  unsigned int flags;
  int clid_len;          /* length of client identifier */
  unsigned char *clid;   /* clientid */
  int hwaddr_len, hwaddr_type;
  unsigned char hwaddr[DHCP_CHADDR_MAX]; 
  char *hostname;
  struct dhcp_netid netid;
  struct in_addr addr;
  time_t decline_time;
  unsigned int lease_time, wildcard_mask;
  struct dhcp_config *next;
};

#define CONFIG_DISABLE           1
#define CONFIG_CLID              2
#define CONFIG_HWADDR            4
#define CONFIG_TIME              8
#define CONFIG_NAME             16
#define CONFIG_ADDR             32
#define CONFIG_NETID            64
#define CONFIG_NOCLID          128
#define CONFIG_FROM_ETHERS     256    /* entry created by /etc/ethers */
#define CONFIG_ADDR_HOSTS      512    /* address added by from /etc/hosts */
#define CONFIG_DECLINED       1024    /* address declined by client */

struct dhcp_opt {
  int opt, len, flags;
  unsigned char *val, *vendor_class;
  struct dhcp_netid *netid;
  struct dhcp_opt *next;
};

#define DHOPT_ADDR               1
#define DHOPT_STRING             2
#define DHOPT_VENDOR_MATCH       4

struct dhcp_boot {
  char *file, *sname;
  struct in_addr next_server;
  struct dhcp_netid *netid;
  struct dhcp_boot *next;
};

struct dhcp_vendor {
  int len, is_vendor;
  char *data;
  struct dhcp_netid netid;
  struct dhcp_vendor *next;
};

struct dhcp_mac {
  unsigned int mask;
  int hwaddr_len, hwaddr_type;
  unsigned char hwaddr[DHCP_CHADDR_MAX];
  struct dhcp_netid netid;
  struct dhcp_mac *next;
};

#if defined(__FreeBSD__) || defined(__DragonFly__)
struct dhcp_bridge {
  char iface[IF_NAMESIZE];
  struct dhcp_bridge *alias, *next;
};
#endif

struct dhcp_context {
  unsigned int lease_time, addr_epoch;
  struct in_addr netmask, broadcast;
  struct in_addr local, router;
  struct in_addr start, end; /* range of available addresses */
  int flags;
  struct dhcp_netid netid, *filter;
  struct dhcp_context *next, *current;
};

#define CONTEXT_STATIC    1
#define CONTEXT_NETMASK   2
#define CONTEXT_BRDCAST   4


typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;


struct dhcp_packet {
  u8 op, htype, hlen, hops;
  u32 xid;
  u16 secs, flags;
  struct in_addr ciaddr, yiaddr, siaddr, giaddr;
  u8 chaddr[DHCP_CHADDR_MAX], sname[64], file[128];
  u8 options[312];
};

struct ping_result {
  struct in_addr addr;
  time_t time;
  struct ping_result *next;
};

struct tftp_file {
  int refcount, fd;
  off_t size;
  char filename[];
};

struct tftp_transfer {
  int sockfd;
  time_t timeout;
  int backoff;
  unsigned int block, blocksize;
  struct sockaddr_in peer;
  char opt_blocksize, opt_transize;
  struct tftp_file *file;
  struct tftp_transfer *next;
};

struct daemon {
  /* datastuctures representing the command-line and 
     config file arguments. All set (including defaults)
     in option.c */

  unsigned int options;
  struct resolvc default_resolv, *resolv_files;
  struct mx_srv_record *mxnames;
  struct txt_record *txt;
  struct ptr_record *ptr;
  char *mxtarget;
  char *lease_file; 
  char *username, *groupname;
  char *domain_suffix;
  char *runfile; 
  char *lease_change_command;
  struct iname *if_names, *if_addrs, *if_except, *dhcp_except;
  struct bogus_addr *bogus_addr;
  struct server *servers;
  int log_fac; /* log facility */
  int cachesize, ftabsize;
  int port, query_port;
  unsigned long local_ttl;
  struct hostsfile *addn_hosts;
  struct dhcp_context *dhcp;
  struct dhcp_config *dhcp_conf;
  struct dhcp_opt *dhcp_opts, *vendor_opts;
  struct dhcp_vendor *dhcp_vendors;
  struct dhcp_mac *dhcp_macs;
  struct dhcp_boot *boot_config;
  struct dhcp_netid_list *dhcp_ignore, *dhcp_ignore_names;
  int dhcp_max, tftp_max; 
  unsigned int min_leasetime;
  struct doctor *doctors;
  unsigned short edns_pktsz;

  /* globally used stuff for DNS */
  char *packet; /* packet buffer */
  int packet_buff_sz; /* size of above */
  char *namebuff; /* MAXDNAME size buffer */
  struct serverfd *sfds;
  struct irec *interfaces;
  struct listener *listeners;
  struct server *last_server;
  struct server *srv_save; /* Used for resend on DoD */
  size_t packet_len;       /*      "        "        */
  pid_t tcp_pids[MAX_PROCS];
 
  /* DHCP state */
  int dhcpfd, helperfd; 
#ifdef HAVE_LINUX_NETWORK
  int netlinkfd;
#else
  int dhcp_raw_fd, dhcp_icmp_fd;
#endif
  struct iovec dhcp_packet;
  char *dhcp_buff, *dhcp_buff2;
  struct ping_result *ping_results;
  FILE *lease_stream;
#if defined(__FreeBSD__) || defined(__DragonFly__)
  struct dhcp_bridge *bridges;
#endif

  /* DBus stuff */
  /* void * here to avoid depending on dbus headers outside dbus.c */
  void *dbus;
#ifdef HAVE_DBUS
  struct watch *watches;
#endif

  /* TFTP stuff */
  struct tftp_transfer *tftp_trans;
  char *tftp_prefix; 
};

/* cache.c */
void cache_init(int cachesize, int log);
void log_query(unsigned short flags, char *name, struct all_addr *addr, 
	       unsigned short type, struct hostsfile *addn_hosts, int index);
struct crec *cache_find_by_addr(struct crec *crecp,
				struct all_addr *addr, time_t now, 
				unsigned short prot);
struct crec *cache_find_by_name(struct crec *crecp, 
				char *name, time_t now, unsigned short  prot);
void cache_end_insert(void);
void cache_start_insert(void);
struct crec *cache_insert(char *name, struct all_addr *addr,
			  time_t now, unsigned long ttl, unsigned short flags);
void cache_reload(int opts, char *buff, char *domain_suffix, struct hostsfile  *addn_hosts);
void cache_add_dhcp_entry(struct daemon *daemon, char *host_name, struct in_addr *host_address, time_t ttd);
void cache_unhash_dhcp(void);
void dump_cache(struct daemon *daemon, time_t now);
char *cache_get_name(struct crec *crecp);

/* rfc1035.c */
unsigned short extract_request(HEADER *header, size_t qlen, 
			       char *name, unsigned short *typep);
size_t setup_reply(HEADER *header, size_t  qlen,
		   struct all_addr *addrp, unsigned short flags,
		   unsigned long local_ttl);
void extract_addresses(HEADER *header, size_t qlen, char *namebuff, 
		       time_t now, struct daemon *daemon);
size_t answer_request(HEADER *header, char *limit, size_t qlen, struct daemon *daemon, 
		   struct in_addr local_addr, struct in_addr local_netmask, time_t now);
int check_for_bogus_wildcard(HEADER *header, size_t qlen, char *name, 
			     struct bogus_addr *addr, time_t now);
unsigned char *find_pseudoheader(HEADER *header, size_t plen,
				 size_t *len, unsigned char **p, int *is_sign);
int check_for_local_domain(char *name, time_t now, struct daemon *daemon);
unsigned int questions_crc(HEADER *header, size_t plen, char *buff);
size_t resize_packet(HEADER *header, size_t plen, 
		  unsigned char *pheader, size_t hlen);

/* util.c */
unsigned short rand16(void);
int legal_char(char c);
int canonicalise(char *s);
unsigned char *do_rfc1035_name(unsigned char *p, char *sval);
void die(char *message, char *arg1);
void complain(char *message, int lineno, char *file);
void *safe_malloc(size_t size);
int sa_len(union mysockaddr *addr);
int sockaddr_isequal(union mysockaddr *s1, union mysockaddr *s2);
int hostname_isequal(char *a, char *b);
time_t dnsmasq_time(void);
int is_same_net(struct in_addr a, struct in_addr b, struct in_addr mask);
int retry_send(void);
void prettyprint_time(char *buf, unsigned int t);
int prettyprint_addr(union mysockaddr *addr, char *buf);
int parse_hex(char *in, unsigned char *out, int maxlen, 
	      unsigned int *wildcard_mask, int *mac_type);
int memcmp_masked(unsigned char *a, unsigned char *b, int len, 
		  unsigned int mask);
int expand_buf(struct iovec *iov, size_t size);
char *print_mac(struct daemon *daemon, unsigned char *mac, int len);
void bump_maxfd(int fd, int *max);
void log_start(struct daemon *daemon);
int read_write(int fd, unsigned char *packet, int size, int rw);

/* option.c */
struct daemon *read_opts (int argc, char **argv, char *compile_opts);

/* forward.c */
void reply_query(struct serverfd *sfd, struct daemon *daemon, time_t now);
void receive_query(struct listener *listen, struct daemon *daemon, time_t now);
unsigned char *tcp_request(struct daemon *daemon, int confd, time_t now,
			   struct in_addr local_addr, struct in_addr netmask);
void server_gone(struct daemon *daemon, struct server *server);
struct frec *get_new_frec(struct daemon *daemon, time_t now, int *wait);

/* network.c */
struct serverfd *allocate_sfd(union mysockaddr *addr, struct serverfd **sfds);
int reload_servers(char *fname, struct daemon *daemon);
void check_servers(struct daemon *daemon);
int enumerate_interfaces(struct daemon *daemon);
struct listener *create_wildcard_listeners(int port, int have_tftp);
struct listener *create_bound_listeners(struct daemon *daemon);
int iface_check(struct daemon *daemon, int family, struct all_addr *addr, 
		struct ifreq *ifr, int *indexp);
int fix_fd(int fd);

/* dhcp.c */
void dhcp_init(struct daemon *daemon);
void dhcp_packet(struct daemon *daemon, time_t now);

struct dhcp_context *address_available(struct dhcp_context *context, struct in_addr addr);
struct dhcp_context *narrow_context(struct dhcp_context *context, struct in_addr taddr);
int match_netid(struct dhcp_netid *check, struct dhcp_netid *pool, int negonly);
int address_allocate(struct dhcp_context *context, struct daemon *daemon,
		     struct in_addr *addrp, unsigned char *hwaddr, int hw_len,
		     struct dhcp_netid *netids, time_t now);
struct dhcp_config *find_config(struct dhcp_config *configs,
				struct dhcp_context *context,
				unsigned char *clid, int clid_len,
				unsigned char *hwaddr, int hw_len, 
				int hw_type, char *hostname);
void dhcp_update_configs(struct dhcp_config *configs);
void dhcp_read_ethers(struct daemon *daemon);
struct dhcp_config *config_find_by_address(struct dhcp_config *configs, struct in_addr addr);
char *strip_hostname(struct daemon *daemon, char *hostname);
char *host_from_dns(struct daemon *daemon, struct in_addr addr);

/* lease.c */
void lease_update_file(struct daemon *daemon, time_t now);
void lease_update_dns(struct daemon *daemon);
void lease_init(struct daemon *daemon, time_t now);
struct dhcp_lease *lease_allocate(struct in_addr addr);
void lease_set_hwaddr(struct dhcp_lease *lease, unsigned char *hwaddr,
		      unsigned char *clid, int hw_len, int hw_type, int clid_len);
void lease_set_hostname(struct dhcp_lease *lease, char *name, 
			char *suffix, int auth);
void lease_set_expires(struct dhcp_lease *lease, unsigned int len, time_t now);
struct dhcp_lease *lease_find_by_client(unsigned char *hwaddr, int hw_len, int hw_type,  
					unsigned char *clid, int clid_len);
struct dhcp_lease *lease_find_by_addr(struct in_addr addr);
void lease_prune(struct dhcp_lease *target, time_t now);
void lease_update_from_configs(struct daemon *daemon);
int do_script_run(struct daemon *daemon);

/* rfc2131.c */
size_t dhcp_reply(struct daemon *daemon, struct dhcp_context *context, char *iface_name, size_t sz, time_t now, int unicast_dest);

/* dnsmasq.c */
int make_icmp_sock(void);
int icmp_ping(struct daemon *daemon, struct in_addr addr);
void clear_cache_and_reload(struct daemon *daemon, time_t now);

/* isc.c */
#ifdef HAVE_ISC_READER
void load_dhcp(struct daemon *daemon, time_t now);
#endif

/* netlink.c */
#ifdef HAVE_LINUX_NETWORK
void netlink_init(struct daemon *daemon);
int iface_enumerate(struct daemon *daemon, void *parm,
		    int (*ipv4_callback)(), int (*ipv6_callback)());
void netlink_multicast(struct daemon *daemon);
#endif

/* bpf.c */
#ifndef HAVE_LINUX_NETWORK
void init_bpf(struct daemon *daemon);
void send_via_bpf(struct daemon *daemon, struct dhcp_packet *mess, size_t len,
		  struct in_addr iface_addr, struct ifreq *ifr);
int iface_enumerate(struct daemon *daemon, void *parm,
		    int (*ipv4_callback)(), int (*ipv6_callback)());
#endif

/* dbus.c */
#ifdef HAVE_DBUS
char *dbus_init(struct daemon *daemon);
void check_dbus_listeners(struct daemon *daemon,
			  fd_set *rset, fd_set *wset, fd_set *eset);
void set_dbus_listeners(struct daemon *daemon, int *maxfdp, 
			fd_set *rset, fd_set *wset, fd_set *eset);
#endif

/* helper.c */
int create_helper(struct daemon *daemon);
void helper_write(struct daemon *daemon);
void queue_script(struct daemon *daemon, int action, 
		  struct dhcp_lease *lease, char *hostname);
int helper_buf_empty(void);

/* tftp.c */
#ifdef HAVE_TFTP
void tftp_request(struct listener *listen, struct daemon *daemon, time_t now);
void check_tftp_listeners(struct daemon *daemon, fd_set *rset, time_t now);
#endif