[exim.git] / src / src / routers / rf_lookup_hostlist.c

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge 1995 - 2015 */
/* See the file NOTICE for conditions of use and distribution. */


#include "../exim.h"
#include "rf_functions.h"


/*************************************************
*     Look up IP addresses for a set of hosts    *
*************************************************/

/* This function is called by a router to fill in the IP addresses for a set of
hosts that are attached to an address. Each host has its name and MX value set;
and those that need processing have their address fields set NULL. Multihomed
hosts cause additional blocks to be inserted into the chain.

This function also supports pseudo-hosts whose names end with "/MX". In this
case, MX records are looked up for the name, and the list of hosts obtained
replaces the incoming "host". In other words, "x/MX" is shorthand for "those
hosts pointed to by x's MX records".

It is also possible for a port to be specified along with the host name or IP
address. The syntax is to add ":port" on to the end. This doesn't work with
IPv6 addresses, so we allow IP addresses to be enclosed in [] in order to make
this work. The specification of the port must come last, that is, after "/MX"
if that is present.

Arguments:
  rblock               the router block
  addr                 the address being routed
  ignore_target_hosts  list of hosts to ignore
  lookup_type          LK_DEFAULT or LK_BYNAME or LK_BYDNS,
		       plus LK_IPV4_{ONLY,PREFER}
  hff_code             what to do for host find failed
  addr_new             passed to rf_self_action for self=reroute

Returns:               OK
                       DEFER host lookup defer
                       PASS  timeout etc and pass_on_timeout set
                       self_action: PASS, DECLINE, DEFER, FAIL, FREEZE
                       hff_code after host find failed
*/

int
rf_lookup_hostlist(router_instance *rblock, address_item *addr,
  uschar *ignore_target_hosts, int lookup_type, int hff_code,
  address_item **addr_new)
{
BOOL self_send = FALSE;

/* Look up each host address. A lookup may add additional items into the chain
if there are multiple addresses. Hence the use of next_h to start each cycle of
the loop at the next original host. If any host is identified as being the local
host, omit it and any subsequent hosts - i.e. treat the list like an ordered
list of MX hosts. If the first host is the local host, act according to the
"self" option in the configuration. */

for (host_item * prev = NULL, * h = addr->host_list, *next_h; h; h = next_h)
  {
  const uschar *canonical_name;
  int rc, len, port, mx, sort_key;

  next_h = h->next;
  if (h->address) { prev = h; continue; }

  DEBUG(D_route|D_host_lookup)
    debug_printf("finding IP address for %s\n", h->name);

  /* Handle any port setting that may be on the name; it will be removed
  from the end of the name. */

  port = host_item_get_port(h);

  /* Store the previous mx and sort_key values, which were assigned in
  host_build_hostlist and will be overwritten by host_find_bydns. */

  mx = h->mx;
  sort_key = h->sort_key;

  /* If the name ends with "/MX", we interpret it to mean "the list of hosts
  pointed to by MX records with this name", and the MX record values override
  the ordering from host_build_hostlist. */

  len = Ustrlen(h->name);
  if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
    {
    int whichrrs = lookup_type & LK_IPV4_ONLY
      ? HOST_FIND_BY_MX | HOST_FIND_IPV4_ONLY
      : lookup_type & LK_IPV4_PREFER
      ? HOST_FIND_BY_MX | HOST_FIND_IPV4_FIRST
      : HOST_FIND_BY_MX;

    DEBUG(D_route|D_host_lookup)
      debug_printf("doing DNS MX lookup for %s\n", h->name);

    mx = MX_NONE;
    h->name = string_copyn(h->name, len - 3);
    rc = host_find_bydns(h,
        ignore_target_hosts,
        whichrrs,			/* look only for MX records */
        NULL,				/* SRV service not relevant */
        NULL,				/* failing srv domains not relevant */
        NULL,				/* no special mx failing domains */
        &rblock->dnssec,		/* dnssec request/require */
        NULL,				/* fully_qualified_name */
        NULL);				/* indicate local host removed */
    }

  /* If explicitly configured to look up by name, or if the "host name" is
  actually an IP address, do a byname lookup. */

  else if (lookup_type & LK_BYNAME || string_is_ip_address(h->name, NULL) != 0)
    {
    DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n");
    rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
      &canonical_name, TRUE);
    }

  /* Otherwise, do a DNS lookup. If that yields "host not found", and the
  lookup type is the default (i.e. "bydns" is not explicitly configured),
  follow up with a byname lookup, just in case. */

  else
    {
    BOOL removed;
    int whichrrs = lookup_type & LK_IPV4_ONLY
      ? HOST_FIND_BY_A
      : lookup_type & LK_IPV4_PREFER
      ? HOST_FIND_BY_A | HOST_FIND_BY_AAAA | HOST_FIND_IPV4_FIRST
      : HOST_FIND_BY_A | HOST_FIND_BY_AAAA;

    DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
    switch (rc = host_find_bydns(h, ignore_target_hosts, whichrrs, NULL,
	NULL, NULL,
	&rblock->dnssec,			/* domains for request/require */
	&canonical_name, &removed))
      {
      case HOST_FOUND:
        if (removed) setflag(addr, af_local_host_removed);
	break;
      case HOST_FIND_FAILED:
	if (lookup_type & LK_DEFAULT)
	  {
	  DEBUG(D_route|D_host_lookup)
	    debug_printf("DNS lookup failed: trying %s\n",
	      f.running_in_test_harness
	      ? "host_fake_gethostbyname" : "getipnodebyname");
	  rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
	    &canonical_name, TRUE);
	  }
	break;
      }
    }

  /* Temporary failure defers, unless pass_on_timeout is set */

  if (rc == HOST_FIND_SECURITY)
    {
    addr->message = string_sprintf("host lookup for %s done insecurely" , h->name);
    addr->basic_errno = ERRNO_DNSDEFER;
    return DEFER;
    }
  if (rc == HOST_FIND_AGAIN)
    {
    if (rblock->pass_on_timeout)
      {
      DEBUG(D_route)
        debug_printf("%s router timed out and pass_on_timeout set\n",
          rblock->name);
      return PASS;
      }
    addr->message = string_sprintf("host lookup for %s did not complete "
      "(DNS timeout?)", h->name);
    addr->basic_errno = ERRNO_DNSDEFER;
    return DEFER;
    }

  /* Permanent failure is controlled by host_find_failed */

  if (rc == HOST_FIND_FAILED)
    {
    if (hff_code == hff_ignore)
      {
      if (prev == NULL) addr->host_list = next_h; else prev->next = next_h;
      continue;   /* With the next host, leave prev unchanged */
      }

    if (hff_code == hff_pass) return PASS;
    if (hff_code == hff_decline) return DECLINE;

    addr->basic_errno = ERRNO_UNKNOWNHOST;
    addr->message =
      string_sprintf("lookup of host \"%s\" failed in %s router%s",
        h->name, rblock->name,
        f.host_find_failed_syntax? ": syntax error in name" : "");

    if (hff_code == hff_defer) return DEFER;
    if (hff_code == hff_fail) return FAIL;

    addr->special_action = SPECIAL_FREEZE;
    return DEFER;
    }

  /* Deal with the settings that were previously cleared:
  port, mx and sort_key. */

  if (port != PORT_NONE)
    for (host_item * hh = h; hh != next_h; hh = hh->next)
      hh->port = port;

  if (mx != MX_NONE)
    for (host_item * hh = h; hh != next_h; hh = hh->next)
      {
      hh->mx = mx;
      hh->sort_key = sort_key;
      }

  /* A local host gets chopped, with its successors, if there are previous
  hosts. Otherwise the self option is used. If it is set to "send", any
  subsequent hosts that are also the local host do NOT get chopped. */

  if (rc == HOST_FOUND_LOCAL && !self_send)
    {
    if (prev)
      {
      DEBUG(D_route)
        {
        debug_printf("Removed from host list:\n");
        for (; h; h = h->next) debug_printf("  %s\n", h->name);
        }
      prev->next = NULL;
      setflag(addr, af_local_host_removed);
      break;
      }
    rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
      rblock->self, addr_new);
    if (rc != OK)
      {
      addr->host_list = NULL;   /* Kill the host list for */
      return rc;                /* anything other than "send" */
      }
    self_send = TRUE;
    }

  /* Ensure that prev is the host before next_h; this will not be h if a lookup
  found multiple addresses or multiple MX records. */

  prev = h;
  while (prev->next != next_h) prev = prev->next;
  }

return OK;
}

/* End of rf_lookup_hostlist.c */
Commit	Line	Data
0756eb3c PH	1	/*************************************************
	2	* Exim - an Internet mail transport agent *
	3	*************************************************/
	4
3386088d	5	/* Copyright (c) University of Cambridge 1995 - 2015 */
0756eb3c PH	6	/* See the file NOTICE for conditions of use and distribution. */
	7
	8
	9	#include "../exim.h"
	10	#include "rf_functions.h"
	11
	12
	13
	14	/*************************************************
	15	* Look up IP addresses for a set of hosts *
	16	*************************************************/
	17
	18	/* This function is called by a router to fill in the IP addresses for a set of
	19	hosts that are attached to an address. Each host has its name and MX value set;
	20	and those that need processing have their address fields set NULL. Multihomed
	21	hosts cause additional blocks to be inserted into the chain.
	22
	23	This function also supports pseudo-hosts whose names end with "/MX". In this
	24	case, MX records are looked up for the name, and the list of hosts obtained
	25	replaces the incoming "host". In other words, "x/MX" is shorthand for "those
	26	hosts pointed to by x's MX records".
	27
7cd1141b PH	28	It is also possible for a port to be specified along with the host name or IP
	29	address. The syntax is to add ":port" on to the end. This doesn't work with
	30	IPv6 addresses, so we allow IP addresses to be enclosed in [] in order to make
	31	this work. The specification of the port must come last, that is, after "/MX"
	32	if that is present.
	33
0756eb3c PH	34	Arguments:
	35	rblock the router block
	36	addr the address being routed
	37	ignore_target_hosts list of hosts to ignore
66387a73 JH	38	lookup_type LK_DEFAULT or LK_BYNAME or LK_BYDNS,
66387a73 JH	39	plus LK_IPV4_{ONLY,PREFER}
0756eb3c PH	40	hff_code what to do for host find failed
	41	addr_new passed to rf_self_action for self=reroute
	42
	43	Returns: OK
	44	DEFER host lookup defer
	45	PASS timeout etc and pass_on_timeout set
	46	self_action: PASS, DECLINE, DEFER, FAIL, FREEZE
	47	hff_code after host find failed
	48	*/
	49
	50	int
	51	rf_lookup_hostlist(router_instance rblock, address_item addr,
	52	uschar *ignore_target_hosts, int lookup_type, int hff_code,
	53	address_item **addr_new)
	54	{
	55	BOOL self_send = FALSE;
0756eb3c PH	56
	57	/* Look up each host address. A lookup may add additional items into the chain
	58	if there are multiple addresses. Hence the use of next_h to start each cycle of
	59	the loop at the next original host. If any host is identified as being the local
	60	host, omit it and any subsequent hosts - i.e. treat the list like an ordered
	61	list of MX hosts. If the first host is the local host, act according to the
	62	"self" option in the configuration. */
	63
d7978c0f	64	for (host_item * prev = NULL, * h = addr->host_list, *next_h; h; h = next_h)
0756eb3c	65	{
55414b25	66	const uschar *canonical_name;
fff1b300	67	int rc, len, port, mx, sort_key;
0756eb3c PH	68
0756eb3c PH	69	next_h = h->next;
fff1b300	70	if (h->address) { prev = h; continue; }
0756eb3c PH	71
	72	DEBUG(D_route\|D_host_lookup)
	73	debug_printf("finding IP address for %s\n", h->name);
	74
7cd1141b PH	75	/* Handle any port setting that may be on the name; it will be removed
	76	from the end of the name. */
	77
	78	port = host_item_get_port(h);
	79
fff1b300 EA	80	/* Store the previous mx and sort_key values, which were assigned in
	81	host_build_hostlist and will be overwritten by host_find_bydns. */
	82
	83	mx = h->mx;
	84	sort_key = h->sort_key;
	85
0756eb3c	86	/* If the name ends with "/MX", we interpret it to mean "the list of hosts
fff1b300 EA	87	pointed to by MX records with this name", and the MX record values override
fff1b300 EA	88	the ordering from host_build_hostlist. */
0756eb3c PH	89
	90	len = Ustrlen(h->name);
	91	if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
	92	{
66387a73 JH	93	int whichrrs = lookup_type & LK_IPV4_ONLY
	94	? HOST_FIND_BY_MX \| HOST_FIND_IPV4_ONLY
	95	: lookup_type & LK_IPV4_PREFER
	96	? HOST_FIND_BY_MX \| HOST_FIND_IPV4_FIRST
	97	: HOST_FIND_BY_MX;
	98
0756eb3c PH	99	DEBUG(D_route\|D_host_lookup)
	100	debug_printf("doing DNS MX lookup for %s\n", h->name);
	101
fff1b300	102	mx = MX_NONE;
7cd1141b	103	h->name = string_copyn(h->name, len - 3);
0756eb3c PH	104	rc = host_find_bydns(h,
0756eb3c PH	105	ignore_target_hosts,
66387a73 JH	106	whichrrs, /* look only for MX records */
	107	NULL, /* SRV service not relevant */
	108	NULL, /* failing srv domains not relevant */
	109	NULL, /* no special mx failing domains */
7cd171b7	110	&rblock->dnssec, /* dnssec request/require */
66387a73 JH	111	NULL, /* fully_qualified_name */
66387a73 JH	112	NULL); /* indicate local host removed */
0756eb3c PH	113	}
	114
	115	/* If explicitly configured to look up by name, or if the "host name" is
	116	actually an IP address, do a byname lookup. */
	117
66387a73	118	else if (lookup_type & LK_BYNAME \|\| string_is_ip_address(h->name, NULL) != 0)
0756eb3c PH	119	{
0756eb3c PH	120	DEBUG(D_route\|D_host_lookup) debug_printf("calling host_find_byname\n");
322050c2 PH	121	rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
322050c2 PH	122	&canonical_name, TRUE);
0756eb3c PH	123	}
	124
	125	/* Otherwise, do a DNS lookup. If that yields "host not found", and the
	126	lookup type is the default (i.e. "bydns" is not explicitly configured),
	127	follow up with a byname lookup, just in case. */
	128
	129	else
	130	{
	131	BOOL removed;
66387a73 JH	132	int whichrrs = lookup_type & LK_IPV4_ONLY
	133	? HOST_FIND_BY_A
	134	: lookup_type & LK_IPV4_PREFER
	135	? HOST_FIND_BY_A \| HOST_FIND_BY_AAAA \| HOST_FIND_IPV4_FIRST
	136	: HOST_FIND_BY_A \| HOST_FIND_BY_AAAA;
	137
0756eb3c	138	DEBUG(D_route\|D_host_lookup) debug_printf("doing DNS lookup\n");
66387a73	139	switch (rc = host_find_bydns(h, ignore_target_hosts, whichrrs, NULL,
fff1b300 EA	140	NULL, NULL,
	141	&rblock->dnssec, /* domains for request/require */
	142	&canonical_name, &removed))
0756eb3c	143	{
fff1b300 EA	144	case HOST_FOUND:
	145	if (removed) setflag(addr, af_local_host_removed);
	146	break;
	147	case HOST_FIND_FAILED:
66387a73	148	if (lookup_type & LK_DEFAULT)
fff1b300 EA	149	{
fff1b300 EA	150	DEBUG(D_route\|D_host_lookup)
a06afb97 JH	151	debug_printf("DNS lookup failed: trying %s\n",
	152	f.running_in_test_harness
	153	? "host_fake_gethostbyname" : "getipnodebyname");
fff1b300 EA	154	rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
	155	&canonical_name, TRUE);
	156	}
	157	break;
0756eb3c PH	158	}
	159	}
	160
	161	/* Temporary failure defers, unless pass_on_timeout is set */
	162
2546388c JH	163	if (rc == HOST_FIND_SECURITY)
	164	{
	165	addr->message = string_sprintf("host lookup for %s done insecurely" , h->name);
	166	addr->basic_errno = ERRNO_DNSDEFER;
	167	return DEFER;
	168	}
0756eb3c PH	169	if (rc == HOST_FIND_AGAIN)
	170	{
	171	if (rblock->pass_on_timeout)
	172	{
	173	DEBUG(D_route)
	174	debug_printf("%s router timed out and pass_on_timeout set\n",
	175	rblock->name);
	176	return PASS;
	177	}
	178	addr->message = string_sprintf("host lookup for %s did not complete "
	179	"(DNS timeout?)", h->name);
	180	addr->basic_errno = ERRNO_DNSDEFER;
	181	return DEFER;
	182	}
	183
	184	/* Permanent failure is controlled by host_find_failed */
	185
	186	if (rc == HOST_FIND_FAILED)
	187	{
c456d9bb PH	188	if (hff_code == hff_ignore)
	189	{
	190	if (prev == NULL) addr->host_list = next_h; else prev->next = next_h;
cd9868ec	191	continue; /* With the next host, leave prev unchanged */
c456d9bb PH	192	}
c456d9bb PH	193
0756eb3c PH	194	if (hff_code == hff_pass) return PASS;
	195	if (hff_code == hff_decline) return DECLINE;
	196
bd4ece7d	197	addr->basic_errno = ERRNO_UNKNOWNHOST;
0756eb3c PH	198	addr->message =
	199	string_sprintf("lookup of host \"%s\" failed in %s router%s",
	200	h->name, rblock->name,
8768d548	201	f.host_find_failed_syntax? ": syntax error in name" : "");
0756eb3c PH	202
	203	if (hff_code == hff_defer) return DEFER;
	204	if (hff_code == hff_fail) return FAIL;
	205
	206	addr->special_action = SPECIAL_FREEZE;
	207	return DEFER;
	208	}
	209
fff1b300 EA	210	/* Deal with the settings that were previously cleared:
fff1b300 EA	211	port, mx and sort_key. */
7cd1141b PH	212
7cd1141b PH	213	if (port != PORT_NONE)
d7978c0f JH	214	for (host_item * hh = h; hh != next_h; hh = hh->next)
d7978c0f JH	215	hh->port = port;
7cd1141b	216
fff1b300	217	if (mx != MX_NONE)
d7978c0f	218	for (host_item * hh = h; hh != next_h; hh = hh->next)
fff1b300 EA	219	{
	220	hh->mx = mx;
	221	hh->sort_key = sort_key;
	222	}
fff1b300	223
0756eb3c PH	224	/* A local host gets chopped, with its successors, if there are previous
	225	hosts. Otherwise the self option is used. If it is set to "send", any
	226	subsequent hosts that are also the local host do NOT get chopped. */
	227
	228	if (rc == HOST_FOUND_LOCAL && !self_send)
	229	{
fff1b300	230	if (prev)
0756eb3c PH	231	{
	232	DEBUG(D_route)
	233	{
	234	debug_printf("Removed from host list:\n");
56dbf856	235	for (; h; h = h->next) debug_printf(" %s\n", h->name);
0756eb3c PH	236	}
	237	prev->next = NULL;
	238	setflag(addr, af_local_host_removed);
	239	break;
	240	}
	241	rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
	242	rblock->self, addr_new);
	243	if (rc != OK)
	244	{
	245	addr->host_list = NULL; /* Kill the host list for */
	246	return rc; /* anything other than "send" */
	247	}
	248	self_send = TRUE;
	249	}
cd9868ec PH	250
	251	/* Ensure that prev is the host before next_h; this will not be h if a lookup
	252	found multiple addresses or multiple MX records. */
	253
	254	prev = h;
	255	while (prev->next != next_h) prev = prev->next;
0756eb3c PH	256	}
	257
	258	return OK;
	259	}
	260
	261	/* End of rf_lookup_hostlist.c */