src/src/routers/rf_lookup_hostlist.c

   1 /* $Cambridge: exim/src/src/routers/rf_lookup_hostlist.c,v 1.7 2006/10/09 14:36:25 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2006 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10
  11 #include "../exim.h"
  12 #include "rf_functions.h"
  13
  14
  15
  16 /*************************************************
  17 *     Look up IP addresses for a set of hosts    *
  18 *************************************************/
  19
  20 /* This function is called by a router to fill in the IP addresses for a set of
  21 hosts that are attached to an address. Each host has its name and MX value set;
  22 and those that need processing have their address fields set NULL. Multihomed
  23 hosts cause additional blocks to be inserted into the chain.
  24
  25 This function also supports pseudo-hosts whose names end with "/MX". In this
  26 case, MX records are looked up for the name, and the list of hosts obtained
  27 replaces the incoming "host". In other words, "x/MX" is shorthand for "those
  28 hosts pointed to by x's MX records".
  29
  30 It is also possible for a port to be specified along with the host name or IP
  31 address. The syntax is to add ":port" on to the end. This doesn't work with
  32 IPv6 addresses, so we allow IP addresses to be enclosed in [] in order to make
  33 this work. The specification of the port must come last, that is, after "/MX"
  34 if that is present.
  35
  36 Arguments:
  37   rblock               the router block
  38   addr                 the address being routed
  39   ignore_target_hosts  list of hosts to ignore
  40   lookup_type          lk_default or lk_byname or lk_bydns
  41   hff_code             what to do for host find failed
  42   addr_new             passed to rf_self_action for self=reroute
  43
  44 Returns:               OK
  45                        DEFER host lookup defer
  46                        PASS  timeout etc and pass_on_timeout set
  47                        self_action: PASS, DECLINE, DEFER, FAIL, FREEZE
  48                        hff_code after host find failed
  49 */
  50
  51 int
  52 rf_lookup_hostlist(router_instance *rblock, address_item *addr,
  53   uschar *ignore_target_hosts, int lookup_type, int hff_code,
  54   address_item **addr_new)
  55 {
  56 BOOL self_send = FALSE;
  57 host_item *h, *next_h, *prev;
  58
  59 /* Look up each host address. A lookup may add additional items into the chain
  60 if there are multiple addresses. Hence the use of next_h to start each cycle of
  61 the loop at the next original host. If any host is identified as being the local
  62 host, omit it and any subsequent hosts - i.e. treat the list like an ordered
  63 list of MX hosts. If the first host is the local host, act according to the
  64 "self" option in the configuration. */
  65
  66 prev = NULL;
  67 for (h = addr->host_list; h != NULL; prev = h, h = next_h)
  68   {
  69   uschar *canonical_name;
  70   int rc, len, port;
  71
  72   next_h = h->next;
  73   if (h->address != NULL) continue;
  74
  75   DEBUG(D_route|D_host_lookup)
  76     debug_printf("finding IP address for %s\n", h->name);
  77
  78   /* Handle any port setting that may be on the name; it will be removed
  79   from the end of the name. */
  80
  81   port = host_item_get_port(h);
  82
  83   /* If the name ends with "/MX", we interpret it to mean "the list of hosts
  84   pointed to by MX records with this name". */
  85
  86   len = Ustrlen(h->name);
  87   if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
  88     {
  89     DEBUG(D_route|D_host_lookup)
  90       debug_printf("doing DNS MX lookup for %s\n", h->name);
  91
  92     h->name = string_copyn(h->name, len - 3);
  93     rc = host_find_bydns(h,
  94         ignore_target_hosts,
  95         HOST_FIND_BY_MX,                /* look only for MX records */
  96         NULL,                           /* SRV service not relevant */
  97         NULL,                           /* failing srv domains not relevant */
  98         NULL,                           /* no special mx failing domains */
  99         NULL,                           /* fully_qualified_name */
 100         NULL);                          /* indicate local host removed */
 101     }
 102
 103   /* If explicitly configured to look up by name, or if the "host name" is
 104   actually an IP address, do a byname lookup. */
 105
 106   else if (lookup_type == lk_byname || string_is_ip_address(h->name, NULL) != 0)
 107     {
 108     DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n");
 109     rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
 110       &canonical_name, TRUE);
 111     }
 112
 113   /* Otherwise, do a DNS lookup. If that yields "host not found", and the
 114   lookup type is the default (i.e. "bydns" is not explicitly configured),
 115   follow up with a byname lookup, just in case. */
 116
 117   else
 118     {
 119     BOOL removed;
 120     DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
 121     rc = host_find_bydns(h, ignore_target_hosts, HOST_FIND_BY_A, NULL, NULL,
 122       NULL, &canonical_name, &removed);
 123     if (rc == HOST_FOUND)
 124       {
 125       if (removed) setflag(addr, af_local_host_removed);
 126       }
 127     else if (rc == HOST_FIND_FAILED)
 128       {
 129       if (lookup_type == lk_default)
 130         {
 131         DEBUG(D_route|D_host_lookup)
 132           debug_printf("DNS lookup failed: trying getipnodebyname\n");
 133         rc = host_find_byname(h, ignore_target_hosts, HOST_FIND_QUALIFY_SINGLE,
 134           &canonical_name, TRUE);
 135         }
 136       }
 137     }
 138
 139   /* Temporary failure defers, unless pass_on_timeout is set */
 140
 141   if (rc == HOST_FIND_AGAIN)
 142     {
 143     if (rblock->pass_on_timeout)
 144       {
 145       DEBUG(D_route)
 146         debug_printf("%s router timed out and pass_on_timeout set\n",
 147           rblock->name);
 148       return PASS;
 149       }
 150     addr->message = string_sprintf("host lookup for %s did not complete "
 151       "(DNS timeout?)", h->name);
 152     addr->basic_errno = ERRNO_DNSDEFER;
 153     return DEFER;
 154     }
 155
 156   /* Permanent failure is controlled by host_find_failed */
 157
 158   if (rc == HOST_FIND_FAILED)
 159     {
 160     if (hff_code == hff_pass) return PASS;
 161     if (hff_code == hff_decline) return DECLINE;
 162
 163     addr->message =
 164       string_sprintf("lookup of host \"%s\" failed in %s router%s",
 165         h->name, rblock->name,
 166         host_find_failed_syntax? ": syntax error in name" : "");
 167
 168     if (hff_code == hff_defer) return DEFER;
 169     if (hff_code == hff_fail) return FAIL;
 170
 171     addr->special_action = SPECIAL_FREEZE;
 172     return DEFER;
 173     }
 174
 175   /* Deal with a port setting */
 176
 177   if (port != PORT_NONE)
 178     {
 179     host_item *hh;
 180     for (hh = h; hh != next_h; hh = hh->next) hh->port = port;
 181     }
 182
 183   /* A local host gets chopped, with its successors, if there are previous
 184   hosts. Otherwise the self option is used. If it is set to "send", any
 185   subsequent hosts that are also the local host do NOT get chopped. */
 186
 187   if (rc == HOST_FOUND_LOCAL && !self_send)
 188     {
 189     if (prev != NULL)
 190       {
 191       DEBUG(D_route)
 192         {
 193         debug_printf("Removed from host list:\n");
 194         for (; h != NULL; h = h->next) debug_printf("  %s\n", h->name);
 195         }
 196       prev->next = NULL;
 197       setflag(addr, af_local_host_removed);
 198       break;
 199       }
 200     rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
 201       rblock->self, addr_new);
 202     if (rc != OK)
 203       {
 204       addr->host_list = NULL;   /* Kill the host list for */
 205       return rc;                /* anything other than "send" */
 206       }
 207     self_send = TRUE;
 208     }
 209   }
 210
 211 return OK;
 212 }
 213
 214 /* End of rf_lookup_hostlist.c */