src/src/routers/rf_lookup_hostlist.c

   1 /* $Cambridge: exim/src/src/routers/rf_lookup_hostlist.c,v 1.3 2005/01/11 15:51:03 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2005 */
   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 Arguments:
  31   rblock               the router block
  32   addr                 the address being routed
  33   ignore_target_hosts  list of hosts to ignore
  34   lookup_type          lk_default or lk_byname or lk_bydns
  35   hff_code             what to do for host find failed
  36   addr_new             passed to rf_self_action for self=reroute
  37
  38 Returns:               OK
  39                        DEFER host lookup defer
  40                        PASS  timeout etc and pass_on_timeout set
  41                        self_action: PASS, DECLINE, DEFER, FAIL, FREEZE
  42                        hff_code after host find failed
  43 */
  44
  45 int
  46 rf_lookup_hostlist(router_instance *rblock, address_item *addr,
  47   uschar *ignore_target_hosts, int lookup_type, int hff_code,
  48   address_item **addr_new)
  49 {
  50 BOOL self_send = FALSE;
  51 host_item *h, *next_h, *prev;
  52
  53 /* Look up each host address. A lookup may add additional items into the chain
  54 if there are multiple addresses. Hence the use of next_h to start each cycle of
  55 the loop at the next original host. If any host is identified as being the local
  56 host, omit it and any subsequent hosts - i.e. treat the list like an ordered
  57 list of MX hosts. If the first host is the local host, act according to the
  58 "self" option in the configuration. */
  59
  60 prev = NULL;
  61 for (h = addr->host_list; h != NULL; prev = h, h = next_h)
  62   {
  63   uschar *canonical_name;
  64   int rc, len;
  65
  66   next_h = h->next;
  67   if (h->address != NULL) continue;
  68
  69   DEBUG(D_route|D_host_lookup)
  70     debug_printf("finding IP address for %s\n", h->name);
  71
  72   /* If the name ends with "/MX", we interpret it to mean "the list of hosts
  73   pointed to by MX records with this name". */
  74
  75   len = Ustrlen(h->name);
  76   if (len > 3 && strcmpic(h->name + len - 3, US"/mx") == 0)
  77     {
  78     DEBUG(D_route|D_host_lookup)
  79       debug_printf("doing DNS MX lookup for %s\n", h->name);
  80
  81     h->name[len-3] = 0;
  82     rc = host_find_bydns(h,
  83         ignore_target_hosts,
  84         HOST_FIND_BY_MX,                /* look only for MX records */
  85         NULL,                           /* SRV service not relevant */
  86         NULL,                           /* failing srv domains not relevant */
  87         NULL,                           /* no special mx failing domains */
  88         NULL,                           /* fully_qualified_name */
  89         NULL);                          /* indicate local host removed */
  90     }
  91
  92   /* If explicitly configured to look up by name, or if the "host name" is
  93   actually an IP address, do a byname lookup. */
  94
  95   else if (lookup_type == lk_byname || string_is_ip_address(h->name, NULL) > 0)
  96     {
  97     DEBUG(D_route|D_host_lookup) debug_printf("calling host_find_byname\n");
  98     rc = host_find_byname(h, ignore_target_hosts, &canonical_name, TRUE);
  99     }
 100
 101   /* Otherwise, do a DNS lookup. If that yields "host not found", and the
 102   lookup type is the default (i.e. "bydns" is not explicitly configured),
 103   follow up with a byname lookup, just in case. */
 104
 105   else
 106     {
 107     BOOL removed;
 108     DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
 109     rc = host_find_bydns(h, ignore_target_hosts, HOST_FIND_BY_A, NULL, NULL,
 110       NULL, &canonical_name, &removed);
 111     if (rc == HOST_FOUND)
 112       {
 113       if (removed) setflag(addr, af_local_host_removed);
 114       }
 115     else if (rc == HOST_FIND_FAILED)
 116       {
 117       if (lookup_type == lk_default)
 118         {
 119         DEBUG(D_route|D_host_lookup)
 120           debug_printf("DNS lookup failed: trying getipnodebyname\n");
 121         rc = host_find_byname(h, ignore_target_hosts, &canonical_name, TRUE);
 122         }
 123       }
 124     }
 125
 126   /* Temporary failure defers, unless pass_on_timeout is set */
 127
 128   if (rc == HOST_FIND_AGAIN)
 129     {
 130     if (rblock->pass_on_timeout)
 131       {
 132       DEBUG(D_route)
 133         debug_printf("%s router timed out and pass_on_timeout set\n",
 134           rblock->name);
 135       return PASS;
 136       }
 137     addr->message = string_sprintf("host lookup for %s did not complete "
 138       "(DNS timeout?)", h->name);
 139     addr->basic_errno = ERRNO_DNSDEFER;
 140     return DEFER;
 141     }
 142
 143   /* Permanent failure is controlled by host_find_failed */
 144
 145   if (rc == HOST_FIND_FAILED)
 146     {
 147     if (hff_code == hff_pass) return PASS;
 148     if (hff_code == hff_decline) return DECLINE;
 149
 150     addr->message =
 151       string_sprintf("lookup of host \"%s\" failed in %s router%s",
 152         h->name, rblock->name,
 153         host_find_failed_syntax? ": syntax error in name" : "");
 154
 155     if (hff_code == hff_defer) return DEFER;
 156     if (hff_code == hff_fail) return FAIL;
 157
 158     addr->special_action = SPECIAL_FREEZE;
 159     return DEFER;
 160     }
 161
 162   /* A local host gets chopped, with its successors, if there are previous
 163   hosts. Otherwise the self option is used. If it is set to "send", any
 164   subsequent hosts that are also the local host do NOT get chopped. */
 165
 166   if (rc == HOST_FOUND_LOCAL && !self_send)
 167     {
 168     if (prev != NULL)
 169       {
 170       DEBUG(D_route)
 171         {
 172         debug_printf("Removed from host list:\n");
 173         for (; h != NULL; h = h->next) debug_printf("  %s\n", h->name);
 174         }
 175       prev->next = NULL;
 176       setflag(addr, af_local_host_removed);
 177       break;
 178       }
 179     rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
 180       rblock->self, addr_new);
 181     if (rc != OK)
 182       {
 183       addr->host_list = NULL;   /* Kill the host list for */
 184       return rc;                /* anything other than "send" */
 185       }
 186     self_send = TRUE;
 187     }
 188   }
 189
 190 return OK;
 191 }
 192
 193 /* End of rf_lookup_hostlist.c */