src/src/routers/rf_lookup_hostlist.c

   1 /* $Cambridge: exim/src/src/routers/rf_lookup_hostlist.c,v 1.5 2005/12/06 10:25:59 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 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, &canonical_name, TRUE);
 110     }
 111
 112   /* Otherwise, do a DNS lookup. If that yields "host not found", and the
 113   lookup type is the default (i.e. "bydns" is not explicitly configured),
 114   follow up with a byname lookup, just in case. */
 115
 116   else
 117     {
 118     BOOL removed;
 119     DEBUG(D_route|D_host_lookup) debug_printf("doing DNS lookup\n");
 120     rc = host_find_bydns(h, ignore_target_hosts, HOST_FIND_BY_A, NULL, NULL,
 121       NULL, &canonical_name, &removed);
 122     if (rc == HOST_FOUND)
 123       {
 124       if (removed) setflag(addr, af_local_host_removed);
 125       }
 126     else if (rc == HOST_FIND_FAILED)
 127       {
 128       if (lookup_type == lk_default)
 129         {
 130         DEBUG(D_route|D_host_lookup)
 131           debug_printf("DNS lookup failed: trying getipnodebyname\n");
 132         rc = host_find_byname(h, ignore_target_hosts, &canonical_name, TRUE);
 133         }
 134       }
 135     }
 136
 137   /* Temporary failure defers, unless pass_on_timeout is set */
 138
 139   if (rc == HOST_FIND_AGAIN)
 140     {
 141     if (rblock->pass_on_timeout)
 142       {
 143       DEBUG(D_route)
 144         debug_printf("%s router timed out and pass_on_timeout set\n",
 145           rblock->name);
 146       return PASS;
 147       }
 148     addr->message = string_sprintf("host lookup for %s did not complete "
 149       "(DNS timeout?)", h->name);
 150     addr->basic_errno = ERRNO_DNSDEFER;
 151     return DEFER;
 152     }
 153
 154   /* Permanent failure is controlled by host_find_failed */
 155
 156   if (rc == HOST_FIND_FAILED)
 157     {
 158     if (hff_code == hff_pass) return PASS;
 159     if (hff_code == hff_decline) return DECLINE;
 160
 161     addr->message =
 162       string_sprintf("lookup of host \"%s\" failed in %s router%s",
 163         h->name, rblock->name,
 164         host_find_failed_syntax? ": syntax error in name" : "");
 165
 166     if (hff_code == hff_defer) return DEFER;
 167     if (hff_code == hff_fail) return FAIL;
 168
 169     addr->special_action = SPECIAL_FREEZE;
 170     return DEFER;
 171     }
 172
 173   /* Deal with a port setting */
 174
 175   if (port != PORT_NONE)
 176     {
 177     host_item *hh;
 178     for (hh = h; hh != next_h; hh = hh->next) hh->port = port;
 179     }
 180
 181   /* A local host gets chopped, with its successors, if there are previous
 182   hosts. Otherwise the self option is used. If it is set to "send", any
 183   subsequent hosts that are also the local host do NOT get chopped. */
 184
 185   if (rc == HOST_FOUND_LOCAL && !self_send)
 186     {
 187     if (prev != NULL)
 188       {
 189       DEBUG(D_route)
 190         {
 191         debug_printf("Removed from host list:\n");
 192         for (; h != NULL; h = h->next) debug_printf("  %s\n", h->name);
 193         }
 194       prev->next = NULL;
 195       setflag(addr, af_local_host_removed);
 196       break;
 197       }
 198     rc = rf_self_action(addr, h, rblock->self_code, rblock->self_rewrite,
 199       rblock->self, addr_new);
 200     if (rc != OK)
 201       {
 202       addr->host_list = NULL;   /* Kill the host list for */
 203       return rc;                /* anything other than "send" */
 204       }
 205     self_send = TRUE;
 206     }
 207   }
 208
 209 return OK;
 210 }
 211
 212 /* End of rf_lookup_hostlist.c */