external/ibm-public/postfix/dist/src/smtp/smtp_unalias.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      smtp_unalias 3
   6 /* SUMMARY
   7 /*      replace host/domain alias by official name
   8 /* SYNOPSIS
   9 /*      #include "smtp.h"
  10 /*
  11 /*      const char *smtp_unalias_name(name)
  12 /*      const char *name;
  13 /*
  14 /*      VSTRING *smtp_unalias_addr(result, addr)
  15 /*      VSTRING *result;
  16 /*      const char *addr;
  17 /* DESCRIPTION
  18 /*      smtp_unalias_name() looks up A or MX records for the specified
  19 /*      name and returns the official name provided in the reply. When
  20 /*      no A or MX record is found, the result is a copy of the input.
  21 /*      In order to improve performance, smtp_unalias_name() remembers
  22 /*      results in a private cache, so a name is looked up only once.
  23 /*
  24 /*      smtp_unalias_addr() returns the input address, which is in
  25 /*      RFC 821 quoted form, after replacing the domain part by the
  26 /*      official name as found by smtp_unalias_name(). When the input
  27 /*      contains no domain part, the result is a copy of the input.
  28 /* LICENSE
  29 /* .ad
  30 /* .fi
  31 /*      The Secure Mailer license must be distributed with this software.
  32 /* AUTHOR(S)
  33 /*      Wietse Venema
  34 /*      IBM T.J. Watson Research
  35 /*      P.O. Box 704
  36 /*      Yorktown Heights, NY 10598, USA
  37 /*--*/
  38
  39 /* System library. */
  40
  41 #include <sys_defs.h>
  42 #include <sys/socket.h>
  43 #include <netinet/in.h>
  44 #include <arpa/inet.h>
  45 #include <stdlib.h>
  46 #include <netdb.h>
  47 #include <string.h>
  48
  49 /* Utility library. */
  50
  51 #include <htable.h>
  52 #include <vstring.h>
  53 #include <msg.h>
  54
  55 /* DNS library. */
  56
  57 #include <dns.h>
  58
  59 /* Application-specific. */
  60
  61 #include "smtp.h"
  62
  63 static int smtp_unalias_flags;
  64
  65 /* smtp_unalias_name - look up the official host or domain name. */
  66
  67 const char *smtp_unalias_name(const char *name)
  68 {
  69     static HTABLE *cache;
  70     VSTRING *fqdn;
  71     char   *result;
  72
  73     if (*name == '[')
  74         return (name);
  75
  76     /*
  77      * Initialize the cache on the fly. The smtp client is designed to exit
  78      * after servicing a limited number of requests, so there is no need to
  79      * prevent the cache from growing too large, or to expire old entries.
  80      */
  81     if (cache == 0)
  82         cache = htable_create(10);
  83
  84     /*
  85      * Look up the fqdn. If none is found use the query name instead, so that
  86      * we won't lose time looking up the same bad name again.
  87      */
  88     if ((result = htable_find(cache, name)) == 0) {
  89         fqdn = vstring_alloc(10);
  90         if (dns_lookup_l(name, smtp_unalias_flags, (DNS_RR **) 0, fqdn,
  91                              (VSTRING *) 0, DNS_REQ_FLAG_NONE, T_MX, T_A,
  92 #ifdef HAS_IPV6
  93                              T_AAAA,
  94 #endif
  95                              0) != DNS_OK)
  96             vstring_strcpy(fqdn, name);
  97         htable_enter(cache, name, result = vstring_export(fqdn));
  98     }
  99     return (result);
 100 }
 101
 102 /* smtp_unalias_addr - rewrite aliases in domain part of address */
 103
 104 VSTRING *smtp_unalias_addr(VSTRING *result, const char *addr)
 105 {
 106     char   *at;
 107     const char *fqdn;
 108
 109     if ((at = strrchr(addr, '@')) == 0 || at[1] == 0) {
 110         vstring_strcpy(result, addr);
 111     } else {
 112         fqdn = smtp_unalias_name(at + 1);
 113         vstring_strncpy(result, addr, at - addr + 1);
 114         vstring_strcat(result, fqdn);
 115     }
 116     return (result);
 117 }
 118
 119 #ifdef TEST
 120
 121  /*
 122   * Test program - read address from stdin, print result on stdout.
 123   */
 124
 125 #include <vstring_vstream.h>
 126
 127 int     main(int unused_argc, char **unused_argv)
 128 {
 129     VSTRING *addr = vstring_alloc(10);
 130     VSTRING *result = vstring_alloc(10);
 131
 132     smtp_unalias_flags |= RES_DEBUG;
 133
 134     while (vstring_fgets_nonl(addr, VSTREAM_IN)) {
 135         smtp_unalias_addr(result, vstring_str(addr));
 136         vstream_printf("%s -> %s\n", vstring_str(addr), vstring_str(result));
 137         vstream_fflush(VSTREAM_OUT);
 138     }
 139     vstring_free(addr);
 140     vstring_free(result);
 141     return (0);
 142 }
 143
 144 #endif