usr/src/cmd/sendmail/cf/sh/check-hostname.sh

   1 #!/bin/sh --
   2 #
   3 # CDDL HEADER START
   4 #
   5 # The contents of this file are subject to the terms of the
   6 # Common Development and Distribution License (the "License").
   7 # You may not use this file except in compliance with the License.
   8 #
   9 # You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10 # or http://www.opensolaris.org/os/licensing.
  11 # See the License for the specific language governing permissions
  12 # and limitations under the License.
  13 #
  14 # When distributing Covered Code, include this CDDL HEADER in each
  15 # file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16 # If applicable, add the following below this CDDL HEADER, with the
  17 # fields enclosed by brackets "[]" replaced with your own identifying
  18 # information: Portions Copyright [yyyy] [name of copyright owner]
  19 #
  20 # CDDL HEADER END
  21 #
  22
  23 # Check hostname configuration as per the sendmail code.
  24 #
  25 # See http://www.sendmail.org/sun-specific/migration.html#FQHN for details.
  26 #
  27 # Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  28 # Use is subject to license terms.
  29 #
  30
  31 PATH=/bin:/usr/sbin
  32
  33 # If $1 has a ".", accept it and exit.
  34
  35 accept_if_fully_qualified() {
  36         case $1 in
  37         *.*)
  38                 echo "Hostname $myhostname OK: fully qualified as $1"
  39                 exit 0
  40                 ;;
  41         esac
  42 }
  43
  44 # Check the `getent hosts $1` output, skipping the 1st entry (IP address).
  45
  46 check_gethostbyname() {
  47         for host in `getent hosts $1 | awk '{for (f=2; f <= NF; f++) print $f}'`
  48         do
  49                 accept_if_fully_qualified $host
  50         done
  51 }
  52
  53 # Parse /etc/hosts, looking for $1 as an entry by itself, and try to find
  54 # a long name on the same line.  First kill all comments, then check for
  55 # $1 as a word by itself, then take just the first such line, then skip
  56 # its first entry (IP address).
  57
  58 check_hosts_file() {
  59         for entry in `sed -e 's/#.*$//' /etc/hosts | \
  60                 awk '/[         ]'$1'([         ]|$)/ \
  61                         {for (f=2; f <= NF; f++) print $f; exit}'`
  62         do
  63                 accept_if_fully_qualified $entry
  64         done
  65 }
  66
  67 # Parse the output of `nslookup $1`, checking the Name and Aliases.
  68
  69 check_dns() {
  70         for host in `nslookup $1 2>/dev/null | \
  71                 awk '$1 == "Name:" || $1 == "Aliases:"{print $2}'`
  72         do
  73                 accept_if_fully_qualified $host
  74         done
  75 }
  76
  77 # Check the `ypmatch $1 hosts` output, skipping the 1st entry (IP address).
  78
  79 check_nis() {
  80         for hst in `ypmatch $1 hosts | awk '{for (f=2; f <= NF; f++) print $f}'`
  81         do
  82                 accept_if_fully_qualified $hst
  83         done
  84 }
  85
  86 # Recommend how to reconfigure to get $1.$2 as the FQHN.
  87 # $3 is the first entry for hosts in /etc/nsswitch.conf .
  88
  89 suggest_fix_and_exit() {
  90         myhost=$1
  91         suggested_domain=$2
  92         fhe=$3
  93         myipaddr=`getent hosts $myhost | head -1 | awk '{print $1}'`
  94
  95         # aliases: skip the 1st & 2nd entries: IP address & canonical name
  96
  97         set -- '' '' '[ aliases ... ]'
  98         set -- `grep "^$myipaddr[        ]" /etc/hosts 2>/dev/null`
  99         result=$?
 100         shift 2
 101         echo "We recommend \c"
 102         if [ "x$fhe" != "xfiles" ] ; then
 103                 echo "listing files first for hosts in /etc/nsswitch.conf"
 104                 echo "and then \c"
 105         fi
 106         if [ $result = 0 ] ; then
 107                 echo "changing the /etc/hosts entry:\n"
 108                 echo "$myipaddr $myhost $*\n"
 109                 echo "to:\n"
 110         else
 111                 echo "adding the /etc/hosts entry:\n"
 112         fi
 113         echo "$myipaddr $myhost $myhost.$suggested_domain $*"
 114         exit 0
 115 }
 116
 117 # Fall back to the NIS domain, minus the first label.  If it is non-null,
 118 # use it but recommend against it.  $2 is just informative, indicating whether
 119 # we're checking the NIS domain.  $3 is to pass on.
 120
 121 check_nis_domain() {
 122         nisdomain=`domainname`
 123         realdomain=`echo $nisdomain | sed 's/[^.]*\.//'`
 124         if [ "x$realdomain" != "x" ] ; then
 125                 echo "Hostname $1 can be fully qualified using NIS$2 domain"
 126                 echo "  $nisdomain"
 127                 echo "resulting in the name"
 128                 echo "  $1.$realdomain"
 129                 echo "but this is bad practice.\n"
 130                 suggest_fix_and_exit $1 $realdomain $3
 131         fi
 132 }
 133
 134 # Goal: try to fully qualify `hostname` as sendmail would.
 135 # Algorithm (stop as soon as a name with a dot is found):
 136 #    1. gethostbyname (simulate with getent hosts)
 137 #    2. fall back to individual hosts: methods in nsswitch.conf, using
 138 #       only those that are configured, in their configured order
 139 #       * files (parse /etc/hosts directly)
 140 #       * dns (parse nslookup output)
 141 #       * nis (parse ypmatch output)
 142 #    3. fall back to the NIS domain name.
 143 # If none of the above succeed, give up.  Recommend:
 144 #    a. the domain entry in /etc/resolv.conf, if one exists
 145 #    b. "pick.some.domain"
 146
 147 myhostname=`hostname`
 148
 149 check_gethostbyname $myhostname
 150
 151 hosts_line=`sed -n -e 's/^hosts:\([^#]*\).*/\1/p' /etc/nsswitch.conf`
 152 first_hosts_entry=`echo $hosts_line | awk '{print $1}'`
 153 nis_domains=""
 154
 155 for entry in $hosts_line
 156 do
 157         case $entry in
 158         files)
 159                 check_hosts_file $myhostname
 160                 ;;
 161         dns)
 162                 check_dns $myhostname
 163                 ;;
 164         nis)
 165                 check_nis $myhostname
 166                 nis_domains="$nis_domains nis"
 167                 ;;
 168         esac
 169 done
 170
 171 for entry in $nis_domains
 172 do
 173         case $entry in
 174         nis)
 175                 check_nis_domain $myhostname "" $first_hosts_entry
 176                 ;;
 177         esac
 178 done
 179
 180 realdomain=`awk '$1 ~ /^domain/ {print $2}' 2>/dev/null < /etc/resolv.conf`
 181 case $realdomain in
 182 *.*)
 183         # OK
 184         ;;
 185 *)
 186         realdomain="pick.some.domain"
 187         ;;
 188 esac
 189
 190 echo "Hostname $myhostname could not be fully qualified."
 191 suggest_fix_and_exit $myhostname $realdomain $first_hosts_entry