contrib/dhcpcd/hooks/30-hostname.in

   1 # Set the hostname from DHCP data if required
   2
   3 # A hostname can either be a short hostname or a FQDN.
   4 # hostname_fqdn=true
   5 # hostname_fqdn=false
   6 # hostname_fqdn=server
   7
   8 # A value of server means just what the server says, don't manipulate it.
   9 # This could lead to an inconsistent hostname on a DHCPv4 and DHCPv6 network
  10 # where the DHCPv4 hostname is short and the DHCPv6 has an FQDN.
  11 # DHCPv6 has no hostname option.
  12 # RFC4702 section 3.1 says FQDN should be prefered over hostname.
  13 #
  14 # As such, the default is hostname_fqdn=true so that a consistent hostname
  15 # is always assigned.
  16 : ${hostname_fqdn:=true}
  17
  18 # If we used to set the hostname, but relinquish control of it, we should
  19 # reset to the default value.
  20 : ${hostname_default=@DEFAULT_HOSTNAME@}
  21
  22 # Some systems don't have hostname(1)
  23 _hostname()
  24 {
  25         if [ -z "${1+x}" ]; then
  26                 if [ -r /proc/sys/kernel/hostname ]; then
  27                         read name </proc/sys/kernel/hostname && echo "$name"
  28                 elif type hostname >/dev/null 2>/dev/null; then
  29                         hostname
  30                 elif sysctl kern.hostname >/dev/null 2>&1; then
  31                         sysctl -n kern.hostname
  32                 elif sysctl kernel.hostname >/dev/null 2>&1; then
  33                         sysctl -n kernel.hostname
  34                 else
  35                         return 1
  36                 fi
  37                 return $?
  38         fi
  39
  40         if [ -w /proc/sys/kernel/hostname ]; then
  41                 echo "$1" >/proc/sys/kernel/hostname
  42         elif [ -n "$1" ] && type hostname >/dev/null 2>&1; then
  43                 hostname "$1"
  44         elif sysctl kern.hostname >/dev/null 2>&1; then
  45                 sysctl -w "kern.hostname=$1" >/dev/null
  46         elif sysctl kernel.hostname >/dev/null 2>&1; then
  47                 sysctl -w "kernel.hostname=$1" >/dev/null
  48         else
  49                 # May fail to set a blank hostname
  50                 hostname "$1"
  51         fi
  52 }
  53
  54 is_default_hostname()
  55 {
  56         case "$1" in
  57         ""|"$hostname_default"|localhost|localhost.localdomain)
  58                 return 0;;
  59         esac
  60         return 1
  61 }
  62
  63 need_hostname()
  64 {
  65         # Always load the hostname variable for future use
  66         hostname="$(_hostname)"
  67         is_default_hostname "$hostname" && return 0
  68
  69         case "$force_hostname" in
  70         [Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|1) return 0;;
  71         esac
  72
  73         if [ -n "$old_fqdn" ]; then
  74                 if ${hfqdn} || ! ${hshort}; then
  75                         [ "$hostname" = "$old_fqdn" ]
  76                 else
  77                         [ "$hostname" = "${old_fqdn%%.*}" ]
  78                 fi
  79         elif [ -n "$old_host_name" ]; then
  80                 if ${hfqdn}; then
  81                         if [ -n "$old_domain_name" ] &&
  82                            [ "$old_host_name" = "${old_host_name#*.}" ]
  83                         then
  84                                 [ "$hostname" = \
  85                                     "$old_host_name.$old_domain_name" ]
  86                         else
  87                                 [ "$hostname" = "$old_host_name" ]
  88                         fi
  89                 elif ${hshort}; then
  90                         [ "$hostname" = "${old_host_name%%.*}" ]
  91                 else
  92                         [ "$hostname" = "$old_host_name" ]
  93                 fi
  94         else
  95                 # No old hostname
  96                 false
  97         fi
  98 }
  99
 100 try_hostname()
 101 {
 102         [ "$hostname" = "$1" ] && return 0
 103         if valid_domainname "$1"; then
 104                 syslog info "Setting hostname: $1"
 105                 _hostname "$1"
 106         else
 107                 syslog err "Invalid hostname: $1"
 108         fi
 109 }
 110
 111 set_hostname()
 112 {
 113         hfqdn=false
 114         hshort=false
 115         case "$hostname_fqdn" in
 116         [Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|1)        hfqdn=true;;
 117         ""|[Ss][Ee][Rr][Vv][Ee][Rr])            ;;
 118         *)                                      hshort=true;;
 119         esac
 120
 121         need_hostname || return
 122
 123         if [ -n "$new_fqdn" ]; then
 124                 if ${hfqdn} || ! ${hshort}; then
 125                         try_hostname "$new_fqdn"
 126                 else
 127                         try_hostname "${new_fqdn%%.*}"
 128                 fi
 129         elif [ -n "$new_host_name" ]; then
 130                 if ${hfqdn}; then
 131                         if [ -n "$new_domain_name" ] &&
 132                            [ "$new_host_name" = "${new_host_name#*.}" ]
 133                         then
 134                                 try_hostname "$new_host_name.$new_domain_name"
 135                         else
 136                                 try_hostname "$new_host_name"
 137                         fi
 138                 elif ${hshort}; then
 139                         try_hostname "${new_host_name%%.*}"
 140                 else
 141                         try_hostname "$new_host_name"
 142                 fi
 143         elif ! is_default_hostname "$hostname"; then
 144                 try_hostname "$hostname_default"
 145         fi
 146 }
 147
 148 # For ease of use, map DHCP6 names onto our DHCP4 names
 149 case "$reason" in
 150 BOUND6|RENEW6|REBIND6|REBOOT6|INFORM6)
 151         new_fqdn="$new_dhcp6_fqdn"
 152         old_fqdn="$old_dhcp6_fqdn"
 153         ;;
 154 esac
 155
 156 if $if_configured && $if_up && [ "$reason" != ROUTERADVERT ]; then
 157         set_hostname
 158 fi