contrib/dhcpcd/hooks/30-hostname

   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 : ${hostname_default=localhost}
  21
  22 # Some systems don't have hostname(1)
  23 _hostname()
  24 {
  25         if [ -z "${1+x}" ]; then
  26                 if type hostname >/dev/null 2>&1; then
  27                         hostname
  28                 elif [ -r /proc/sys/kernel/hostname ]; then
  29                         read name </proc/sys/kernel/hostname && echo "$name"
  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         # Always prefer hostname(1) if we have it
  41         if type hostname >/dev/null 2>&1; then
  42                 hostname "$1"
  43         elif [ -w /proc/sys/kernel/hostname ]; then
  44                 echo "$1" >/proc/sys/kernel/hostname
  45         elif sysctl kern.hostname >/dev/null 2>&1; then
  46                 sysctl -w "kern.hostname=$1"
  47         elif sysctl kernel.hostname >/dev/null 2>&1; then
  48                 sysctl -w "kernel.hostname=$1"
  49         else
  50                 # We know this will fail, but it will now fail
  51                 # with an error to stdout
  52                 hostname "$1"
  53         fi
  54 }
  55
  56 set_hostname_vars()
  57 {
  58         hfqdn=false
  59         hshort=false
  60         case "$hostname_fqdn" in
  61         [Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|1)        hfqdn=true;;
  62         ""|[Ss][Ee][Rr][Vv][Ee][Rr])            ;;
  63         *)                                      hshort=true;;
  64         esac
  65 }
  66
  67 need_hostname()
  68 {
  69         # Always load the hostname variable for future use
  70         hostname="$(_hostname)"
  71         case "$hostname" in
  72         ""|"(none)"|localhost|localhost.localdomain|"$hostname_default")
  73                 return 0;;
  74         esac
  75
  76         case "$force_hostname" in
  77         [Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|1) return 0;;
  78         esac
  79
  80         set_hostname_vars
  81
  82         if [ -n "$old_fqdn" ]; then
  83                 if ${hfqdn} || ! ${hshort}; then
  84                         [ "$hostname" = "$old_fqdn" ]
  85                 else
  86                         [ "$hostname" = "${old_fqdn%%.*}" ]
  87                 fi
  88         elif [ -n "$old_host_name" ]; then
  89                 if ${hfqdn}; then
  90                         if [ -n "$old_domain_name" ] &&
  91                            [ "$old_host_name" = "${old_host_name#*.}" ]
  92                         then
  93                                 [ "$hostname" = \
  94                                     "$old_host_name.$old_domain_name" ]
  95                         else
  96                                 [ "$hostname" = "$old_host_name" ]
  97                         fi
  98                 elif ${hshort}; then
  99                         [ "$hostname" = "${old_host_name%%.*}" ]
 100                 else
 101                         [ "$hostname" = "$old_host_name" ]
 102                 fi
 103         else
 104                 # No old hostname
 105                 false
 106         fi
 107 }
 108
 109 try_hostname()
 110 {
 111         [ "$hostname" = "$1" ] && return 0
 112         if valid_domainname "$1"; then
 113                 syslog info "Setting hostname: $1"
 114                 _hostname "$1"
 115         else
 116                 syslog err "Invalid hostname: $1"
 117         fi
 118 }
 119
 120 set_hostname()
 121 {
 122         need_hostname || return
 123
 124         set_hostname_vars
 125
 126         if [ -n "$new_fqdn" ]; then
 127                 if ${hfqdn} || ! ${hshort}; then
 128                         try_hostname "$new_fqdn"
 129                 else
 130                         try_hostname "${new_fqdn%%.*}"
 131                 fi
 132         elif [ -n "$new_host_name" ]; then
 133                 if ${hfqdn}; then
 134                         if [ -n "$new_domain_name" ] &&
 135                            [ "$new_host_name" = "${new_host_name#*.}" ]
 136                         then
 137                                 try_hostname "$new_host_name.$new_domain_name"
 138                         else
 139                                 try_hostname "$new_host_name"
 140                         fi
 141                 elif ${hshort}; then
 142                         try_hostname "${new_host_name%%.*}"
 143                 else
 144                         try_hostname "$new_host_name"
 145                 fi
 146         elif [ -n "${hostname_default+x}" ]; then
 147                 try_hostname "$hostname_default"
 148         fi
 149 }
 150
 151 # For ease of use, map DHCP6 names onto our DHCP4 names
 152 case "$reason" in
 153 BOUND6|RENEW6|REBIND6|REBOOT6|INFORM6)
 154         new_fqdn="$new_dhcp6_fqdn"
 155         old_fqdn="$old_dhcp6_fqdn"
 156         ;;
 157 esac
 158
 159 if $if_up; then
 160         set_hostname
 161 fi