Handbook:Alpha/Networking/Extending/cs

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Standard function hooks

Four functions can be defined in /etc/conf.d/net:

• preup(), called before an interface is brought up;
• predown(), called before an interface is brought down;
• postup(), called after an interface is brought up; and
• postdown(), called after an interface is brought down.

Each of these these functions is called with the interface name, available within each function via the IFACE variable, so that one function can control multiple interfaces.

The return values for the preup() and predown() functions should be:

• 0 to indicate success, and that configuration or de-configuration of the interface can continue.
• A non-zero value otherwise.

If preup() returns a non-zero value, interface configuration will be aborted. If predown() returns a non-zero value, the interface will not be allowed to continue de-configuration.

Return values for the postup() and postdown() functions are ignored since there's nothing to do if they indicate failure.

${IFACE} is set to the interface being brought up/down. ${IFVAR} is ${IFACE} converted to variable name bash allows.

FILE /etc/conf.d/netpre/post up/down function examples

preup() {
  # Test for link on the interface prior to bringing it up.  This
  # only works on some network adapters and requires the ethtool
  # package to be installed.
  if ethtool ${IFACE} | grep -q 'Link detected: no'; then
    ewarn "No link on ${IFACE}, aborting configuration"
    return 1
  fi
  
  # Remember to return 0 on success
  return 0
}
  
predown() {
  # The default in the script is to test for NFS root and disallow
  # downing interfaces in that case.  Note that if you specify a
  # predown() function you will override that logic.  Here it is, in
  # case you still want it...
  if is_net_fs /; then
    eerror "root filesystem is network mounted -- can't stop ${IFACE}"
    return 1
  fi
  
  # Remember to return 0 on success
  return 0
}
  
postup() {
  # This function could be used, for example, to register with a
  # dynamic DNS service.  Another possibility would be to
  # send/receive mail once the interface is brought up.
       return 0
}
  
postdown() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)
  return 0
}

Poznámka
For more information on writing functions, please read /usr/share/doc/netifrc-*/net.example.bz2.

Wireless function hooks

Poznámka
This will not work with WPA Supplicant - but the ${ESSID} and ${ESSIDVAR} variables are available in the postup() function.

Two functions can be defined in /etc/conf.d/net:

• preassociate(), called before association.
• postassociate(), called after association.

Each of these these functions is called with the interface name, available within each function via the IFACE variable, so that one function can control multiple interfaces.

The return values for the preassociate() function should be:

• 0 to indicate success, and to continue configuration.
• A non-zero value otherwise.

If preassociate() returns a non-zero value, interface configuration will be aborted.

The return value for the postassociate() function is ignored since there's nothing to do if it indicates failure.

Within each function, the exact ESSID of the AP the system is connecting to is available via the ESSID variable. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.

FILE /etc/conf.d/netpre/post association functions

preassociate() {
  # The below adds two configuration variables leap_user_ESSID
  # and leap_pass_ESSID. When they are both configured for the ESSID
  # being connected to then we run the CISCO LEAP script
  
  local user pass
  eval user=\"\$\{leap_user_${ESSIDVAR}\}\"
  eval pass=\"\$\{leap_pass_${ESSIDVAR}\}\"
  
  if [[ -n ${user} && -n ${pass} ]]; then
    if [[ ! -x /opt/cisco/bin/leapscript ]]; then
      eend "For LEAP support, please emerge net-misc/cisco-aironet-client-utils"
      return 1
    fi
    einfo "Waiting for LEAP Authentication on \"${ESSID//\\\\//}\""
    if /opt/cisco/bin/leapscript ${user} ${pass} | grep -q 'Login incorrect'; then
      ewarn "Login Failed for ${user}"
      return 1
    fi
  fi
  
  return 0
}
  
postassociate() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)
  
  return 0
}

Poznámka
${ESSID} and ${ESSIDVAR} are unavailable in predown() and postdown() functions.

Poznámka
For more information on writing custom functions, please read /usr/share/doc/netifrc-*/net.example.bz2.

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