[Bug 1545363] Re: wpa-roam does not support logical "master" interfaces

[Paul Donohue]

** Description changed:

  There are situations where I have multiple APs (living on separate
  networks) in range simultaneously and I need to be able to manually
  choose between them (to manually move between those separate networks).
  
  To handle this, I have multiple wpa_supplicant config files for each of the APs, and I use logical interfaces in /etc/network/interfaces to select the appropriate config file.  For example:
  iface public inet manual
-   wpa-conf /etc/wpa_supplicant/public.conf
+   wpa-conf /etc/wpa_supplicant/public.conf
  iface private inet manual
-   wpa-conf /etc/wpa_supplicant/private.conf
+   wpa-conf /etc/wpa_supplicant/private.conf
  To select the appropriate AP, I simply run `ifup wlan0=public` or `ifup wlan0=private`.  This part works fine.
  
  However, I would like to change the "wpa-conf" lines in the above
  example to use "wpa-roam" instead, so I can also handle roaming in
  conjunction with multiple wpa_supplicant config files.  Unfortunately
  this doesn't work.  When the "master" interface is already using a
  logical interface in /etc/network/interfaces, wpa-roam fails to load the
  logical interface specified by id_str.
  
  The problem is that the ifup() function in functions.sh runs `grep -q
  "^$WPA_IFACE=$WPA_IFACE" "$IFSTATE_FILE"` to determine if the interface
  is already up, then runs /sbin/ifup either with or without '--force'
  depending on whether the interface is "up".  If the "master" interface
  is defined in /etc/network/interfaces as a logical interface rather than
  a physical interface, then grep will not match, '--force' will not be
  used, and /sbin/ifup will fail because the interface is already
  configured and '--force' was not used.
  
  The attached patch fixes this issue by running `ifquery` to determine
- whether the physical interface is currently up and configured as a
- wpasupplicant "master" interface, and will run /sbin/ifup with '--force'
- even if the "master" interface is a logical interface in
- /etc/network/interfaces.  If the physical interface is already up but is
- not configured as a "master" interface, then it is likely we received
- two "CONNECT" events without a "DISCONNECT" between them, so `ifdown` is
- run on the old logical interface before `ifup` is run on the new one.
+ whether the physical interface is currently configured as a
+ wpasupplicant "master" interface and needs the '--force' argument to
+ /sbin/ifup.

** Attachment added: "patch"
   https://bugs.launchpad.net/ubuntu/+source/wpa/+bug/1545363/+attachment/4572525/+files/patch

** Patch removed: "patch"
   https://bugs.launchpad.net/ubuntu/+source/wpa/+bug/1545363/+attachment/4571280/+files/patch

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https://bugs.launchpad.net/bugs/1545363

Title:
  wpa-roam does not support logical "master" interfaces

Status in wpa package in Ubuntu:
  New

Bug description:
  There are situations where I have multiple APs (living on separate
  networks) in range simultaneously and I need to be able to manually
  choose between them (to manually move between those separate
  networks).

  To handle this, I have multiple wpa_supplicant config files for each of the APs, and I use logical interfaces in /etc/network/interfaces to select the appropriate config file.  For example:
  iface public inet manual
    wpa-conf /etc/wpa_supplicant/public.conf
  iface private inet manual
    wpa-conf /etc/wpa_supplicant/private.conf
  To select the appropriate AP, I simply run `ifup wlan0=public` or `ifup wlan0=private`.  This part works fine.

  However, I would like to change the "wpa-conf" lines in the above
  example to use "wpa-roam" instead, so I can also handle roaming in
  conjunction with multiple wpa_supplicant config files.  Unfortunately
  this doesn't work.  When the "master" interface is already using a
  logical interface in /etc/network/interfaces, wpa-roam fails to load
  the logical interface specified by id_str.

  The problem is that the ifup() function in functions.sh runs `grep -q
  "^$WPA_IFACE=$WPA_IFACE" "$IFSTATE_FILE"` to determine if the
  interface is already up, then runs /sbin/ifup either with or without '
  --force' depending on whether the interface is "up".  If the "master"
  interface is defined in /etc/network/interfaces as a logical interface
  rather than a physical interface, then grep will not match, '--force'
  will not be used, and /sbin/ifup will fail because the interface is
  already configured and '--force' was not used.

  The attached patch fixes this issue by running `ifquery` to determine
  whether the physical interface is currently configured as a
  wpasupplicant "master" interface and needs the '--force' argument to
  /sbin/ifup.

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