network/tasks/detected_network.yml: can_be_ap grep failed on absence of regex

[holta]

Emergency patch to help those whose laptops don't even mention AP at all in the output of iw list

Building on:

• Internal WiFi [IIAB hotspot] not working on a Old PC (Panasonic Toughbook CF-52) #3057
• PR Detect, record if wifi can be AP and suppress installing supporting files #3070
• PR Check hardware for AP and if so record 'can_be_ap = True' to /etc/iiab/iiab.ini #3222

[holta]

Quickly tested and Ed in the UK will now further test after merge.

[holta]

1. Thank you to Ed from Zimbabwe (@EMG70) for surfacing this bug!

2. There are related issues he'll be posting about on another ticket — as he tries to get IIAB working on his Dell Inspiron 1750 laptop — trying to get any kind of WiFi learning hotspot working (internal WiFi ideally, but USB WiFi dongle if necessary!?)

[jvonau]

Now was iw preinstalled by the os when the first failure occurred?
#3070 f55f4f3
4d5143e

[holta]

was iw preinstalled by the os when the first failure occurred?

Not by the OS per se, but I believe that yes iw was already pre-installed — by roles/1-prep here:

iiab/roles/1-prep/tasks/main.yml

Lines 38 to 40 in 2efd7c0

	- name: Install ~12 network/wifi/related packages + Squid if necessary + configure /etc/sysctl.conf -- full configuration LATER in 'network', after Stage 9
	include_tasks: roles/network/tasks/install.yml
	when: network_install and network_installed is undefined

Which ran:

iiab/roles/network/tasks/install.yml

Lines 22 to 38 in 2efd7c0

	- name: 'Install 11 network packages: avahi-daemon, hostapd, iproute2, iptables-persistent, iw, libnss-mdns, netmask, net-tools, rfkill, wireless-tools, wpasupplicant -- later used by https://github.com/iiab/iiab/tree/master/roles/network'
	package:
	name:
	- avahi-daemon # 97kB download: RasPiOS (and package libnss-mnds, below) install this regardless -- holdover from the XO days and used to advertise ssh/admin-console being available via avahi-daemon -- used with https://github.com/iiab/iiab/blob/master/roles/network/tasks/avahi.yml
	#- avahi-discover # 46kB download: 2021-07-27: Commented out long ago
	- hostapd # 764kB download: IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP Authenticator -- has its service masked out of the box, and only used when IIAB's network roles detects the presence of WiFi and an AP is desired
	#- inetutils-syslogd # 240kB download: 2021-07-27: Error logging facility -- holdover from the XO days, journalctl has replaced this in newer distros
	- iproute2 # 902kB download: RasPiOS installs this regardless -- the new networking and traffic control tools, meant to replace net-tools
	- iptables-persistent # 12kB download: Boot-time loader for netfilter rules, iptables (firewall) plugin -- however Netfilter / nftables is ever moving forward so keep an eye on it!
	- iw # 97kB download: RasPiOS installs this regardless -- configure Linux wireless devices -- hard dependence for ap0 creation, SEE https://github.com/iiab/iiab/blob/master/roles/network/templates/hostapd/iiab-clone-wifi.service.j2
	- libnss-mdns # 27kB download: RasPiOS (and package avahi-daemon, above) install this regardless -- client-side library -- provides name resolution via mDNS (Multicast DNS) using Zeroconf/Bonjour e.g. Avahi
	- netmask # 25kB download: Handy utility -- helps determine network masks
	- net-tools # 248kB download: RasPiOS installs this regardless -- @jvonau suggests possibly deleting this...unless oldtimers really want these older commands in iiab-diagnostics output?
	- rfkill # 87kB download: RasPiOS installs this regardless -- enable & disable wireless devices
	- wireless-tools # 112kB download: RasPiOS installs this regardless -- manipulate Linux Wireless Extensions
	- wpasupplicant # 1188kB download: RasPiOS installs this regardless -- client library for connections to a WiFi AP
	state: present

[holta]

Please move the discussion to his actual ticket if possible?

• Dell inspiron 1750 wlan issues [trying for any hotspot, internal or WiFi USB dongle] #3324

[jvonau]

was iw preinstalled by the os when the first failure occurred?

Not by the OS per se, but I believe that yes iw was already pre-installed — by roles/1-prep here:

That doesn't answer the question of why the stanza failed on the first pass.. Then at some point recorded can_be_ap as True

[holta]

why the stanza failed on the first pass

Recap, of what's explained in this PR itself:

Our Ansible logic was just wrong (prior to this PR).

As it failed when attempted on any laptop (machine) like the one @EMG70 is attempting to get working with IIAB — e.g. when 'AP' (or anything like it) is not contained anywhere in the output of iw list

In short, the logic that we had in place was just wrong, failing to account for the above kind of situation — when the shell command fails — as a result of grep return code of 1.

As mentioned earlier today: this failure occurs regardless of the whatever regex grep is scanning for. Specifically: when the regular expression (whatever regex) is not found in the output of iw list

[jvonau]

That is why there was ' | wc -l' which was vetted against the live test of subject #3057 and later changed with f55f4f3 but was not cherry-picked into the tree then 4d5143e that I suspect was not tested against non-AP capable hardware... back over to you to fix..

[holta]

Indeed the earlier regular expression had serious errors (counting the wrong kinds of lines until about May, which is now cleaned up).

I agree a simple simple existence test is what's really needed (no counting, no fancy corner cases, just a Dead Simple yes-or-no presence test which things like grep -q were designed for).

So the code is not the most elegant as is — but so be it at least it's finally fixed yay.

Thanks go to @EMG70 for uncovering this.

[jvonau]

Indeed the earlier regular expression had serious errors (counting the wrong kinds of lines until about May, which is now cleaned up).

You have never shown any supporting evidence or issues reported to support that claim.

[holta]

Erroneous results were in fact extremely common, caused be strings that happen to contain the letters 'AP' within another word.

As documented here:

iiab/roles/network/tasks/detected_network.yml

Line 112 in d99fcad

# shell: iw list | grep -v AP: | grep AP | wc -l # False positives 'EAP' etc

This is the reason the regex was much improved around May (of this year).

(Apparently EAP = Extensible Authentication Protocol)

[jvonau]

In the face of the lack of presented evidence that statement is hearsay and nothing more.