avail_nets fails sometimes when an HP printer network is present

[keithrbennett]

(This issue reported at https://apple.stackexchange.com/questions/341517/airport-s-x-returns-truncated-output.)

The avail_nets command calls airport -s -x to get available network information in (pseudo-)XML format. In several locations, if there is an HP printer network, the output terminates somewhere in that element, and the command fails. For example:

       <key>SSID_STR</key>
       <string>DIRECT-0E-HP OfficeJet 4650</string>
       <key>WPS_PROB_RESP_IE</key>
       <dict>
                <key>IE_KEY_WPS_AP_SETUP_LOCKED</key>
                <true/>
                <key>IE_KEY_WPS_CFG_METHODS</key>
                <integer>0</integer>
                <key>IE_KEY_WPS_DEV_NAME</key>
                <string>DIRECT-0E-HP OfficeJet 4650</string>
                <key>IE_KEY_WPS_DEV_NAME_DATA</key>
                <data>
                RElSRUNULTBFLUhQIE9mZmljZUpldCA0NjUw
                </data>
                <key>IE_KEY_WPS_MANUFACTURER</key>
                <string>HP</string>
                <key>IE_KEY_WPS_MODEL_NAME</key>
                <string>OfficeJet 4650 series

Without the -x option, the output works, but, as I say, there is the space issue that prevents me from relying on it:

                        SSID BSSID             RSSI CHANNEL HT CC SECURITY (auth/unicast/group)
                NETGEAR25-5G a0:04:60:1a:5a:89 -67  153,-1  Y  -- WPA2(PSK/AES/AES)
 DIRECT-0E-HP OfficeJet 4650 ac:e2:d3:a9:d9:0f -90  6       Y  -- WPA2(PSK/AES/AES)
                      iPhone b2:8d:6c:9f:dd:00 -49  1       Y  US WPA2(PSK/AES/AES)
                   NETGEAR25 a0:04:60:1a:5a:87 -62  9       Y  -- WPA2(PSK/AES/AES)
                   CBCI-4F58 60:3d:26:57:4f:5c -86  6       Y  -- WPA2(PSK/AES/AES)

[keithrbennett]

Apparently there are others who have discovered this bug: An excerpt from https://clburlison.com/macos-wifi-scanning/:

When you run airport with the --xml flag the command would fail to output properly formatted xml data. I did not spend a bunch of time trying to find the root issue since I wanted a working solution now and knew any potential bug fixes would take 3-18 months. One idea is that HP printers are broadcasting a SSID with unsafe characters, or maybe the airport command chokes when scanning in a highly saturated area.

You can see the result of a failed run below, without proper ending tags:

<dict>
    <!-- removed for brevity-->
    <key>SSID_STR</key>
    <string>DIRECT-54-HP ENVY 4520 series</string>
    <key>WPS_PROB_RESP_IE</key>
    <dict>
        <key>IE_KEY_WPS_AP_SETUP_LOCKED</key>
        <true/>
        <key>IE_KEY_WPS_CFG_METHODS</key>
        <integer>0</integer>
        <key>IE_KEY_WPS_DEV_NAME</key>
        <string>DIRECT-54-HP ENVY 4520 series</string>
        <key>IE_KEY_WPS_DEV_NAME_DATA</key>
        <data>
        RElSRUNULTU0LUhQIEVOVlkgNDUyMCBzZXJpZXM=
        </data>
        <key>IE_KEY_WPS_MANUFACTURER</key>
        <string>HP</string>
        <key>IE_KEY_WPS_MODEL_NAME</key>
        <string>ENVY 4520 series

[gonewest818]

fwiw, this airport bug is still the case on Catalina 10.15.2.