add wifi_monitor package

[furushchev]

this pull request adds wifi_monitor package, including nodes publishing wifi network status.

---
header: 
  seq: 2
  stamp: 
    secs: 1472354728
    nsecs: 479886054
  frame_id: ''
interface: wlan0
enabled: True
connected: True
ssid: <hidden>
frequency: 2.43700003624
access_point: <hidden>
bitrate: 144.399993896
tx_power: 22A4:12:42:47:E8:FD
link_quality: 0.714285731316
signal_level: -60

---

[naveedhd]

The output of iwconfig differs from driver to driver, so parsing the output requires considering different fields.

Running your program gives the following error at my system:

[ERROR] [WallTime: 1472630848.523563] Failed to publish status: 'Tx-Power'
[ERROR] [WallTime: 1472630848.524472] Traceback (most recent call last):
  File ".../wifi_monitor/scripts/network_status.py", line 114, in publish_status
    msg.tx_power = extract_number(self.iwconfig.status["Tx-Power"])
KeyError: 'Tx-Power'

Here is the output of iwconfig:

wlan2     IEEE 802.11AC  ESSID:"<hidden>"  Nickname:"<hidden>"
          Mode:Managed  Frequency:5.785 GHz  Access Point: <hidden>   
          Bit Rate:867 Mb/s   Sensitivity:0/0  
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=100/100  Signal level=100/100  Noise level=0/100
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

[furushchev]

@naveedhd Thank you for reviewing! I just did not know that.

This is at my system:

wlan0     IEEE 802.11abgn  ESSID:"<hidden>"  
          Mode:Managed  Frequency:2.462 GHz  Access Point: <hidden>  
          Bit Rate=130 Mb/s   Tx-Power=13 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=48/70  Signal level=-62 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:113   Missed beacon:0

It seems that for example there is no Tx-Power at your system.
Well, what is the output of iwlist wlan2 txpower at your system?

[naveedhd]

iwlist wlan2 txpower gives:

wlan2 unknown transmit-power information.

[naveedhd]

Also you can notice the difference in output of Signal Level. One is in dBm and other is x/100.

[reinzor]

What's the status on this? I also have my custom wireless monitor solution now: ros/diagnostics#87

Could we add this to this repo?

[k-okada]

@reinzor can you add your work to this package? Thanks in advance.

[reinzor]

@reinzor can you add your work to this package? Thanks in advance.

Just added a new PR with the mentioned work.