[Profile] Use Tasker to update Google Domains DynDNS

[codesplice]

I whipped up a profile that I'm fairly pleased with... since Google Domains just added dynamic DNS support (as well as an API for updating the records), I created a Tasker profile to automatically update a DynDNS record for my phone whenever it's connected to Wifi. It's not a particularly useful profile (unless you plan on hosting a website on your phone? I'm not going to judge) but it was a fun challenge to put together. Besides, it's been a while since I've whipped up a profile from scratch.

I also figured this was a good time to start using that domain name I purchased for something - a wild blog post appears!

Anyhoo, here are the deets:

Profile: DynDNS

Notification: no

State: Wifi Connected [ SSID:* MAC:* IP:* ]

Enter: DDNS

A1: Wait [ MS:0 Seconds:5 Minutes:0 Hours:0 Days:0 ]

A2: HTTP Get [ Server:Port:http://ipv4.icanhazip.com/ Path: Attributes: Cookies: User Agent: Timeout:20 Mime Type: Output File: Trust Any Certificate:Off ]

A3: If [ %HTTPD !~ %PUB_IP ]

A4: Variable Set [ Name:%PUB_IP To:%HTTPD Do Maths:Off Append:Off ]

A5: HTTP Post [ Server:Port:https://username:password@domains.google.com Path:/nic/update?hostname=nexusXXXXX.codesplice.net&myip=%PUB_IP Data / File: Cookies: User Agent: Timeout:10 Content Type: Output File: Trust Any Certificate:Off ]

A6: Wait [ MS:0 Seconds:0 Minutes:2 Hours:0 Days:0 ]

A7: Variable Set [ Name:%newline To:
Do Maths:Off Append:Off ]

A8: Run Shell [ Command:nslookup nexusXXXXX.codesplice.net Timeout (Seconds):0 Use Root:Off Store Output In:%NSLOOKUP Store Errors In: Store Result In: ]

A9: Variable Split [ Name:%NSLOOKUP Splitter:%newline Delete Base:Off ]

A10: Notify [ Title:%NSLOOKUP4 Text:%NSLOOKUP5 Icon:hd_ab_navigation_accept Number:0 Permanent:Off Priority:1 ]

A11: Variable Clear [ Name:%NSLOOKUP* Pattern Matching:On ]

A12: End If

Line-by-line explanations:

1. Profile: DynDNS
   The name given to the profile.
2. Notification: no
   This profile will be a "fire-and-forget" sort of thing, so I don't want an ongoing notification when it's active.
3. State: Wifi Connected [ SSID:* MAC:* IP:* ]
   I'm going to attempt to update DynDNS when connected to Wifi.
4. Enter: DDNS
   Name of the Enter (and only) Task.
5. A1: Wait [ MS:0 Seconds:5 Minutes:0 Hours:0 Days:0 ]
   Wait 5 seconds after connecting to Wifi (to allow time to receive local DHCP IP and establish Internet connection).
6. A2: HTTP Get [ Server:port:http://ipv4.icanhazip.com/ Path: Attributes: Cookies: User Agent: Timeout:20 Mime Type: Output File: Trust Any Certificate:Off ]
   Connect to a dead-simple service for resolving the phone's public-facing IP. icanhazip.com returns just the IP address in plain-text with no filler, which means I don't have to do any crazy string parsing (yay!). Tasker automatically stores the returned data of an HTTP GET request into the global variable %HTTPD. Only the Server:port field is required.
   
7. A3: If [ %HTTPD !~ %PUB_IP ]
   I don't want to run the rest of the task (and submit repeated DynDNS updates) if the current public IP matches what I've already registered. I store the current IP in the%PUB_IP variable. For this If statement, I'm just checking to see if the HTTP GET return does not match the value of %PUB_IP. If TRUE (if it doesn't match), I run the rest of the Task; if FALSE (if it does match), I just skip to the end.
8. A4: Variable Set [ Name:%PUB_IP To:%HTTPD Do Maths:Off Append:Off ]
   Store the public IP as %PUB_IP.
9. A5: HTTP Post [ Server:port:https://username:password@domains.google.com Path:/nic/update?hostname=nexusXXXXX.codesplice.net&myip=%PUB_IP Data / File: Cookies: User Agent: Timeout:10 Content Type: Output File: Trust Any Certificate:Off ]
   This is the heavy lifter. Username and password should be the autogenerated values obtained from Google's Dynamic DNS Synthetic Records Creator Thing - NOT your Google credentials (pls). Replace nexusXXXXX.codesplice.net with your DynDNS record's subdomain (duh).
   
   
10. A6: Wait [ MS:0 Seconds:0 Minutes:2 Hours:0 Days:0 ]
    I'm feeling patient, so let's wait two minutes before we check to see if the DNS change has propagated.
11. A7: Variable Set [ Name:%newline To:
12. Do Maths:Off Append:Off ]
    Set the local %newline variable to a newline character (carriage return - just press Enter on your Android keyboard). This will come in handy shortly.
13. A8: Run Shell [ Command:nslookup nexusXXXXX.codesplice.net Timeout (Seconds):0 Use Root:Off Store Output In:%NSLOOKUP Store Errors In: Store Result In: ]
    Run the nslookup command against the hopefully-updated DynDNS record and store the returned data (command output) in %NSLOOKUP. The output of nslookup will look something like this:
    

    Server: google-public-dns-a.google.com
    Address: 8.8.8.8 
    
    Name: nexusXXXXX.codesplice.net
    Address: 71.228.X.X

14. A9: Variable Split [ Name:%NSLOOKUP Splitter:%newline Delete Base:Off ]
    Split the variable %NSLOOKUP into multiple variables at each newline character. We're really only interested in the last two lines of the nslookup output.
15. A10: Notify [ Title:%NSLOOKUP4 Text:%NSLOOKUP5 Icon:hd_ab_navigation_accept Number:0 Permanent:Off Priority:1 ]
    Create a low-priority notification to display the name of the DynDNS record (%NSLOOKUP4) and the public-facing IP (%NSLOOKUP5).
    
    
16. A11: Variable Clear [ Name:%NSLOOKUP* Pattern Matching:On ]
    Clean up some of the variable mess.
17. A12: End If
    FIN.

Ask if you have questions or, better yet, give me some tips on what I can use this for.