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83 lines
2.7 KiB
Markdown
83 lines
2.7 KiB
Markdown
# TXT record testing
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We recently discovered a strange bug with processing TXT records and
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double-quotes. Sadly we haven't been able to determine a way to test this
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automatically. Therefore, I've written up this methodology.
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# The problem
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The problem relates to TXT records that have a string with quotes in them.
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If a user creates a TXT record whose contents are `"something"` (yes, with
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double quotes), some APIs get confused.
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This bug is most likely to appear in a provider that uses
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`RecordConfig.PopulateFromString()` (see `models/t_parse.go`) to create TXT
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records. That function assumes the string should always have the quotes
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stripped, though it is more likely that the string should be taken verbatim.
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# The test
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To complete this test, you will need a test domain that you can add records to.
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It won't be modified otherwise.
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This bug has to do with double-quotes at the start and end of TXT records. If
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your provider doesn't permit double-quotes in TXT records (you'd be surprised!)
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you don't have to worry about this bug because those records are banned
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in your `auditrecords.go` file.
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## Step 1: Create the test records
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Log into your DNS provider's web UI (portal) and create these 4 TXT records. (Don't use DNSControl!) Yes, include the double-quotes on test 2 and 3!
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| Hostname | TXT |
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|---------------|-----------|
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| t0 | test0 |
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| t1 | test1 |
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| t2 | "test2" |
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| t3 | "test3" |
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## Step 2: Update `dnsconfig.js`
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Now in your `dnsconfig.js` file, add these records to the domain:
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TXT("t0", "test0"),
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TXT("t1", "\"test1\""),
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TXT("t2", "test2"),
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TXT("t3", "\"test3\""),
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## Step 3: Preview
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When you do a `dnscontrol preview`, you should see changes for t1 and t2.
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```text
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#1: MODIFY TXT t1.example.com: ("test1" ttl=1) -> ("\"test1\"" ttl=1)
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#2: MODIFY TXT t2.example.com: ("\"test2\"" ttl=1) -> ("test2" ttl=1)
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```
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If you don't see those changes, that's a bug. For example, we found that
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Cloudflare left t2 alone but would try to add double-quotes to t3! This was
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fixed in [PR#1543](https://github.com/StackExchange/dnscontrol/pull/1543).
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## Step 4: Push
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Let's assume you DO see the changes. Push them using `dnscontrol push`
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then check the webui to see that the changes are correct.
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```text
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2 corrections
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#1: MODIFY TXT t1.stackoverflow.help: ("test1" ttl=1) -> ("\"test1\"" ttl=1)
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SUCCESS!
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#2: MODIFY TXT t2.stackoverflow.help: ("\"test2\"" ttl=1) -> ("test2" ttl=1)
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SUCCESS!
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```
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Refresh your provider's web UI and you should see the changes as expected: t1
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should have double-quotes and t2 shouldn't. If the change wasn't correctly
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done, that's a bug.
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## Step 5: That's it!
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Remove the lines from `dnsconfig.js` and run `dnscontrol push` to clean up.
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