Normalize Fee extension XML tags in EPP response

[weiminyu]

Nomulus currently supports multiple versions of the Fee extensions. Our current tooling requires that each version must use a unique namespace tag, e.g., fee11, fee12, etc.

Some client registrars are sensitive to the tag literal used by the version of the extension they use. For example, a few registrars currently using v0.6 have requested that the fee literal be used on the versions they currently use. With registrars upgrading at their own schedule, this kind of requests are impossible to satisfy.

This PR instroduces a namespace normalizer class for EPP responses. The key optimization is that each EPP response never mixes multiple versions of a service extension. Therefore we can define a canonical tag for each extension, and change the tag of the extension in use in a response to that. This normalizer only handles Fee extensions right now, but the idea can be extended to others if use cases come up.

This normalizer will be applied to all flows in a future PR.

See b/478848482

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This change is 

[weiminyu]

@weiminyu resolved 2 discussions.
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[CydeWeys]

@CydeWeys made 2 comments.
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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 55 at r2 (raw file):

 *
 * <p>Some registrars are not XML namespace-aware and rely on the XML tags being specific literals.
 * This makes it impossible to perform seamless rollout of new versions. Nomulus and the all

Grammar error here

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 63 at r2 (raw file):

 * versions from the message, thus freeing up the canonical tag ('fee') for the active version.
 */
public class FeeExtensionXmlTagNormalizer {

What are the performance implications of this approach? This is running a nontrivial amount of XML parsing code for each command response we return, right?

[weiminyu]

@weiminyu made 2 comments.
Reviewable status: 0 of 13 files reviewed, 2 unresolved discussions (waiting on @CydeWeys and @gbrodman).

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 55 at r2 (raw file):

Previously, CydeWeys (Ben McIlwain) wrote…

Grammar error here

Done.

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 63 at r2 (raw file):

Previously, CydeWeys (Ben McIlwain) wrote…

What are the performance implications of this approach? This is running a nontrivial amount of XML parsing code for each command response we return, right?

This is on par with the XmlSanitier that masks passwords: actions range between a few milliseconds to 10s of milliseconds.

Since the input is produced by our EppXmlTransformer, we know the format and can use regex. Rewrote it and processing is pretty consistent at 1 - 2 milliseconds per call, and it scales well with larger messages.

[weiminyu]

@weiminyu made 1 comment.
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[weiminyu]

@weiminyu resolved 1 discussion.
Reviewable status: 0 of 13 files reviewed, 2 unresolved discussions (waiting on @CydeWeys and @gbrodman).

[CydeWeys]

@CydeWeys resolved 2 discussions.
Reviewable status: 0 of 13 files reviewed, all discussions resolved (waiting on @gbrodman).

[CydeWeys]

@CydeWeys made 1 comment.
Reviewable status: 0 of 13 files reviewed, 1 unresolved discussion (waiting on @gbrodman and @weiminyu).

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 76 at r4 (raw file):

   * than XML stream parsers.
   */
  public static String normalize(String xml) {

Is this being called on every single XML response we're returning? If so, is there an easy way to only call it when we know the fee extension is already in use? Inside the relevant flows they definitely know when the fee extension is being used at least (and also, which version).

[CydeWeys]

@CydeWeys made 1 comment.
Reviewable status: 0 of 13 files reviewed, 1 unresolved discussion (waiting on @gbrodman and @weiminyu).

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 76 at r4 (raw file):

Previously, CydeWeys (Ben McIlwain) wrote…

Is this being called on every single XML response we're returning? If so, is there an easy way to only call it when we know the fee extension is already in use? Inside the relevant flows they definitely know when the fee extension is being used at least (and also, which version).

And also, this definitely never needs to be called on host flows; is it?

[weiminyu]

@weiminyu made 1 comment.
Reviewable status: 0 of 13 files reviewed, 1 unresolved discussion (waiting on @CydeWeys and @gbrodman).

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core/src/main/java/google/registry/flows/FeeExtensionXmlTagNormalizer.java line 76 at r4 (raw file):

Previously, CydeWeys (Ben McIlwain) wrote…

And also, this definitely never needs to be called on host flows; is it?

Yeah, Host flows don't need them. And we can make sure this is only applied to responses that include fee extensions.

On the other hand, it is takes just a simple pattern match to discover if fee extension is in use in a response. The cost is tiny when compared with marshalling.

[CydeWeys]

@CydeWeys reviewed 13 files and all commit messages, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @gbrodman).