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Comment by shereadsthenews | Hacker News Reader

Ok but these messages are isomorphic on the wire:

  message enc {
    int foo = 1;
    SomeMessage bar = 2;
  }

  message dec {
    bool should_explode = 1;
    string why = 2;
  }

You can successfully decode the latter from an encoding of the former.

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Minor nit, but not necessarily. For basically all values of SomeMessage, dec should fail to parse due to improperly encoded UTF8 data for field 2 (modulo some proto2 vs. proto3 and language binding implementation differences).

Change field 2 to a bytes field instead of a string field and then yes.

True but UTF8 enforcements was quite absent in all implementations until proto3, and the empty string would be a special case.

I should mention that I consider this a feature not a bug. The isomorphism permits an endpoint to use ‘bytes submessage_i_dont_need_to_decode’ to cheaply handle nested message structures that need to be preserved but not inspected, such as in a proxy application.

Bool will decode from int’s encoding??

Yes, they are both varint encoded on the wire. Refer to https://developers.google.com/protocol-buffers/docs/encoding...

Sigh.

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