On Tuesday, 13 February 2018 at 22:13:36 UTC, H. S. Teoh wrote:


Ironically, the general advice I found online w.r.t XML vulnerabilities is "don't allow DTDs", "don't expand entities", "don't resolve externals", etc.. There also aren't many XML parsers out there that fully support all the features called for in the spec. IOW, this basically amounts to "just use dxml and forget about everything else". :-D

Now of course, there *are* valid use cases for DTDs... but a naïve implementation of the spec is only going to end in tears. My current inclination is, just merge dxml into Phobos, then whoever dares implement DTD support can do so on top of dxml, and shoulder their own responsibility for vulnerabilities or whatever. (I mean, seriously, just for the sake of being able to say "my XML is validated" we have to implement network access, local filesystem access, a security framework, and what amounts to a sandbox to control pathological behaviour like exponentially recursive entities? And all of this, just to handle rare corner cases? That's completely ridiculous. It's an obvious design smell to me. The only thing missing from this poisonous mix is Turing completeness, which would have made XML hackers' heaven. Oh wait, on further googling, I see that XSLT *is* Turing complete. Great, just great. Now I know why I've always had this gut feeling that *something* is off about the whole XML mania.)


T

Thanks for the analysis. I'd say you're right. It makes no sense to keep dxml from becoming std.xml's successor only because it doesn't support DTDs. Also, as I said before, if we had DTD support in std.xml, people would complain about the lack of efficiency, and the discussion about interpreting the specs correctly, implementing them 100%, complaints about the lack of security would just never end.

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