src: some refactoring of node_url.cc

• src: minor cleanups to node_url.cc

  • Remove pointless pointers
  • Make WriteHost take a const argument so that it’s functionality is clear from the signature
  • Make FindLongestZeroSequence templated to accommodate the constness in WriteHost and because using uint16_t is an articifial, unnecessary restriction
  • Remove string copying when no copies are needed
  • Make PercentDecode just return its return value
  • Make ParseHost (string-only version) take its constant argument as a constant reference

• src: move url internals into anonymous namespace

  This helps because static doesn’t work for C++ classes, but refactoring url_host into a proper C++ class seems the most reasonable soluation for the memory leak fixed by the next commit.

• src: make url host a proper C++ class

  • Gives URLHost a proper destructor that clears memory depending on the type of the host (This fixes a memory leak)
  • Hide the host type enums and class layout as implementation details
  • Make the Parse methods members of URLHost
  • Turn WriteHost into a ToString() method on the URLHost class
  • Verify that at the beginning of a parse attempt, the type is set to “failed”
  • Remove a lot of gotos from the source code 🐢🚀

  Fixes: https://github.com/nodejs/node/issues/17448

• src: use correct OOB check for IPv6 parsing

  last_piece pointed to the end of the 8×16 bit array, so piece_pointer == last_piece already means that the pointer is not writable any longer.

  Previously, this still worked most of the time but could result in an out-of-bounds-write.

  Also, rename last_piece to buffer_end to avoid this pitfall.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

src/node_url.cc

Not sure how to write tests but it makes valgrind happy about @TimothyGu’s example from #17448 (closed)