[util] Add method http_get

[dagurval]

No description provided.

[dagurval]

I need this for fetching runtime statistics from electrum server. Pushing as a separate pull request to check if all the new boost stuff works on travis.

[sickpig]

@dagurval

../../src/utilhttp.cpp:4:10: fatal error: 'boost/beast/core.hpp' file not found
#include <boost/beast/core.hpp>
         ^~~~~~~~~~~~~~~~~~~~~~

[dagurval]

Looks like this requires boost 1.651.66, while BU is on boost 1.64. Can we upgrade? :-)

[sickpig]

@dagurval

we could upgrade the dependencies to use boost 1.65 rather than 1.64.

Even bionic come with 1.65. If we decide to upgrade and ask boost >= 1.65 as requirement we should provide some guidance to the people who are using older but still supported distro and are not using gitian binaries or ubuntu ppa repo.

What other people think?

[dagurval]

Re-written to use libevent instead of boost. This is worse, but it doesn't require newer boost functionality.

[sickpig]

@dagurval thanks for doing it!

I wonder if we could move all out util*.{cpp,h} in separate dir, maybe src/util?

This something for another PR thou.

[gandrewstone]

    DbgAssert(static_cast<size_t>(s) <= sizeof buffer, {return });

has an error. just use:

    DbgAssert(static_cast<size_t>(s) <= sizeof buffer, return);