This ensures one can't instanciate a DNSResolver object by
mistake, but uses the singleton. A separate create static
function is added for cases where a new object is explicitely
needed.
Based on tewinget's update.
Make OpenAlias address format independent of existing DNS functions.
Add tests.
Test:
make debug-test
cd build/debug/tests/unit_tests
# test that regular DNS functions work, including IPv4 lookups.
# also test function that converts OpenAlias address format
make && ./unit_tests --gtest_filter=DNSResolver*
# test that OpenAlias addresses like donate@getmonero.org work from
# wallet tools
make && ./unit_tests --gtest_filter=AddressFromURL.Success
Due to a bug in unbound, we were passing a string containing a null
character to ub_ctx_resolvconf and ub_ctx_hosts rather than a NULL
pointer. On *nix this wasn't causing headache, but on Windows this was
causing unbound to not correctly load DNS settings from the OS.
Note on the bug: in a Windows-specific code branch in the function
ub_ctx_hosts(), if the hosts file specified was a NULL pointer, a call
to getenv() was stored in a local char* and later freed. This is
incorrect, as we do not own that data, and caused the program to crash.
DNSSEC is now implemented with the hardcoded key from unbound.
This will need to be not hardcoded in the future, but is okay for now.
Unit tests updated for DNSSEC (as well as for the fact that, contrary to
previous assumption, example.com does not have a static IP address).
Note: DNSResolver does not yet *use* DNSSEC, but rather this commit is
preparation for including DNSSEC validation. The function in
src/wallet/wallet2.cpp that uses DNSResolver still needs its parameters
updated accordingly.
ldns dependency was only still around for constants defined in ldns/rr.h,
but those constants are RFC specified DNS constants, and to reduce deps
have been replicated in dns_utils.h instead of including ldns/rr.h.
