Signed-off-by: David Goulet <dgoulet@torproject.org>

First, this commit moves the code used to prune the service list when
reloading Tor (HUP signal for instance) to a function from
rend_config_services().

Second, fix bug #21054, improve the code by using the newly added
circuit_get_next_service_intro_circ() function instead of poking at the global
list directly and add _many_ more comments.

Fixes #21054.

Signed-off-by: David Goulet <dgoulet@torproject.org>

Signed-off-by: David Goulet <dgoulet@torproject.org>

This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.

It also closes TROVE-2016-10-001 (aka bug 20384).

("ours" merge because there is a separate 20384 patch for 026)

This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.

(ours merge -- there is a separate 0.2.5 patch for 20384.)

This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.

These updates were made after the December 2016 list was created.

Self-testing circuits don't use guards, and nobody uses guards when
UseEntryGuards is disabled.

Fixes bug 21007; bug not in any released Tor.

"Ours" merge to avoid version bump.

"Ours" merge to avoid version bump.

"ours" merge to avoid version bump.