[tor-bugs] #17027 [Tor]: policies_parse_exit_policy_internal should block all IPv4 and IPv6 local addresses

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#17027: policies_parse_exit_policy_internal should block all IPv4 and IPv6 local
addresses
------------------------+----------------------------------------
     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  major   |  Milestone:
    Component:  Tor     |    Version:  Tor: 0.2.7.2-alpha
   Resolution:          |   Keywords:  TorCoreTeam201509 security
Actual Points:          |  Parent ID:
       Points:          |
------------------------+----------------------------------------
Changes (by teor):

 * keywords:  TorCoreTeam201509 security 026-backport => TorCoreTeam201509
     security
 * milestone:  Tor: 0.2.7.x-final =>


Comment:

 Anything we do here will always have edge cases, like (multihomed) NAT, or
 NAT without an autodetected IP address.

 That said, I think I can fix this by:
 * refactoring `get_interface_address6` as a wrapper for a new
 `get_interface_address6_list`, which produces a smartlist of local
 addresses. (Similarly, create `get_interface_address_list`, a wrapper
 which produces a list of IPv4 addresses.)
 * blocking connections to all IPv4 addresses from
 `get_interface_address_list`, as long as rejectprivate and local_address
 are non-zero.
 * blocking connections to all IPv6 addresses from
 `get_interface_address6_list`, as long as rejectprivate and local_address
 and ipv6_exit are non-zero. (Otherwise, we're blocking all IPv6 addresses
 anyway.)
 * Creating or updating unit tests for `get_interface_address6_list`,
 `get_interface_address_list`, and `policies_parse_exit_policy_internal`.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17027#comment:2>
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