[tor-commits] [tor/master] Fix a comment that misunderstood is_canonical

[nickm@xxxxxxxxxxxxxx]

commit 427ae164f33aad6004290fc407d53ab3315b399a
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date:   Wed Sep 20 09:38:50 2017 -0400

    Fix a comment that misunderstood is_canonical
    
    is_canonical doesn't mean "am I connected to the one true address of
    this relay"; it means "does this relay tell me that the address I'm
    connected to belong to it."  The point is to prevent TCP-based MITM,
    not to prevent the relay from multi-homing.
    
    Related to 22890.
---
 src/or/channeltls.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/or/channeltls.c b/src/or/channeltls.c
index 7f6882448..827781318 100644
--- a/src/or/channeltls.c
+++ b/src/or/channeltls.c
@@ -1793,12 +1793,11 @@ channel_tls_process_netinfo_cell(cell_t *cell, channel_tls_t *chan)
       return;
     }
     /* A relay can connect from anywhere and be canonical, so
-     * long as it tells you from where it came. This may be a bit
-     * concerning.. Luckily we have another check in
-     * channel_tls_matches_target_method() to ensure that extends
-     * only go to the IP they ask for.
-     *
-     * XXX: Bleh. That check is not used if the connection is canonical.
+     * long as it tells you from where it came. This may sound a bit
+     * concerning... but that's what "canonical" means: that the
+     * address is one that the relay itself has claimed.  The relay
+     * might be doing something funny, but nobody else is doing a MITM
+     * on the relay's TCP.
      */
     if (tor_addr_eq(&addr, &(chan->conn->real_addr))) {
       connection_or_set_canonical(chan->conn, 1);

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