[tor-bugs] #33074 [Core Tor/Tor]: tor opens multiple ports if `ExtORPort auto` is used multiple times; only uses one of them

[Tor Bug Tracker & Wiki]

#33074: tor opens multiple ports if `ExtORPort auto` is used multiple times; only
uses one of them
------------------------------+--------------------
     Reporter:  dcf           |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+--------------------
 Create a file `logenv` and make it executable:
 {{{#!sh
 #!/bin/sh
 env >> env.txt
 }}}
 Run tor with this torrc:
 {{{
 SocksPort 0
 ORPort auto
 BridgeRelay 1
 PublishServerDescriptor 0

 ServerTransportPlugin logenv exec ./logenv

 ExtORPort auto
 ExtORPort auto
 ExtORPort auto
 ExtORPort auto
 ExtORPort auto
 }}}

 The 5 instances of `ExtORPort auto` cause tor to open 5 separate ports:
 {{{
 Jan 28 02:13:57.497 [notice] Opening Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Extended OR listener listening on port 45725.
 Jan 28 02:13:57.497 [notice] Opened Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Opening Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Extended OR listener listening on port 38173.
 Jan 28 02:13:57.497 [notice] Opened Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Opening Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Extended OR listener listening on port 34313.
 Jan 28 02:13:57.497 [notice] Opened Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.497 [notice] Opening Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.498 [notice] Extended OR listener listening on port 44593.
 Jan 28 02:13:57.498 [notice] Opened Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.498 [notice] Opening Extended OR listener on 127.0.0.1:0
 Jan 28 02:13:57.498 [notice] Extended OR listener listening on port 40255.
 Jan 28 02:13:57.498 [notice] Opened Extended OR listener on 127.0.0.1:0
 }}}

 Only one of them (the first one logged) is actually given to the pluggable
 transport:
 {{{
 $ grep ^TOR_PT_EXTENDED_SERVER_PORT env.txt
 TOR_PT_EXTENDED_SERVER_PORT=127.0.0.1:45725
 }}}

 I expected that tor would report an error if `ExtORPort` were used more
 than once, or perhaps deduplicate multiple identical `ExtORPort` lines.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33074>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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