(regression) torsocks → fatal: socket: Function not implemented

torsocks version: 2.4.0-1

After upgrading from Bullseye to Bookworm, this is what happens in the logs when sending a Tor-routed message:

(/var/log/mail.log)

===8<----------------------------------------
2024-04-25T13:10:25.165542+02:00 MannysHost postfix/smtpd[*]: connect from localhost[127.0.0.1]
2024-04-25T13:10:25.186729+02:00 MannysHost postfix/smtpd[*]: 2D6EFE313A: client=localhost[127.0.0.1]
2024-04-25T13:10:25.232021+02:00 MannysHost postfix/cleanup[*]: 2D6EFE313A: message-id=<timestamp.yadayada@MannysHost>
2024-04-25T13:10:25.236765+02:00 MannysHost postfix/qmgr[*]: 2D6EFE313A: from=<[manny’s@email.addy]>, size=1181, nrcpt=1 (queue active)
2024-04-25T13:10:25.236875+02:00 MannysHost postfix/smtpd[*]: disconnect from localhost[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
2024-04-25T13:10:25.298945+02:00 MannysHost postfix/smtp[*]: fatal: socket: Function not implemented
2024-04-25T13:10:26.357045+02:00 MannysHost postfix/smtp[*]: fatal: socket: Function not implemented
2024-04-25T13:10:27.444922+02:00 MannysHost postfix/smtp[*]: fatal: socket: Function not implemented
…
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This is what the log looked like in Bullseye just before the upgrade, when sending over Tor still worked correctly:

(/var/log/mail.log)

===8<----------------------------------------
Apr 24 09:37:17 MannysHost postfix/postfix-script[2130]: refreshing the Postfix mail system
Apr 24 09:37:17 MannysHost postfix/master[1026]: reload -- version 3.5.24, configuration /etc/postfix
Apr 24 09:37:17 MannysHost postfix/postfix-script[2168]: refreshing the Postfix mail system
Apr 24 09:37:17 MannysHost postfix/master[1026]: reload -- version 3.5.24, configuration /etc/postfix
Apr 24 12:32:42 MannysHost postfix/submission/smtpd[27946]: connect from localhost[127.0.0.1]
Apr 24 12:32:42 MannysHost postfix/submission/smtpd[27946]: 3C344E3262: client=localhost[127.0.0.1]
Apr 24 12:32:42 MannysHost postfix/submission/cleanup/cleanup[27949]: 3C344E3262: message-id=<timestamp.yadayada@MannysHost>
Apr 24 12:32:42 MannysHost postfix/submission/smtpd[27946]: disconnect from localhost[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Apr 24 12:32:42 MannysHost postfix/qmgr[2173]: 3C344E3262: from=<manny’s@email.addy>, size=1126, nrcpt=1 (queue active)
Apr 24 12:32:50 MannysHost postfix/smtptor/smtp[27956]: 3C344E3262: to=<tor@recipient.addy>, relay=recipient.mx.server[1.2.3.4]:587, delay=8.1, delays=0.07/0.13/5.8/2.1, dsn=2.0.0, status=sent (250 OK id=yadayada)
===8<----------------------------------------

Sending over clearnet has no issues in any version. It’s only when a message must go over the Tor network that there is a problem.

The configuration consists of the following:

(/etc/postfix/master.cf)

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# The syslog_name option is not needed. It can be set to
# anything. It’s just to add distinction in mail.log between clearnet
# and Tor mail (otherwise both kinds of transmission are prefixed as
# “postfix/smtp”).
#
smtptor      unix  -       -       n       -       -       smtp_tor
  -o smtp_address_preference=ipv4
  -o smtp_dns_support_level=disabled
  -o smtp_tls_security_level=none
  -o debug_peer_level=2
  -o syslog_name=postfix/smtptor
===8<----------------------------------------

(/usr/lib/postfix/sbin/smtp_tor)

===8<----------------------------------------
!/bin/bash

typeset -r dir_cmd=$(/usr/sbin/postconf -h command_directory)
typeset -r exec_smtp=$("$dir_cmd"/postconf -h daemon_directory)/smtp

setx_output()
{
    if [[ $1 ]]; then
        exec 4>>"$1"
        BASH_XTRACEFD=4
        PS4='\D{+%F}T\t $LINENO: '
        set -x
    else
        set +x
        #BASH_XTRACEFD=2
        exec 4>&-
    fi
}
setx_output /var/log/mail_${0##*/}.log

torsocks "$exec_smtp" "$@"

setx_output
===8<----------------------------------------

To setup routing, the transport db is used.

(/etc/postfix/tor_transport)

===8<----------------------------------------
…
.onion smtptor:
===8<----------------------------------------