.Dd July 16, 2023
.Dt POUNCE 1
.Os
.
.Sh NAME
.Nm pounce
.Nd IRC bouncer
.
.Sh SYNOPSIS
.Nm
.Op Fl LNTev
.Op Fl A Ar local-ca
.Op Fl C Ar local-cert
.Op Fl H Ar local-host
.Op Fl K Ar local-priv
.Op Fl P Ar local-port
.Op Fl Q Ar queue-interval
.Op Fl R Ar blind-req
.Op Fl S Ar bind
.Op Fl U Ar local-path
.Op Fl W Ar local-pass
.Op Fl a Ar sasl-plain
.Op Fl c Ar client-cert
.Op Fl f Ar save
.Op Fl h Ar host
.Op Fl j Ar join
.Op Fl k Ar client-priv
.Op Fl m Ar mode
.Op Fl n Ar nick
.Op Fl p Ar port
.Op Fl q Ar quit
.Op Fl r Ar real
.Op Fl t Ar trust
.Op Fl s Ar size
.Op Fl u Ar user
.Op Fl w Ar pass
.Op Fl y Ar away
.Op Ar config ...
.
.Nm
.Fl o
.Op Fl S Ar bind
.Op Fl h Ar host
.Op Fl p Ar port
.Op Ar config ...
.
.Nm
.Op Fl A Ar ca
.Fl g Ar cert
.
.Nm
.Fl x
.
.Sh DESCRIPTION
The
.Nm
program
is a multi-client, TLS-only IRC bouncer.
It maintains a persistent connection to an IRC server
while allowing clients to connect and disconnect,
receiving messages that were missed upon reconnection.
Clients must uniquely identify themselves to
.Nm
by their IRC username
(not nickname).
The IRCv3
.Sy server-time
extension is used to indicate
when messages were originally received.
See
.Sx Client Configuration
for details.
.
.Pp
The local server portion of
.Nm
requires a TLS certificate,
which can be obtained for example
by an ACME client such as
.Xr acme-client 8 .
The private key
must be made readable by
the user running
.Nm .
.
.Pp
One instance of
.Nm
must be configured for each IRC network.
Instances of
.Nm
must either use different local ports with
.Cm local-port
or different local host names with
.Cm local-host
and
.Cm local-path
to be dispatched from the same port by
.Xr calico 1 .
.
.Pp
Client connections are not accepted
until successful login to the server.
If the server connection is lost,
the
.Nm
process exits.
.
.Pp
Options can be loaded from
files listed on the command line.
Files are searched for in
.Pa $XDG_CONFIG_DIRS/pounce
.Po
usually
.Pa ~/.config/pounce
.Pc
unless the path starts with
.Ql / ,
.Ql \&./
or
.Ql \&../ .
Certificate and private key paths
are searched for in the same manner.
Files and flags
listed later on the command line
take precedence over those listed earlier.
.
.Pp
Each option is placed on a line,
and lines beginning with
.Ql #
are ignored.
The options are listed below
following their corresponding flags.
.
.Ss Local Server Options
.Bl -tag -width Ds
.It Fl A Ar path | Cm local-ca No = Ar path
Require clients to authenticate
using a TLS client certificate
either contained in
or signed by a certificate in
the file loaded from
.Ar path .
The file is reloaded when the
.Dv SIGUSR1
signal is received.
See
.Sx Generating Client Certificates .
If
.Cm local-pass
is also set,
clients may instead authenticate
with a server password.
.
.It Fl C Ar path | Cm local-cert No = Ar path
Load TLS certificate from
.Ar path .
The file is reloaded when the
.Dv SIGUSR1
signal is received.
The default path is
.Ar host Ns .pem ,
where
.Ar host
is set by
.Cm local-host .
.
.It Fl H Ar host | Cm local-host No = Ar host
Bind to
.Ar host .
The default host is localhost.
.
.It Fl K Ar path | Cm local-priv No = Ar path
Load TLS private key from
.Ar path .
The file is reloaded when the
.Dv SIGUSR1
signal is received.
The default path is
.Ar host Ns .key ,
where
.Ar host
is set by
.Cm local-host .
.
.It Fl L | Cm palaver
Advertise the
.Sy palaverapp.com
IRCv3 vendor-specific capability to clients.
This option only enables the capability;
push notifications must be provided by the
.Xr pounce-palaver 1
special-purpose client.
.
.It Fl P Ar port | Cm local-port No = Ar port
Bind to
.Ar port .
The default port is 6697.
.
.It Fl T | Cm no-sts
Do not advertise a
strict transport security (STS) policy
to clients.
.
.It Fl U Ar path | Cm local-path No = Ar path
Bind to a UNIX-domain socket at
.Ar path .
Clients are only accepted as dispatched by
.Xr calico 1 .
If
.Ar path
is a directory,
the
.Ar host
set by
.Cm local-host
is appended to it.
This option takes precedence over
.Cm local-host
and
.Cm local-port .
.
.It Fl W Ar pass | Cm local-pass No = Ar pass
Require the server password
.Ar pass
for clients to connect.
The
.Ar pass
string must be hashed using
.Fl x .
If
.Cm local-ca
is also set,
clients may instead authenticate
using a TLS client certificate.
.
.It Fl f Ar path | Cm save No = Ar path
Save and load the contents of the buffer from
.Ar path
in
.Pa $XDG_DATA_DIRS/pounce ,
usually
.Pa ~/.local/share/pounce ,
or an absolute or relative path if
.Ar path
starts with
.Ql / ,
.Ql \&./
or
.Ql \&../ .
The file is truncated after loading.
.
.It Fl s Ar size | Cm size No = Ar size
Set the number of messages contained in the buffer to
.Ar size .
This sets the maximum number
of recent messages
which can be relayed
to a reconnecting client.
The size must be a power of two.
The default size is 4096.
.El
.
.Ss Remote Server Options
.Bl -tag -width Ds
.It Fl N | Cm no-names
Do not request
.Ql NAMES
for each channel when a client connects.
This avoids already connected clients
receiving unsolicited responses
but prevents new clients from populating user lists.
.
.It Fl Q Ar ms | Cm queue-interval No = Ar ms
Set the server send queue interval in milliseconds.
The queue is used
to send automated messages from
.Nm
to the server.
Messages from clients
are sent to the server directly.
The default interval is 200 milliseconds.
.
.It Fl R Ar caps | Cm blind-req No = Ar caps
Blindly request the IRCv3 capabilities
.Ar caps ,
which must be supported by
.Nm .
This can be used to enable hidden capabilities,
such as
.Sy userhost-in-names
on some networks.
.
.It Fl S Ar host | Cm bind No = Ar host
Bind to source address
.Ar host
when connecting to the server.
To connect from any address
over IPv4 only,
use 0.0.0.0.
To connect from any address
over IPv6 only,
use ::.
.
.It Fl a Ar user : Ns Ar pass | Cm sasl-plain No = Ar user : Ns Ar pass
Authenticate as
.Ar user
with
.Ar pass
using SASL PLAIN.
Since this method requires
the account password in plaintext,
it is recommended to use CertFP instead with
.Cm sasl-external .
.
.It Fl c Ar path | Cm client-cert No = Ar path
Load the TLS client certificate from
.Ar path .
If the private key is in a separate file,
it is loaded with
.Cm client-priv .
With
.Cm sasl-external ,
authenticate using SASL EXTERNAL.
Certificates can be generated with
.Fl g .
.
.It Fl e | Cm sasl-external
Authenticate using SASL EXTERNAL,
also known as CertFP.
The TLS client certificate is loaded with
.Cm client-cert .
See
.Sx Configuring CertFP .
.
.It Fl h Ar host | Cm host No = Ar host
Connect to
.Ar host .
.
.It Fl j Ar channels Oo Ar keys Oc | Cm join No = Ar channels Op Ar keys
Join the comma-separated list of
.Ar channels
with the optional comma-separated list of channel
.Ar keys .
.
.It Fl k Ar path | Cm client-priv No = Ar path
Load the TLS client private key from
.Ar path .
.
.It Fl m Ar mode | Cm mode No = Ar mode
Set the user
.Ar mode .
.
.It Fl n Ar nick | Cm nick No = Ar nick
Set nickname to
.Ar nick .
The default nickname is the user's name.
.
.It Fl p Ar port | Cm port No = Ar port
Connect to
.Ar port .
The default port is 6697.
.
.It Fl q Ar mesg | Cm quit No = Ar mesg
Quit with message
.Ar mesg
when shutting down.
.
.It Fl r Ar real | Cm real No = Ar real
Set realname to
.Ar real .
The default realname is the same as the nickname.
.
.It Fl t Ar path | Cm trust No = Ar path
Trust the certificate loaded from
.Ar path .
Server name verification is disabled.
See
.Sx Connecting to Servers with Self-signed Certificates .
.
.It Fl u Ar user | Cm user No = Ar user
Set username to
.Ar user .
The default username is the same as the nickname.
.
.It Fl w Ar pass | Cm pass No = Ar pass
Log in with the server password
.Ar pass .
.
.It Fl y Ar mesg | Cm away No = Ar mesg
Set away status to
.Ar mesg
when no clients are connected
and no other away status has been set.
.El
.
.Ss Other Options
.Bl -tag -width Ds
.It Fl g Ar path
Generate a TLS client certificate using
.Xr openssl 1
and write it to
.Ar path .
The certificate is signed
by the certificate authority if
.Fl A
is set,
otherwise it is self-signed.
.
.It Fl o
Print the server certificate chain
to standard output in PEM format
and exit.
.
.It Fl v | Cm verbose
Log IRC messages to standard output:
.Pp
.Bl -tag -width "<<" -compact
.It <<
from
.Nm
to the server
.It >>
from the server to
.Nm
.It ->
from clients to
.Nm
.It <-
from
.Nm
to clients
.El
.
.It Fl x
Prompt for a password
and output a hash
for use with
.Cm local-pass .
.El
.
.Ss Client Configuration
Clients should be configured to
connect to the host and port set by
.Cm local-host
and
.Cm local-port ,
with TLS or SSL enabled.
If
.Cm local-pass
is used,
clients must send a server password.
If
.Cm local-ca
is used,
clients must connect with a client certificate
and may request SASL EXTERNAL.
If both are used,
clients may authenticate with either method.
.
.Pp
Clients must register with unique usernames (not nicknames),
for example the name of the client software
or location from which it is connecting.
New clients with the same username
are assumed to be reconnections
and will cause previous connections
to stop receiving messages.
The nickname and real name
sent by clients are ignored.
.
.Pp
Normally a client sending
.Ic QUIT
will simply be disconnected from
.Nm .
If, however,
the quit message
starts with the keyword
.Sy $pounce ,
.Nm
itself will quit.
The remainder of the message
following the keyword
will be used as
.Nm Ap s
quit message,
or the default set by
.Cm quit
if there isn't any.
.
.Pp
Clients which request the
.Sy causal.agency/passive
capability
or with usernames beginning with hyphen
.Ql -
are considered passive
and do not affect automatic away status.
.
.Pp
Pass-through of the following IRCv3 capabilities
is supported:
.Sy account-notify ,
.Sy account-tag ,
.Sy away-notify ,
.Sy batch ,
.Sy cap-notify ,
.Sy chghost ,
.Sy echo-message ,
.Sy extended-join ,
.Sy extended-monitor ,
.Sy invite-notify ,
.Sy labeled-response ,
.Sy message-tags ,
.Sy multi-prefix ,
.Sy server-time ,
.Sy setname ,
.Sy userhost-in-names .
.
.Pp
Private messages and notices
sent to the user's own nickname
are relayed only to other clients,
not to the server.
.
.Ss Generating Client Certificates
.Bl -enum
.It
Generate self-signed client certificates and private keys:
.Bd -literal -offset indent
$ pounce -g client1.pem
$ pounce -g client2.pem
.Ed
.It
Concatenate the certificate public keys into a CA file:
.Bd -literal -offset indent
$ openssl x509 -subject -in client1.pem \e
	>> ~/.config/pounce/auth.pem
$ openssl x509 -subject -in client2.pem \e
	>> ~/.config/pounce/auth.pem
.Ed
.It
Configure
.Nm
to verify client certificates
against the CA file:
.Bd -literal -offset indent
local-ca = auth.pem
# or: $ pounce -A auth.pem
.Ed
.El
.
.Pp
Alternatively,
client certificates can be signed
by a generated certificate authority:
.
.Bl -enum
.It
Generate a self-signed certificate authority:
.Bd -literal -offset indent
$ pounce -g auth.pem
.Ed
.It
Generate and sign client certificates
using the CA:
.Bd -literal -offset indent
$ pounce -A auth.pem -g client1.pem
$ pounce -A auth.pem -g client2.pem
.Ed
.It
Since only the public key is needed
for certificate verification,
extract it from the CA:
.Bd -literal -offset indent
$ openssl x509 -in auth.pem -out ~/.config/pounce/auth.crt
.Ed
.It
Configure
.Nm
to verify client certificates
against the CA:
.Bd -literal -offset indent
local-ca = auth.crt
# or: $ pounce -A auth.crt
.Ed
.El
.
.Ss Configuring CertFP
.Bl -enum
.It
Generate a new TLS client certificate:
.Bd -literal -offset indent
$ pounce -g ~/.config/pounce/example.pem
.Ed
.It
Connect to the server using the certificate:
.Bd -literal -offset indent
client-cert = example.pem
# or: $ pounce -c example.pem
.Ed
.It
Identify with services or use
.Cm sasl-plain ,
then add the certificate fingerprint to your account:
.Bd -literal -offset indent
/msg NickServ CERT ADD
.Ed
.It
Enable SASL EXTERNAL
to require successful authentication when connecting:
.Bd -literal -offset indent
client-cert = example.pem
sasl-external
# or: $ pounce -e -c example.pem
.Ed
.El
.
.Ss Connecting to Servers with Self-signed Certificates
.Bl -enum
.It
Connect to the server
and write its certificate to a file:
.Bd -literal -offset indent
$ pounce -o -h irc.example.org > ~/.config/pounce/example.pem
.Ed
.It
Configure
.Nm
to trust the certificate:
.Bd -literal -offset indent
trust = example.pem
# or: $ pounce -t example.pem
.Ed
.El
.
.Sh ENVIRONMENT
.Bl -tag -width Ds
.It Ev USER
The default nickname.
.El
.
.Sh FILES
.Bl -tag -width Ds
.It Pa $XDG_CONFIG_DIRS/pounce
Configuration files, certificates and private keys
are searched for first in
.Ev $XDG_CONFIG_HOME ,
usually
.Pa ~/.config ,
followed by the colon-separated list of paths
.Ev $XDG_CONFIG_DIRS ,
usually
.Pa /etc/xdg .
.It Pa ~/.config/pounce
The most likely location of configuration files.
.
.It Pa $XDG_DATA_DIRS/pounce
Save files are searched for first in
.Ev $XDG_DATA_HOME ,
usually
.Pa ~/.local/share ,
followed by the colon-separated list of paths
.Ev $XDG_DATA_DIRS ,
usually
.Pa /usr/local/share:/usr/share .
New save files are created in
.Ev $XDG_DATA_HOME .
.It Pa ~/.local/share/pounce
The most likely location of save files.
.El
.
.Sh EXAMPLES
Start
.Nm :
.Bd -literal -offset indent
$ pounce -H irc.example.org -h irc.tilde.chat -j '#ascii.town'
.Ed
.Pp
Write an equivalent configuration file to
.Pa ~/.config/pounce/tilde.conf :
.Bd -literal -offset indent
local-host = irc.example.org
host = irc.tilde.chat
join = #ascii.town
.Ed
.Pp
Load the configuration file:
.Bd -literal -offset indent
$ pounce tilde.conf
.Ed
.
.Pp
Add a certificate to
.Xr acme-client.conf 5 :
.Bd -literal -offset indent
domain irc.example.org {
	domain key "/home/user/.config/pounce/irc.example.org.key"
	domain full chain certificate \e
		"/home/user/.config/pounce/irc.example.org.pem"
	sign with letsencrypt
}
.Ed
.Pp
Obtain the certificate
and make the private key readable by
.Nm :
.Bd -literal -offset indent
# acme-client irc.example.org
# chown user /home/user/.config/pounce/irc.example.org.key
.Ed
.Pp
Renew and reload the certificate with a
.Xr cron 8
job:
.Bd -literal -offset indent
~ * * * *	acme-client irc.example.org && pkill -USR1 pounce
.Ed
.
.Sh DIAGNOSTICS
Upon receiving the
.Dv SIGINFO
signal,
.Nm
prints the current producer position
and the positions of each consumer
identified by username.
Following each consumer position
is the number by which it trails the producer.
On systems lacking
.Dv SIGINFO ,
.Dv SIGUSR2
is used.
.
.Pp
If a client reconnects
after having missed more messages
than the size of the buffer,
.Nm
will print a warning:
.Bd -ragged -offset indent
consumer
.Em name
dropped
.Em n
messages
.Ed
.Pp
The size of the buffer
can be adjusted with
.Fl s .
.
.Sh SEE ALSO
.Xr calico 1
.
.Sh STANDARDS
.Bl -item
.It
.Rs
.%A Waldo Bastian
.%A Ryan Lortie
.%A Lennart Poettering
.%T XDG Base Directory Specification
.%U https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
.%D November 24, 2010
.Re
.It
.Rs
.%A Kyle Fuller
.%A St\('ephan Kochen
.%A Alexey Sokolov
.%A James Wheare
.%T server-time Extension
.%I IRCv3 Working Group
.%U https://ircv3.net/specs/extensions/server-time
.Re
.It
.Rs
.%A Lee Hardy
.%A Perry Lorier
.%A Kevin L. Mitchell
.%A Attila Molnar
.%A Daniel Oakley
.%A William Pitcock
.%A James Wheare
.%T IRCv3 Client Capability Negotiation
.%I IRCv3 Working Group
.%U https://ircv3.net/specs/core/capability-negotiation
.Re
.It
.Rs
.%A S. Josefsson
.%T The Base16, Base32, and Base64 Data Encodings
.%I IETF
.%R RFC 4648
.%U https://tools.ietf.org/html/rfc4648
.%D October 2006
.Re
.It
.Rs
.%A C. Kalt
.%T Internet Relay Chat: Client Protocol
.%I IETF
.%R RFC 2812
.%U https://tools.ietf.org/html/rfc2812
.%D April 2000
.Re
.It
.Rs
.%A Attila Molnar
.%A James Wheare
.%T IRCv3 Strict Transport Security
.%I IRCv3 Working Group
.%U https://ircv3.net/specs/extensions/sts
.Re
.It
.Rs
.%A Attila Molnar
.%A William Pitcock
.%T IRCv3.2 SASL Authentication
.%I IRCv3 Working Group
.%U https://ircv3.net/specs/extensions/sasl-3.2
.Re
.It
.Rs
.%A K. Zeilenga, Ed.
.%T The PLAIN Simple Authentication and Security Layer (SASL) Mechanism
.%I IETF
.%R RFC 4616
.%U https://tools.ietf.org/html/rfc4616
.%D August 2006
.Re
.El
.
.Ss Extensions
The
.Sy causal.agency/consumer
vendor-specific IRCv3 capability
enables the
.Sy causal.agency/pos
message tag.
The value of this tag
is a 64-bit unsigned integer
indicating the consumer position of the client
after receiving each message,
e.g.\&
.Ql @causal.agency/pos=42069 .
This capability may be requested
with the value of the last
.Sy causal.agency/pos
tag received by the client,
e.g.\&
.Ql CAP REQ causal.agency/consumer=42069 ,
setting its consumer position.
By persisting this value across connections,
a client can ensure no messages are missed,
even in case of network issues or application crashes.
.
.Pp
.%T IRCv3 Client Capability Negotiation
specifies that capabilities MAY have values in
.Ql CAP LS
or
.Ql CAP NEW
responses.
It does not, however,
indicate if
.Ql CAP REQ
capabilities MUST NOT have values.
The
.Nm
implementation parses
.Ql CAP REQ
values in the same way as
.Ql CAP LS
values.
.
.Pp
The
.Sy causal.agency/passive
vendor-specific IRCv3 capability
indicates that a client
should not affect the automatic away status.
.
.Sh AUTHORS
.An June McEnroe Aq Mt june@causal.agency
.
.Sh BUGS
Send mail to
.Aq Mt list+pounce@causal.agency
or join
.Li #ascii.town
on
.Li irc.tilde.chat .
.
.Pp
A client will sometimes receive its own message,
causing it to be displayed twice.
This happens when a message is sent
while responses are not yet consumed.