From d85772c0b5b2ef9623be0377180b6d03ac60b1f5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edgar=20Fu=C3=9F?= <ef@math.uni-bonn.de>
Date: Thu, 7 May 2026 16:01:37 +0200
Subject: [PATCH] Make printer's DNS-SD Service Names freely configurable

Introduce a configuration variable DNSSDServiceName which, if set, provides a template for the DNS-SD Service Name used to register a printer. In the string, the following placeholders are substituted:
	%n: the printer's name
	%i: the printer's info field
	%l: the printer's location field
	%m: the printer's make & model field
	%c: the server's name
	%%: a literal percent sign

If DNSSDServiceName is unset (the default), the existing behaviour is used.
---
 man/cupsd.conf.5   | 19 +++++++++++++++++++
 scheduler/conf.c   |  1 +
 scheduler/dirsvc.c | 40 +++++++++++++++++++++++++++++++++++++++-
 scheduler/dirsvc.h |  5 ++++-
 4 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/man/cupsd.conf.5 b/man/cupsd.conf.5
index a34d16a08d..592448e2bc 100644
--- a/man/cupsd.conf.5
+++ b/man/cupsd.conf.5
@@ -146,6 +146,25 @@ The value "none" disables the "@ Computer Name" suffix added to shared printer n
 \fBDNSSDHostName \fIHOSTNAME\fR
 Specifies the fully-qualified domain name for the server that is used for DNS-SD sharing.
 The default is typically the server's ".local" hostname and is updated whenever that hostname changes.
+.\"#DNSSDServiceName
+.TP 5
+\fBDNSSDServiceName \fIservice-name\fR
+Specifies the service name announced for a shared printer.
+\fIservice-name\fR may contain the following placeholders:
+.RS
+.IP %n 5
+The printer's name.
+.IP %i 5
+The printer's \fIinfo\fR field.
+.IP %l 5
+The printer's \fIlocation\fR field.
+.IP %m 5
+The printer's \fImake & model\fR field.
+.IP %c 5
+The server's name.
+.IP %% 5
+A literal percent sign.
+.RE
 .\"#ErrorPolicy
 .TP 5
 \fBErrorPolicy abort-job\fR
diff --git a/scheduler/conf.c b/scheduler/conf.c
index e55afdbd7e..7910871835 100644
--- a/scheduler/conf.c
+++ b/scheduler/conf.c
@@ -81,6 +81,7 @@ static const cupsd_var_t	cupsd_vars[] =
   { "DirtyCleanInterval",	&DirtyCleanInterval,	CUPSD_VARTYPE_TIME },
   { "DNSSDComputerName",	&DNSSDComputerName,	CUPSD_VARTYPE_STRING },
   { "DNSSDHostName",		&DNSSDHostName,		CUPSD_VARTYPE_STRING },
+  { "DNSSDServiceName",		&DNSSDServiceName,	CUPSD_VARTYPE_STRING },
   { "ErrorPolicy",		&ErrorPolicy,		CUPSD_VARTYPE_STRING },
   { "FilterLimit",		&FilterLimit,		CUPSD_VARTYPE_INTEGER },
 #ifdef HAVE_GSSAPI
diff --git a/scheduler/dirsvc.c b/scheduler/dirsvc.c
index 1c05c80ad6..0530cc0bbd 100644
--- a/scheduler/dirsvc.c
+++ b/scheduler/dirsvc.c
@@ -485,7 +485,45 @@ dnssdRegisterPrinter(
 
   if (!p->reg_name)
   {
-    if (p->info && strlen(p->info) > 0)
+    if (DNSSDServiceName && DNSSDServiceName[0] != '\0') {
+        char *s = DNSSDServiceName, *e = name + sizeof(name), *q = name, c;
+
+        while (1) {
+            c = *s++;
+            /* assert(q < e); */
+            if (c == '\0' || q == e - 1) {
+                *q = '\0';
+                break;
+            } else if (c == '%') {
+                c = *s++;
+                if (c == '\0') { /* putting this into the case would need a break 2 */
+                    *q = '\0';
+                    break;
+                } else if (c == '%') { /* could be put into case */
+                    *q++ = '%';
+                } else {
+                    char *r;
+                    switch (c) {
+                        case 'n': r = p->name; break;
+                        case 'l': r = p->location; break;
+                        case 'i': r = p->info; break;
+                        case 'm': r = p->make_model; break;
+                        case 'c': r = DNSSDComputerName; break;
+                        default: continue;
+                    }
+                    if (r == NULL) continue;
+                    q += strlcpy(q, r, e - q);
+                    if (q >= e) {
+                        *(e - 1) = '\0';
+                        break;
+                    }
+                }
+            } else {
+                *q++ = c;
+            }
+        }
+    }
+    else if (p->info && strlen(p->info) > 0)
     {
       if (DNSSDComputerName)
 	snprintf(name, sizeof(name), "%s @ %s", p->info, DNSSDComputerName);
diff --git a/scheduler/dirsvc.h b/scheduler/dirsvc.h
index 77d8c36dcc..70b20ba05d 100644
--- a/scheduler/dirsvc.h
+++ b/scheduler/dirsvc.h
@@ -36,8 +36,11 @@ VAR char		*DNSSDHostName	VALUE(NULL);
 					/* Hostname */
 VAR int			DNSSDHostNameConfigured VALUE(0);
 					/* Was the DNSSDHostName value configured in cupsd.conf? */
-VAR char		*DNSSDSubTypes VALUE(NULL);
+VAR char		*DNSSDSubTypes VALUE(NULL).
 					/* Bonjour registration subtypes */
+			*DNSSDServiceName
+					VALUE(NULL);
+					/* DNSSD service name */
 VAR cups_array_t	*DNSSDAlias	VALUE(NULL);
 					/* List of dynamic ServerAlias's */
 VAR int			DNSSDPort	VALUE(0);