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Make printer's DNS-SD Service Names freely configurable #1570

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Make printer's DNS-SD Service Names freely configurable #1570

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19 changes: 19 additions & 0 deletions man/cupsd.conf.5
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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1 change: 1 addition & 0 deletions scheduler/conf.c
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Expand Up @@ -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
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40 changes: 39 additions & 1 deletion scheduler/dirsvc.c
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Expand Up @@ -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;
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@michaelrsweet michaelrsweet May 7, 2026

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The normal coding style here would be to set the end pointer to "name + sizeof(name) - 1" to leave room for the NUL at the end.

Also, you might use "src", "dst", and "dstend" as variable names to make things clearer... :)


while (1) {
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@michaelrsweet michaelrsweet May 7, 2026

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"while (*src && dst < dstend)"?

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;
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@michaelrsweet michaelrsweet May 7, 2026

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Maybe log a warning message for unknown substitution characters?

}
if (r == NULL) continue;
q += strlcpy(q, r, e - q);
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@michaelrsweet michaelrsweet May 7, 2026

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strlcpy isn't standard. cupsCopyString is the CUPS API that uses strlcpy or its equivalent. But the return value is the number of characters that would have been copied if there was infinite space - I usually do copy and then "q += strlen(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);
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5 changes: 4 additions & 1 deletion scheduler/dirsvc.h
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Expand Up @@ -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);
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