From b6cf29f98adce7355e8c51a6af1e338a5f94e16e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@redhat.com>
Date: Tue, 11 Apr 2023 15:29:59 +0200
Subject: [PATCH] Ensure each label is at least one byte long

The only allowed exception is single dot, where it should return empty
string.

Fixes #454.
---
 avahi-common/domain-test.c | 14 ++++++++++++++
 avahi-common/domain.c      |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/avahi-common/domain-test.c b/avahi-common/domain-test.c
index cf763eca6..3acc1c1e4 100644
--- a/avahi-common/domain-test.c
+++ b/avahi-common/domain-test.c
@@ -45,6 +45,20 @@ int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char *argv[]) {
     printf("%s\n", s = avahi_normalize_name_strdup("fo\\\\o\\..f oo."));
     avahi_free(s);
 
+    printf("%s\n", s = avahi_normalize_name_strdup("."));
+    avahi_free(s);
+
+    s = avahi_normalize_name_strdup(",.=.}.=.?-.}.=.?.?.}.}.?.?.?.z.?.?.}.}."
+		    "}.?.?.?.r.=.=.}.=.?.}}.}.?.?.?.zM.=.=.?.?.}.}.?.?.}.}.}"
+		    ".?.?.?.r.=.=.}.=.?.}}.}.?.?.?.zM.=.=.?.?.}.}.?.?.?.zM.?`"
+		    "?.}.}.}.?.?.?.r.=.?.}.=.?.?.}.?.?.?.}.=.?.?.}??.}.}.?.?."
+		    "?.z.?.?.}.}.}.?.?.?.r.=.=.}.=.?.}}.}.?.?.?.zM.?`?.}.}.}."
+		    "??.?.zM.?`?.}.}.}.?.?.?.r.=.?.}.=.?.?.}.?.?.?.}.=.?.?.}?"
+		    "?.}.}.?.?.?.z.?.?.}.}.}.?.?.?.r.=.=.}.=.?.}}.}.?.?.?.zM."
+		    "?`?.}.}.}.?.?.?.r.=.=.?.?`.?.?}.}.}.?.?.?.r.=.?.}.=.?.?."
+		    "}.?.?.?.}.=.?.?.}");
+    assert(s == NULL);
+
     printf("%i\n", avahi_domain_equal("\\065aa bbb\\.\\046cc.cc\\\\.dee.fff.", "Aaa BBB\\.\\.cc.cc\\\\.dee.fff"));
     printf("%i\n", avahi_domain_equal("A", "a"));
 
diff --git a/avahi-common/domain.c b/avahi-common/domain.c
index 3b1ab6834..e66d2416c 100644
--- a/avahi-common/domain.c
+++ b/avahi-common/domain.c
@@ -201,7 +201,7 @@ char *avahi_normalize_name(const char *s, char *ret_s, size_t size) {
         }
 
         if (!empty) {
-            if (size < 1)
+            if (size < 2)
                 return NULL;
 
             *(r++) = '.';