[PATCH] fix handling of zero length domain names in dn_expand

[Natanael Copa <ncopa@alpinelinux.org>]

Copy a zero length string instead of returning error when trying to
expand a zero lentgh domain name (null terminator).

This fixes a regression introduced with 56b57f37a46dab432.
---
This should issue with kamailio handling NAPTR records for enum.

I have verified that this correcponds with how uclibc handles zero
length domain names.

I have also verified that none of the 2 places in musl that uses
__dn_expand should break. (I have read the code but not actually run
tested it)

 src/network/dn_expand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
index 849df19..3264faf 100644
--- a/src/network/dn_expand.c
+++ b/src/network/dn_expand.c
@@ -6,7 +6,7 @@ int __dn_expand(const unsigned char *base, const unsigned char *end, const unsig
 	const unsigned char *p = src;
 	char *dend = dest + (space > 254 ? 254 : space);
 	int len = -1, i, j;
-	if (p==end || !*p) return -1;
+	if (p==end) return -1;
 	/* detect reference loop using an iteration counter */
 	for (i=0; i < end-base; i+=2) {
 		if (*p & 0xc0) {
-- 
2.0.4