de-duplicate dn_expand, fix return value and signature, clean up

the duplicate code in dn_expand and its incorrect return values are
both results of the history of the code: the version in __dns.c was
originally written with no awareness of the legacy resolver API, and
was later copy-and-paste duplicated to provide the legacy API.

this commit is the first of a series that will restructure the
internal dns code to share as much code as possible with the legacy
resolver API functions.

I have also removed the loop detection logic, since the output buffer
length limit naturally prevents loops. in order to avoid long runtime
when encountering a loop if the caller provided a ridiculously long
buffer, the caller-provided length is clamped at the maximum dns name
length.

1 files changed, 1 insertions, 1 deletions

diff --git a/include/resolv.h b/include/resolv.h
index cdedd274..259e4bc1 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -134,7 +134,7 @@ int res_search(const char *, int, int, unsigned char *, int);
 int res_mkquery(int, const char *, int, int, char *, int, struct rrec *, char *, int);
 int res_send(const char *, int, char *, int);
 int dn_comp(unsigned char *, unsigned char *, int, unsigned char **, unsigned char *, unsigned char **);
-int dn_expand(unsigned char *, unsigned char *, unsigned char *, unsigned char *, int);
+int dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
 int dn_skipname(const unsigned char *, const unsigned char *);
 
 #ifdef __cplusplus