[uclibc-ng-devel] [PATCH] inet/resolv: Try search domains first for unqualified names

When resolving an unqualified host name, the resolver tries the original name first before appending the domains from the search list. If a TLD with the same name exists, the query will succeed (but yield no A record) and the resolver will return HOST_NOT_FOUND without trying the search domains. This patch changes the lookup order for unqualified host names (without dots) to try the search domains first and the original name last. Signed-off-by: Ingo van Lil &lt;inguin(a)gmx.de&gt; --- libc/inet/resolv.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index e3ad513..d380d44 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -1266,6 +1266,7 @@ int __dns_lookup(const char *name, int local_id = local_id; /* for compiler */ int sdomains = 0; bool ends_with_dot; + bool contains_dot; sockaddr46_t sa; fd = -1; @@ -1277,12 +1278,14 @@ int __dns_lookup(const char *name, if (!packet || !lookup || !name[0]) goto fail; ends_with_dot = (name[name_len - 1] == '.'); + contains_dot = strchr(name, '.') != NULL; /* no strcpy! paranoia, user might change name[] under us */ memcpy(lookup, name, name_len); DPRINTF("Looking up type %d answer for '%s'\n", type, name); retries_left = 0; /* for compiler */ do { + unsigned act_variant; int pos; unsigned reply_timeout; @@ -1306,11 +1309,16 @@ int __dns_lookup(const char *name, sdomains = __searchdomains; } lookup[name_len] = '\0'; - if ((unsigned)variant < sdomains) { + /* For qualified names, act_variant = MAX_UINT, 0, .., sdomains-1 + * => Try original name first, then append search domains + * For names without domain, act_variant = 0, 1, .., sdomains + * => Try search domains first, original name last */ + act_variant = contains_dot ? variant : variant + 1; + if (act_variant < sdomains) { /* lookup is name_len + 1 + MAXLEN_searchdomain + 1 long */ /* __searchdomain[] is not bigger than MAXLEN_searchdomain */ lookup[name_len] = '.'; - strcpy(&lookup[name_len + 1], __searchdomain[variant]); + strcpy(&lookup[name_len + 1], __searchdomain[act_variant]); } /* first time? pick starting server etc */ if (local_ns_num < 0) { -- 2.5.5