* [PATCH] resolv: Do not send queries for non-host-names in nss_dns
@ 2019-01-18 20:10 Florian Weimer
0 siblings, 0 replies; only message in thread
From: Florian Weimer @ 2019-01-18 20:10 UTC (permalink / raw)
To: libc-alpha
Another precursor to fixing bug 20018.
Thanks,
Florian
-----
2019-01-18 Florian Weimer <fweimer@redhat.com>
resolv: Do not send queries for non-host-names in nss_dns.
* resolv/nss_dns/dns-host.c (check_name): New function.
(_nss_dns_gethostbyname2_r): Use it.
(_nss_dns_gethostbyname_r): Likewise.
(_nss_dns_gethostbyname4_r): Likewise.
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index d5210c1479..a18b8a6bf4 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -274,11 +274,26 @@ gethostbyname3_context (struct resolv_context *ctx,
return status;
}
+/* Verify that the name looks like a host name. There is no point in
+ sending a query which will not produce a usable name in the
+ response. */
+static enum nss_status
+check_name (const char *name, int *h_errnop)
+{
+ if (res_hnok (name))
+ return NSS_STATUS_SUCCESS;
+ *h_errnop = HOST_NOT_FOUND;
+ return NSS_STATUS_NOTFOUND;
+}
+
enum nss_status
_nss_dns_gethostbyname2_r (const char *name, int af, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *h_errnop)
{
+ enum nss_status status = check_name (name, h_errnop);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
return _nss_dns_gethostbyname3_r (name, af, result, buffer, buflen, errnop,
h_errnop, NULL, NULL);
}
@@ -289,6 +304,9 @@ _nss_dns_gethostbyname_r (const char *name, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *h_errnop)
{
+ enum nss_status status = check_name (name, h_errnop);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
struct resolv_context *ctx = __resolv_context_get ();
if (ctx == NULL)
{
@@ -296,7 +314,7 @@ _nss_dns_gethostbyname_r (const char *name, struct hostent *result,
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_UNAVAIL;
}
- enum nss_status status = NSS_STATUS_NOTFOUND;
+ status = NSS_STATUS_NOTFOUND;
if (res_use_inet6 ())
status = gethostbyname3_context (ctx, name, AF_INET6, result, buffer,
buflen, errnop, h_errnop, NULL, NULL);
@@ -313,6 +331,9 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
char *buffer, size_t buflen, int *errnop,
int *herrnop, int32_t *ttlp)
{
+ enum nss_status status = check_name (name, herrnop);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
struct resolv_context *ctx = __resolv_context_get ();
if (ctx == NULL)
{
@@ -347,7 +368,6 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
int ans2p_malloced = 0;
int olderr = errno;
- enum nss_status status;
int n = __res_context_search (ctx, name, C_IN, T_QUERY_A_AND_AAAA,
host_buffer.buf->buf, 2048, &host_buffer.ptr,
&ans2p, &nans2p, &resplen2, &ans2p_malloced);
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2019-01-18 20:10 [PATCH] resolv: Do not send queries for non-host-names in nss_dns Florian Weimer
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