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[v2,03/13] resolv: Add internal __res_binary_hnok function

Message ID dc060e3166aa0ee7e52478d9180ad6950b7a93d2.1661509943.git.fweimer@redhat.com
State New
Headers show
Series nss_dns: Fix handling of non-host CNAMEs (bug 12154) | expand

Commit Message

Florian Weimer Aug. 26, 2022, 10:33 a.m. UTC
During package parsing, only the binary representation is available,
and it is convenient to check that directly for conformance with host
name requirements.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
---
 include/resolv.h           |  3 +++
 resolv/res-name-checking.c | 14 +++++++++-----
 2 files changed, 12 insertions(+), 5 deletions(-)
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Patch

diff --git a/include/resolv.h b/include/resolv.h
index 3590b6f496..4dbbac3800 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -70,5 +70,8 @@  libc_hidden_proto (__libc_res_nameinquery)
 extern __typeof (__res_queriesmatch) __libc_res_queriesmatch;
 libc_hidden_proto (__libc_res_queriesmatch)
 
+/* Variant of res_hnok which operates on binary (but uncompressed) names.  */
+bool __res_binary_hnok (const unsigned char *dn) attribute_hidden;
+
 # endif /* _RESOLV_H_ && !_ISOMAC */
 #endif
diff --git a/resolv/res-name-checking.c b/resolv/res-name-checking.c
index 07a412d8ff..213edceaf3 100644
--- a/resolv/res-name-checking.c
+++ b/resolv/res-name-checking.c
@@ -138,6 +138,12 @@  binary_leading_dash (const unsigned char *dn)
   return dn[0] > 0 && dn[1] == '-';
 }
 
+bool
+__res_binary_hnok (const unsigned char *dn)
+{
+  return !binary_leading_dash (dn) && binary_hnok (dn);
+}
+
 /* Return 1 if res_hnok is a valid host name.  Labels must only
    contain [0-9a-zA-Z_-] characters, and the name must not start with
    a '-'.  The latter is to avoid confusion with program options.  */
@@ -145,11 +151,9 @@  int
 ___res_hnok (const char *dn)
 {
   unsigned char buf[NS_MAXCDNAME];
-  if (!printable_string (dn)
-      || __ns_name_pton (dn, buf, sizeof (buf)) < 0
-      || binary_leading_dash (buf))
-    return 0;
-  return binary_hnok (buf);
+  return (printable_string (dn)
+	  && __ns_name_pton (dn, buf, sizeof (buf)) >= 0
+	  && __res_binary_hnok (buf));
 }
 versioned_symbol (libc, ___res_hnok, res_hnok, GLIBC_2_34);
 versioned_symbol (libc, ___res_hnok, __libc_res_hnok, GLIBC_PRIVATE);