[glibc] nss_dns: Do not use deprecated packet parsing functions

[glibc] nss_dns: Do not use deprecated packet parsing functions

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2ff32dd4926c7ec3bb6c09b58a12a8e828a4cc58

commit 2ff32dd4926c7ec3bb6c09b58a12a8e828a4cc58
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Jul 15 08:28:50 2021 +0200

    nss_dns: Do not use deprecated packet parsing functions
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    Tested-by: Carlos O'Donell <carlos@redhat.com>

Diff:
---
 resolv/nss_dns/dns-canon.c | 13 ++++++++-----
 resolv/nss_dns/dns-host.c  | 28 ++++++++++++----------------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/resolv/nss_dns/dns-canon.c b/resolv/nss_dns/dns-canon.c
index cb321a0650..1cdc9a86c9 100644
--- a/resolv/nss_dns/dns-canon.c
+++ b/resolv/nss_dns/dns-canon.c
@@ -150,15 +150,18 @@ _nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen,
 	      if (type != ns_t_cname)
 		goto unavail;
 
-	      if (__ns_get16 (ptr) != ns_c_in)
+	      uint16_t rrclass;
+	      NS_GET16 (rrclass, ptr);
+	      if (rrclass != ns_c_in)
 		goto unavail;
 
-	      /* Also skip over class and TTL.  */
-	      ptr += sizeof (uint16_t) + sizeof (uint32_t);
+	      /* Skip over TTL.  */
+	      ptr += sizeof (uint32_t);
 
 	      /* Skip over RDATA length and RDATA itself.  */
-	      uint16_t rdatalen = __ns_get16 (ptr);
-	      ptr += sizeof (uint16_t);
+	      uint16_t rdatalen;
+	      NS_GET16 (rdatalen, ptr);
+
 	      /* Not enough room for RDATA.  */
 	      if (endptr - ptr < rdatalen)
 		goto unavail;
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index 47e851db55..d6a69a602a 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -782,14 +782,11 @@ getanswer_r (struct resolv_context *ctx,
 	  continue;
 	}
 
-      type = __ns_get16 (cp);
-      cp += INT16SZ;			/* type */
-      class = __ns_get16 (cp);
-      cp += INT16SZ;			/* class */
-      int32_t ttl = __ns_get32 (cp);
-      cp += INT32SZ;			/* TTL */
-      n = __ns_get16 (cp);
-      cp += INT16SZ;			/* len */
+      NS_GET16 (type, cp);
+      NS_GET16 (class, cp);
+      int32_t ttl;
+      NS_GET32 (ttl, cp);
+      NS_GET16 (n, cp);		/* RDATA length.  */
 
       if (end_of_message - cp < n)
 	{
@@ -1116,14 +1113,13 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
 	  continue;
 	}
 
-      int type = __ns_get16 (cp);
-      cp += INT16SZ;			/* type */
-      int class = __ns_get16 (cp);
-      cp += INT16SZ;			/* class */
-      int32_t ttl = __ns_get32 (cp);
-      cp += INT32SZ;			/* TTL */
-      n = __ns_get16 (cp);
-      cp += INT16SZ;			/* len */
+      uint16_t type;
+      NS_GET16 (type, cp);
+      uint16_t class;
+      NS_GET16 (class, cp);
+      int32_t ttl;
+      NS_GET32 (ttl, cp);
+      NS_GET16 (n, cp);		/* RDATA length.  */
 
       if (end_of_message - cp < n)
 	{