resolv: Move ns_name_ntop to its own file and into libc

Reformat to GNU style.  Avoid out-of-bounds pointer arithmetic
(e.g., use eom - dn < 2 instead of dn + 1 >= eom).  Inline the
labellen function and fold the compression pointer check into
the length check (l >= 64).  Assume ASCII encoding.

The symbol was moved using scripts/move-symbol-to-libc.py.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

4 files changed, 152 insertions, 129 deletions

diff --git a/resolv/Makefile b/resolv/Makefile
index f14b149..bb16175 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -32,6 +32,7 @@ routines := \
   inet_addr \
   inet_ntop \
   inet_pton \
+  ns_name_ntop \
   nsap_addr \
   res-close \
   res-state \
diff --git a/resolv/Versions b/resolv/Versions
index 3b53283..4bf1a13 100644
--- a/resolv/Versions
+++ b/resolv/Versions
@@ -24,6 +24,9 @@ libc {
     getaddrinfo_a;
 %endif
   }
+  GLIBC_2.9 {
+    ns_name_ntop;
+  }
   GLIBC_2.34 {
 %if PTHREAD_IN_LIBC
     gai_cancel;
@@ -31,6 +34,7 @@ libc {
     gai_suspend;
     getaddrinfo_a;
 %endif
+    ns_name_ntop;
   }
   GLIBC_PRIVATE {
 %if !PTHREAD_IN_LIBC
@@ -40,6 +44,7 @@ libc {
     __inet_aton_exact;
     __inet_pton_length;
     __res_iclose;
+    __ns_name_ntop;
     __resolv_context_get;
     __resolv_context_get_override;
     __resolv_context_get_preinit;
@@ -137,7 +142,6 @@ libresolv {
     ns_msg_getflag;
     ns_name_compress;
     ns_name_ntol;
-    ns_name_ntop;
     ns_name_pack;
     ns_name_pton;
     ns_name_rollback;
@@ -158,7 +162,6 @@ libresolv {
   GLIBC_PRIVATE {
     __ns_get16;
     __ns_get32;
-    __ns_name_ntop;
     __ns_name_unpack;
     __res_context_hostalias;
     __res_context_query;
diff --git a/resolv/ns_name.c b/resolv/ns_name.c
index 73213fe..4990003 100644
--- a/resolv/ns_name.c
+++ b/resolv/ns_name.c
@@ -35,8 +35,6 @@ static const char	digits[] = "0123456789";
 
 /* Forward. */
 
-static int		special(int);
-static int		printable(int);
 static int		dn_find(const u_char *, const u_char *,
 				const u_char * const *,
 				const u_char * const *);
@@ -44,93 +42,6 @@ static int		labellen(const u_char *);
 
 /* Public. */
 
-/*%
- *	Convert an encoded domain name to printable ascii as per RFC1035.
-
- * return:
- *\li	Number of bytes written to buffer, or -1 (with errno set)
- *
- * notes:
- *\li	The root is returned as "."
- *\li	All other domains are returned in non absolute form
- */
-int
-ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
-{
-	const u_char *cp;
-	char *dn, *eom;
-	u_char c;
-	u_int n;
-	int l;
-
-	cp = src;
-	dn = dst;
-	eom = dst + dstsiz;
-
-	while ((n = *cp++) != 0) {
-		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
-			/* Some kind of compression pointer. */
-			__set_errno (EMSGSIZE);
-			return (-1);
-		}
-		if (dn != dst) {
-			if (dn >= eom) {
-				__set_errno (EMSGSIZE);
-				return (-1);
-			}
-			*dn++ = '.';
-		}
-		if ((l = labellen(cp - 1)) < 0) {
-			__set_errno (EMSGSIZE);
-			return(-1);
-		}
-		if (dn + l >= eom) {
-			__set_errno (EMSGSIZE);
-			return (-1);
-		}
-		for ((void)NULL; l > 0; l--) {
-			c = *cp++;
-			if (special(c)) {
-				if (dn + 1 >= eom) {
-					__set_errno (EMSGSIZE);
-					return (-1);
-				}
-				*dn++ = '\\';
-				*dn++ = (char)c;
-			} else if (!printable(c)) {
-				if (dn + 3 >= eom) {
-					__set_errno (EMSGSIZE);
-					return (-1);
-				}
-				*dn++ = '\\';
-				*dn++ = digits[c / 100];
-				*dn++ = digits[(c % 100) / 10];
-				*dn++ = digits[c % 10];
-			} else {
-				if (dn >= eom) {
-					__set_errno (EMSGSIZE);
-					return (-1);
-				}
-				*dn++ = (char)c;
-			}
-		}
-	}
-	if (dn == dst) {
-		if (dn >= eom) {
-			__set_errno (EMSGSIZE);
-			return (-1);
-		}
-		*dn++ = '.';
-	}
-	if (dn >= eom) {
-		__set_errno (EMSGSIZE);
-		return (-1);
-	}
-	*dn++ = '\0';
-	return (dn - dst);
-}
-libresolv_hidden_def (ns_name_ntop)
-strong_alias (ns_name_ntop, __ns_name_ntop)
 
 /*%
  *	Convert an ascii string into an encoded domain name as per RFC1035.
@@ -517,7 +428,7 @@ ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
 
 	if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
 		return (-1);
-	if (ns_name_ntop(tmp, dst, dstsiz) == -1)
+	if (__ns_name_ntop (tmp, dst, dstsiz) == -1)
 		return (-1);
 	return (n);
 }
@@ -608,43 +519,6 @@ libresolv_hidden_def (ns_name_skip)
 
 /*%
  *	Thinking in noninternationalized USASCII (per the DNS spec),
- *	is this character special ("in need of quoting") ?
- *
- * return:
- *\li	boolean.
- */
-static int
-special(int ch) {
-	switch (ch) {
-	case 0x22: /*%< '"' */
-	case 0x2E: /*%< '.' */
-	case 0x3B: /*%< ';' */
-	case 0x5C: /*%< '\\' */
-	case 0x28: /*%< '(' */
-	case 0x29: /*%< ')' */
-	/* Special modifiers in zone files. */
-	case 0x40: /*%< '@' */
-	case 0x24: /*%< '$' */
-		return (1);
-	default:
-		return (0);
-	}
-}
-
-/*%
- *	Thinking in noninternationalized USASCII (per the DNS spec),
- *	is this character visible and not a space when printed ?
- *
- * return:
- *\li	boolean.
- */
-static int
-printable(int ch) {
-	return (ch > 0x20 && ch < 0x7f);
-}
-
-/*%
- *	Thinking in noninternationalized USASCII (per the DNS spec),
  *	convert this character to lower case if it's upper case.
  */
 static int
diff --git a/resolv/ns_name_ntop.c b/resolv/ns_name_ntop.c
new file mode 100644
index 0000000..4dab3a3
--- /dev/null
+++ b/resolv/ns_name_ntop.c
@@ -0,0 +1,145 @@
+/* Convert DNS domain names from network format to textual presentation format.
+ * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 1996,1999 by Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+ * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <arpa/nameser.h>
+#include <errno.h>
+#include <shlib-compat.h>
+#include <stdbool.h>
+
+/* Thinking in noninternationalized US-ASCII (per the DNS spec), is
+   this character special ("in need of quoting")?  */
+static inline bool
+special (int ch)
+{
+  switch (ch)
+    {
+    case '"':
+    case '.':
+    case ';':
+    case '\\':
+    case '(':
+    case ')':
+      /* Special modifiers in zone files.  */
+    case '@':
+    case '$':
+      return true;
+    default:
+      return false;
+    }
+}
+
+/* Thinking in noninternationalized US-ASCII (per the DNS spec), is
+   this character visible and not a space when printed?  */
+static inline bool
+printable (int ch)
+{
+  return ch > 0x20 && ch < 0x7f;
+}
+
+/* Converts an uncompressed, encoded domain name to printable ASCII as
+   per RFC1035.  Returns the number of bytes written to buffer, or -1
+   (with errno set).  The root is returned as "."  All other domains
+   are returned in non absolute form.  */
+int
+___ns_name_ntop (const unsigned char *src, char *dst, size_t dstsiz)
+{
+  const unsigned char *cp;
+  char *dn, *eom;
+  unsigned char c;
+  int l;
+
+  cp = src;
+  dn = dst;
+  eom = dst + dstsiz;
+
+  while ((l = *cp++) != 0)
+    {
+      if (l >= 64)
+        {
+          /* Some kind of compression pointer.  */
+          __set_errno (EMSGSIZE);
+          return -1;
+        }
+      if (dn != dst)
+        {
+          if (dn >= eom)
+            {
+              __set_errno (EMSGSIZE);
+              return -1;
+            }
+          *dn++ = '.';
+        }
+      for (; l > 0; l--)
+        {
+          c = *cp++;
+          if (special (c))
+            {
+              if (eom - dn < 2)
+                {
+                  __set_errno (EMSGSIZE);
+                  return -1;
+                }
+              *dn++ = '\\';
+              *dn++ = c;
+            }
+          else if (!printable (c))
+            {
+              if (eom - dn < 4)
+                {
+                  __set_errno (EMSGSIZE);
+                  return -1;
+                }
+              *dn++ = '\\';
+              *dn++ = '0' + (c / 100);
+              *dn++ = '0' + ((c % 100) / 10);
+              *dn++ = '0' + (c % 10);
+            }
+          else
+            {
+              if (eom - dn < 2)
+                {
+                  __set_errno (EMSGSIZE);
+                  return -1;
+                }
+              *dn++ = c;
+            }
+        }
+    }
+  if (dn == dst)
+    {
+      if (dn >= eom)
+        {
+          __set_errno (EMSGSIZE);
+          return -1;
+        }
+      *dn++ = '.';
+    }
+  if (dn >= eom)
+    {
+      __set_errno (EMSGSIZE);
+      return -1;
+    }
+  *dn++ = '\0';
+  return dn - dst;
+}
+versioned_symbol (libc, ___ns_name_ntop, ns_name_ntop, GLIBC_2_34);
+versioned_symbol (libc, ___ns_name_ntop, __ns_name_ntop, GLIBC_PRIVATE);
+libc_hidden_ver (___ns_name_ntop, __ns_name_ntop)
+
+#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
+compat_symbol (libresolv, ___ns_name_ntop, ns_name_ntop, GLIBC_2_9);
+#endif