resolv: Move ns_name_pack into its own file and into libc

And reformat to GNU style, and eliminate the labellen function.

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>

resolv/ns_name_pack.c

@@ -0,0 +1,202 @@
+/* Compression of DNS domain names.
+ * 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 <string.h>
+#include <shlib-compat.h>
+
+/* Thinking in noninternationalized USASCII (per the DNS spec),
+   convert this character to lower case if it's upper case.  */
+static int
+mklower (int ch)
+{
+  if (ch >= 'A' && ch <= 'Z')
+    return ch - 'A' + 'a';
+  return ch;
+}
+
+/* Search for the counted-label name in an array of compressed names.
+   Returns the offset from MSG if found, or -1.
+
+   DNPTRS is the pointer to the first name on the list, not the
+   pointer to the start of the message.  */
+static int
+dn_find (const unsigned char *domain, const unsigned char *msg,
+         const unsigned char **dnptrs,
+         const unsigned char **lastdnptr)
+{
+  const unsigned char *dn, *cp, *sp;
+  const unsigned char **cpp;
+  unsigned int n;
+
+  for (cpp = dnptrs; cpp < lastdnptr; cpp++)
+    {
+    sp = *cpp;
+    /* Terminate search on: root label, compression pointer, unusable
+       offset.  */
+    while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 && (sp - msg) < 0x4000)
+      {
+        dn = domain;
+        cp = sp;
+        while ((n = *cp++) != 0)
+          {
+            /* Check for indirection.  */
+            switch (n & NS_CMPRSFLGS)
+              {
+              case 0:                 /* Normal case, n == len.  */
+                if (n != *dn++)
+                  goto next;
+
+                for (; n > 0; n--)
+                  if (mklower (*dn++) != mklower (*cp++))
+                    goto next;
+                /* Is next root for both?  */
+                if (*dn == '\0' && *cp == '\0')
+                  return sp - msg;
+                if (*dn)
+                  continue;
+                goto next;
+              case NS_CMPRSFLGS: /* Indirection.  */
+                cp = msg + (((n & 0x3f) << 8) | *cp);
+                break;
+
+              default:          /* Illegal type.  */
+                __set_errno (EMSGSIZE);
+                return -1;
+              }
+          }
+      next: ;
+        sp += *sp + 1;
+      }
+    }
+  __set_errno (ENOENT);
+  return -1;
+}
+
+/* Packs domain name SRC into DST.  Returns size of the compressed
+   name, or -1.
+
+   DNPTRS is an array of pointers to previous compressed names.
+   DNPTRS[0] is a pointer to the beginning of the message. The array
+   ends with NULL.  LASTDNPTR is a pointer to the end of the array
+   pointed to by 'dnptrs'.
+
+   The list of pointers in DNPTRS is updated for labels inserted into
+   the message as we compress the name.  If DNPTRS is NULL, we don't
+   try to compress names. If LASTDNPTR is NULL, we don't update the
+   list.  */
+int
+___ns_name_pack (const unsigned char *src, unsigned char *dst, int dstsiz,
+                 const unsigned char **dnptrs, const unsigned char **lastdnptr)
+{
+  unsigned char *dstp;
+  const unsigned char **cpp, **lpp, *eob, *msg;
+  const unsigned char *srcp;
+  int n, l, first = 1;
+
+  srcp = src;
+  dstp = dst;
+  eob = dstp + dstsiz;
+  lpp = cpp = NULL;
+  if (dnptrs != NULL)
+    {
+      if ((msg = *dnptrs++) != NULL)
+        {
+          for (cpp = dnptrs; *cpp != NULL; cpp++)
+            ;
+          lpp = cpp;            /* End of list to search.  */
+        }
+    }
+  else
+    msg = NULL;
+
+  /* Make sure the domain we are about to add is legal.  */
+  l = 0;
+  do
+    {
+      n = *srcp;
+      if (n >= 64)
+        {
+          __set_errno (EMSGSIZE);
+          return -1;
+        }
+      l += n + 1;
+      if (l > MAXCDNAME)
+        {
+          __set_errno (EMSGSIZE);
+          return -1;
+        }
+      srcp += n + 1;
+    }
+  while (n != 0);
+
+  /* from here on we need to reset compression pointer array on error */
+  srcp = src;
+  do
+    {
+      /* Look to see if we can use pointers.  */
+      n = *srcp;
+      if (n != 0 && msg != NULL)
+        {
+          l = dn_find (srcp, msg, dnptrs, lpp);
+          if (l >= 0)
+            {
+              if (eob - dstp <= 1)
+                goto cleanup;
+              *dstp++ = (l >> 8) | NS_CMPRSFLGS;
+              *dstp++ = l % 256;
+              return dstp - dst;
+            }
+          /* Not found, save it.  */
+          if (lastdnptr != NULL && cpp < lastdnptr - 1
+              && (dstp - msg) < 0x4000 && first)
+            {
+              *cpp++ = dstp;
+              *cpp = NULL;
+              first = 0;
+            }
+        }
+      /* Copy label to buffer.  */
+      if (n >= 64)
+        /* Should not happen.  */
+        goto cleanup;
+      if (n + 1 > eob - dstp)
+        goto cleanup;
+      memcpy (dstp, srcp, n + 1);
+      srcp += n + 1;
+      dstp += n + 1;
+    }
+  while (n != 0);
+
+  if (dstp > eob)
+    {
+    cleanup:
+      if (msg != NULL)
+        *lpp = NULL;
+      __set_errno (EMSGSIZE);
+      return -1;
+    }
+  return dstp - dst;
+}
+versioned_symbol (libc, ___ns_name_pack, ns_name_pack, GLIBC_2_34);
+versioned_symbol (libc, ___ns_name_pack, __ns_name_pack, GLIBC_PRIVATE);
+libc_hidden_ver (___ns_name_pack, __ns_name_pack)
+
+#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
+compat_symbol (libresolv, ___ns_name_pack, ns_name_pack, GLIBC_2_9);
+#endif