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      1 /* -*- Mode: C; tab-width: 4 -*-
      2  *
      3  * Copyright (c) 2008 Apple Inc. All rights reserved.
      4  *
      5  * Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc.
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      8  * constitutes acceptance of these terms.  If you do not agree with these terms,
      9  * please do not use, install, modify or redistribute this Apple software.
     10  *
     11  * In consideration of your agreement to abide by the following terms, and subject
     12  * to these terms, Apple grants you a personal, non-exclusive license, under Apple's
     13  * copyrights in this original Apple software (the "Apple Software"), to use,
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     24  * Software may be incorporated.
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     26  * The Apple Software is provided by Apple on an "AS IS" basis.  APPLE MAKES NO
     27  * WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
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     39  */
     40 
     41 #include <ctype.h>
     42 #include <stdio.h>			// For stdout, stderr
     43 
     44 #include "ClientCommon.h"
     45 
     46 const char *GetNextLabel(const char *cstr, char label[64])
     47 	{
     48 	char *ptr = label;
     49 	while (*cstr && *cstr != '.')				// While we have characters in the label...
     50 		{
     51 		char c = *cstr++;
     52 		if (c == '\\' && *cstr)					// If we have a backslash, and it's not the last character of the string
     53 			{
     54 			c = *cstr++;
     55 			if (isdigit(cstr[-1]) && isdigit(cstr[0]) && isdigit(cstr[1]))
     56 				{
     57 				int v0 = cstr[-1] - '0';						// then interpret as three-digit decimal
     58 				int v1 = cstr[ 0] - '0';
     59 				int v2 = cstr[ 1] - '0';
     60 				int val = v0 * 100 + v1 * 10 + v2;
     61 				// If valid three-digit decimal value, use it
     62 				// Note that although ascii nuls are possible in DNS labels
     63 				// we're building a C string here so we have no way to represent that
     64 				if (val == 0) val = '-';
     65 				if (val <= 255) { c = (char)val; cstr += 2; }
     66 				}
     67 			}
     68 		*ptr++ = c;
     69 		if (ptr >= label+64) { label[63] = 0; return(NULL); }	// Illegal label more than 63 bytes
     70 		}
     71 	*ptr = 0;													// Null-terminate label text
     72 	if (ptr == label) return(NULL);								// Illegal empty label
     73 	if (*cstr) cstr++;											// Skip over the trailing dot (if present)
     74 	return(cstr);
     75 	}
     76