1/* -*- Mode: C; tab-width: 4 -*-
2 *
3 * Copyright (c) 2008-2011 Apple Inc. All rights reserved.
4 *
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39 */
40
41#include <ctype.h>
42#include <stdio.h>          // For stdout, stderr
43
44#include "ClientCommon.h"
45
46const 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 == '\\')                          // If escape character, check next character
53        {
54            if (*cstr == '\0') break;           // If this is the end of the string, then break
55            c = *cstr++;
56            if (isdigit(cstr[-1]) && isdigit(cstr[0]) && isdigit(cstr[1]))
57            {
58                int v0 = cstr[-1] - '0';                        // then interpret as three-digit decimal
59                int v1 = cstr[ 0] - '0';
60                int v2 = cstr[ 1] - '0';
61                int val = v0 * 100 + v1 * 10 + v2;
62                // If valid three-digit decimal value, use it
63                // Note that although ascii nuls are possible in DNS labels
64                // we're building a C string here so we have no way to represent that
65                if (val == 0) val = '-';
66                if (val <= 255) { c = (char)val; cstr += 2; }
67            }
68        }
69        *ptr++ = c;
70        if (ptr >= label+64) { label[63] = 0; return(NULL); }   // Illegal label more than 63 bytes
71    }
72    *ptr = 0;                                                   // Null-terminate label text
73    if (ptr == label) return(NULL);                             // Illegal empty label
74    if (*cstr) cstr++;                                          // Skip over the trailing dot (if present)
75    return(cstr);
76}
77