1 /* -*- Mode: C; tab-width: 4 -*-
2 *
3 * Copyright (c) 2008-2011 Apple Inc. All rights reserved.
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39 */
40
41 #include <ctype.h>
42 #include <stdio.h> // For stdout, stderr
43
44 #include "ClientCommon.h"
45
GetNextLabel(const char * cstr,char label[64])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 == '\\') // 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