xref: /titanic_52/usr/src/cmd/cmd-inet/usr.bin/dns-sd/ClientCommon.c (revision 5ffb0c9b03b5149ff4f5821a62be4a52408ada2a)

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2008 Apple Inc. All rights reserved.
 *
 * Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc.
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 * constitutes acceptance of these terms.  If you do not agree with these terms,
 * please do not use, install, modify or redistribute this Apple software.
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 * to these terms, Apple grants you a personal, non-exclusive license, under Apple's
 * copyrights in this original Apple software (the "Apple Software"), to use,
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 * WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
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#include <ctype.h>
#include <stdio.h>          // For stdout, stderr

#include "ClientCommon.h"

const char *GetNextLabel(const char *cstr, char label[64])
{
    char *ptr = label;
    while (*cstr && *cstr != '.')               // While we have characters in the label...
    {
        char c = *cstr++;
        if (c == '\\' && *cstr)                 // If we have a backslash, and it's not the last character of the string
        {
            c = *cstr++;
            if (isdigit(cstr[-1]) && isdigit(cstr[0]) && isdigit(cstr[1]))
            {
                int v0 = cstr[-1] - '0';                        // then interpret as three-digit decimal
                int v1 = cstr[ 0] - '0';
                int v2 = cstr[ 1] - '0';
                int val = v0 * 100 + v1 * 10 + v2;
                // If valid three-digit decimal value, use it
                // Note that although ascii nuls are possible in DNS labels
                // we're building a C string here so we have no way to represent that
                if (val == 0) val = '-';
                if (val <= 255) { c = (char)val; cstr += 2; }
            }
        }
        *ptr++ = c;
        if (ptr >= label+64) { label[63] = 0; return(NULL); }   // Illegal label more than 63 bytes
    }
    *ptr = 0;                                                   // Null-terminate label text
    if (ptr == label) return(NULL);                             // Illegal empty label
    if (*cstr) cstr++;                                          // Skip over the trailing dot (if present)
    return(cstr);
}