Make Your Own Programming Language

Re:Make Your Own Programming Language by gue5t on Saturday January 03, 2015 @04:48PM (#8832133)

In glibc's libresolv, this is caused by res_hnok in resolv/res_name.c returning 0:

    /*
     * Verify that a domain name uses an acceptable character set.
     */

    /*
     * Note the conspicuous absence of ctype macros in these definitions.  On
     * non-ASCII hosts, we can't depend on string literals or ctype macros to
     * tell us anything about network-format data.  The rest of the BIND system
     * is not careful about this, but for some reason, we're doing it right here.
     */
    #define PERIOD 0x2e
    #define	hyphenchar(c) ((c) == 0x2d)
    #define	underscorechar(c) ((c) == 0x5f)
    #define bslashchar(c) ((c) == 0x5c)
    #define periodchar(c) ((c) == PERIOD)
    #define asterchar(c) ((c) == 0x2a)
    #define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
		       || ((c) >= 0x61 && (c) <= 0x7a))
    #define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)

    #define borderchar(c) (alphachar(c) || digitchar(c))
    #define middlechar(c) (borderchar(c) || hyphenchar(c) || underscorechar(c))
    #define	domainchar(c) ((c) > 0x20 && (c) < 0x7f)

    int
    res_hnok(const char *dn) {
	    int pch = PERIOD, ch = *dn++;

	    while (ch != '\0') {
		    int nch = *dn++;

		    if (periodchar(ch)) {
			    (void)NULL;
		    } else if (periodchar(pch)) {
			    if (!borderchar(ch))
				    return (0);
		    } else if (periodchar(nch) || nch == '\0') {
			    if (!borderchar(ch))
				    return (0);
		    } else {
			    if (!middlechar(ch))
				    return (0);
		    }
		    pch = ch, ch = nch;
	    }
	    return (1);
    }

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Re:Make Your Own Programming Language by gue5t on Saturday January 03, 2015 @05:08PM (#8832192)

And the hack fix:

    /*
    hnokpre.c: LD_PRELOAD shim to bypass valid hostname checking in glibc
    gcc -fPIC -shared hnokpre.c -o libhnokpre.so
    LD_PRELOAD=./libhnokpre.so curl http://mattias-.github.io/
    */

    int res_hnok(const char* dn)
    {
        return 1;
    }

    int __res_hnok(const char* dn)
    {
        return 1;
    }

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Re:Make Your Own Programming Language by poizan42 on Saturday January 03, 2015 @05:45PM (#8832360)

I'm kinda wondering what's the reason for that that check to begin with. Just being pedantic for pedentrys sake?

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Re:Make Your Own Programming Language by poizan42 on Saturday January 03, 2015 @05:43PM (#8832352)

     * Note the conspicuous absence of ctype macros in these definitions.  On
     * non-ASCII hosts, we can't depend on string literals or ctype macros to
     * tell us anything about network-format data.  The rest of the BIND system
     * is not careful about this, but for some reason, we're doing it right here.

Well that is only a problem if the charset is converted to something else. Are there still systems out there without a C compiler that can be told to use ASCII?

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