[Bug 62459] mod_jk: Forwarding URLs containing escaped slashes (e.g. for REST services) fail with syntactical-wrong double-escaping

[bu...@apache.org]

https://bz.apache.org/bugzilla/show_bug.cgi?id=62459

--- Comment #1 from Guido Jäkel <G....@DNB.DE> ---
I think the issue have to be handled within  native/common/jk_url.c , L.116ff.
at function jk_canonenc().

Here, the percent sign isn't in "allowed", therefore it will be escaped.

But concerning the issue, the incoming string have the sequence '%2F', which
MUST NOT be not re-encoded. I'm not sure to claim that ANY legal '%hh' MUST NOT
be re-encoded at this point. Maybe this will be more the truth if one take care
of the actual semantic position inside the URL pattern.

If I'm able to get spare time, i'll try to propose a patch.

/*
 * Convert a URL-encoded string to canonical form.
 * It encodes those which must be encoded, and does not touch
 * those which must not be touched.
 * String x must be '\0'-terminated.
 * String y must be pre-allocated with len maxlen
 * (including the terminating '\0').
 */
int jk_canonenc(const char *x, char *y, int maxlen)
{
    int i, j;
    int ch = x[0];
    char *allowed;  /* characters which should not be encoded */
    char *reserved; /* characters which much not be en/de-coded */

/*
 * N.B. in addition to :@&=, this allows ';' in an http path
 * and '?' in an ftp path -- this may be revised
 */
    allowed = "~$-_.+!*'(),;:@&=";
    reserved = "/";

    for (i = 0, j = 0; ch != '\0' && j < maxlen; i++, j++, ch=x[i]) {
/* always handle '/' first */
        if (strchr(reserved, ch)) {
            y[j] = ch;
            continue;
        }
/* recode it, if necessary */
        if (!jk_isalnum(ch) && !strchr(allowed, ch)) {
            if (j+2<maxlen) {
                jk_c2hex(ch, &y[j]);
                j += 2;
            }
            else {
                return JK_FALSE;
            }
        }
        else {
            y[j] = ch;
        }
    }
    if (j<maxlen) {
        y[j] = '\0';
        return JK_TRUE;
    }
    else {
        return JK_FALSE;
    }
}

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