escaping.cc

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// -*- mode: c++; c-basic-offset:4 -*-
 
// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.
 
// Copyright (c) 2002,2003 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
 
// Copyright (c) 1996, California Institute of Technology.
// ALL RIGHTS RESERVED.   U.S. Government Sponsorship acknowledged.
//
// Please read the full copyright notice in the file COPYRIGHT_URI
// in this directory.
//
// Author: Todd Karakashian, NASA/Jet Propulsion Laboratory
//         Todd.K.Karakashian@jpl.nasa.gov
//
// $RCSfile: escaping.cc,v $ - Miscellaneous routines for OPeNDAP HDF server
//
// These two routines are for escaping/unescaping strings that are identifiers
// in DAP2
// id2www() -- escape (using WWW hex codes) non-allowable characters in a
// DAP2 identifier
// www2id() -- given an WWW hexcode escaped identifier, restore it
//
// These two routines are for escaping/unescaping strings storing attribute
// values.  They use traditional octal escapes (\nnn) because they are
// intended to be viewed by a user
// escattr() -- escape (using traditional octal backslash) non-allowable
// characters in the value of a DAP2 attribute
// unescattr() -- given an octally escaped string, restore it
//
// These are routines used by the above, not intended to be called directly:
//
// hexstring()
// unhexstring()
// octstring()
// unoctstring()
//
// -Todd
 
#include "config.h"
 
#include <ctype.h>
 
#include <iomanip>
#include <sstream>
#include <string>
 
#include "Error.h"
#include "GNURegex.h"
#include "InternalErr.h"
// #define DODS_DEBUG
#include "debug.h"
 
using namespace std;
 
namespace libdap {
 
// The next four functions were originally defined static, but I removed that
// to make testing them (see generalUtilTest.cc) easier to write. 5/7/2001
// jhrg
 
string hexstring(unsigned char val) {
    ostringstream buf;
    buf << hex << setw(2) << setfill('0') << static_cast<unsigned int>(val);
 
    return buf.str();
}
 
string unhexstring(string s) {
    int val;
    istringstream ss(s);
    ss >> hex >> val;
    char tmp_str[2];
    tmp_str[0] = static_cast<char>(val);
    tmp_str[1] = '\0';
    return string(tmp_str);
}
 
string octstring(unsigned char val) {
    ostringstream buf;
    buf << oct << setw(3) << setfill('0') << static_cast<unsigned int>(val);
 
    return buf.str();
}
 
string unoctstring(string s) {
    int val;
 
    istringstream ss(s);
    ss >> oct >> val;
 
    DBG(cerr << "unoctstring: " << val << endl);
 
    char tmp_str[2];
    tmp_str[0] = static_cast<char>(val);
    tmp_str[1] = '\0';
    return string(tmp_str);
}

string id2www(string in, const string &allowable) {
    string::size_type i = 0;
    DBG(cerr << "Input string: [" << in << "]" << endl);
    while ((i = in.find_first_not_of(allowable, i)) != string::npos) {
        DBG(cerr << "Found escapee: [" << in[i] << "]");
        in.replace(i, 1, "%" + hexstring(in[i]));
        DBGN(cerr << " now the string is: " << in << endl);
        i += 3; // i++;
    }
 
    return in;
}

string id2www_ce(string in, const string &allowable) { return id2www(in, allowable); }

string www2id(const string &in, const string &escape, const string &except) {
    string::size_type i = 0;
    string res = in;
    while ((i = res.find_first_of(escape, i)) != string::npos) {
        if (except.find(res.substr(i, 3)) != string::npos) {
            i += 3;
            continue;
        }
        res.replace(i, 3, unhexstring(res.substr(i + 1, 2)));
        ++i;
    }
 
    return res;
}
 
static string entity(char c) {
    switch (c) {
    case '>':
        return "&gt;";
    case '<':
        return "&lt;";
    case '&':
        return "&amp;";
    case '\'':
        return "&apos;";
    case '\"':
        return "&quot;";
    default:
        throw InternalErr(__FILE__, __LINE__, "Unrecognized character.");
    }
}
 
// Assumption: There are always exactly two octal digits in the input
// and two hex digits in the result.
string octal_to_hex(const string &octal_digits) {
    int val;
 
    istringstream ss(octal_digits);
    ss >> oct >> val;
 
    ostringstream ds;
    ds << hex << setw(2) << setfill('0') << val;
    return ds.str();
}

string id2xml(string in, const string &not_allowed) {
    string::size_type i = 0;
 
    while ((i = in.find_first_of(not_allowed, i)) != string::npos) {
        in.replace(i, 1, entity(in[i]));
        ++i;
    }
#if 0
    // Removed the encoding of octal escapes. This function is used by
    // AttrTable to encode the stuff that is the value of the <value>
    // element in the DDX. The problem is that some of the values are not
    // valid UTF-8 and that makes a XML parser gag.; ticket 1512.
    // jhrg 3/19/10
 
    // OK, now scan for octal escape sequences like \\012 (where the '\'
    // is itself escaped). This type of attribute value comes from the netCDF
    // handler and maybe others. Assumption: The '\' will always appear as
    // in its escaped form: '\\'. NB: Both backslashes must be escaped in the
    // C++ string.
    string octal_escape = "\\\\";
    i = 0;
    string::size_type length = in.length();
    while ((i = in.find(octal_escape, i)) != string::npos) {
        // Get the three octal digits following the '\\0'
        string::size_type j = i + 2;
        if (j + 1 >= length)  // Check that we're not past the end
            break;
        string octal_digits = in.substr(j, 3);
        // convert to a &#xdd; XML escape
        string hex_escape = string("&#x");
        hex_escape.append(octal_to_hex(octal_digits));
        hex_escape.append(string(";"));
 
        // replace the octal escape with an XML/hex escape
        in.replace(i, 5, hex_escape);
 
        // increment i
        i += 6;
    }
#endif
    return in;
}

string xml2id(string in) {
    string::size_type i = 0;
 
    while ((i = in.find("&gt;", i)) != string::npos)
        in.replace(i, 4, ">");
 
    i = 0;
    while ((i = in.find("&lt;", i)) != string::npos)
        in.replace(i, 4, "<");
 
    i = 0;
    while ((i = in.find("&amp;", i)) != string::npos)
        in.replace(i, 5, "&");
 
    i = 0;
    while ((i = in.find("&apos;", i)) != string::npos)
        in.replace(i, 6, "'");
 
    i = 0;
    while ((i = in.find("&quot;", i)) != string::npos)
        in.replace(i, 6, "\"");
 
    return in;
}

string esc2underscore(string s) {
    string::size_type pos;
    while ((pos = s.find('%')) != string::npos)
        s.replace(pos, 3, "_");
 
    return s;
}

string escattr(string s) {
    const string printable =
        " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789~`!@#$%^&*()_-+={[}]|\\:;<,>.?/'\"\n\t\r";
    const string ESC = "\\";
    const string DOUBLE_ESC = ESC + ESC;
    const string QUOTE = "\"";
    const string ESCQUOTE = ESC + QUOTE;
 
    // escape \ with a second backslash
    string::size_type ind = 0;
    while ((ind = s.find(ESC, ind)) != string::npos) {
        s.replace(ind, 1, DOUBLE_ESC);
        ind += DOUBLE_ESC.length();
    }
 
    // escape non-printing characters with octal escape
    ind = 0;
    while ((ind = s.find_first_not_of(printable, ind)) != string::npos)
        s.replace(ind, 1, ESC + octstring(s[ind]));
 
    // escape " with backslash
    ind = 0;
    while ((ind = s.find(QUOTE, ind)) != string::npos) {
        s.replace(ind, 1, ESCQUOTE);
        ind += ESCQUOTE.length();
    }
 
    return s;
}

string escattr_xml(string s) {
    const string printable =
        " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789~`!@#$%^&*()_-+={[}]|\\:;<,>.?/'\"\n\t\r";
 
    const string ESC = "\\";
    const char null_char = '\0';
 
    string::size_type ind = 0;
 
    // Unlike escaping the special characters for DAS, we don't need to handle quote or double quote.
    // However, we would like to treate NULL as a printable character. Otherwise, a '\000'
    // will be added to many Nullterm string. Note: we have to search the '\0' character like
    // the code below. Put the '\0' inside the string "printable" still doesn't recongize the '\0' as a printable
    // character. KY 2022-08-22
    while ((ind = s.find_first_not_of(printable, ind)) != string::npos) {
        if (s[ind] != null_char)
            s.replace(ind, 1, ESC + octstring(s[ind]));
        else
            ind++;
    }
 
    return s;
}

string unescattr(string s) {
    const Regex octal("\\\\[0-3][0-7][0-7]"); // matches 4 characters
    const Regex esc_quote("\\\\\"");          // matches 3 characters
    const Regex esc_esc("\\\\\\\\");          // matches 2 characters
    const string ESC = "\\";
    const string QUOTE = "\"";
    int matchlen;
    unsigned int index;
 
    DBG(cerr << "0XX" << s << "XXX" << endl);
    // unescape any escaped backslashes
    index = esc_esc.search(s.c_str(), s.length(), matchlen, 0);
    while (index < s.length()) {
        DBG(cerr << "1aXX" << s << "XXX index: " << index << endl);
        s.replace(index, 2, ESC);
        DBG(cerr << "1bXX" << s << "XXX index: " << index << endl);
        index = esc_esc.search(s.c_str(), s.length(), matchlen, 0);
    }
 
    // unescape any escaped double quote characters
    index = esc_quote.search(s.c_str(), s.length(), matchlen, 0);
    while (index < s.length()) {
        s.replace(index, 2, QUOTE);
        DBG(cerr << "2XX" << s << "XXX index: " << index << endl);
        index = esc_quote.search(s.c_str(), s.length(), matchlen, 0);
    }
 
    // unescape octal characters
    index = octal.search(s.c_str(), s.length(), matchlen, 0);
    while (index < s.length()) {
        s.replace(index, 4, unoctstring(s.substr(index + 1, 3)));
        DBG(cerr << "3XX" << s << "XXX index: " << index << endl);
        index = octal.search(s.c_str(), s.length(), matchlen, 0);
    }
 
    DBG(cerr << "4XX" << s << "XXX" << endl);
    return s;
}
 
string munge_error_message(string msg) {
    // First, add enclosing quotes if needed.
    if (*msg.begin() != '"')
        msg.insert(msg.begin(), '"');
    if (*(msg.end() - 1) != '"')
        msg += "\"";
 
    // Now escape any internal double quotes that aren't escaped.
    string::iterator miter;
    for (miter = msg.begin() + 1; miter != msg.end() - 1; miter++)
        if (*miter == '"' && *(miter - 1) != '\\')
            miter = msg.insert(miter, '\\');
 
    return msg;
}

string escape_double_quotes(string source) {
    string::size_type idx = 0;
    while ((idx = source.find('\"', idx)) != string::npos) {
        source.replace(idx, 1, "\\\""); // a backslash and a double quote
        idx += 2;
    }
 
    return source;
}

string unescape_double_quotes(string source) {
    string::size_type idx = 0;
    while ((idx = source.find("\\\"", idx)) != string::npos) {
        source.replace(idx, 2, "\""); // a backslash and a double quote
        ++idx;
    }
 
    return source;
}
 
} // namespace libdap