Function ParseTorReplyMapping

src/torcontrol.cpp:272–357

Parse reply arguments in the form 'METHODS=COOKIE,SAFECOOKIE COOKIEFILE=".../control_auth_cookie"'. * Returns a map of keys to values, or an empty map if there was an error. * Grammar is implicitly defined in https://spec.torproject.org/control-spec by * the server reply formats for PROTOCOLINFO (S3.21), AUTHCHALLENGE (S3.24), * and ADD_ONION (S3.27). See also sections 2.1 and 2.3. */

 * and ADD_ONION (S3.27). See also sections 2.1 and 2.3.
 */
std::map<std::string,std::string> ParseTorReplyMapping(const std::string &s)
{
    std::map<std::string,std::string> mapping;
    size_t ptr=0;
    while (ptr < s.size()) {
        std::string key, value;
        while (ptr < s.size() && s[ptr] != '=' && s[ptr] != ' ') {
            key.push_back(s[ptr]);
            ++ptr;
        }
        if (ptr == s.size()) // unexpected end of line
            return std::map<std::string,std::string>();
        if (s[ptr] == ' ') // The remaining string is an OptArguments
            break;
        ++ptr; // skip '='
        if (ptr < s.size() && s[ptr] == '"') { // Quoted string
            ++ptr; // skip opening '"'
            bool escape_next = false;
            while (ptr < s.size() && (escape_next || s[ptr] != '"')) {
                // Repeated backslashes must be interpreted as pairs
                escape_next = (s[ptr] == '\\' && !escape_next);
                value.push_back(s[ptr]);
                ++ptr;
            }
            if (ptr == s.size()) // unexpected end of line
                return std::map<std::string,std::string>();
            ++ptr; // skip closing '"'
            /**
             * Unescape value. Per https://spec.torproject.org/control-spec section 2.1.1:
             *
             *   For future-proofing, controller implementors MAY use the following
             *   rules to be compatible with buggy Tor implementations and with
             *   future ones that implement the spec as intended:
             *
             *     Read \n \t \r and \0 ... \377 as C escapes.
             *     Treat a backslash followed by any other character as that character.
             */
            std::string escaped_value;
            for (size_t i = 0; i < value.size(); ++i) {
                if (value[i] == '\\') {
                    // This will always be valid, because if the QuotedString
                    // ended in an odd number of backslashes, then the parser
                    // would already have returned above, due to a missing
                    // terminating double-quote.
                    ++i;
                    if (value[i] == 'n') {
                        escaped_value.push_back('\n');
                    } else if (value[i] == 't') {
                        escaped_value.push_back('\t');
                    } else if (value[i] == 'r') {
                        escaped_value.push_back('\r');
                    } else if ('0' <= value[i] && value[i] <= '7') {
                        size_t j;
                        // Octal escape sequences have a limit of three octal digits,
                        // but terminate at the first character that is not a valid
                        // octal digit if encountered sooner.
                        for (j = 1; j < 3 && (i+j) < value.size() && '0' <= value[i+j] && value[i+j] <= '7'; ++j) {}
                        // Tor restricts first digit to 0-3 for three-digit octals.