MimeMultipart.cpp

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/*
 * Copyright (C) 2019-2021 Tobias Flaig.
 *
 * This file is part of nawa.
 *
 * nawa is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License,
 * version 3, as published by the Free Software Foundation.
 *
 * nawa 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 nawa.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#include <boost/algorithm/string.hpp>
#include <nawa/Exception.h>
#include <nawa/util/MimeMultipart.h>
#include <nawa/util/utils.h>
#include <regex>
 
using namespace nawa;
using namespace std;
 
struct MimeMultipart::Data {
    string contentType;
    vector<Part> parts;
};
 
struct MimeMultipart::Part::Data {
    string partName;
    string filename;
    string contentType;
    unordered_map<string, string> headers;
    string content;
};
 
NAWA_DEFAULT_DESTRUCTOR_IMPL(MimeMultipart)
 
NAWA_DEFAULT_CONSTRUCTOR_IMPL(MimeMultipart)
 
NAWA_COPY_CONSTRUCTOR_IMPL(MimeMultipart)
 
NAWA_COPY_ASSIGNMENT_OPERATOR_IMPL(MimeMultipart)
 
NAWA_MOVE_CONSTRUCTOR_IMPL(MimeMultipart)
 
NAWA_MOVE_ASSIGNMENT_OPERATOR_IMPL(MimeMultipart)
 
NAWA_DEFAULT_DESTRUCTOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_DEFAULT_CONSTRUCTOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_COPY_CONSTRUCTOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_COPY_ASSIGNMENT_OPERATOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_MOVE_CONSTRUCTOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_MOVE_ASSIGNMENT_OPERATOR_IMPL_WITH_NS(MimeMultipart, Part)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart::Part, partName, string)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart::Part, filename, string)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart::Part, contentType, string)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart::Part, headers, MimeMultipart::HeadersMap)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart::Part, content, string)
 
NAWA_COMPLEX_DATA_ACCESSORS_IMPL(MimeMultipart, parts, vector<MimeMultipart::Part>)
 
MimeMultipart::MimeMultipart(string const& contentType, string content) : MimeMultipart() {
    parse(contentType, move(content));
}
 
void MimeMultipart::parse(string const& contentType, string content) {
    regex findBoundary(R"X(boundary="?([A-Za-z0-9'()+_,\-.\/:=? ]+)"?)X");
    smatch boundaryMatch;
    if (!regex_search(contentType, boundaryMatch, findBoundary) || boundaryMatch.size() != 2) {
        throw Exception(__PRETTY_FUNCTION__, 1, "Could not find boundary in content type.");
    }
    string boundary = "--";
    boundary += boundaryMatch[1];
    size_t boundaryLen = boundary.length();
 
    regex matchPartAndFileName(R"X((;| )name="?([^"]+)"?(; ?filename="?([^"]+)"?)?)X");
    auto extractPartAndFileName = [&](string const& contentDisposition) -> pair<string, string> {
        smatch sm;
        if (!regex_search(contentDisposition, sm, matchPartAndFileName) || sm.size() < 3) {
            return make_pair(string(), string());
        }
        return make_pair(sm[2], sm.size() >= 5 ? sm[4] : string());
    };
 
    // parse content
    while (!content.empty()) {
 
        // check for boundary
        if (content.length() < boundaryLen + 2 || content.substr(0, boundaryLen) != boundary) {
            throw Exception(__PRETTY_FUNCTION__, 2, "Malformed MIME payload.");
        }
        content = content.substr(boundaryLen);
 
        // if followed by --, this is the end
        if (content.substr(0, 2) == "--") {
            break;
        }
 
        // newline must follow, and content must still have at least 2 (\r\n) + 1 (hdrs) + 2 (\r\n) + boundaryLen + 2 chars
        if (content.length() < boundaryLen + 6 || content.substr(0, 2) != "\r\n") {
            throw Exception(__PRETTY_FUNCTION__, 2, "Malformed MIME payload.");
        }
        content = content.substr(2);
 
        // find next boundary
        size_t nextBoundaryPos = content.find(boundary);
        if (nextBoundaryPos == string::npos) {
            throw Exception(__PRETTY_FUNCTION__, 2, "Malformed MIME payload.");
        }
 
        // headers section goes until the next \r\n\r\n or, alternatively, the next boundary
        size_t headersEndPos = content.find("\r\n\r\n");
        if (headersEndPos > nextBoundaryPos) {
            headersEndPos = nextBoundaryPos;
        }
        if (headersEndPos < 4) {
            throw Exception(__PRETTY_FUNCTION__, 2, "Malformed MIME payload.");
        }
 
        Part currentPart;
        currentPart.data->headers = utils::parseHeaders(content.substr(0, headersEndPos));
        currentPart.data->contentType = currentPart.data->headers.count("content-type") ? currentPart.data->headers.at(
                                                                                                  "content-type")
                                                                                        : "";
        if (currentPart.data->headers.count("content-disposition")) {
            tie(currentPart.data->partName, currentPart.data->filename) = extractPartAndFileName(
                    currentPart.data->headers.at("content-disposition"));
        }
 
        // is there a part content in between? (headersEndPos + "\r\n\r\n" + content + "\r\n")
        if (nextBoundaryPos > headersEndPos + 7) {
            currentPart.data->content = content.substr(headersEndPos + 4, nextBoundaryPos - 2 - (headersEndPos + 4));
        }
 
        data->parts.push_back(currentPart);
        content = content.substr(nextBoundaryPos);
    }
 
    data->contentType = contentType.substr(0, contentType.find_first_of(';'));
}
 
void MimeMultipart::clear() {
    data->contentType.clear();
    data->parts.clear();
}