Method postMultipart

Tests/Libraries/Http/HttpTestClient.cpp:162–250

    parser.type       = HttpParser::Type::Response;
    responseHasNoBody = false;
    return connectAsync.start(*eventLoop, clientSocket, localHost);
}

SC::Result SC::HttpTestClient::postMultipart(AsyncEventLoop& loop, StringSpan url, StringSpan fieldName,
                                             StringSpan fileName, StringSpan fileContent, TimeMs delay)
{
    bodyDelay         = delay;
    eventLoop         = &loop;
    responseHasNoBody = false;

    uint16_t      port;
    HttpURLParser urlParser;
    SC_TRY(urlParser.parse(url));
    if (urlParser.protocol != "http")
        return Result::Error(HttpResultCategory, HttpError::UnsupportedProtocol);
    // TODO: Make DNS Resolution asynchronous
    char       buffer[256];
    Span<char> ipAddress = {buffer};
    SC_TRY(SocketDNS::resolveDNS(urlParser.hostname, ipAddress))
    port = urlParser.port;
    SocketIPAddress localHost;
    SC_TRY(localHost.fromAddressPort({ipAddress, true, StringEncoding::Ascii}, port));
    SC_TRY(eventLoop->createAsyncTCPSocket(localHost.getAddressFamily(), clientSocket));

    // Generate a unique boundary
    StringSpan boundary    = "----SCFormBoundary7MA4YWxkTrZu0gW";
    size_t     boundaryLen = boundary.sizeInBytes();

    {
        GrowableBuffer<decltype(content)> gb = {content};

        HttpStringAppend& sb = static_cast<HttpStringAppend&>(static_cast<IGrowableBuffer&>(gb));
        sb.clear();

        // Build the multipart body first to know content length
        // Body format:
        // --boundary\r\n
        // Content-Disposition: form-data; name="fieldName"; filename="fileName"\r\n
        // Content-Type: application/octet-stream\r\n
        // \r\n
        // fileContent
        // \r\n--boundary--\r\n

        // Calculate body size
        size_t bodySize = 0;
        bodySize += 2 + boundaryLen + 2;                                            // --boundary\r\n
        bodySize += 38 + fieldName.sizeInBytes() + 13 + fileName.sizeInBytes() + 3; // Content-Disposition: ...\r\n
        bodySize += 40;                        // Content-Type: application/octet-stream\r\n
        bodySize += 2;                         // \r\n
        bodySize += fileContent.sizeInBytes(); // file content
        bodySize += 4 + boundaryLen + 4;       // \r\n--boundary--\r\n

        // Build HTTP headers
        SC_TRY(sb.append("POST "));
        SC_TRY(sb.append(urlParser.path));
        SC_TRY(sb.append(" HTTP/1.1\r\n"));
        SC_TRY(sb.append("User-agent: SC\r\n"));
        SC_TRY(sb.append("Host: 127.0.0.1\r\n"));