Function prep_headers

test/httpd.cpp:121–158

* Sends the HTTP 200 OK header, the server string, for a few types of files, it * can also send the content type based on the file extension. It also sends the * content length header. Finally it send a '\r\n' in a line by itself * signalling the end of headers and the beginning of any content. * */

 * signalling the end of headers and the beginning of any content.
 * */
size_t
prep_headers(std::string_view path, off_t len, std::span<char> send_buffer) {
    char format_buffer[64];
    const auto start = send_buffer.begin();

    memwrite(send_buffer, "HTTP/1.0 200 OK\r\n");
    memwrite(send_buffer, SERVER_STRING);

    /*
     * Check the file extension for certain common types of files
     * on web pages and send the appropriate content-type header.
     * Since extensions can be mixed case like JPG, jpg or Jpg,
     * we turn the extension into lower case before checking.
     * */
    std::string_view file_ext = get_filename_ext(path);
    if ("htm"sv == file_ext || "html"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: text/html\r\n");
    } else if ("png"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: image/png\r\n");
    } else if ("gif"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: image/gif\r\n");
    } else if ("jpg"sv == file_ext || "jpeg"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: image/jpeg\r\n");
    } else if ("js"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: application/javascript\r\n");
    } else if ("css"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: text/css\r\n");
    } else if ("txt"sv == file_ext) {
        memwrite(send_buffer, "Content-Type: text/plain\r\n");
    }

    (void)sprintf(format_buffer, "content-length: %ld\r\n", len);
    // BUG check
    memwrite(send_buffer, format_buffer);
    memwrite(send_buffer, "\r\n");

    return send_buffer.begin() - start;
}

std::span<char> get_line(std::span<char> src) {
    auto pos = std::string_view{src.begin(), src.end()}.find("\r\n");