binary_buffer_response.cpp

/*
     This file is part of libhttpserver
     Copyright (C) 2011-2025 Sebastiano Merlino

     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
*/

// binary_buffer_response.cpp - serve binary data (e.g., images) directly
// from an in-memory buffer. std::string holds arbitrary bytes, including
// null characters, making it suitable for any binary content.
//
// To test:
//   curl -o output.png http://localhost:8080/image

#include <string>

#include <httpserver.hpp>

// Generate a minimal valid 1x1 red PNG image in memory.
// In a real application, this could come from a camera capture, image
// processing library, database blob, etc.
static std::string generate_png_data() {
    // Minimal 1x1 red pixel PNG (68 bytes)
    static const unsigned char png[] = {
        0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a,  // PNG signature
        0x00, 0x00, 0x00, 0x0d, 0x49, 0x48, 0x44, 0x52,  // IHDR chunk
        0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01,  // 1x1
        0x08, 0x02, 0x00, 0x00, 0x00, 0x90, 0x77, 0x53,  // 8-bit RGB
        0xde, 0x00, 0x00, 0x00, 0x0c, 0x49, 0x44, 0x41,  // IDAT chunk
        0x54, 0x08, 0xd7, 0x63, 0xf8, 0xcf, 0xc0, 0x00,  // compressed data
        0x00, 0x00, 0x03, 0x00, 0x01, 0x36, 0x28, 0x19,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4e,  // IEND chunk
        0x44, 0xae, 0x42, 0x60, 0x82
    };
    return std::string(reinterpret_cast<const char*>(png), sizeof(png));
}

int main() {
    httpserver::webserver ws{httpserver::create_webserver(8080)};

    ws.on_get("/image", [](const httpserver::http_request&) {
        // The response sends the exact bytes in the string — the size is
        // tracked internally, so null bytes and non-printable characters
        // are transmitted correctly.
        return httpserver::http_response::string(generate_png_data(), "image/png");
    });

    ws.start(true);
    return 0;
}