Serving binary file with ESP8266WebServer

Question

I am currently using a Nodemcu ESP8266-12E with the Arduino IDE in order to control my boiler. Everything is working fine, however I haven't figured out yet how to serve binary files, eg. images. (I am hosting them on a server at the moment).

ESP8266WebServer server(80);

void setup()
{
  [...]
  server.on("/", handleResponse);
  server.onNotFound(handleResponse);
  server.begin();
}

void handleResponse() {
  if (server.uri() == "/style.css") {
    server.send(200, "text/css", "[css]");
    return;
  }
  if (server.uri() == "/favicon.ico") {
    server.send(404, "text/html", "Not set");
    return;
  }
  [...]
}

unsigned char favicon_ico[] = {
  0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x10, 0x10, 0x00, 0x00, 0x01, 0x00,
  0x18, 0x00, 0x68, 0x03, 0x00,......... 0x00
};
unsigned int favicon_ico_len = 894;

Converting the arary to a string and serving it with server.send does not work and server.stream expects a file.

score 7 · Accepted Answer · answered Jul 13 '16 at 11:05

It looks like you can use the send_P function to send raw PROGMEM data:

void send_P(int code, PGM_P content_type, PGM_P content, size_t contentLength);

I.e., (from what I can gather):

PGM_P favicon = {
  0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x10, 0x10, 0x00, 0x00, 0x01, 0x00,
  0x18, 0x00, 0x68, 0x03, 0x00,......... 0x00
};

server.send_P(200, "image/x-icon", favicon, sizeof(favicon));

Incidentally, PGM_P is just a typedef for const char *.

Serving binary file with ESP8266WebServer

1 Answers1