CORS with LWIP

clock.1166 · ‎2024-03-14

Hi - can anyone tell me how to insert a CORS header into LWIP?

(Cross-Origin Resource Sharing) header directly into the httpd.c? file of LwIP)

i.e.Access-Control-Allow-Origin: *

I am using vscode to debug an index.shtml file file, but i need to get responses from my H743 webserver to be able to debug fully.

Any ideas?

Thanks

Chris

Andrew Neil · ‎2024-03-14

From https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS it looks like they're just standard HTTP headers ?

clock.1166 · ‎2024-03-15

Thanks Andrew,

Thats quite interesting - but I'm trying to find out where and how to insert these headers into the LWIP response CODE. I have found various places, but none of my attempts appear to work.

Unfortunately, I am not an expert in LWIP webserver code and I do not have weeks of time to spare!

Chris

Andrew Neil · ‎2024-03-15

neither am I.

But, given they're just ordinary HTTP headers, then inserting them should should be the as inserting any other headers?

clock.1166 · ‎2024-03-15

Apparently, you cant just add CORS headers directly to the HTML file.

I'm trying to find exactly where in the LWIP (perhaps httpd.c) code I can add them!

Andrew Neil · ‎2024-03-15

That doesn't sound right: HTTP is a transport protocol - HTML is a payload format.

🤔

clock.1166 · ‎2024-03-15

From what I've deduced from searching, the way to dynamically add the CORS header into LWIP is somewhere in the httpd.c file.

But where and how?

Jporcel777 · ‎2024-03-22

Hello!

I am facing the same problem! I think we need to add the CORS policy headers in this section:

static const char *const g_psHTTPHeaderStrings[] = {
  "HTTP/1.0 200 OK\r\n",
  "HTTP/1.0 404 File not found\r\n",
  "HTTP/1.0 400 Bad Request\r\n",
  "HTTP/1.0 501 Not Implemented\r\n",
  "HTTP/1.1 200 OK\r\n",
  "HTTP/1.1 404 File not found\r\n",
  "HTTP/1.1 400 Bad Request\r\n",
  "HTTP/1.1 501 Not Implemented\r\n",
  "Content-Length: ",
  "Connection: Close\r\n",
  "Connection: keep-alive\r\n",
  "Connection: keep-alive\r\nContent-Length: ",
  "Server: "HTTPD_SERVER_AGENT"\r\n",
  // Add CORS headers
  "Access-Control-Allow-Origin: *\r\n",
  "Access-Control-Allow-Methods: GET, POST, OPTIONS\r\n",
  "Access-Control-Allow-Headers: Content-Type\r\n",
  "\r\n<html><body><h2>404: The requested file cannot be found.</h2></body></html>\r\n"
#if LWIP_HTTPD_SUPPORT_11_KEEPALIVE
  , "Connection: keep-alive\r\nContent-Length: 77\r\n\r\n<html><body><h2>404: The requested file cannot be found.</h2></body></html>\r\n"
#endif
};

But there is something missing.

Let me know if you find any solution.

clock.1166 · ‎2024-03-22

Hi Jp - i've tried that already - makes no difference. I need to do a bit (lot) of studying!!

Good Luck!