• Registered: 2024-07-02
  • Posts: 7

Topic: wolfssl_write error: DTLS trying to send too much in single datagram

I have a wolfssl dtls server application (c++) that is trying to send a message, but failing due to: DTLS trying to send too much in single datagram

The message size is 1412 Bytes.

I have attempted to set the MTU to a larger size using wolfssl_dtls_set_mtu(ssl, size), but when I compile my application I get an undefined reference to this function.  I'm assuming I missed something during compilation of the package that needed added, although my ide is able to reference the function fine. 

Other smaller messages are fine.

I do see some references in server-dtls-callback.c to setting the size of the rx buffer, but in my case I'm not sure how I'd do this.

my server is essentially the same as the dtls-server.c example.  I should note that I'm testing both client and server on localhost only at the moment.


What are my options here?

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  • Registered: 2021-07-06
  • Posts: 152

Re: wolfssl_write error: DTLS trying to send too much in single datagram

Hi bp787,

To enable wolfssl_dtls_set_mtu, you will need to build with WOLFSSL_DTLS_MTU defined, or if you are using ./configure, you can use --enable-dtls-mtu.

Setting the rx buffer size doesn't apply if you are not using IO callbacks.  Please try setting the MTU and let me know if it helps.

Thanks,
Karee

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  • Registered: 2024-07-02
  • Posts: 7

Re: wolfssl_write error: DTLS trying to send too much in single datagram

This fixed my issue.  Thanks!

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