Re: [lwip-users] POST message Length Limitation

[Ajay Bhargav]

On Tue, Oct 8, 2019 at 7:47 PM Siva Munnaluri <address@hidden> wrote:
>
> Reposting as my internet got disconnected, not sure the previous Post is
> posted or not.
> Hi LWIP Team,
>
> We are using
> http://git.savannah.nongnu.org/cgit/lwip.git/tree/contrib/examples/httpd/post_example
> for posting JSON data from a web page. If the JSON characters are more than
> 3000, entire data is not available on web server side.
>
> In lwipopts.h we found a vairable TCP_MSS which we set to (3000- 40). If we
> increase it to 4000 we are getting lwip_sanity_check
>
> #if TCP_SNDLOWAT >= (0xFFFF - (4 * TCP_MSS))
> #error "lwip_sanity_check: WARNING: TCP_SNDLOWAT must at least be 4*MSS
> below u16_t overflow!"
> #endif
>
> Is there a way to accept POST messages with more than 3000 characters. Our
> requirement is to post 15000 characters of JSON data.
>
> Regards,
> Siva
>
>
>
> --
> Sent from: http://lwip.100.n7.nabble.com/lwip-users-f3.html
>
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Looks like you're confusing yourself with HTTP payload with TCP MSS.
For your reference: https://en.wikipedia.org/wiki/Maximum_segment_size

- Ajay Bhargav