sdkconfig - CONFIG_HTTPD_MAX_REQ_HDR_LEN=512 byte default value too small

[celerity]

The default in build for this configuration parameter: CONFIG_HTTPD_MAX_REQ_HDR_LEN is 512 bytes.
This is causing "Header fields are too long for server to interpret" errors on a single field form post.
It needs to be set at least 768 bytes, but 1024 would be better.

This is a burden for customers using Arduino because the binary isn't easy to recompile.

For example, using Wireshark, this is the "post" header for Google Chrome on MacOS on the latest Catalina:
(it's 554 bytes plus CR/LFs not shown)

Host: 192.168.4.1
Connection: keep-alive
Content-Length: 95
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://192.168.4.1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.55 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://192.168.4.1/
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9,pl;q=0.8


For a Chrome "get" header is at least 478 bytes ....

Host: 192.168.4.1\r\n
Connection: keep-alive\r\n
Upgrade-Insecure-Requests: 1\r\n
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.55 Safari/537.36\r\n
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9\r\n
Referer: http://192.168.4.1/\r\n
Accept-Encoding: gzip, deflate\r\n
Accept-Language: en-US,en;q=0.9,pl;q=0.8\r\n
\r\n

[ESP_igrr]

I think for Arduino project it's pretty easy to set a larger default value in the configuration used to compile the libraries. Could you please open an issue about that at https://github.com/espressif/arduino-esp32/issues?

[celerity]

Done: https://github.com/espressif/arduino-esp32/issues/5969

However, I believe this default should not just be changed in Arduino but rather system-wide as Chrome has likely "grown" the header to a point where specifying a max value of 512 for that header buffer is just too small.

Post Packet 218

Wireshark trace post packet Packet 218.png (625.55 KiB) Viewed 12811 times

Post Response Error Packet 219

Wireshark trace post response error Packet 219.png (486.02 KiB) Viewed 12811 times