Attempting to resolve a DNS name with a length of 64 characters or greater fails when using the CIPDOMAIN command.
Example:
AT+CIPDOMAIN="firmware-catalog-media-ca57.s3.dualstack.us-east-1.amazonaws.com"
DNS Fail
ERROR
The above DNS name should resolve as a CNAME record to s3.dualstack.us-east-1.amazonaws.com
Reducing the string to 63 characters works (-ca57 has been replaced with -ca1)
AT+CIPDOMAIN="firmware-catalog-media-ca1.s3.dualstack.us-east-1.amazonaws.com"
+CIPDOMAIN:54.231.72.106
OK
The above is also a CNAME record which points to s3.dualstack.us-east-1.amazonaws.com.
I dumped the the libat.a archive and found the at_setupCipomain function which seems to allocate only a character string of 64 bytes to be copied on the stack.
First, can someone confirm this limitation?
Second, can we get an updated firmware with a larger allocation? Or just a fix?
ESP8266 CIPDOMAIN limitation
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- Posts: 2
- Joined: Sat Jul 08, 2017 4:11 am
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- Posts: 2
- Joined: Sat Jul 08, 2017 4:11 am
Re: ESP8266 CIPDOMAIN limitation
Postby imsherlock » Tue Jul 11, 2017 12:31 am
Is there any chance we can get an increase in size? The RFC for DNS states that the domain name may be up to 253 characters, while a given label may contain up to 63 characters. Shouldn't the command be updated to align with this?
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