[lwip-users] How to manage non null-terminated strings

[Giuseppe Modugno]

Many times in the application payloads you have a message with non 
null-terminated string, where the length of the string is in another 
variable (derived from the length of the packet).

I think of MQTT messages that have strings. The callback parameters are 
the pointer to the first char of string and the length of string.

Many times I need to compare the string against a fixed reference 
string. However I can't use strncmp(), because it would success if the 
string is shorter than the reference string.

I could copy the string in another array, but I think there's a better 
method.