Proposed solution to "double free or corruption (out)"

[chil-dk]

I downloaded the code, and the examples didn't work.
I located what I think is an error in the buffer management.
The data type for the data waiting to be sent shouldn't be const char *, but strings.

struct Connection
{
    list<string>       buffer;     // <-- string and not const char*
    map<string,string> keyValueMap;
    time_t             createTime;
};

`
A copy of the incoming data should be made when pushing to the buffer:

A const char is just a pointer. If a pointer is pushed onto the buffer, and the pointer is for some reason no longer valid, then the buffer contains ... invalid data.
That's what I found when I put some debug statements into the code.
Here is what the echo server told me:

[cppWebSockets] Callback Receive
[cppWebSockets] Received: hjghjk
[cppWebSockets] send, socketID = 8 data = 'hjghjk'
[cppWebSockets] Callback Server Writeable, fd = 8
[cppWebSockets] == Elements in buffer: 1
[cppWebSockets] == Element : ���� [cppWebSockets] Sending '����'

The buffer elements was first pushed to the buffer in the WebSocketServer::send, and when the callback receive function asked for them, they were no longer valid.

Changing the datatype to string as shown solved the problem.