HTTPD bug fix which is caused by stack overflow.

Dependents:   mbed_controller_demo

Fork of HTTPD by Suga koubou

Original HTTPD implementation of Suga koubou is great but has some bug inside unfortunately. The most critical bug was accessing buffer with the index of out of range like following.

problematic code

char buf[256];

n = httpd->_state[id].client->receive(buf, sizeof(buf));
buf[n] =0;

With above code, it could set buf[256] = 0 when more that 255 data is received. Setting buf[256] causes some other area of memory is corrupted so that system can be predictive status since than.

bug fixed code

n = httpd->_state[id].client->receive(buf, sizeof(buf)-1);
buf[n] =0;

CBuffer.h

Committer:
hillkim7
Date:
2015-04-10
Revision:
2:584ce0a1a76e
Parent:
0:d18dff347122

File content as of revision 2:584ce0a1a76e:

/* Copyright (C) 2012 mbed.org, MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
 * and associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef CIRCBUFFER_H_
#define CIRCBUFFER_H_

template <class T>
class CircBuffer {
public:
    CircBuffer(int length) {
        write = 0;
        read = 0;
        size = length + 1;
        buf = (T *)malloc(size * sizeof(T));
    };

    bool isFull() {
        return (((write + 1) % size) == read);
    };

    bool isEmpty() {
        return (read == write);
    };

    void queue(T k) {
        if (isFull()) {
            read++;
            read %= size;
        }
        buf[write++] = k;
        write %= size;
    }
    
    void flush() {
        read = 0;
        write = 0;
    }
    

    uint32_t available() {
        return (write >= read) ? write - read : size - read + write;
    };

    bool dequeue(T * c) {
        bool empty = isEmpty();
        if (!empty) {
            *c = buf[read++];
            read %= size;
        }
        return(!empty);
    };

private:
    volatile uint32_t write;
    volatile uint32_t read;
    uint32_t size;
    T * buf;
};

#endif