jamulus-issue-2046-fuzz.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int iCurNumChannels;
int vecChannelOrder[100];
unsigned int vecChannels[100];
#define INVALID_CHANNEL_ID 101

void InitChannel(int iNewChanID, unsigned int InetAddr)
{
    vecChannels[iNewChanID] = InetAddr;
}

int CompareAddresses(unsigned int InetAddr1, unsigned int InetAddr2)
{
    // return InetAddr1 < InetAddr2 ? -1 : InetAddr1 > InetAddr2 ? 1
    //                                                           : 0;
    return (int)InetAddr1 - (int)InetAddr2;
}

unsigned int GenerateRandomAddress()
{
    unsigned int iRand = rand();
    if (rand() % 2 == 0)
    {
        // rand() does not return negative numbers, so force iRand to go into negative range.
        iRand |= 1 << 31;
    }
    return iRand;
}

void DumpChannels()
{
    int i;
    for (i = 0; i < iCurNumChannels; i++)
    {
        printf("%d: %d => %u\n", i, vecChannelOrder[i], vecChannels[vecChannelOrder[i]]);
    }
}

int FindChannel(int CheckAddr)
{
    int iNewChanID = INVALID_CHANNEL_ID;
    int l = 0, r = iCurNumChannels, i;

    // use binary search to find the channel
    while (r > l)
    {
        int t = (r + l) / 2;
        int cmp = CompareAddresses(CheckAddr, vecChannels[vecChannelOrder[t]]);

        if (cmp == 0)
        {
            // address and port match
            return vecChannelOrder[t];
        }

        if (cmp < 0)
        {
            l = t + 1;
        }
        else
        {
            r = t;
        }
    }

    // allocate a new channel
    i = iCurNumChannels++; // save index of free channel and increment count
    iNewChanID = vecChannelOrder[i];
    InitChannel(iNewChanID, CheckAddr);

    // now l == r == position in vecChannelOrder to insert iNewChanID
    // move channel IDs up by one starting at the top and working down
    while (i > r)
    {
        int j = i--;
        vecChannelOrder[j] = vecChannelOrder[i];
    }
    // insert the new channel ID in the correct place
    vecChannelOrder[i] = iNewChanID;

    return iNewChanID;
}

int seed = 78;
int main()
{
    int i;
    int iMaxNumChannels = 100;

    srand(seed);

    // Reset the state
    iCurNumChannels = 0;
    for (i = 0; i < iMaxNumChannels; i++)
    {
        vecChannelOrder[i] = i;
    }

    // Generate 16 random addresses
    srand(seed);
    unsigned int address[16];
    for (i = 0; i < 16; i++)
    {
        address[i] = GenerateRandomAddress();
    }

    // Use `FindChannel` to allocate a channel for each address
    int channelIds[16];
    for (i = 0; i < 16; i++)
    {
        int chanID = FindChannel(address[i]);
        printf("Assigned channel %d to address %u\n", chanID, address[i]);
        channelIds[i] = chanID;
    }

    // Print the channels
    DumpChannels();

    // Try again... This time we should get the same channel ID back.
    // If not, list all the violations.
    int violations = 0;
    for (i = 0; i < 16; i++)
    {
        int chanID = FindChannel(address[i]);
        int prevChanID = channelIds[i];
        if (chanID != prevChanID)
        {
            printf("Address %u got channel ID %d, which is different from previous channel ID %d\n", address[i], chanID, prevChanID);
            violations++;
        }
    }
    printf("seed=%d, %d violations\n", seed, violations);
}