path: root/core/DHT.c

#include "DHT.h"


//Function to send packet(data) of length length to ip_port
int sendpacket(IP_Port ip_port, char * data, uint32_t length)
{
    ADDR addr = {.family = AF_INET, .ip = ip_port.ip, .port = ip_port.port};
    
    return sendto(sock, data, length, 0, (struct sockaddr *)&addr, sizeof(addr));
}

//Compares client_id1 and client_id2 with client_id
//return 0 if both are same distance
//return 1 if client_id1 is closer.
//return 2 if client_id2 is closer.
int id_closest(char * client_id, char * client_id1, char * client_id2)
{
    uint32_t i;
    for(i = 0; i < CLIENT_ID_SIZE; i++)
    {
        if(abs(client_id[i] ^ client_id1[i]) < abs(client_id[i] ^ client_id2[i]))
        {
            return 1;
        }
        else if(abs(client_id[i] ^ client_id1[i]) > abs(client_id[i] ^ client_id2[i]))
        {
            return 2;
        }
        
    }
    
    return 0;
}

//check if client with client_id is already in list of length length.
//return True(1) or False(0)
int client_in_list(Client_data * list, uint32_t length, char * client_id)
{
    uint32_t i, j;
    for(i = 0; i < length; i++)
    {
        for(j = 0; j < CLIENT_ID_SIZE; j++)
        {
        
            if(list[i].client_id[j] != client_id[j])
            {
                break;
            }
        }
        if((j - 1) == CLIENT_ID_SIZE)
        {
            return 1;
        }
    }
    return 0;
}

//the number of seconds for a non responsive node to become bad.
#define BAD_NODE_TIMEOUT 130

//replace first bad (or empty) node with this one
//return 0 if successfull
//return 1 if not (list contains no bad nodes)
int replace_bad(Client_data * list, uint32_t length, char * client_id, IP_Port ip_port)
{
    uint32_t i;
    for(i = 0; i < length; i++)
    {
        if(list[i].timestamp + BAD_NODE_TIMEOUT < unix_time())
        {
            memcpy(list[i].client_id, client_id, CLIENT_ID_SIZE);
            list[i].ip_port = ip_port;
            list[i].timestamp = unix_time();
            return 0;
        }
    }
    return 1;
}

//replace the first good node further to the comp_client_id than that of the client_id 
int replace_good(Client_data * list, uint32_t length, char * client_id, IP_Port ip_port, char * comp_client_id)
{
    uint32_t i;
    for(i = 0; i < length; i++)
    {
        if(id_closest(comp_client_id, list[i].client_id, client_id) == 2)
        {
            memcpy(list[i].client_id, client_id, CLIENT_ID_SIZE);
            list[i].ip_port = ip_port;
            list[i].timestamp = unix_time();
            return 0;
        }
    }
    return 1;
}

//Attempt to add client with ip_port and client_id to the friends client list and close_clientlist
int addto_lists(IP_Port ip_port, char * client_id)
{
    uint32_t i, j;
    
    //NOTE: current behaviour if there are two clients with the same id is to only keep one (the first one)
    if(!client_in_list(close_clientlist, LCLIENT_LIST, client_id))
    {
         
        if(replace_bad(close_clientlist, LCLIENT_LIST, client_id, ip_port))
        {
            //if we can't replace bad nodes we try replacing good ones
            replace_good(close_clientlist, LCLIENT_LIST, client_id, ip_port, self_client_id);
        }
        
    }
    for(i = 0; i < num_friends; i++)
    {
        if(!client_in_list(friends_list[i].client_list, LCLIENT_LIST, client_id))
        {
            
            if(replace_bad(friends_list[i].client_list, LCLIENT_LIST, client_id, ip_port))
            {
                //if we can't replace bad nodes we try replacing good ones
                replace_good(friends_list[i].client_list, LCLIENT_LIST, client_id, ip_port, self_client_id);
            }
            
        }  
    }
    
    
}


//send a ping request
//Currently incomplete: missing the ping_id part
int pingreq(IP_Port ip_port)
{
    char data[5 + CLIENT_ID_SIZE];
    data[0] = 0;
    
    memcpy(data + 5, self_client_id, CLIENT_ID_SIZE);
    
    sendpacket(ip_port, data, sizeof(data));
    
}

//send a ping response
//Currently incomplete: missing the ping_id part
int pingres(IP_Port ip_port, uint32_t ping_id)
{
    char data[5 + CLIENT_ID_SIZE];
    data[0] = 1;
    
    memcpy(data + 1, &ping_id, 4);
    memcpy(data + 5, self_client_id, CLIENT_ID_SIZE);
    
    sendpacket(ip_port, data, sizeof(data));
    
}

//send a getnodes request
//Currently incomplete: missing the ping_id part
int getnodes(IP_Port ip_port, char * client_id)
{
   char data[5 + CLIENT_ID_SIZE*2];
   data[0] = 2;
   
   memcpy(data + 5, self_client_id, CLIENT_ID_SIZE);
   memcpy(data + 5 + CLIENT_ID_SIZE, client_id, CLIENT_ID_SIZE);
   
   sendpacket(ip_port, data, sizeof(data));
}

//send a getnodes request
//Currently incomplete: missing the ping_id part
int sendnodes(IP_Port ip_port, char * client_id)
{
   char data[5 + (CLIENT_ID_SIZE + 6)*8];
   data[0] = 3;
   
   memcpy(data + 5, self_client_id, CLIENT_ID_SIZE);
   memcpy(data + 5 + CLIENT_ID_SIZE, client_id, CLIENT_ID_SIZE);
   
   sendpacket(ip_port, data, sizeof(data));
}




//Packet handling functions
//One to handle each types of packets

int handle_pingreq(char * packet, uint32_t length, IP_Port source)
{
    if(length != 5 + CLIENT_ID_SIZE)
    {
        return 1;
    }
    
    uint32_t ping_id;
    
    memcpy(&ping_id, packet + 1, 4);
    pingres(source, ping_id);
    
    
    
    return 0;
}

int handle_pingres(char * packet, uint32_t length, IP_Port source)
{
    if(length != (5 + CLIENT_ID_SIZE))
    {
        return 1;
    }
    
    addto_lists(source, packet + 5);
}

int handle_getnodes(char * packet, uint32_t length, IP_Port source)
{
    if(length != (5 + CLIENT_ID_SIZE*2))
    {
        return 1;
    }
    
    
    
    
    return 0;   
}

int handle_sendnodes(char * packet, uint32_t length, IP_Port source)
{
    if(length > 325 || (length - 5) % (CLIENT_ID_SIZE + 6) != 0)
    {
        return 1;
    } 
    addto_lists(source, packet + 5);
    
}





void addfriend(char * client_id)
{
    
    
    
    
}





char delfriend(char * client_id)
{
    
    
    
    
}





IP_Port getfriendip(char * client_id)
{
    
    
    
}




void DHT_recvpacket(char * packet, uint32_t length, IP_Port source)
{
    switch (packet[0]) {
    case 0:
        handle_pingreq(packet, length, source);
        break;        
    case 1:
        handle_pingres(packet, length, source);
        break;        
    case 2:
        handle_getnodes(packet, length, source);
        break;        
    case 3:
        handle_sendnodes(packet, length, source);
        break;
    default: 
        return;
        
    }
    

}

//Ping each client in the "friends" list every 60 seconds.
//Send a get nodes request every 20 seconds to a random good node for each "friend" in our "friends" list.
void doFriends()
{
    
    
    
}


void doClose()
{
    
    
    
}



void doDHT()
{
    
    
    
}




void bootstrap(IP_Port ip_port)
{

    getnodes(ip_port, self_client_id);
    
}