[palacios.git] / palacios / src / devices / vnet.c

/* 
 * This file is part of the Palacios Virtual Machine Monitor developed
 * by the V3VEE Project with funding from the United States National 
 * Science Foundation and the Department of Energy.  
 *
 * The V3VEE Project is a joint project between Northwestern University
 * and the University of New Mexico.  You can find out more at 
 * http://www.v3vee.org
 *
 * Copyright (c) 2009, Lei Xia <lxia@northwestern.edu> 
 * Copyright (c) 2009, Yuan Tang <ytang@northwestern.edu> 
 * Copyright (c) 2009, Jack Lange <jarusl@cs.northwestern.edu> 
 * Copyright (c) 2009, Peter Dinda <pdinda@northwestern.edu>
 * Copyright (c) 2009, The V3VEE Project <http://www.v3vee.org> 
 * All rights reserved.
 *
 * Author: Lei Xia <lxia@northwestern.edu>
 *                Yuan Tang <ytang@northwestern.edu>
 *                Jack Lange <jarusl@cs.northwestern.edu> 
 *                Peter Dinda <pdinda@northwestern.edu
 *
 * This is free software.  You are permitted to use,
 * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
 */
 
#include <devices/vnet.h>

#define ANY "any"
#define NOT "not"
#define NONE "none"
#define EMPTY "empty"

#define ANY_TYPE 0
#define NOT_TYPE 1
#define NONE_TYPE 2
#define EMPTY_TYPE 3

#define INTERFACE "INTERFACE"
#define EDGE "EDGE"
#define ANY_SRC "ANY"

#define INTERFACE_TYPE 0
#define EDGE_TYPE 1
#define ANY_SRC_TYPE 2

struct raw_ethernet_pkt {
    int size;
    int type; // vm or link type:  INTERFACE|EDGE
    char data[ETHERNET_PACKET_LEN];
};

//static char *vnet_version = "0.9";
static int vnet_server = 0;
static bool use_tcp = false;

static uint_t vnet_udp_port = 22;

#define MAX_LINKS 1
#define MAX_ROUTES 1
#define MAX_DEVICES 16


static struct topology g_links[MAX_LINKS];

static int g_num_links; //The current number of links
static int g_first_link;
static int g_last_link;

static struct routing g_routes[MAX_ROUTES];
static int g_num_routes; //The current number of routes
static int g_first_route;
static int g_last_route;

static struct device_list g_devices[MAX_DEVICES];
static int g_num_devices;
static int g_first_device;
static int g_last_device;

static SOCK g_udp_sockfd;
static struct gen_queue * g_inpkt_q; //packet receiving queue


static void print_packet(char *pkt, int size) {
    PrintDebug("Vnet: print_data_packet: size: %d\n", size);
    v3_hexdump(pkt, size, NULL, 0);
}

#if 0
static void print_packet_addr(char *pkt) {
    PrintDebug("Vnet: print_packet_destination_addr: ");
    v3_hexdump(pkt + 8, 6, NULL, 0);
    
    PrintDebug("Vnet: print_packet_source_addr: ");
    v3_hexdump(pkt + 14, 6, NULL, 0);
}

static void print_device_addr(char *ethaddr) {
    PrintDebug("Vnet: print_device_addr: ");
    v3_hexdump(ethaddr, 6, NULL, 0);
} 
#endif

//network connection functions 

#if 0
static int raw_ethernet_pkt_sendUdp(struct raw_ethernet_pkt *pt, int sock_fd, int ip, short port) {
    int size;

    PrintDebug("Vnet: sending by UDP socket %d  ip: %x,  port: %d\n", sock_fd, ip, port);
  
    if ((size = V3_SendTo_IP(sock_fd, ip, port, pt->data, pt->size)) != pt->size) {
        PrintError("Vnet: sending by UDP Exception, %x\n", size);
        return -1;
    }
 
    return 0;
}

#endif

static void raw_ethernet_packet_init(struct raw_ethernet_pkt * pt, const char *data, const size_t size) {
    pt->size = size;
    memcpy(pt->data, data, size);
}



#define HASH_KEY_SIZE 16
#define MIN_CACHE_SIZE 100

/* Hash key format:
 * 0-5:     src_eth_addr
 * 6-11:    dest_eth_addr
 * 12:      src type
 * 13-16:   src index
 */
typedef char * route_hashkey_t;

// This is the hash value, Format: 0: num_matched_routes, 1...n: matches[] -- TY
struct route_cache_entry {
    int num_matched_routes;
    int * matches; 
};

//Header of the route cache
static struct hashtable * g_route_cache; 

static uint_t hash_from_key_fn(addr_t hashkey) {
    uint_t hash = 0;
    uint_t temp = 0; 
    int i;

    char * key = (char *)hashkey;

    for (i = 0; i < HASH_KEY_SIZE; i++) {
        hash = (hash << 4) + *(key + i) + i;

        if ((temp = (hash & 0xF0000000))) {
              hash ^= (temp >> 24);
        }

        hash &= ~temp;
    }
    PrintDebug("Hash Value: %lu\n", (unsigned long)hash);
        
    return hash;
}

static int hash_key_equal(addr_t left, addr_t right) {
    int i;
    char * key1, * key2;
 
    key1 = (char *)left;
    key2 = (char *)right;
        
    for (i = 0; i < HASH_KEY_SIZE; i++) {
        if (key1[i] != key2[i]) {
            PrintDebug("HASHes not equal\n");
            return -1;
        }
    }
    return 0;
}

static int init_route_cache() {
    g_route_cache = v3_create_htable(MIN_CACHE_SIZE, &hash_from_key_fn, &hash_key_equal);

    if (g_route_cache == NULL){
        PrintError("Vnet: Route Cache Initiate Failurely\n");
        return -1;
    }

    return 0;
}

static void make_hash_key(route_hashkey_t hashkey, char src_addr[6], char dest_addr[6], char src_type, int src_index) {
    int j;

    for (j = 0; j < 6; j++) {
        hashkey[j] = src_addr[j];
        hashkey[j + 6] = dest_addr[j] + 1;
    }

    hashkey[12] = src_type;

    *(int *)(hashkey + 12) = src_index;
}

static int add_route_to_cache(route_hashkey_t hashkey, int num_matched_r, int * matches) {
    struct route_cache_entry * new_entry = NULL;
    int i;
    
    new_entry = (struct route_cache_entry *)V3_Malloc(sizeof(struct route_cache_entry));
    if (new_entry == NULL){
        PrintError("Vnet: Malloc fails\n");
        return -1;
    }
    
    new_entry->num_matched_routes = num_matched_r;

    new_entry->matches = (int *)V3_Malloc(num_matched_r * sizeof(int));
    
    if (new_entry->matches == NULL){
        PrintError("Vnet: Malloc fails\n");
        return -1;
    }
    
    for(i = 0; i < num_matched_r; i++) {
        new_entry->matches[i] = matches[i];
    }
    
    //here, when v3_htable_insert return 0, it means insert fails
    if (v3_htable_insert(g_route_cache, (addr_t)hashkey, (addr_t)new_entry) == 0){
        PrintError("Vnet: Insert new route entry to cache failed\n");
        V3_Free(new_entry->matches);
        V3_Free(new_entry);
    }
    
    return 0;
}

static int clear_hash_cache() {
    v3_free_htable(g_route_cache, 1, 1);
                
    g_route_cache = v3_create_htable(MIN_CACHE_SIZE, hash_from_key_fn, hash_key_equal);
    
    if (g_route_cache == NULL){
        PrintError("Vnet: Route Cache Create Failurely\n");
        return -1;
    }

    return 0;
}

static int look_into_cache(route_hashkey_t hashkey, int * matches) {
    int n_matches = -1;
    int i = 0;
    struct route_cache_entry * found = NULL;
    
    found = (struct route_cache_entry *)v3_htable_search(g_route_cache, (addr_t)hashkey);
   
    if (found != NULL) {
        n_matches = found->num_matched_routes;

        for (i = 0; i < n_matches; i++) {
            matches[i] = found->matches[i];
        }
    }

    return n_matches;
}




static inline uint8_t hex_nybble_to_nybble(const uint8_t hexnybble) {
    uint8_t x = toupper(hexnybble);

    if (isdigit(x)) {
        return x - '0';
    } else {
        return 10 + (x - 'A');
    }
}

static inline uint8_t hex_byte_to_byte(const uint8_t hexbyte[2]) {
    return ((hex_nybble_to_nybble(hexbyte[0]) << 4) + 
            (hex_nybble_to_nybble(hexbyte[1]) & 0xf));
}


static inline void string_to_mac(const char * str, uint8_t mac[6]) {
    int k;

    for (k = 0; k < 6; k++) {
        mac[k] = hex_byte_to_byte(&(str[(2 * k) + k]));
    }
}

static inline void mac_to_string(uint8_t mac[6], char * buf) {
    snprintf("%x:%x:%x:%x:%x:%x", 
             mac[0], mac[1], mac[2],
             mac[3], mac[4], mac[5]);
}

#if 0
static void ip_to_string(uint32_t addr, char * buf) {
    uint32_t addr_st;
    char * tmp_str;
    
    addr_st = v3_htonl(addr);
    tmp_str = v3_inet_ntoa(addr_st);
    
    memcpy(buf, tmp_str, strlen(tmp_str));
}
#endif

int find_link_by_fd(SOCK sock) {
    int i;

    FOREACH_LINK(i, g_links, g_first_link) {
        if (g_links[i].link_sock == sock) {
            return i;
        }
    }
    
    return -1;
}

int vnet_add_link_entry(unsigned long dest, int type, int data_port,  SOCK fd) {
    int i;
    
    for (i = 0; i < MAX_LINKS; i++) {
        if (g_links[i].use == 0) {
            g_links[i].dest = dest;
            g_links[i].type = type;
            g_links[i].link_sock = fd;
            g_links[i].remote_port = data_port;
            g_links[i].use = 1;

            if (g_first_link == -1) {
                g_first_link = i;
            }

            g_links[i].prev = g_last_link;
            g_links[i].next = -1;
            
            if (g_last_link != -1) {
                g_links[g_last_link].next = i;
            }
            
            g_last_link = i;
            
            g_num_links++;
            
            return i;
        }
    }
    
    return -1;
}


int add_sock(struct sock_list *socks, int  len, int *first_sock, int *last_sock, SOCK fd) {
    int i;

    for (i = 0; i < len; i++) {
        if (socks[i].sock == -1) {
            socks[i].sock = fd;
            
            if (*first_sock == -1) {
                *first_sock = i;
            }
            
            socks[i].prev = *last_sock;
            socks[i].next = -1;
            
            if (*last_sock != -1) {
                socks[*last_sock].next = i;
            }
            
            *last_sock = i;
            
            return i;
        }
    }
    return -1;
}


int vnet_add_route_entry(char src_mac[6], char dest_mac[6], int src_mac_qual, int dest_mac_qual, int dest, int type, int src, int src_type) {
    int i;
    
    for(i = 0; i < MAX_ROUTES; i++) {
        if (g_routes[i].use == 0) {
            
            if ((src_mac_qual != ANY_TYPE) && (src_mac_qual != NONE_TYPE)) {
                memcpy(g_routes[i].src_mac, src_mac, 6);
            } else {
                memset(g_routes[i].src_mac, 0, 6);
            }
            
            if ((dest_mac_qual != ANY_TYPE) && (dest_mac_qual != NONE_TYPE)) {
                memcpy(g_routes[i].dest_mac, dest_mac, 6);
            } else {
                memset(g_routes[i].dest_mac, 0, 6);
            }
            
            g_routes[i].src_mac_qual = src_mac_qual;
            g_routes[i].dest_mac_qual = dest_mac_qual;
            g_routes[i].dest = dest;
            g_routes[i].type = type;
            g_routes[i].src = src;
            g_routes[i].src_type = src_type;
            g_routes[i].use = 1;
            
            if (g_first_route == -1) {
                g_first_route = i;
            }
            
            g_routes[i].prev = g_last_route;
            g_routes[i].next = -1;
            
            if (g_last_route != -1) {
                g_routes[g_last_route].next = i;
            }
            
            g_last_route = i;
            
            g_num_routes++;
            
            return i;
        }
    }
    
    clear_hash_cache();
    
    return -1;
}


static int find_link_entry(unsigned long dest, int type) {
    int i;

    FOREACH_LINK(i, g_links, g_first_link) {
        if ((g_links[i].dest == dest) && 
            ((type == -1) || (g_links[i].type == type)) ) {
            return i;
        }
    } 
    
    return -1;
}

static int delete_link_entry(int index) {
    int next_i;
    int prev_i;
  
    if (g_links[index].use == 0) {
        return -1;
    }

    g_links[index].dest = 0;
    g_links[index].type = 0;
    g_links[index].link_sock = -1;
    g_links[index].use = 0;

    prev_i = g_links[index].prev;
    next_i = g_links[index].next;

    if (prev_i != -1) {
        g_links[prev_i].next = g_links[index].next;
    }    

    if (next_i != -1) {
        g_links[next_i].prev = g_links[index].prev;
    }
    
    if (g_first_link == index) {
        g_first_link = g_links[index].next;
    }    

    if (g_last_link == index) {
        g_last_link = g_links[index].prev;
    }    

    g_links[index].next = -1;
    g_links[index].prev = -1;
    
    g_num_links--;
    
    return 0;
}

int vnet_delete_link_entry_by_addr(unsigned long dest, int type) {
    int index = find_link_entry(dest, type);
  
    if (index == -1) {
        return -1;
    }

    return delete_link_entry(index);
}


static int find_route_entry(char src_mac[6], 
                            char dest_mac[6], 
                            int src_mac_qual, 
                            int dest_mac_qual, 
                            int dest, 
                            int type, 
                            int src, 
                            int src_type) {
    int i;
    char temp_src_mac[6];
    char temp_dest_mac[6];
  
    if ((src_mac_qual != ANY_TYPE) && (src_mac_qual != NONE_TYPE)) {
        memcpy(temp_src_mac, src_mac, 6);
    } else {
        memset(temp_src_mac, 0, 6);
    }
    
    if ((dest_mac_qual != ANY_TYPE) && (dest_mac_qual != NONE_TYPE)) {
        memcpy(temp_dest_mac, dest_mac, 6);
    } else {
        memset(temp_dest_mac, 0, 6);
    }
    
    FOREACH_LINK(i, g_routes, g_first_route) {
        if ( (memcmp(temp_src_mac, g_routes[i].src_mac, 6) == 0) && 
             (memcmp(temp_dest_mac, g_routes[i].dest_mac, 6) == 0) &&
             (g_routes[i].src_mac_qual == src_mac_qual) &&
             (g_routes[i].dest_mac_qual == dest_mac_qual)  &&
             ( (type == -1) || 
               ( (type == g_routes[i].type) && (g_routes[i].dest == dest)) ) &&
             ( (src_type == -1) || 
               ( (src_type == g_routes[i].src_type) && (g_routes[i].src == src)) ) ) {
                return i;
            }
    } 
    
    return -1;
}

static int delete_route_entry(int index) {
  
    int next_i;
    int prev_i;

    memset(g_routes[index].src_mac, 0, 6);
    memset(g_routes[index].dest_mac, 0, 6);

    g_routes[index].dest = 0;
    g_routes[index].src = 0;
    g_routes[index].src_mac_qual = 0;
    g_routes[index].dest_mac_qual = 0;
    g_routes[index].type = -1;
    g_routes[index].src_type = -1;
    g_routes[index].use = 0;

    prev_i = g_routes[index].prev;
    next_i = g_routes[index].next;
  
    if (prev_i != -1) {
        g_routes[prev_i].next = g_routes[index].next;
    }
    
    if (next_i != -1) {
        g_routes[next_i].prev = g_routes[index].prev;
    }
    
    if (g_first_route == index) {
        g_first_route = g_routes[index].next;
    }    

    if (g_last_route == index) {
        g_last_route = g_routes[index].prev;
    }    

    g_routes[index].next = -1;
    g_routes[index].prev = -1;
    
    g_num_routes--;
    
    clear_hash_cache();
    
    return 0;
}

int vnet_delete_route_entry_by_addr(char src_mac[6], 
                                    char dest_mac[6], 
                                    int src_mac_qual, 
                                    int dest_mac_qual, 
                                    int dest, 
                                    int type, 
                                    int src, 
                                    int src_type) {
    int index = find_route_entry(src_mac, dest_mac, src_mac_qual, 
                                 dest_mac_qual, dest, type, src, src_type);
    
    if (index == -1) {
        return -1;
    }
    
    delete_route_entry(index);
    
    return 0;
}

int delete_sock(struct sock_list * socks, int * first_sock, int * last_sock, SOCK fd) {
    int i;
    int prev_i;
    int next_i;
    
  
    FOREACH_SOCK(i, socks, (*first_sock)) {
        if (socks[i].sock == fd) {
            V3_Close_Socket(socks[i].sock);
            socks[i].sock = -1;
            
            prev_i = socks[i].prev;
            next_i = socks[i].next;
            
            if (prev_i != -1) {
                socks[prev_i].next = socks[i].next;
            }
            
            if (next_i != -1) {
                socks[next_i].prev = socks[i].prev;
            }
            
            if (*first_sock == i) {
                *first_sock = socks[i].next;
            }
            
            if (*last_sock == i) {
                *last_sock = socks[i].prev;
            }
            
            socks[i].next = -1;
            socks[i].prev = -1;
            
            return 0;
        }
    }
    return -1;
}

//setup the topology of the testing network
static void store_topologies(SOCK fd) {
    int i;
    int src_mac_qual = ANY_TYPE;
    int dest_mac_qual = ANY_TYPE;
    uint_t dest;
#ifndef VNET_SERVER
    dest = (0 | 172 << 24 | 23 << 16 | 1 );
    PrintDebug("VNET: store_topologies. NOT VNET_SERVER, dest = %x\n", dest);
#else
    dest = (0 | 172 << 24 | 23 << 16 | 2 );
    PrintDebug("VNET: store_topologies. VNET_SERVER, dest = %x\n", dest);
#endif

    int type = UDP_TYPE;
    int src = 0;
    int src_type= ANY_SRC_TYPE;
    int data_port = 22;
    
    //store link table
    for (i = 0; i < MAX_LINKS; i++) {
        if (g_links[i].use == 0) {
            g_links[i].dest = (int)dest;
            g_links[i].type = type;
            g_links[i].link_sock = fd;
            g_links[i].remote_port = data_port;
            g_links[i].use = 1;
            
            if (g_first_link == -1) {
                g_first_link = i;
            }       

            g_links[i].prev = g_last_link;
            g_links[i].next = -1;
            
            if (g_last_link != -1) {
                g_links[g_last_link].next = i;
            }
            
            g_last_link = i;
            
            g_num_links++;
            PrintDebug("VNET: store_topologies. new link: socket: %d, remote %x:[%d]\n", g_links[i].link_sock, (uint_t)g_links[i].dest, g_links[i].remote_port);
        }
    }
    
    
    //store route table
    
    type = EDGE_TYPE;
    dest = 0;
    
    for (i = 0; i < MAX_ROUTES; i++) {
        if (g_routes[i].use == 0) {
            if ((src_mac_qual != ANY_TYPE) && (src_mac_qual != NONE_TYPE)) {
                //                  memcpy(g_routes[i].src_mac, src_mac, 6);
            } else {
                memset(g_routes[i].src_mac, 0, 6);
            }
            
            if ((dest_mac_qual != ANY_TYPE) && (dest_mac_qual != NONE_TYPE)) {
                //                  memcpy(g_routes[i].dest_mac, dest_mac, 6);
            } else {
                memset(g_routes[i].dest_mac, 0, 6);
            }
            
            g_routes[i].src_mac_qual = src_mac_qual;
            g_routes[i].dest_mac_qual = dest_mac_qual;
            g_routes[i].dest = (int)dest;
            g_routes[i].type = type;
            g_routes[i].src = src;
            g_routes[i].src_type = src_type;
            
            g_routes[i].use = 1;
            
            if (g_first_route == -1) {
                g_first_route = i;
            }
            
            g_routes[i].prev = g_last_route;
            g_routes[i].next = -1;
            
            if (g_last_route != -1) {
                g_routes[g_last_route].next = i;
            }
            
            g_last_route = i;
            
            g_num_routes++;
            
            PrintDebug("VNET: store_topologies. new route: src_mac: %s, dest_mac: %s, dest: %d\n", g_routes[i].src_mac, g_routes[i].dest_mac, dest);
            
        }
    }
}

static int match_route(char *src_mac, char *dst_mac, int src_type, int src_index, int * matches) { 
    int values[MAX_ROUTES];
    int matched_routes[MAX_ROUTES];
    
    int num_matches = 0;
    int i;
    int max = 0;
    int no = 0;
    int exact_match = 0;
    
    FOREACH_ROUTE(i, g_routes, g_first_route) {
        if ((g_routes[i].src_type != ANY_SRC_TYPE) &&
            ((g_routes[i].src_type != src_type) ||
             ((g_routes[i].src != src_index) &&
              (g_routes[i].src != -1)))) {
            PrintDebug("Vnet: MatchRoute: Source route is on and does not match\n");
            continue;
        }
        
        if ( (g_routes[i].dest_mac_qual == ANY_TYPE) &&
             (g_routes[i].src_mac_qual == ANY_TYPE) ) {      
            matched_routes[num_matches] = i;
            values[num_matches] = 3;
            num_matches++;
        }
        
        if (memcmp((void *)&g_routes[i].src_mac, (void *)src_mac, 6) == 0) {
            if (g_routes[i].src_mac_qual !=  NOT_TYPE) {
                if (g_routes[i].dest_mac_qual == ANY_TYPE) {
                    matched_routes[num_matches] = i;
                    values[num_matches] = 6;
                    
                    num_matches++;
                } else if (memcmp((void *)&g_routes[i].dest_mac, (void *)dst_mac, 6) == 0) {
                    if (g_routes[i].dest_mac_qual != NOT_TYPE) {   
                        matched_routes[num_matches] = i;
                        values[num_matches] = 8;    
                        exact_match = 1;
                        num_matches++;
                    }
                }
            }
        }
        
        if (memcmp((void *)&g_routes[i].dest_mac, (void *)dst_mac, 6) == 0) {
            if (g_routes[i].dest_mac_qual != NOT_TYPE) {
                if (g_routes[i].src_mac_qual == ANY_TYPE) {
                    matched_routes[num_matches] = i;
                    values[num_matches] = 6;
                    
                    num_matches++;
                } else if (memcmp((void *)&g_routes[i].src_mac, (void *)src_mac, 6) == 0) {
                    if (g_routes[i].src_mac_qual != NOT_TYPE) {
                        if (exact_match == 0) {
                            matched_routes[num_matches] = i;
                            values[num_matches] = 8;
                            num_matches++;
                        }
                    }
                }
            }
        }
        
        if ((g_routes[i].dest_mac_qual == NOT_TYPE) &&
            (memcmp((void *)&g_routes[i].dest_mac, (void *)dst_mac, 6) != 0)) {
            if (g_routes[i].src_mac_qual == ANY_TYPE) {
                matched_routes[num_matches] = i;
                values[num_matches] = 5;                    
                num_matches++;    
            } else if (memcmp((void *)&g_routes[i].src_mac, (void *)src_mac, 6) == 0) {
                if (g_routes[i].src_mac_qual != NOT_TYPE) {      
                    matched_routes[num_matches] = i;
                    values[num_matches] = 7;                  
                    num_matches++;
                }
            }
        }
        
        if ((g_routes[i].src_mac_qual == NOT_TYPE) &&
            (memcmp((void *)&g_routes[i].src_mac, (void *)src_mac, 6) != 0)) {
            if (g_routes[i].dest_mac_qual == ANY_TYPE) {
                matched_routes[num_matches] = i;
                values[num_matches] = 5;            
                num_matches++;
            } else if (memcmp((void *)&g_routes[i].dest_mac, (void *)dst_mac, 6) == 0) {
                if (g_routes[i].dest_mac_qual != NOT_TYPE) { 
                    matched_routes[num_matches] = i;
                    values[num_matches] = 7;
                    num_matches++;
                }
            }
        }
    }
    //end FOREACH_ROUTE
    
    FOREACH_ROUTE(i, g_routes, g_first_route) {
        if ((memcmp((void *)&g_routes[i].src_mac, (void *)src_mac, 6) == 0) &&
            (g_routes[i].dest_mac_qual == NONE_TYPE) &&
            ((g_routes[i].src_type == ANY_SRC_TYPE) ||
             ((g_routes[i].src_type == src_type) &&
              ((g_routes[i].src == src_index) ||
               (g_routes[i].src == -1))))) {
            matched_routes[num_matches] = i;
            values[num_matches] = 4;
            PrintDebug("Vnet: MatchRoute: We matched a default route (%d)\n", i);
            num_matches++;
        }
    }
    
    //If many rules have been matched, we choose one which has the highest value rating
    if (num_matches == 0) {
        return 0;
    }
    
    for (i = 0; i < num_matches; i++) {
        if (values[i] > max) {
            no = 0;
            max = values[i];
            matches[no] = matched_routes[i];
            no++;
        } else if (values[i] == max) {
            matches[no] = matched_routes[i];
            no++;
        }
    }
    
    return no;
}

static inline int if_write_pkt(struct vnet_if_device *iface, struct raw_ethernet_pkt * pkt) {
    return iface->input((uchar_t *)pkt->data, pkt->size);
}

static int handle_one_pkt(struct raw_ethernet_pkt * pkt) {
    int src_link_index = 0;     //the value of src_link_index of udp always is 0
    int i;
    char src_mac[6];
    char dst_mac[6];

    int matches[g_num_routes];
    int num_matched_routes = 0;

    struct HEADERS headers;
  
    // get the ethernet and ip headers from the packet
    memcpy((void *)&headers, (void *)pkt->data, sizeof(headers));

    int j;
    for (j = 0;j < 6; j++) {
        src_mac[j] = headers.ethernetsrc[j];
        dst_mac[j] = headers.ethernetdest[j];
    }


#ifdef DEBUG
    char dest_str[18];
    char src_str[18];
    
    mac_to_string(src_mac, src_str);  
    mac_to_string(dst_mac, dest_str);
    
    PrintDebug("Vnet: HandleDataOverLink. SRC(%s), DEST(%s)\n", src_str, dest_str);
#endif
    
    char hash_key[HASH_KEY_SIZE];
    make_hash_key(hash_key, src_mac, dst_mac, EDGE_TYPE, src_link_index);
    
    num_matched_routes = look_into_cache((route_hashkey_t)hash_key, matches);
    
    if (num_matched_routes == -1) {  //no match
        num_matched_routes = match_route(src_mac, dst_mac, pkt->type, src_link_index, matches);
        
        if (num_matched_routes > 0) {
            add_route_to_cache(hash_key, num_matched_routes,matches);      
        }
    }
    
    PrintDebug("Vnet: HandleDataOverLink: Matches=%d\n", num_matched_routes);
    
    for (i = 0; i < num_matched_routes; i++) {
        int route_index = -1;
        int link_index = -1;
        int dev_index = -1;
        
        route_index = matches[i];
        
        PrintDebug("Vnet: HandleDataOverLink: Forward packet from link according to Route entry %d\n", route_index);
        
        if (g_routes[route_index].type == EDGE_TYPE) {
            link_index = g_routes[route_index].dest;
            
            if(g_links[link_index].type == UDP_TYPE) {
                int size;
                
                if ((size = V3_SendTo_IP(g_links[link_index].link_sock,  g_links[link_index].dest,  g_links[link_index].remote_port, pkt->data, pkt->size)) != pkt->size)  {
                    PrintError("Vnet: sending by UDP Exception, %x\n", size);
                    return -1;
                }
                
                PrintDebug("Vnet: HandleDataOverLink: Serializing UDP Packet to link_sock [%d], dest [%x], remote_port [%d], size [%d]\n", g_links[link_index].link_sock, (uint_t)g_links[link_index].dest,  g_links[link_index].remote_port, (int)pkt->size);
                
            } else if (g_links[link_index].type == TCP_TYPE) {
                
            }
        } else if (g_routes[route_index].type == INTERFACE_TYPE) {
            dev_index = g_routes[route_index].dest;
      
            PrintDebug("Writing Packet to device=%s\n", g_devices[dev_index].device->name);

            if (if_write_pkt(g_devices[dev_index].device, pkt) == -1) {
                PrintDebug("Can't write output packet to link\n");
                return -1;
            }
        } else {
            PrintDebug("Vnet: Wrong Edge type\n");
        }
    }

     return 0;
}

static int send_ethernet_pkt(char * buf, int length) {
        struct raw_ethernet_pkt * pt;

        pt = (struct raw_ethernet_pkt *)V3_Malloc(sizeof(struct raw_ethernet_pkt));
        raw_ethernet_packet_init(pt, buf, length);  //====here we copy sending data once 
        
        PrintDebug("VNET: vm_send_pkt: transmitting packet: (size:%d)\n", (int)pt->size);
        print_packet((char *)buf, length);
        
        v3_enqueue(g_inpkt_q, (addr_t)pt);
        return 0;
        
}

int V3_Send_pkt(uchar_t *buf, int length) {
    PrintDebug("VNET: In V3_Send_pkt: pkt length %d\n", length);
    
    return send_ethernet_pkt((char *)buf, length);
}

static int add_device_to_table(struct vnet_if_device*device, int type) {
    int i;
    
    for (i = 0; i < MAX_DEVICES; i++) {
        if (g_devices[i].use == 0) {
            g_devices[i].type = type;
            g_devices[i].use = 1;
            
            if (g_first_device == -1) {
                g_first_device = i;
            }       

            g_devices[i].prev = g_last_device;
            g_devices[i].next = -1;
            
            if (g_last_device != -1) {
                g_devices[g_last_device].next = i;
            }

            g_last_device = i;
            g_num_devices++;
            
            return i;
        }
    }
    
    return -1;
}

static int search_device(char *device_name) {
    int i;

    for (i = 0; i < MAX_DEVICES; i++) {
        if (g_devices[i].use == 1) {
            if (!strcmp(device_name, g_devices[i].device->name)) {
                return i;
            }
        }
    }
    
    return -1;
}

static struct vnet_if_device * delete_device_from_table(int index) {
    int next_i;
    int prev_i;
    struct vnet_if_device * device = NULL;

    if (g_devices[index].use == 0) {
        return NULL;
    }

    g_devices[index].use = 0;

    prev_i = g_devices[index].prev;
    next_i = g_devices[index].next;

    if (prev_i != -1) {
        g_devices[prev_i].next = g_devices[index].next;
    }

    if (next_i != -1) {
        g_devices[next_i].prev = g_devices[index].prev;
    }

    if (g_first_device == index) {
        g_first_device = g_devices[index].next;
    }

    if (g_last_device == index) {
        g_last_device = g_devices[index].prev;
    }

    g_devices[index].next = -1;
    g_devices[index].prev = -1;

    device = g_devices[index].device;
    g_devices[index].device = NULL;

    g_num_devices--;

    return device;
}


int vnet_register_device(char * dev_name, int (*netif_input)(uchar_t * pkt, uint_t size), void * data) {
    struct vnet_if_device * dev;
    
    dev = (struct vnet_if_device *)V3_Malloc(sizeof(struct vnet_if_device));
    
    if (dev == NULL){
        PrintError("VNET: Malloc fails\n");
        return -1;
    }
    
    strncpy(dev->name, dev_name, 50);
    dev->input = netif_input;
    dev->data = data;
    
    if (add_device_to_table(dev, GENERAL_NIC) == -1) {
        return -1;
    }
    
    return 0;
}

int vnet_unregister_device(char * dev_name) {
    int i;

    i = search_device(dev_name);
    
    if (i == -1) {
        return -1;
    }

    struct vnet_if_device * device = delete_device_from_table(i);

    if (device == NULL) {
        return -1;
    }

    V3_Free(device);

    return 0;
}

int V3_Register_pkt_event(int (*netif_input)(uchar_t * pkt, uint_t size)) {
    return vnet_register_device("NE2000", netif_input, NULL);
}

int vnet_pkt_process() {
    struct raw_ethernet_pkt * pt;
    int i;

    PrintDebug("VNET: In vnet_check\n");
        
    while ((pt = (struct raw_ethernet_pkt *)v3_dequeue(g_inpkt_q)) != NULL) {
        PrintDebug("VNET: In vnet_check: pt length %d, pt type %d\n", (int)pt->size, (int)pt->type);
        v3_hexdump(pt->data, pt->size, NULL, 0);
        
        if(handle_one_pkt(pt)) {
            PrintDebug("VNET: vnet_check: handle one packet!\n");  
        }
        
        V3_Free(pt); //be careful here
    }
    
    return 0;
}

static int process_tcpdata() {
    return 0;
}

static int process_udpdata() {
  struct raw_ethernet_pkt * pt;

  uint32_t dest = 0;
  uint16_t remote_port = 0;
  SOCK link_sock = g_udp_sockfd;
  int length = sizeof(struct raw_ethernet_pkt) - (2 * sizeof(int));   //minus the "size" and "type" 

  //run in a loop to get packets from outside network, adding them to the incoming packet queue
  while (1) {
      pt = (struct raw_ethernet_pkt *)V3_Malloc(sizeof(struct raw_ethernet_pkt));
      if (pt == NULL){
          PrintError("Vnet: process_udp: Malloc fails\n");
          continue;
      }
      
      PrintDebug("Vnet: route_thread: socket: [%d]. ready to receive from ip [%x], port [%d] or from VMs\n", link_sock, (uint_t)dest, remote_port);
      pt->size = V3_RecvFrom_IP( link_sock, dest, remote_port, pt->data, length);
      PrintDebug("Vnet: route_thread: socket: [%d] receive from ip [%x], port [%d]\n", link_sock, (uint_t)dest, remote_port);
      
      if (pt->size <= 0) {
          PrintDebug("Vnet: process_udp: receiving packet from UDP fails\n");
          V3_Free(pt);
          return -1;
      }
      
      PrintDebug("Vnet: process_udp: get packet\n");
      print_packet(pt->data, pt->size);
      
      v3_enqueue(g_inpkt_q, (addr_t)pt);
      
      //V3_Yield();
  }
}

static int indata_handler( ) {
    if (use_tcp) {
        process_tcpdata();
    } else {
        process_udpdata( );       
    }
    
    return 0;   
}

static int start_recv_data() {
    if (use_tcp) {
        
    } else {
        SOCK udp_data_socket;
        
        if ((udp_data_socket = V3_Create_UDP_Socket()) < 0) {
            PrintError("VNET: Can't setup udp socket\n");
            return -1; 
        }

        PrintDebug("Vnet: vnet_setup_udp: get socket: %d\n", udp_data_socket);
        g_udp_sockfd = udp_data_socket;
        
        store_topologies(udp_data_socket);
        
        if (V3_Bind_Socket(udp_data_socket, vnet_udp_port) < 0) { 
            PrintError("VNET: Can't bind socket\n");
            return -1;
        }

        PrintDebug("VNET: vnet_setup_udp: bind socket successful\n");
    }
    
    V3_CREATE_THREAD(&indata_handler, NULL, "VNET_DATA_HANDLER");

    return 0;
}

static void init_link_table() {
    int i;

    for (i = 0; i < MAX_LINKS; i++) {
        g_links[i].use = 0;
        g_links[i].next = -1;
        g_links[i].prev = -1;
    }
        
    g_first_link = -1;
    g_last_link = -1;
    g_num_links = 0;
}

static void init_device_table() {
    int i;

    for (i = 0; i < MAX_DEVICES; i++) {
        g_devices[i].use = 0;
        g_devices[i].next = -1;
        g_devices[i].prev = -1;
    }
        
    g_first_device = -1;
    g_last_device = -1;
    g_num_devices = 0;
}

static void init_route_table() {        
    int i;

    for (i = 0; i < MAX_ROUTES; i++) {
        g_routes[i].use = 0;
        g_routes[i].next = -1;
        g_routes[i].prev = -1;
    }
        
     g_first_route = -1;
     g_last_route = -1;
     g_num_routes = 0;
}

static void init_tables() {
    init_link_table();
    init_device_table();
    init_route_table();
    init_route_cache();
}

static void init_pkt_queue() {
    PrintDebug("VNET Init package receiving queue\n");

    g_inpkt_q = v3_create_queue();
    v3_init_queue(g_inpkt_q);
}

void v3_vnet_init() {   
        vnet_server = 0;
        #ifdef VNET_SERVER
                vnet_server = 1;
        #endif

        PrintDebug("VNET Init: Vnet input queue successful.\n");

        init_tables();
        init_pkt_queue();
 
        start_recv_data();
}