Linux平台下基于BitTorrent应用层协议的下载软件开发--peer模块（peer.c）

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include "peer.h"
#include "message.h"
#include "bitfield.h"

extern Bitmap *bitmap;

// 指向当前与之进行通信的peer列表
Peer *peer_head = NULL;

int  initialize_peer(Peer *peer)
{
if(peer == NULL)   return -1;

peer->socket = -1;
memset(peer->ip,0,16);
peer->port = 0;
memset(peer->id,0,21);
peer->state = INITIAL;

peer->in_buff      = NULL;
peer->out_msg      = NULL;
peer->out_msg_copy = NULL;

peer->in_buff = (char *)malloc(MSG_SIZE);
if(peer->in_buff == NULL)  goto OUT;
memset(peer->in_buff,0,MSG_SIZE);
peer->buff_len = 0;

peer->out_msg = (char *)malloc(MSG_SIZE);
if(peer->out_msg == NULL)  goto OUT;
memset(peer->out_msg,0,MSG_SIZE);
peer->msg_len  = 0;

peer->out_msg_copy = (char *)malloc(MSG_SIZE);//这里为out_ms_copy分配了16KB的缓存空间
if(peer->out_msg_copy == NULL)  goto OUT;
memset(peer->out_msg_copy,0,MSG_SIZE);
peer->msg_copy_len   = 0;
peer->msg_copy_index = 0;

peer->am_choking      = 1;
peer->am_interested   = 0;
peer->peer_choking    = 1;
peer->peer_interested = 0;

peer->bitmap.bitfield        = NULL;
peer->bitmap.bitfield_length = 0;
peer->bitmap.valid_length    = 0;

peer->Request_piece_head     = NULL;
peer->Requested_piece_head   = NULL;

peer->down_total = 0;
peer->up_total   = 0;

peer->start_timestamp     = 0;
peer->recet_timestamp     = 0;

peer->last_down_timestamp = 0;
peer->last_up_timestamp   = 0;
peer->down_count          = 0;
peer->up_count            = 0;
peer->down_rate           = 0.0;
peer->up_rate             = 0.0;

peer->next = (Peer *)0;
return 0;

OUT:
if(peer->in_buff != NULL)      free(peer->in_buff);
if(peer->out_msg != NULL)      free(peer->out_msg);
if(peer->out_msg_copy != NULL) free(peer->out_msg_copy);
return -1;
}

Peer* add_peer_node()
{
int  ret;
Peer *node, *p;

// 分配内存空间
node = (Peer *)malloc(sizeof(Peer));
if(node == NULL)  {
printf("%s:%d error\n",__FILE__,__LINE__);
return NULL;
}

// 进行初始化
ret = initialize_peer(node);
if(ret < 0) {
printf("%s:%d error\n",__FILE__,__LINE__);
free(node);
return NULL;
}

// 将node加入到peer链表中
if(peer_head == NULL)  { peer_head = node; }
else {
p = peer_head;
while(p->next != NULL)  p = p->next;
p->next = node;
}

return node;
}

int del_peer_node(Peer *peer)
{
Peer *p = peer_head, *q;

if(peer == NULL)  return -1;

while(p != NULL) {
if( p == peer ) {
if(p == peer_head)  peer_head = p->next;
else  q->next = p->next;
free_peer_node(p);  // 可能存在问题
return 0;
} else {
q = p;
p = p->next;
}
}

return -1;
}

// 撤消当前请求队列
int cancel_request_list(Peer *node)
{
Request_piece  *p;

p = node->Request_piece_head;  //这里的关键是需要一个变量，用于对节点的释放
while(p != NULL) {
node->Request_piece_head = node->Request_piece_head->next;
free(p);
p = node->Request_piece_head;
}

return 0;
}

// 撤消当前被请求队列
int cancel_requested_list(Peer *node)
{
Request_piece  *p;

p = node->Requested_piece_head;//同样也是需要一个变量，用于释放内存
while(p != NULL) {
node->Requested_piece_head = node->Requested_piece_head->next;
free(p);
p = node->Requested_piece_head;
}

return 0;
}

void  free_peer_node(Peer *node) //将peer结构体本身的内存，以及为peer结构体所分配的内存，都统统释放掉
{
if(node == NULL)  return;
if(node->bitmap.bitfield != NULL) {
free(node->bitmap.bitfield);
node->bitmap.bitfield = NULL;
}
if(node->in_buff != NULL) {
free(node->in_buff);
node->in_buff = NULL;
}
if(node->out_msg != NULL) {
free(node->out_msg);
node->out_msg = NULL;
}
if(node->out_msg_copy != NULL) {
free(node->out_msg_copy);
node->out_msg_copy = NULL;
}

cancel_request_list(node);
cancel_requested_list(node);

// 释放完peer成员的内存后,再释放peer所占的内存
free(node);
}

void  release_memory_in_peer()//由peer_head起始，然后删除所链接的节点
{
Peer *p;

if(peer_head == NULL)  return;

p = peer_head;
while(p != NULL) {
peer_head = peer_head->next;
free_peer_node(p);
p = peer_head;
}
}

void print_peers_data()
{
Peer *p    = peer_head;
int  index = 0;

while(p != NULL) {
printf("peer: %d  down_rate: %.2f \n", index, p->down_rate);

index++;
p = p->next;
}
}