#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "parse_metafile.h"
#include "peer.h"
#include "tracker.h"
extern unsigned char info_hash[20];//这两个数据都是在种子解析文件中定义的
extern unsigned char peer_id[20];
extern Announce_list *announce_list_head;//为存放各个Tracker的URL
extern int *sock;//连接Tracker的套接字
extern struct sockaddr_in *tracker;
extern int *valid;//traker服务器的状态
extern int tracker_count;//tracker服务器的状态
extern int *peer_sock;//链接peer的套接字
extern struct sockaddr_in *peer_addr;
extern int *peer_valid;//指示连接peer的状态
extern int peer_count;//尝试与多少个peer建立连接
Peer_addr *peer_addr_head = NULL;//根据多少个Tracker服务器,建立多少个peer_addr
int http_encode(unsigned char *in,int len1,char *out,int len2)//http协议说明,非数字和字母都要进行装换
{ //函数参数为一个是转换输入,另一个为转换输出
int i, j;
char hex_table[16] = "0123456789abcdef";
if( (len1 != 20) || (len2 <= 90) ) return -1;
for(i = 0, j = 0; i < 20; i++, j++) { //如果len1不等于20或者len2小于等于90,则出错
if( isalpha(in[i]) || isdigit(in[i]) )
out[j] = in[i];
else {
out[j] = '%';//这是编码部分,至于为何是20与90,不太清楚
j++;
out[j] = hex_table[in[i] >> 4];
j++;
out[j] = hex_table[in[i] & 0xf];
}
}
out[j] = '\0';
#ifdef DEBUG
//printf("http encoded:%s\n",out);
#endif
return 0;
}
int get_tracker_name(Announce_list *node,char *name,int len)
{
int i = 0, j = 0;
if( (len < 64) || (node == NULL) ) return -1;
if( memcmp(node->announce,"http://",7) == 0 )
i = i + 7;
while( (node->announce[i] != '/') && (node->announce[i] != ':') ) {//因为本书就是要得到主机的名字
name[j] = node->announce[i];//将主机名写入name中
i++;
j++;
if( i == strlen(node->announce) ) break;//这种情况下说明其URL中没有‘/’以及‘:’所以才要靠这个来判断
}
name[j] = '\0';
#ifdef DEBUG
printf("%s\n",node->announce);
printf("tracker name:%s\n",name);
#endif
return 0;
}
int get_tracker_port(Announce_list *node,unsigned short *port)
{
int i = 0;
if( (node == NULL) || (port == NULL) ) return -1;
if( memcmp(node->announce,"http://",7) == 0 ) i = i + 7;
*port = 0;
while( i < strlen(node->announce) ) {
if( node->announce[i] != ':') { i++; continue; }
i++; // skip ':'
while( isdigit(node->announce[i]) ) {
*port = *port * 10 + (node->announce[i] - '0');//如果判断为数字,则求出其端口号
i++;
}
break;
}
if(*port == 0) *port = 80;
#ifdef DEBUG
printf("tracker port:%d\n",*port);
#endif
return 0;
}
int create_request(char *request,int len,Announce_list *node,
unsigned short port,long long down,long long up,
long long left,int numwant)
{
char encoded_info_hash[100];
char encoded_peer_id[100];
int key;
char tracker_name[128];
unsigned short tracker_port;
http_encode(info_hash,20,encoded_info_hash,100);//这就可以解释为何输入字节数为20了,因为它为info_hash或者为peer_id的长度
http_encode(peer_id,20,encoded_peer_id,100);
srand(time(NULL));
key = rand() / 10000;//得到随机的key值
get_tracker_name(node,tracker_name,128);
get_tracker_port(node,&tracker_port);
sprintf(request,
"GET /announce?info_hash=%s&peer_id=%s&port=%u"
"&uploaded=%lld&downloaded=%lld&left=%lld"
"&event=started&key=%d&compact=1&numwant=%d HTTP/1.0\r\n"
"Host: %s\r\nUser-Agent: Bittorrent\r\nAccept: */*\r\n"
"Accept-Encoding: gzip\r\nConnection: closed\r\n\r\n", //包含上传数据量,以及下载数据量,left为还有多少剩余,numwant,表示希望返回的peer数
encoded_info_hash,encoded_peer_id,port,up,down,left,
key,numwant,tracker_name);//key关键字一般用来标识客户端,但是已经有了peer_id,所以这个参数可选
#ifdef DEBUG
printf("request:%s\n",request);
#endif
return 0;
}
int get_response_type(char *buffer,int len,int *total_length)//这里的total_length用于在之后的调用函数中分配内存
{
int i, content_length = 0;
for(i = 0; i < len-7; i++) {
if(memcmp(&buffer[i],"5:peers",7) == 0) {
i = i+7;
break; //相当于在buffer所指向的字符串数组中查找‘5:peers’,如果下标=len-7,则buffer中没有机会存储“5:peers”字符串
}
}
if(i == len-7) return -1; // 返回的消息不含"5:peers"关键字
if(buffer[i] != 'l') return 0; //这说明消息并不是B编码的列表,所以返回的消息的类型为第一种
*total_length = 0;
for(i = 0; i < len-16; i++) {
if(memcmp(&buffer[i],"Content-Length: ",16) == 0) {
i = i+16;
break;
}
}
if(i != len-16) {//用于判断是否找到content_length,不相等,说明找到
while(isdigit(buffer[i])) {
content_length = content_length * 10 + (buffer[i] - '0');//用于计算content_length
i++;
}
for(i = 0; i < len-4; i++) {//用于判断是否找到“\r\n\r\n”
if(memcmp(&buffer[i],"\r\n\r\n",4) == 0) { i = i+4; break; }//用于计算total_length
}
if(i != len-4) *total_length = content_length + i;
}
if(*total_length == 0) return -1;
else return 1;
}
int prepare_connect_tracker(int *max_sockfd)
{
int i, flags, ret, count = 0;
struct hostent *ht;//通过gethostbyname 返回的类型
/* hostent的定义如下:
struct hostent {
char *h_name;
char **h_aliases;
int h_addrtype;
int h_length;
char **h_addr_list;
#define h_addr h_addr_list[0]
};
h_name – 地址的正式名称。
h_aliases – 空字节-地址的预备名称的指针。
h_addrtype –地址类型; 通常是AF_INET。
h_length – 地址的比特长度。
h_addr_list – 零字节-主机网络地址指针。网络字节顺序。
h_addr - h_addr_list中的第一地址*/
Announce_list *p = announce_list_head;
while(p != NULL) { count++; p = p->next; }
tracker_count = count; //得到Tracker服务器的个数
sock = (int *)malloc(count * sizeof(int));//有多少个Tracker服务器就有多少个套接字
if(sock == NULL) goto OUT;
tracker = (struct sockaddr_in *)malloc(count * sizeof(struct sockaddr_in));//用来保存地址信息
if(tracker == NULL) goto OUT;
valid = (int *)malloc(count * sizeof(int));//用来查看是否有效
if(valid == NULL) goto OUT;
p = announce_list_head;
for(i = 0; i < count; i++) {
char tracker_name[128];
unsigned short tracker_port = 0;
sock[i] = socket(AF_INET,SOCK_STREAM,0);//创建TCP套接字,针对Tracker地址
if(sock < 0) {
printf("%s:%d socket create failed\n",__FILE__,__LINE__);
valid[i] = 0;
p = p->next;
continue;
}
get_tracker_name(p,tracker_name,128);
get_tracker_port(p,&tracker_port);
// 从主机名获取IP地址
ht = gethostbyname(tracker_name);
if(ht == NULL) {
printf("gethostbyname failed:%s\n",hstrerror(h_errno)); //如果出错的话,错误信息是写入h_errno当中的
valid[i] = 0;
} else {
memset(&tracker[i], 0, sizeof(struct sockaddr_in));
memcpy(&tracker[i].sin_addr.s_addr, ht->h_addr_list[0], 4);//将得到的地址信息存储到多对应的tracker结构中
tracker[i].sin_port = htons(tracker_port);//设置端口号以及相关参数
tracker[i].sin_family = AF_INET;
valid[i] = -1;//此时的这个状态还没有建立链接
}
p = p->next;//对每一个Tracker服务器,都构建一个套接字
}
for(i = 0; i < tracker_count; i++) {
if(valid[i] != 0) {
if(sock[i] > *max_sockfd) *max_sockfd = sock[i];
// 设置套接字为非阻塞
flags = fcntl(sock[i],F_GETFL,0);//关于fcntl的相关设置为P163值,关键在获得文件打开的方式,成功返回标志值
fcntl(sock[i],F_SETFL,flags|O_NONBLOCK);//设置文件的打开方式为第三个参数指定的方式,等于原打开方式加上非阻塞方式
// 连接tracker
ret = connect(sock[i],(struct sockaddr *)&tracker[i], //有套接字,并且有相关的Tracker地址信息,那么就可以建立连接
sizeof(struct sockaddr));
if(ret < 0 && errno != EINPROGRESS) valid[i] = 0; //等于0,说明链接建立失败
// 如果返回0,说明连接已经建立
if(ret == 0) valid[i] = 1; //只有在全部建立完成之后,才会叫valid设置为1
}
}
return 0;
OUT:
if(sock != NULL) free(sock);
if(tracker != NULL) free(tracker);
if(valid != NULL) free(valid);
return -1;
}
//以非阻塞的方式来链接peer。下面的这个函数与prepare_connect_tracker基本上一样
int prepare_connect_peer(int *max_sockfd)//max_sockfd为最大套接字的值
{
int i, flags, ret, count = 0;
Peer_addr *p;
p = peer_addr_head;//这个时候peer_addr_head的值为NULL
while(p != 0) { count++; p = p->next; }
peer_count = count;
peer_sock = (int *)malloc(count*sizeof(int));//这边所有的sock都加上了前缀peer
if(peer_sock == NULL) goto OUT;
peer_addr = (struct sockaddr_in *)malloc(count*sizeof(struct sockaddr_in));
if(peer_addr == NULL) goto OUT;
peer_valid = (int *)malloc(count*sizeof(int));
if(peer_valid == NULL) goto OUT;
p = peer_addr_head; // 此处p重新赋值
for(i = 0; i < count && p != NULL; i++) {
peer_sock[i] = socket(AF_INET,SOCK_STREAM,0);
if(peer_sock[i] < 0) {
printf("%s:%d socket create failed\n",__FILE__,__LINE__);
valid[i] = 0;
p = p->next;
continue;
}
memset(&peer_addr[i], 0, sizeof(struct sockaddr_in));
peer_addr[i].sin_addr.s_addr = inet_addr(p->ip);//因为p的类型为Peer_addr,所以其包含ip地址信息
peer_addr[i].sin_port = htons(p->port);
peer_addr[i].sin_family = AF_INET;
peer_valid[i] = -1;
p = p->next;
}
count = i;
for(i = 0; i < count; i++) {
if(peer_sock[i] > *max_sockfd) *max_sockfd = peer_sock[i];
// 设置套接字为非阻塞
flags = fcntl(peer_sock[i],F_GETFL,0);//获得文件的打开方式
fcntl(peer_sock[i],F_SETFL,flags|O_NONBLOCK);//重新设置文件的打开方式,加上非阻塞
// 连接peer
ret = connect(peer_sock[i],(struct sockaddr *)&peer_addr[i],
sizeof(struct sockaddr));
if(ret < 0 && errno != EINPROGRESS) peer_valid[i] = 0;
// 如果返回0,说明连接已经建立
if(ret == 0) peer_valid[i] = 1;
}
free_peer_addr_head();
return 0;
OUT:
if(peer_sock != NULL) free(peer_sock);
if(peer_addr != NULL) free(peer_addr);
if(peer_valid != NULL) free(peer_valid);
return -1;
}
int parse_tracker_response1(char *buffer,int ret,char *redirection,int len)//对Tracker服务器返回的第一种类型的消息解析
{
int i, j, count = 0;
unsigned char c[4];
Peer_addr *node, *p;
for(i = 0; i < ret - 10; i++) {
if(memcmp(&buffer[i],"Location: ",10) == 0) {
i = i + 10;
j = 0;
while(buffer[i]!='?' && iip,"%u.%u.%u.%u",c[0],c[1],c[2],c[3]);//将得到的IP地址存储在Peer_addr结构体中
i += 4;
node->port = ntohs(*(unsigned short*)&buffer[i]);//unsigned short为两个字节,所以确定了根据起始地址如何取值
i += 2;
node->next = NULL;
// 判断当前peer是否已经存在于链表中
p = peer_addr_head;
while(p != NULL) {
if( memcmp(node->ip,p->ip,strlen(node->ip)) == 0 ) {
free(node);
break;
}
p = p->next;
}
// 将当前结点添加到链表中
if(p == NULL) {//此时说明这个peer_addr节点没有在peer_addr_head的链表中,可以添加进去
if(peer_addr_head == NULL)
peer_addr_head = node;
else {
p = peer_addr_head;
while(p->next != NULL) p = p->next;
p->next = node;
}
}
}
#ifdef DEBUG
count = 0;
p = peer_addr_head;
while(p != NULL) {
printf("+++ connecting peer %-16s:%-5d +++ \n",p->ip,p->port);//调试信息,将链接的peer的地址以及端口信息打印出来
p = p->next;
count++;
}
printf("peer count is :%d \n",count);
#endif
return 0;
}
//解析Tracker服务器返回的第二种消息
int parse_tracker_response2(char *buffer,int ret)
{
int i, ip_len, port;
Peer_addr *node = NULL, *p = peer_addr_head;
if(peer_addr_head != NULL) {
printf("Must free peer_addr_head\n");
return -1;
}
for(i = 0; i < ret; i++) {
if(memcmp(&buffer[i],"2:ip",4) == 0) {//第二种消息的查找更简单,查找ip,查找port,构造peer_addr,然后加入peer_addr_head中就可以了
i += 4;
ip_len = 0;
while(isdigit(buffer[i])) {
ip_len = ip_len * 10 + (buffer[i] - '0');
i++;
}//确定ip地址所占有的字节数
i++; // skip ":"
node = (Peer_addr*)malloc(sizeof(Peer_addr));
if(node == NULL) {
printf("%s:%d error",__FILE__,__LINE__);
continue;
}
memcpy(node->ip,&buffer[i],ip_len);//因为在第二种方式中,已经包含了格式,所以直接拷贝就可以了,因为为字符串,所以最后家少‘\0’
(node->ip)[ip_len] = '\0';
node->next = NULL;
}
if(memcmp(&buffer[i],"4:port",6) == 0) {
i += 6;
i++; // skip "i"//这个很关键
port = 0;
while(isdigit(buffer[i])) {
port = port * 10 + (buffer[i] - '0');
i++;
}
if(node != NULL) node->port = port;//因为i之后就是port,所以直接赋值就可以了
else continue;
printf("+++ add a peer %-16s:%-5d +++ \n",node->ip,node->port);
if(p == peer_addr_head) { peer_addr_head = node; p = node; }//加入到pee_addr_head中
else p->next = node;
node = NULL;
}
}
return 0;
}
int add_peer_node_to_peerlist(int *sock,struct sockaddr_in saptr)//这个函数相当与将peer_addr与peer建立了联系
{
Peer *node;
node = add_peer_node();//在这个地方构建peer_head队列
if(node == NULL) return -1;
node->socket = *sock; //相当于对peer的前几个元素进行赋值进行赋值
node->port = ntohs(saptr.sin_port);
node->state = INITIAL;
strcpy(node->ip,inet_ntoa(saptr.sin_addr));
node->start_timestamp = time(NULL);
return 0;
}
void free_peer_addr_head()
{
Peer_addr *p = peer_addr_head;
while(p != NULL) {
p = p->next;
free(peer_addr_head);
peer_addr_head = p;
}
peer_addr_head = NULL;
}