C++ &引用；在此服务器上找不到请求的URL/公告；bittorrent HTTP请求出错

我正在尝试向bittorrent tracker服务器发出HTTP请求以获取对等列表

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>  // for gethostbyname()
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <iostream>
using namespace std;

struct in_addr *atoaddr( const char* address)
{
static struct hostent *host;
static struct in_addr saddr;

// First try nnn.nnn.nnn.nnn form
saddr.s_addr = inet_addr(address);
if (saddr.s_addr != -1)
    return &saddr;

host = gethostbyname(address);
if( host )
    return (struct in_addr *) *host->h_addr_list;

return 0;
}

int main(){
int numbytes=0;
int m_Port=80;
string m_Host="torrent.ubuntu.com";
int m_Sock;
struct hostent *host;
static struct in_addr saddr;
string buffer;
char* buf;

//HTTP request string
buffer.append("GET http://torrent.ubuntu.com:6969/announce HTTP/1.1\r\n");
buffer.append("Host: torrent.ubuntu.com\r\n");
buffer.append("Accept-Encoding: identity\r\n");
buffer.append("info_hash: %36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58\r\n");
buffer.append("peer_id: ABCDEFGHIJKLMNOPQRST\r\n");
buffer.append("port: 6881\r\n");
buffer.append("compact: 1\r\n");
buffer.append("uploaded: 0\r\n");
buffer.append("downloaded: 0\r\n");
buffer.append("left: 987758592\r\n");
buffer.append("event: started\r\n");
buffer.append("\r\n");

in_addr* addr = atoaddr( m_Host.c_str() );
if( !addr )
{
    cout<<"Error address\n";
    return 1;
}

sockaddr_in address;
memset( (char*)&address, 0, sizeof(address) );
address.sin_family = AF_INET;
address.sin_port = htons( m_Port );
address.sin_addr.s_addr = addr->s_addr;

m_Sock = socket( AF_INET, SOCK_STREAM, 0 );
if(m_Sock<0){
    cout<<"Socket error\n";
    return 1;
}

if( ::connect( m_Sock, (sockaddr const*)&address, sizeof(address) ) < 0 )
{
    cout<<"connect error";
    return 1;
}

buf = (char*)buffer.c_str();
numbytes = buffer.length();
while( numbytes > 0 )
{
    int n = ::send( m_Sock, buf, buffer.size(), 0 );
    std::cout<<"\n\n--HTTP request:\n"<<buf<<std::endl;
    if( n<0 )
    {
        cout<<"number of bytes sent <0\n";
        return 1;
    }
    numbytes -= n;
    buf += n;
}

cout<<"\ngetting response: \n";
unsigned char recvBuf[ 2048 ];
int a;
do{
    a = recv( m_Sock, (char*)recvBuf, sizeof(recvBuf), 0 );
    fwrite(recvBuf, 1, a, stdout);
}while(a!=0);

if(m_Sock>0)
    close(m_Sock);

return 0;
}

---

这就是我希望在从我的C代码发出请求时看到的。我做错了什么？

我相信您的代码失败是因为您犯了一个小错误：您不应该将套接字连接到端口80，而应该连接到端口6969，然后发送

GET/announce

查询，而不是在

GET

方法中发送完整的URL。

我使用了Wireshark（感谢一位老朋友的建议）用于获取邮递员发送的请求。 以下是对我有用的代码：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>  // for gethostbyname()
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <iostream>
using namespace std;

// Try to work out address from string
// returns 0 if bad
struct in_addr *atoaddr( const char* address) 
{
static struct hostent *host;
static struct in_addr saddr;

// First try nnn.nnn.nnn.nnn form
saddr.s_addr = inet_addr(address);
if (saddr.s_addr != -1)
    return &saddr;

host = gethostbyname(address);
if( host )
    return (struct in_addr *) *host->h_addr_list;

return 0;
}

int main(){
int numbytes=0;
int m_Port=6969;
string m_Host="torrent.ubuntu.com";
int m_Sock;
struct hostent *host;
static struct in_addr saddr;
string buffer;
char* buf;

//  HTTP request string

//  buffer.append("GET /announce HTTP/1.1\r\n");
//  buffer.append("Host: torrent.ubuntu.com:6969\r\n");
//  buffer.append("Accept-Encoding: identity\r\n");
//  buffer.append("info_hash:     %36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58\r\n");
//  buffer.append("peer_id: ABCDEFGHIJKLMNOPQRST\r\n");
//  buffer.append("port: 6881\r\n");
//  buffer.append("uploaded: 0\r\n");
//  buffer.append("downloaded: 0\r\n");
//  buffer.append("left: 987758592\r\n");
//  buffer.append("compact: 1\r\n");
//  buffer.append("event: started\r\n");
buffer.append("GET /announce?info_hash=%36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58&"
        "peer_id=ABCDEFGHIJKLMNOPQRST&"
        "port=6881&"
        "compact=1&"
        "uploaded=0&"
        "downloaded=0&"
        "left=987758592&"
        "event=started HTTP/1.1\r\n");
buffer.append("\r\n");

in_addr* addr = atoaddr( m_Host.c_str() );
if( !addr )
{
    cout<<"Error address\n";
    return 1;
}

sockaddr_in address;
memset( (char*)&address, 0, sizeof(address) );
address.sin_family = AF_INET;
address.sin_port = htons( m_Port );
address.sin_addr.s_addr = addr->s_addr;

m_Sock = socket( AF_INET, SOCK_STREAM, 0 );
if(m_Sock<0){
    cout<<"Socket error\n";
    return 1;
}

if( ::connect( m_Sock, (sockaddr const*)&address, sizeof(address) ) < 0 )
{
    cout<<"connect error";
    return 1;
}

buf = (char*)buffer.c_str();
numbytes = buffer.length();
while( numbytes > 0 )
{
    int n = ::send( m_Sock, buf, buffer.size(), 0 );
    std::cout<<"\n\n--HTTP request:\n"<<buf<<std::endl;
    if( n<0 )
    {
        cout<<"number of bytes sent <0\n";
        return 1;
    }
    numbytes -= n;
    buf += n;
}

cout<<"\ngetting response: \n";
unsigned char recvBuf[ 2048 ];
int a;
do{
    a = recv( m_Sock, (char*)recvBuf, sizeof(recvBuf), 0 );
    fwrite(recvBuf, 1, a, stdout);
}while(a!=0);
cout<<"\n";

if(m_Sock>0)
    close(m_Sock);

return 0;
}

#包括
#包括
#包括
#包含//用于gethostbyname（）
#包括
#包括
#包括
#包括
#包括
使用名称空间std；
//尝试从字符串中算出地址
//如果错误，则返回0
_addr*atoaddr中的结构（常量字符*地址）
{
静态结构主机*主机；
静态结构在地址中；
//先试试nnn.nnn.nnn.nnn表格
saddr.s_addr=inet_addr（地址）；
如果（saddr.s_addr！=-1）
返回&saddr；
主机=gethostbyname（地址）；
如果（主机）
返回（struct in_addr*）*host->h_addr_列表；
返回0；
}
int main（）{
int numbytes=0；
int m_端口=6969；
字符串m_Host=“torrent.ubuntu.com”；
int m_袜子；
结构主机*主机；
静态结构在地址中；
字符串缓冲区；
char*buf；
//HTTP请求字符串
//append（“获取/宣布HTTP/1.1\r\n”）；
//append（“主机：torrent.ubuntu.com:6969\r\n”）；
//append（“接受编码：标识\r\n”）；
//缓冲区。追加（“信息散列：%36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58\r\n”）；
//append（“peer_id:ABCDEFGHIJKLMNOPQRST\r\n”）；
//buffer.append（“端口：6881\r\n”）；
//buffer.append（“上载：0\r\n”）；
//buffer.append（“已下载：0\r\n”）；
//buffer.append（“左：987758592\r\n”）；
//buffer.append（“compact:1\r\n”）；
//buffer.append（“事件：已启动\r\n”）；
buffer.append（“GET/announce？info_hash=%36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58&”
“peer_id=ABCDEFGHIJKLMNOPQRST&”
“端口=6881&”
“紧凑型=1&”
“上传=0&”
“已下载=0&”
“左=987758592&”
“事件=已启动HTTP/1.1\r\n”）；
buffer.append（“\r\n”）；
in_addr*addr=atoaddr（m_Host.c_str（））；
如果（！addr）
{
我相信您只需要在
GET
行中指定路径，因此：
GET/announcehttp/1.1\r\n
而不是完整的URL。我也尝试了。我得到了相同的响应。我认为您的问题在于连接端口。您应该连接到端口6969，而不是代码中显示的端口80（变量
m_port
）。此外，正如@Kninnug所告诉的，您应该发送
GET/announce HTTP/1.1\r\n
，而不是完整的URL。现在我得到了“HTTP/1.0 400错误请求内容长度：34内容类型：text/plain您发送给我的垃圾-无信息散列”我验证了我的信息散列，它就在那里：
d8:completei12e10:incompletei1e8:intervali1800e5:peers18:[�_�����4&N=;8��e

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>  // for gethostbyname()
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <iostream>
using namespace std;

// Try to work out address from string
// returns 0 if bad
struct in_addr *atoaddr( const char* address) 
{
static struct hostent *host;
static struct in_addr saddr;

// First try nnn.nnn.nnn.nnn form
saddr.s_addr = inet_addr(address);
if (saddr.s_addr != -1)
    return &saddr;

host = gethostbyname(address);
if( host )
    return (struct in_addr *) *host->h_addr_list;

return 0;
}

int main(){
int numbytes=0;
int m_Port=6969;
string m_Host="torrent.ubuntu.com";
int m_Sock;
struct hostent *host;
static struct in_addr saddr;
string buffer;
char* buf;

//  HTTP request string

//  buffer.append("GET /announce HTTP/1.1\r\n");
//  buffer.append("Host: torrent.ubuntu.com:6969\r\n");
//  buffer.append("Accept-Encoding: identity\r\n");
//  buffer.append("info_hash:     %36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58\r\n");
//  buffer.append("peer_id: ABCDEFGHIJKLMNOPQRST\r\n");
//  buffer.append("port: 6881\r\n");
//  buffer.append("uploaded: 0\r\n");
//  buffer.append("downloaded: 0\r\n");
//  buffer.append("left: 987758592\r\n");
//  buffer.append("compact: 1\r\n");
//  buffer.append("event: started\r\n");
buffer.append("GET /announce?info_hash=%36%be%21%35%ab%cc%f4%03%2f%bb%28%bb%1b%0d%4f%da%f7%49%f8%58&"
        "peer_id=ABCDEFGHIJKLMNOPQRST&"
        "port=6881&"
        "compact=1&"
        "uploaded=0&"
        "downloaded=0&"
        "left=987758592&"
        "event=started HTTP/1.1\r\n");
buffer.append("\r\n");

in_addr* addr = atoaddr( m_Host.c_str() );
if( !addr )
{
    cout<<"Error address\n";
    return 1;
}

sockaddr_in address;
memset( (char*)&address, 0, sizeof(address) );
address.sin_family = AF_INET;
address.sin_port = htons( m_Port );
address.sin_addr.s_addr = addr->s_addr;

m_Sock = socket( AF_INET, SOCK_STREAM, 0 );
if(m_Sock<0){
    cout<<"Socket error\n";
    return 1;
}

if( ::connect( m_Sock, (sockaddr const*)&address, sizeof(address) ) < 0 )
{
    cout<<"connect error";
    return 1;
}

buf = (char*)buffer.c_str();
numbytes = buffer.length();
while( numbytes > 0 )
{
    int n = ::send( m_Sock, buf, buffer.size(), 0 );
    std::cout<<"\n\n--HTTP request:\n"<<buf<<std::endl;
    if( n<0 )
    {
        cout<<"number of bytes sent <0\n";
        return 1;
    }
    numbytes -= n;
    buf += n;
}

cout<<"\ngetting response: \n";
unsigned char recvBuf[ 2048 ];
int a;
do{
    a = recv( m_Sock, (char*)recvBuf, sizeof(recvBuf), 0 );
    fwrite(recvBuf, 1, a, stdout);
}while(a!=0);
cout<<"\n";

if(m_Sock>0)
    close(m_Sock);

return 0;
}