Winsock - Connect to Internet through specified adapter
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Hi everyone, I try to develop a network program using WINSOCK. I am trying to connect to the internet from a laptop with some network adapters ( LAN, WIRELESS,A USB ADSL Modem). It sounds, when I call connect function, it tries to connect using LAN, so because LAN is not connected it fails. Here are my questions: 1)How can I force a socket to use a specified Network Adapter? 2)How can I find which adapter is connected to internet? Thanks for reading and answering :) Here is my code, the connect function fails (err code :10060 )
//The function for handling HTTP
BOOL HTTPSubmitForm(char* HostName, char* Action,char* ObjectName, char* Headers,int HeadersLen, char* Body,int BodyLen)
{
SOCKET conn;
struct hostent* host=NULL;
int iRet = SOCKET_ERROR;
conn = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(conn==INVALID_SOCKET)
{
return FALSE;
}
for (int iTry=0;iTry<3 && host==NULL;iTry++)
host= gethostbyname(HostName);
if(host==NULL)
{
closesocket(conn);
return FALSE;
}
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = *((unsigned long*)host->h_addr_list);
clientService.sin_port = htons( 80 );
///*********************** This part doesn't work properly. I brought error code 10060
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
iRet= connect( conn, (SOCKADDR*) &clientService, sizeof(clientService) ) ;
int iError = WSAGetLastError(); //THIS returns 10060
if ( iRet== SOCKET_ERROR)
{
closesocket(conn);
return FALSE;
}
char RequestFirstLine[512];
sprintf(RequestFirstLine,"%s %s HTTP/1.0\r\n",Action,ObjectName);
iRet= SOCKET_ERROR;
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
{
send(conn,RequestFirstLine,strlen(RequestFirstLine),0);
send(conn,Headers,HeadersLen,0);
iRet=send(conn,Body,BodyLen,0);
}
closesocket(conn);
return iRet!=SOCKET_ERROR;
}//The Caller Function
void CtestDlg::OnBnClickedBtnhttp()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 0 );
err=WSAStartup(wVersionRequested,&wsaData);
HTTPSubmitForm("www.yahoo.com","GET","/","",0,"",0);
WSACleanup();
} -
MrDooDoo wrote:
I am trying to connect to the internet
Exactly what do you mean by this? Are you trying to connect to a specific host and is that host accessible from your laptop?
Veni, vidi, abiit domum
I am talking about building a client software which connects to internet (for e.g to Google) by winsock. But when I try to call connect function a dial dialog appears which lists all of my lan connections. but I am connected to internet by my wireless or another network adapter. I think this is because the socket is built for my LAN and I must build a socket for specific adapter. I looked up MSDN,I found the GetBestInterface. I used it and it returns the index of my wireless adapter. then I tried to use the bind function to associate my socket to my wireless adapter but it doesn't work.
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Hi everyone, I try to develop a network program using WINSOCK. I am trying to connect to the internet from a laptop with some network adapters ( LAN, WIRELESS,A USB ADSL Modem). It sounds, when I call connect function, it tries to connect using LAN, so because LAN is not connected it fails. Here are my questions: 1)How can I force a socket to use a specified Network Adapter? 2)How can I find which adapter is connected to internet? Thanks for reading and answering :) Here is my code, the connect function fails (err code :10060 )
//The function for handling HTTP
BOOL HTTPSubmitForm(char* HostName, char* Action,char* ObjectName, char* Headers,int HeadersLen, char* Body,int BodyLen)
{
SOCKET conn;
struct hostent* host=NULL;
int iRet = SOCKET_ERROR;
conn = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(conn==INVALID_SOCKET)
{
return FALSE;
}
for (int iTry=0;iTry<3 && host==NULL;iTry++)
host= gethostbyname(HostName);
if(host==NULL)
{
closesocket(conn);
return FALSE;
}
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = *((unsigned long*)host->h_addr_list);
clientService.sin_port = htons( 80 );
///*********************** This part doesn't work properly. I brought error code 10060
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
iRet= connect( conn, (SOCKADDR*) &clientService, sizeof(clientService) ) ;
int iError = WSAGetLastError(); //THIS returns 10060
if ( iRet== SOCKET_ERROR)
{
closesocket(conn);
return FALSE;
}
char RequestFirstLine[512];
sprintf(RequestFirstLine,"%s %s HTTP/1.0\r\n",Action,ObjectName);
iRet= SOCKET_ERROR;
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
{
send(conn,RequestFirstLine,strlen(RequestFirstLine),0);
send(conn,Headers,HeadersLen,0);
iRet=send(conn,Body,BodyLen,0);
}
closesocket(conn);
return iRet!=SOCKET_ERROR;
}//The Caller Function
void CtestDlg::OnBnClickedBtnhttp()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 0 );
err=WSAStartup(wVersionRequested,&wsaData);
HTTPSubmitForm("www.yahoo.com","GET","/","",0,"",0);
WSACleanup();
}To force a socket to use a specific network adapter pass the local IP address of the adapter to the
bind()function. To check if a specific interface is connected to the Internet, try to establish a connection to some server. To get information about installed adapters, you can use the IP Helper API[^] functions. -
I am talking about building a client software which connects to internet (for e.g to Google) by winsock. But when I try to call connect function a dial dialog appears which lists all of my lan connections. but I am connected to internet by my wireless or another network adapter. I think this is because the socket is built for my LAN and I must build a socket for specific adapter. I looked up MSDN,I found the GetBestInterface. I used it and it returns the index of my wireless adapter. then I tried to use the bind function to associate my socket to my wireless adapter but it doesn't work.
MrDooDoo wrote:
I am talking about building a client software which connects to internet (for e.g to Google) by winsock.
Well the first thing you need is to find the IP address of a Google server that you wish to connect to. You will then need to add some code to build HTTP requests that you send to it, and code to interpret the responses.
MrDooDoo wrote:
I tried to use the bind function to associate my socket to my wireless adapter but it doesn't work.
"Doesn't work" is not a valid description of an error. You need to show the code that you are using and the exact error message or status that you receive. In general you do not need to be concerned about which interface to use. Just create a socket and try to connect to an IP address and you will get a response or status returned, depending on whether the target is reachable from your client system or not.
Veni, vidi, abiit domum
-
Hi everyone, I try to develop a network program using WINSOCK. I am trying to connect to the internet from a laptop with some network adapters ( LAN, WIRELESS,A USB ADSL Modem). It sounds, when I call connect function, it tries to connect using LAN, so because LAN is not connected it fails. Here are my questions: 1)How can I force a socket to use a specified Network Adapter? 2)How can I find which adapter is connected to internet? Thanks for reading and answering :) Here is my code, the connect function fails (err code :10060 )
//The function for handling HTTP
BOOL HTTPSubmitForm(char* HostName, char* Action,char* ObjectName, char* Headers,int HeadersLen, char* Body,int BodyLen)
{
SOCKET conn;
struct hostent* host=NULL;
int iRet = SOCKET_ERROR;
conn = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(conn==INVALID_SOCKET)
{
return FALSE;
}
for (int iTry=0;iTry<3 && host==NULL;iTry++)
host= gethostbyname(HostName);
if(host==NULL)
{
closesocket(conn);
return FALSE;
}
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = *((unsigned long*)host->h_addr_list);
clientService.sin_port = htons( 80 );
///*********************** This part doesn't work properly. I brought error code 10060
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
iRet= connect( conn, (SOCKADDR*) &clientService, sizeof(clientService) ) ;
int iError = WSAGetLastError(); //THIS returns 10060
if ( iRet== SOCKET_ERROR)
{
closesocket(conn);
return FALSE;
}
char RequestFirstLine[512];
sprintf(RequestFirstLine,"%s %s HTTP/1.0\r\n",Action,ObjectName);
iRet= SOCKET_ERROR;
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
{
send(conn,RequestFirstLine,strlen(RequestFirstLine),0);
send(conn,Headers,HeadersLen,0);
iRet=send(conn,Body,BodyLen,0);
}
closesocket(conn);
return iRet!=SOCKET_ERROR;
}//The Caller Function
void CtestDlg::OnBnClickedBtnhttp()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 0 );
err=WSAStartup(wVersionRequested,&wsaData);
HTTPSubmitForm("www.yahoo.com","GET","/","",0,"",0);
WSACleanup();
}You cannot specify an adapter to use. What does determine the adapter is the TCP/IP route table. The IP address you're connecting to is looked up in this route table and an appropriate adapter to get to the destination address is chosen based on that.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
MrDooDoo wrote:
I am talking about building a client software which connects to internet (for e.g to Google) by winsock.
Well the first thing you need is to find the IP address of a Google server that you wish to connect to. You will then need to add some code to build HTTP requests that you send to it, and code to interpret the responses.
MrDooDoo wrote:
I tried to use the bind function to associate my socket to my wireless adapter but it doesn't work.
"Doesn't work" is not a valid description of an error. You need to show the code that you are using and the exact error message or status that you receive. In general you do not need to be concerned about which interface to use. Just create a socket and try to connect to an IP address and you will get a response or status returned, depending on whether the target is reachable from your client system or not.
Veni, vidi, abiit domum
Thanks for your answer I brought my code here. the connect functions fails and WSAGetLastError returns 10060 (Connection timed out) The code:
//The function for handling HTTP
BOOL HTTPSubmitForm(char* HostName, char* Action,char* ObjectName, char* Headers,int HeadersLen, char* Body,int BodyLen)
{
SOCKET conn;
struct hostent* host=NULL;
int iRet = SOCKET_ERROR;
conn = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(conn==INVALID_SOCKET)
{
return FALSE;
}
for (int iTry=0;iTry<3 && host==NULL;iTry++)
host= gethostbyname(HostName);
if(host==NULL)
{
closesocket(conn);
return FALSE;
}
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = *((unsigned long*)host->h_addr_list);
clientService.sin_port = htons( 80 );
///*********************** This part doesn't work properly. I brought error code 10060
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
iRet= connect( conn, (SOCKADDR*) &clientService, sizeof(clientService) ) ;
int iError = WSAGetLastError(); //THIS returns 10060
if ( iRet== SOCKET_ERROR)
{
closesocket(conn);
return FALSE;
}
char RequestFirstLine[512];
sprintf(RequestFirstLine,"%s %s HTTP/1.0\r\n",Action,ObjectName);
iRet= SOCKET_ERROR;
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
{
send(conn,RequestFirstLine,strlen(RequestFirstLine),0);
send(conn,Headers,HeadersLen,0);
iRet=send(conn,Body,BodyLen,0);
}
closesocket(conn);
return iRet!=SOCKET_ERROR;
}//The Caller Function
void CtestDlg::OnBnClickedBtnhttp()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 0 );
err=WSAStartup(wVersionRequested,&wsaData);
HTTPSubmitForm("www.yahoo.com","GET","/","",0,"",0);
WSACleanup();
} -
You cannot specify an adapter to use. What does determine the adapter is the TCP/IP route table. The IP address you're connecting to is looked up in this route table and an appropriate adapter to get to the destination address is chosen based on that.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
thanks, but are you sure? suppose the condition which someone is building a server and in this situation he/she needs to specify the adapter. I did the same in C# before. but I couldn't do in C++. regards. :-O
That's how the network stack works. By trying to pick an adapter you are essentially trying to remove the Transport layer from the network stack. I'm wondering how you did it in C#. Since you need TCP/IP to be bound to the adapter and have a valid route in order for it to work, I'm guessing that you really didn't do that, or that stuff was setup for you and you didn't know it.
A guide to posting questions on CodeProject[^]
Dave Kreskowiak -
Thanks for your answer I brought my code here. the connect functions fails and WSAGetLastError returns 10060 (Connection timed out) The code:
//The function for handling HTTP
BOOL HTTPSubmitForm(char* HostName, char* Action,char* ObjectName, char* Headers,int HeadersLen, char* Body,int BodyLen)
{
SOCKET conn;
struct hostent* host=NULL;
int iRet = SOCKET_ERROR;
conn = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(conn==INVALID_SOCKET)
{
return FALSE;
}
for (int iTry=0;iTry<3 && host==NULL;iTry++)
host= gethostbyname(HostName);
if(host==NULL)
{
closesocket(conn);
return FALSE;
}
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = *((unsigned long*)host->h_addr_list);
clientService.sin_port = htons( 80 );
///*********************** This part doesn't work properly. I brought error code 10060
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
iRet= connect( conn, (SOCKADDR*) &clientService, sizeof(clientService) ) ;
int iError = WSAGetLastError(); //THIS returns 10060
if ( iRet== SOCKET_ERROR)
{
closesocket(conn);
return FALSE;
}
char RequestFirstLine[512];
sprintf(RequestFirstLine,"%s %s HTTP/1.0\r\n",Action,ObjectName);
iRet= SOCKET_ERROR;
for(int iTry=0;iTry<3 && iRet==SOCKET_ERROR;iTry++)
{
send(conn,RequestFirstLine,strlen(RequestFirstLine),0);
send(conn,Headers,HeadersLen,0);
iRet=send(conn,Body,BodyLen,0);
}
closesocket(conn);
return iRet!=SOCKET_ERROR;
}//The Caller Function
void CtestDlg::OnBnClickedBtnhttp()
{
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 0 );
err=WSAStartup(wVersionRequested,&wsaData);
HTTPSubmitForm("www.yahoo.com","GET","/","",0,"",0);
WSACleanup();
}Your code just needs to be modified at the point where you select the remote host ip address, thus:
clientService.sin\_addr.s\_addr = \*((unsigned long\*)host->h\_addr\_list\[0\]);as
h_addr_listis an array of addresses pointers to addresses, not a single pointer. In a live application, you may also need to try each address in the list in turn until one succeeds. [edit]Corrected as strikeout above.[edit]Veni, vidi, abiit domum
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Your code just needs to be modified at the point where you select the remote host ip address, thus:
clientService.sin\_addr.s\_addr = \*((unsigned long\*)host->h\_addr\_list\[0\]);as
h_addr_listis an array of addresses pointers to addresses, not a single pointer. In a live application, you may also need to try each address in the list in turn until one succeeds. [edit]Corrected as strikeout above.[edit]Veni, vidi, abiit domum