socks5tcp_accept Subroutine

Purpose

Awaits an incoming connection to a socket from a previous socks5tcp_bind() call.

Library

Standard C Library (libc.a)

Syntax

#include <stdlib.h>
#include <netinet/in.h>
#include <sys/socket.h>

int socks5tcp_accept(Socket, Dst, DstLen, Svr, SvrLen)
int Socket;
struct sockaddr *Dst;
size_t DstLen;
struct sockaddr *Svr;
size_t SrvLen;

Description

The socks5tcp_accept subroutine blocks until an incoming connection is established on a listening socket that was requested in a previous call to socks5tcp_bind. Upon success, subsequent writes to and reads from Socket will be relayed through Svr.

Socket must be an open socket descriptor of type SOCK_STREAM.

The socket applications can be compiled with COMPAT_43 defined. This will make the sockaddr structure BSD 4.3 compatible. For more details refer to socket.h.

Parameters

Item	Description
Socket	Specifies the unique name of the socket.
Dst	If non-NULL, buffer for receiving the address of the remote client which initiated an incoming connection
DstLength	Specifies the length of the address structure in Dst.
Svr	If non-NULL, specifies the address of the SOCKSv5 server to use to request the relayed connection; on success, this space will be overwritten with the server-side address of the incoming connection.
SvrLength	Specifies the length of the address structure in Svr.

Return Values

Upon successful completion, the socks5tcp_accept subroutine returns a value of 0, and modifies Dst and Svr to reflect the actual endpoints of the incoming external socket.

If the socks5tcp_accept subroutine is unsuccessful, the system handler performs the following functions:

Returns a value of -1 to the calling program.
Moves an error code, indicating the generic system error, into the errno global variable.
Moves an error code, indicating the specific SOCKSv5 error, into the socks5_errno global variable.

Error Codes (placed in errno; inherited from underlying call to connect())

The socks5tcp_bindaccept subroutine is unsuccessful if any of the following errors occurs:

Error	Description
EBADF	The Socket parameter is not valid.
EAFNOSUPPORT	The addresses in the specified address family cannot be used with this socket.
ENETUNREACH	No route to the network or host is present.
EFAULT	The Dst or Svr parameter is not in a writable part of the user address space.
EINVAL	One or more of the specified arguments is invalid.
ENETDOWN	The specified physical network is down.
ENOSPC	There is no space left on a device or system table.
ENOTCONN	The socket could not be connected.

Error Codes (placed in socks5_errno; SOCKSv5-specific errors)

The socks5tcp_connect subroutine is unsuccessful if any of the following errors occurs:

Error	Description
S5_ESRVFAIL	General SOCKSv5 server failure.
S5_EPERM	SOCKSv5 server ruleset rejection.
S5_ENETUNREACH	SOCKSv5 server could not reach target network.
S5_EHOSTUNREACH	SOCKSv5 server could not reach target host.
S5_ECONNREFUSED	SOCKSv5 server connection request refused by target host.
S5_ETIMEDOUT	SOCKSv5 server connection failure due to TTL expiry.
S5_EOPNOTSUPP	Command not supported by SOCKSv5 server.
S5_EAFNOSUPPORT	Address family not supported by SOCKSv5 server.
S5_EADDRINUSE	Requested bind address is already in use (at the SOCKSv5 server).
S5_ENOSERV	No server found.

Examples

The following program fragment illustrates the use of the socks5tcp_accept and socks5tcp_bind subroutines by a client to request a listening socket from a server and wait for an incoming connection on the server side.

struct sockaddr_in svr;
struct sockaddr_in dst;
.
.
.
socks5tcp_bind(s,(struct sockaddr*)&dst, sizeof(dst), (struct sockaddr *)&svr, sizeof(svr), &res, sizeof(svr));
.
.
.
socks5tcp_accept(s, (struct sockaddr *)&dst, sizeof(dst), (struct sockaddr *)&svr, sizeof(svr));