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socketpair.c
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socketpair.c
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/* socketpair.c
* Copyright 2007, 2010 by Nathan C. Myers <ncm@cantrip.org>
* This code is Free Software. It may be copied freely, in original or
* modified form, subject only to the restrictions that (1) the author is
* relieved from all responsibilities for any use for any purpose, and (2)
* this copyright notice must be retained, unchanged, in its entirety. If
* for any reason the author might be held responsible for any consequences
* of copying or use, license is withheld.
*/
/* Changes:
* 2012-03-15:
* always init the socks[] to -1/INVALID_SOCKET on error, both on Win32/64
* and UNIX/other platforms
* 2010-03-31:
* set addr to 127.0.0.1 because win32 getsockname does not always set it.
* 2010-02-25:
* set SO_REUSEADDR option to avoid leaking some windows resource.
* Windows System Error 10049, "Event ID 4226 TCP/IP has reached
* the security limit imposed on the number of concurrent TCP connect
* attempts." Bleah.
* 2007-04-25:
* preserve value of WSAGetLastError() on all error returns.
* 2007-04-22: (Thanks to Matthew Gregan <kinetik@flim.org>)
* s/EINVAL/WSAEINVAL/ fix trivial compile failure
* s/socket/WSASocket/ enable creation of sockets suitable as stdin/stdout
* of a child process.
* add argument make_overlapped
*/
#include <string.h>
#ifdef WIN32
# include <ws2tcpip.h> /* socklen_t, et al (MSVC20xx) */
# include <windows.h>
# include <io.h>
#else
# include <sys/types.h>
# include <sys/socket.h>
# include <errno.h>
#endif
#ifdef WIN32
/* dumb_socketpair:
* If make_overlapped is nonzero, both sockets created will be usable for
* "overlapped" operations via WSASend etc. If make_overlapped is zero,
* socks[0] (only) will be usable with regular ReadFile etc., and thus
* suitable for use as stdin or stdout of a child process. Note that the
* sockets must be closed with closesocket() regardless.
*/
int dumb_socketpair(SOCKET socks[2], int make_overlapped)
{
union {
struct sockaddr_in inaddr;
struct sockaddr addr;
} a;
SOCKET listener;
int e;
socklen_t addrlen = sizeof(a.inaddr);
DWORD flags = (make_overlapped ? WSA_FLAG_OVERLAPPED : 0);
int reuse = 1;
if (socks == 0) {
WSASetLastError(WSAEINVAL);
return SOCKET_ERROR;
}
socks[0] = socks[1] = INVALID_SOCKET;
listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (listener == INVALID_SOCKET)
return SOCKET_ERROR;
memset(&a, 0, sizeof(a));
a.inaddr.sin_family = AF_INET;
a.inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
a.inaddr.sin_port = 0;
for (;;) {
if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR,
(char*) &reuse, (socklen_t) sizeof(reuse)) == -1)
break;
if (bind(listener, &a.addr, sizeof(a.inaddr)) == SOCKET_ERROR)
break;
memset(&a, 0, sizeof(a));
if (getsockname(listener, &a.addr, &addrlen) == SOCKET_ERROR)
break;
// win32 getsockname may only set the port number, p=0.0005.
// ( http://msdn.microsoft.com/library/ms738543.aspx ):
a.inaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
a.inaddr.sin_family = AF_INET;
if (listen(listener, 1) == SOCKET_ERROR)
break;
socks[0] = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, flags);
if (socks[0] == INVALID_SOCKET)
break;
if (connect(socks[0], &a.addr, sizeof(a.inaddr)) == SOCKET_ERROR)
break;
socks[1] = accept(listener, NULL, NULL);
if (socks[1] == INVALID_SOCKET)
break;
closesocket(listener);
return 0;
}
e = WSAGetLastError();
closesocket(listener);
closesocket(socks[0]);
closesocket(socks[1]);
WSASetLastError(e);
socks[0] = socks[1] = INVALID_SOCKET;
return SOCKET_ERROR;
}
#else
int dumb_socketpair(int socks[2], int dummy)
{
if (socks == 0) {
errno = EINVAL;
return -1;
}
dummy = socketpair(AF_LOCAL, SOCK_STREAM, 0, socks);
if (dummy)
socks[0] = socks[1] = -1;
return dummy;
}
#endif