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- /* Copyright (c) 2003-2004, Roger Dingledine
- * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2018, The Tor Project, Inc. */
- #include "lib/net/socketpair.h"
- #include "lib/net/socket.h"
- #include "lib/net/address.h"
- #include <errno.h>
- #include <string.h>
- #ifdef NEED_ERSATZ_SOCKETPAIR
- static inline socklen_t
- SIZEOF_SOCKADDR(int domain)
- {
- switch (domain) {
- case AF_INET:
- return sizeof(struct sockaddr_in);
- case AF_INET6:
- return sizeof(struct sockaddr_in6);
- default:
- return 0;
- }
- }
- /**
- * Helper used to implement socketpair on systems that lack it, by
- * making a direct connection to localhost.
- */
- STATIC int
- tor_ersatz_socketpair(int family, int type, int protocol, tor_socket_t fd[2])
- {
- /* This socketpair does not work when localhost is down. So
- * it's really not the same thing at all. But it's close enough
- * for now, and really, when localhost is down sometimes, we
- * have other problems too.
- */
- tor_socket_t listener = TOR_INVALID_SOCKET;
- tor_socket_t connector = TOR_INVALID_SOCKET;
- tor_socket_t acceptor = TOR_INVALID_SOCKET;
- tor_addr_t listen_tor_addr;
- struct sockaddr_storage connect_addr_ss, listen_addr_ss;
- struct sockaddr *listen_addr = (struct sockaddr *) &listen_addr_ss;
- uint16_t listen_port = 0;
- tor_addr_t connect_tor_addr;
- uint16_t connect_port = 0;
- struct sockaddr *connect_addr = (struct sockaddr *) &connect_addr_ss;
- socklen_t size;
- int saved_errno = -1;
- int ersatz_domain = AF_INET;
- memset(&connect_tor_addr, 0, sizeof(connect_tor_addr));
- memset(&connect_addr_ss, 0, sizeof(connect_addr_ss));
- memset(&listen_tor_addr, 0, sizeof(listen_tor_addr));
- memset(&listen_addr_ss, 0, sizeof(listen_addr_ss));
- if (protocol
- #ifdef AF_UNIX
- || family != AF_UNIX
- #endif
- ) {
- #ifdef _WIN32
- return -WSAEAFNOSUPPORT;
- #else
- return -EAFNOSUPPORT;
- #endif
- }
- if (!fd) {
- return -EINVAL;
- }
- listener = tor_open_socket(ersatz_domain, type, 0);
- if (!SOCKET_OK(listener)) {
- int first_errno = tor_socket_errno(-1);
- if (first_errno == SOCK_ERRNO(EPROTONOSUPPORT)
- && ersatz_domain == AF_INET) {
- /* Assume we're on an IPv6-only system */
- ersatz_domain = AF_INET6;
- listener = tor_open_socket(ersatz_domain, type, 0);
- if (!SOCKET_OK(listener)) {
- /* Keep the previous behaviour, which was to return the IPv4 error.
- * (This may be less informative on IPv6-only systems.)
- * XX/teor - is there a better way to decide which errno to return?
- * (I doubt we care much either way, once there is an error.)
- */
- return -first_errno;
- }
- }
- }
- /* If there is no 127.0.0.1 or ::1, this will and must fail. Otherwise, we
- * risk exposing a socketpair on a routable IP address. (Some BSD jails
- * use a routable address for localhost. Fortunately, they have the real
- * AF_UNIX socketpair.) */
- if (ersatz_domain == AF_INET) {
- tor_addr_from_ipv4h(&listen_tor_addr, INADDR_LOOPBACK);
- } else {
- tor_addr_parse(&listen_tor_addr, "[::1]");
- }
- tor_assert(tor_addr_is_loopback(&listen_tor_addr));
- size = tor_addr_to_sockaddr(&listen_tor_addr,
- 0 /* kernel chooses port. */,
- listen_addr,
- sizeof(listen_addr_ss));
- if (bind(listener, listen_addr, size) == -1)
- goto tidy_up_and_fail;
- if (listen(listener, 1) == -1)
- goto tidy_up_and_fail;
- connector = tor_open_socket(ersatz_domain, type, 0);
- if (!SOCKET_OK(connector))
- goto tidy_up_and_fail;
- /* We want to find out the port number to connect to. */
- size = sizeof(connect_addr_ss);
- if (getsockname(listener, connect_addr, &size) == -1)
- goto tidy_up_and_fail;
- if (size != SIZEOF_SOCKADDR (connect_addr->sa_family))
- goto abort_tidy_up_and_fail;
- if (connect(connector, connect_addr, size) == -1)
- goto tidy_up_and_fail;
- size = sizeof(listen_addr_ss);
- acceptor = tor_accept_socket(listener, listen_addr, &size);
- if (!SOCKET_OK(acceptor))
- goto tidy_up_and_fail;
- if (size != SIZEOF_SOCKADDR(listen_addr->sa_family))
- goto abort_tidy_up_and_fail;
- /* Now check we are talking to ourself by matching port and host on the
- two sockets. */
- if (getsockname(connector, connect_addr, &size) == -1)
- goto tidy_up_and_fail;
- /* Set *_tor_addr and *_port to the address and port that was used */
- tor_addr_from_sockaddr(&listen_tor_addr, listen_addr, &listen_port);
- tor_addr_from_sockaddr(&connect_tor_addr, connect_addr, &connect_port);
- if (size != SIZEOF_SOCKADDR (connect_addr->sa_family)
- || tor_addr_compare(&listen_tor_addr, &connect_tor_addr, CMP_SEMANTIC)
- || listen_port != connect_port) {
- goto abort_tidy_up_and_fail;
- }
- tor_close_socket(listener);
- fd[0] = connector;
- fd[1] = acceptor;
- return 0;
- abort_tidy_up_and_fail:
- #ifdef _WIN32
- saved_errno = WSAECONNABORTED;
- #else
- saved_errno = ECONNABORTED; /* I hope this is portable and appropriate. */
- #endif
- tidy_up_and_fail:
- if (saved_errno < 0)
- saved_errno = errno;
- if (SOCKET_OK(listener))
- tor_close_socket(listener);
- if (SOCKET_OK(connector))
- tor_close_socket(connector);
- if (SOCKET_OK(acceptor))
- tor_close_socket(acceptor);
- return -saved_errno;
- }
- #endif /* defined(NEED_ERSATZ_SOCKETPAIR) */
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