diff options
Diffstat (limited to 'src/lib/net/socket.c')
| -rw-r--r-- | src/lib/net/socket.c | 697 |
1 files changed, 697 insertions, 0 deletions
diff --git a/src/lib/net/socket.c b/src/lib/net/socket.c new file mode 100644 index 0000000000..cd7c9685cd --- /dev/null +++ b/src/lib/net/socket.c @@ -0,0 +1,697 @@ +/* Copyright (c) 2003-2004, Roger Dingledine + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file socket.c + * \brief Compatibility and utility functions for working with network + * sockets. + **/ + +#define SOCKET_PRIVATE +#include "lib/net/socket.h" +#include "lib/net/socketpair.h" +#include "lib/net/address.h" +#include "lib/cc/compat_compiler.h" +#include "lib/err/torerr.h" +#include "lib/lock/compat_mutex.h" +#include "lib/log/log.h" +#include "lib/log/util_bug.h" + +#ifdef _WIN32 +#include <winsock2.h> +#include <windows.h> +#endif +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif +#ifdef HAVE_FCNTL_H +#include <fcntl.h> +#endif +#include <stddef.h> +#include <string.h> + +/** Called before we make any calls to network-related functions. + * (Some operating systems require their network libraries to be + * initialized.) */ +int +network_init(void) +{ +#ifdef _WIN32 + /* This silly exercise is necessary before windows will allow + * gethostbyname to work. */ + WSADATA WSAData; + int r; + r = WSAStartup(0x101,&WSAData); + if (r) { + log_warn(LD_NET,"Error initializing windows network layer: code was %d",r); + return -1; + } + if (sizeof(SOCKET) != sizeof(tor_socket_t)) { + log_warn(LD_BUG,"The tor_socket_t type does not match SOCKET in size; Tor " + "might not work. (Sizes are %d and %d respectively.)", + (int)sizeof(tor_socket_t), (int)sizeof(SOCKET)); + } + /* WSAData.iMaxSockets might show the max sockets we're allowed to use. + * We might use it to complain if we're trying to be a server but have + * too few sockets available. */ +#endif /* defined(_WIN32) */ + return 0; +} + +/* When set_max_file_sockets() is called, update this with the max file + * descriptor value so we can use it to check the limit when opening a new + * socket. Default value is what Debian sets as the default hard limit. */ +static int max_sockets = 1024; + +/** Return the maximum number of allowed sockets. */ +int +get_max_sockets(void) +{ + return max_sockets; +} + +/** Set the maximum number of allowed sockets to <b>n</b> */ +void +set_max_sockets(int n) +{ + max_sockets = n; +} + +#undef DEBUG_SOCKET_COUNTING +#ifdef DEBUG_SOCKET_COUNTING +#include "lib/container/bitarray.h" + +/** A bitarray of all fds that should be passed to tor_socket_close(). Only + * used if DEBUG_SOCKET_COUNTING is defined. */ +static bitarray_t *open_sockets = NULL; +/** The size of <b>open_sockets</b>, in bits. */ +static int max_socket = -1; +#endif /* defined(DEBUG_SOCKET_COUNTING) */ + +/** Count of number of sockets currently open. (Undercounts sockets opened by + * eventdns and libevent.) */ +static int n_sockets_open = 0; + +/** Mutex to protect open_sockets, max_socket, and n_sockets_open. */ +static tor_mutex_t *socket_accounting_mutex = NULL; + +/** Helper: acquire the socket accounting lock. */ +static inline void +socket_accounting_lock(void) +{ + if (PREDICT_UNLIKELY(!socket_accounting_mutex)) + socket_accounting_mutex = tor_mutex_new(); + tor_mutex_acquire(socket_accounting_mutex); +} + +/** Helper: release the socket accounting lock. */ +static inline void +socket_accounting_unlock(void) +{ + tor_mutex_release(socket_accounting_mutex); +} + +/** As close(), but guaranteed to work for sockets across platforms (including + * Windows, where close()ing a socket doesn't work. Returns 0 on success and + * the socket error code on failure. */ +int +tor_close_socket_simple(tor_socket_t s) +{ + int r = 0; + + /* On Windows, you have to call close() on fds returned by open(), + * and closesocket() on fds returned by socket(). On Unix, everything + * gets close()'d. We abstract this difference by always using + * tor_close_socket to close sockets, and always using close() on + * files. + */ + #if defined(_WIN32) + r = closesocket(s); + #else + r = close(s); + #endif + + if (r != 0) { + int err = tor_socket_errno(-1); + log_info(LD_NET, "Close returned an error: %s", tor_socket_strerror(err)); + return err; + } + + return r; +} + +/** @{ */ +#ifdef DEBUG_SOCKET_COUNTING +/** Helper: if DEBUG_SOCKET_COUNTING is enabled, remember that <b>s</b> is + * now an open socket. */ +static inline void +mark_socket_open(tor_socket_t s) +{ + /* XXXX This bitarray business will NOT work on windows: sockets aren't + small ints there. */ + if (s > max_socket) { + if (max_socket == -1) { + open_sockets = bitarray_init_zero(s+128); + max_socket = s+128; + } else { + open_sockets = bitarray_expand(open_sockets, max_socket, s+128); + max_socket = s+128; + } + } + if (bitarray_is_set(open_sockets, s)) { + log_warn(LD_BUG, "I thought that %d was already open, but socket() just " + "gave it to me!", s); + } + bitarray_set(open_sockets, s); +} +static inline void +mark_socket_closed(tor_socket_t s) +{ + if (s > max_socket || ! bitarray_is_set(open_sockets, s)) { + log_warn(LD_BUG, "Closing a socket (%d) that wasn't returned by tor_open_" + "socket(), or that was already closed or something.", s); + } else { + tor_assert(open_sockets && s <= max_socket); + bitarray_clear(open_sockets, s); + } +} +#else /* !(defined(DEBUG_SOCKET_COUNTING)) */ +#define mark_socket_open(s) ((void) (s)) +#define mark_socket_closed(s) ((void) (s)) +#endif /* defined(DEBUG_SOCKET_COUNTING) */ +/** @} */ + +/** As tor_close_socket_simple(), but keeps track of the number + * of open sockets. Returns 0 on success, -1 on failure. */ +MOCK_IMPL(int, +tor_close_socket,(tor_socket_t s)) +{ + int r = tor_close_socket_simple(s); + + socket_accounting_lock(); + mark_socket_closed(s); + if (r == 0) { + --n_sockets_open; + } else { +#ifdef _WIN32 + if (r != WSAENOTSOCK) + --n_sockets_open; +#else + if (r != EBADF) + --n_sockets_open; // LCOV_EXCL_LINE -- EIO and EINTR too hard to force. +#endif /* defined(_WIN32) */ + r = -1; + } + + tor_assert_nonfatal(n_sockets_open >= 0); + socket_accounting_unlock(); + return r; +} + +/** As socket(), but counts the number of open sockets. */ +MOCK_IMPL(tor_socket_t, +tor_open_socket,(int domain, int type, int protocol)) +{ + return tor_open_socket_with_extensions(domain, type, protocol, 1, 0); +} + +/** Mockable wrapper for connect(). */ +MOCK_IMPL(tor_socket_t, +tor_connect_socket,(tor_socket_t sock, const struct sockaddr *address, + socklen_t address_len)) +{ + return connect(sock,address,address_len); +} + +/** As socket(), but creates a nonblocking socket and + * counts the number of open sockets. */ +tor_socket_t +tor_open_socket_nonblocking(int domain, int type, int protocol) +{ + return tor_open_socket_with_extensions(domain, type, protocol, 1, 1); +} + +/** As socket(), but counts the number of open sockets and handles + * socket creation with either of SOCK_CLOEXEC and SOCK_NONBLOCK specified. + * <b>cloexec</b> and <b>nonblock</b> should be either 0 or 1 to indicate + * if the corresponding extension should be used.*/ +tor_socket_t +tor_open_socket_with_extensions(int domain, int type, int protocol, + int cloexec, int nonblock) +{ + tor_socket_t s; + + /* We are about to create a new file descriptor so make sure we have + * enough of them. */ + if (get_n_open_sockets() >= max_sockets - 1) { +#ifdef _WIN32 + WSASetLastError(WSAEMFILE); +#else + errno = EMFILE; +#endif + return TOR_INVALID_SOCKET; + } + +#if defined(SOCK_CLOEXEC) && defined(SOCK_NONBLOCK) + int ext_flags = (cloexec ? SOCK_CLOEXEC : 0) | + (nonblock ? SOCK_NONBLOCK : 0); + s = socket(domain, type|ext_flags, protocol); + if (SOCKET_OK(s)) + goto socket_ok; + /* If we got an error, see if it is EINVAL. EINVAL might indicate that, + * even though we were built on a system with SOCK_CLOEXEC and SOCK_NONBLOCK + * support, we are running on one without. */ + if (errno != EINVAL) + return s; +#endif /* defined(SOCK_CLOEXEC) && defined(SOCK_NONBLOCK) */ + + s = socket(domain, type, protocol); + if (! SOCKET_OK(s)) + return s; + +#if defined(FD_CLOEXEC) + if (cloexec) { + if (fcntl(s, F_SETFD, FD_CLOEXEC) == -1) { + log_warn(LD_FS,"Couldn't set FD_CLOEXEC: %s", strerror(errno)); + tor_close_socket_simple(s); + return TOR_INVALID_SOCKET; + } + } +#else /* !(defined(FD_CLOEXEC)) */ + (void)cloexec; +#endif /* defined(FD_CLOEXEC) */ + + if (nonblock) { + if (set_socket_nonblocking(s) == -1) { + tor_close_socket_simple(s); + return TOR_INVALID_SOCKET; + } + } + + goto socket_ok; /* So that socket_ok will not be unused. */ + + socket_ok: + tor_take_socket_ownership(s); + return s; +} + +/** + * For socket accounting: remember that we are the owner of the socket + * <b>s</b>. This will prevent us from overallocating sockets, and prevent us + * from asserting later when we close the socket <b>s</b>. + */ +void +tor_take_socket_ownership(tor_socket_t s) +{ + socket_accounting_lock(); + ++n_sockets_open; + mark_socket_open(s); + socket_accounting_unlock(); +} + +/** + * For socket accounting: declare that we are no longer the owner of the + * socket <b>s</b>. This will prevent us from overallocating sockets, and + * prevent us from asserting later when we close the socket <b>s</b>. + */ +void +tor_release_socket_ownership(tor_socket_t s) +{ + socket_accounting_lock(); + --n_sockets_open; + mark_socket_closed(s); + socket_accounting_unlock(); +} + +/** As accept(), but counts the number of open sockets. */ +tor_socket_t +tor_accept_socket(tor_socket_t sockfd, struct sockaddr *addr, socklen_t *len) +{ + return tor_accept_socket_with_extensions(sockfd, addr, len, 1, 0); +} + +/** As accept(), but returns a nonblocking socket and + * counts the number of open sockets. */ +tor_socket_t +tor_accept_socket_nonblocking(tor_socket_t sockfd, struct sockaddr *addr, + socklen_t *len) +{ + return tor_accept_socket_with_extensions(sockfd, addr, len, 1, 1); +} + +/** As accept(), but counts the number of open sockets and handles + * socket creation with either of SOCK_CLOEXEC and SOCK_NONBLOCK specified. + * <b>cloexec</b> and <b>nonblock</b> should be either 0 or 1 to indicate + * if the corresponding extension should be used.*/ +tor_socket_t +tor_accept_socket_with_extensions(tor_socket_t sockfd, struct sockaddr *addr, + socklen_t *len, int cloexec, int nonblock) +{ + tor_socket_t s; + + /* We are about to create a new file descriptor so make sure we have + * enough of them. */ + if (get_n_open_sockets() >= max_sockets - 1) { +#ifdef _WIN32 + WSASetLastError(WSAEMFILE); +#else + errno = EMFILE; +#endif + return TOR_INVALID_SOCKET; + } + +#if defined(HAVE_ACCEPT4) && defined(SOCK_CLOEXEC) \ + && defined(SOCK_NONBLOCK) + int ext_flags = (cloexec ? SOCK_CLOEXEC : 0) | + (nonblock ? SOCK_NONBLOCK : 0); + s = accept4(sockfd, addr, len, ext_flags); + if (SOCKET_OK(s)) + goto socket_ok; + /* If we got an error, see if it is ENOSYS. ENOSYS indicates that, + * even though we were built on a system with accept4 support, we + * are running on one without. Also, check for EINVAL, which indicates that + * we are missing SOCK_CLOEXEC/SOCK_NONBLOCK support. */ + if (errno != EINVAL && errno != ENOSYS) + return s; +#endif /* defined(HAVE_ACCEPT4) && defined(SOCK_CLOEXEC) ... */ + + s = accept(sockfd, addr, len); + if (!SOCKET_OK(s)) + return s; + +#if defined(FD_CLOEXEC) + if (cloexec) { + if (fcntl(s, F_SETFD, FD_CLOEXEC) == -1) { + log_warn(LD_NET, "Couldn't set FD_CLOEXEC: %s", strerror(errno)); + tor_close_socket_simple(s); + return TOR_INVALID_SOCKET; + } + } +#else /* !(defined(FD_CLOEXEC)) */ + (void)cloexec; +#endif /* defined(FD_CLOEXEC) */ + + if (nonblock) { + if (set_socket_nonblocking(s) == -1) { + tor_close_socket_simple(s); + return TOR_INVALID_SOCKET; + } + } + + goto socket_ok; /* So that socket_ok will not be unused. */ + + socket_ok: + tor_take_socket_ownership(s); + return s; +} + +/** Return the number of sockets we currently have opened. */ +int +get_n_open_sockets(void) +{ + int n; + socket_accounting_lock(); + n = n_sockets_open; + socket_accounting_unlock(); + return n; +} + +/** + * Allocate a pair of connected sockets. (Like socketpair(family, + * type,protocol,fd), but works on systems that don't have + * socketpair.) + * + * Currently, only (AF_UNIX, SOCK_STREAM, 0) sockets are supported. + * + * Note that on systems without socketpair, this call will fail if + * localhost is inaccessible (for example, if the networking + * stack is down). And even if it succeeds, the socket pair will not + * be able to read while localhost is down later (the socket pair may + * even close, depending on OS-specific timeouts). + * + * Returns 0 on success and -errno on failure; do not rely on the value + * of errno or WSAGetLastError(). + **/ +/* It would be nicer just to set errno, but that won't work for windows. */ +int +tor_socketpair(int family, int type, int protocol, tor_socket_t fd[2]) +{ + int r; +//don't use win32 socketpairs (they are always bad) +#if defined(HAVE_SOCKETPAIR) && !defined(_WIN32) + +#ifdef SOCK_CLOEXEC + r = socketpair(family, type|SOCK_CLOEXEC, protocol, fd); + if (r == 0) + goto sockets_ok; + /* If we got an error, see if it is EINVAL. EINVAL might indicate that, + * even though we were built on a system with SOCK_CLOEXEC support, we + * are running on one without. */ + if (errno != EINVAL) + return -errno; +#endif /* defined(SOCK_CLOEXEC) */ + + r = socketpair(family, type, protocol, fd); + if (r < 0) + return -errno; +#else + r = tor_ersatz_socketpair(family, type, protocol, fd); + if (r < 0) + return -r; +#endif + +#if defined(FD_CLOEXEC) + if (SOCKET_OK(fd[0])) { + r = fcntl(fd[0], F_SETFD, FD_CLOEXEC); + if (r == -1) { + close(fd[0]); + close(fd[1]); + return -errno; + } + } + if (SOCKET_OK(fd[1])) { + r = fcntl(fd[1], F_SETFD, FD_CLOEXEC); + if (r == -1) { + close(fd[0]); + close(fd[1]); + return -errno; + } + } +#endif /* defined(FD_CLOEXEC) */ + goto sockets_ok; /* So that sockets_ok will not be unused. */ + + sockets_ok: + socket_accounting_lock(); + if (SOCKET_OK(fd[0])) { + ++n_sockets_open; + mark_socket_open(fd[0]); + } + if (SOCKET_OK(fd[1])) { + ++n_sockets_open; + mark_socket_open(fd[1]); + } + socket_accounting_unlock(); + + return 0; +} + +/** Mockable wrapper for getsockname(). */ +MOCK_IMPL(int, +tor_getsockname,(tor_socket_t sock, struct sockaddr *address, + socklen_t *address_len)) +{ + return getsockname(sock, address, address_len); +} + +/** + * Find the local address associated with the socket <b>sock</b>, and + * place it in *<b>addr_out</b>. Return 0 on success, -1 on failure. + * + * (As tor_getsockname, but instead places the result in a tor_addr_t.) */ +int +tor_addr_from_getsockname(struct tor_addr_t *addr_out, tor_socket_t sock) +{ + struct sockaddr_storage ss; + socklen_t ss_len = sizeof(ss); + memset(&ss, 0, sizeof(ss)); + + if (tor_getsockname(sock, (struct sockaddr *) &ss, &ss_len) < 0) + return -1; + + return tor_addr_from_sockaddr(addr_out, (struct sockaddr *)&ss, NULL); +} + +/** Turn <b>socket</b> into a nonblocking socket. Return 0 on success, -1 + * on failure. + */ +int +set_socket_nonblocking(tor_socket_t sock) +{ +#if defined(_WIN32) + unsigned long nonblocking = 1; + ioctlsocket(sock, FIONBIO, (unsigned long*) &nonblocking); +#else + int flags; + + flags = fcntl(sock, F_GETFL, 0); + if (flags == -1) { + log_warn(LD_NET, "Couldn't get file status flags: %s", strerror(errno)); + return -1; + } + flags |= O_NONBLOCK; + if (fcntl(sock, F_SETFL, flags) == -1) { + log_warn(LD_NET, "Couldn't set file status flags: %s", strerror(errno)); + return -1; + } +#endif /* defined(_WIN32) */ + + return 0; +} + +/** Read from <b>sock</b> to <b>buf</b>, until we get <b>count</b> bytes or + * reach the end of the file. Return the number of bytes read, or -1 on + * error. Only use if fd is a blocking fd. */ +ssize_t +read_all_from_socket(tor_socket_t sock, char *buf, size_t count) +{ + size_t numread = 0; + ssize_t result; + + if (count > SIZE_T_CEILING || count > SSIZE_MAX) { + errno = EINVAL; + return -1; + } + + while (numread < count) { + result = tor_socket_recv(sock, buf+numread, count-numread, 0); + if (result<0) + return -1; + else if (result == 0) + break; + numread += result; + } + return (ssize_t)numread; +} + +/** Write <b>count</b> bytes from <b>buf</b> to <b>sock</b>. Return the number + * of bytes written, or -1 on error. Only use if fd is a blocking fd. */ +ssize_t +write_all_to_socket(tor_socket_t fd, const char *buf, size_t count) +{ + size_t written = 0; + ssize_t result; + raw_assert(count < SSIZE_MAX); + + while (written != count) { + result = tor_socket_send(fd, buf+written, count-written, 0); + if (result<0) + return -1; + written += result; + } + return (ssize_t)count; +} + +/** + * On Windows, WSAEWOULDBLOCK is not always correct: when you see it, + * you need to ask the socket for its actual errno. Also, you need to + * get your errors from WSAGetLastError, not errno. (If you supply a + * socket of -1, we check WSAGetLastError, but don't correct + * WSAEWOULDBLOCKs.) + * + * The upshot of all of this is that when a socket call fails, you + * should call tor_socket_errno <em>at most once</em> on the failing + * socket to get the error. + */ +#if defined(_WIN32) +int +tor_socket_errno(tor_socket_t sock) +{ + int optval, optvallen=sizeof(optval); + int err = WSAGetLastError(); + if (err == WSAEWOULDBLOCK && SOCKET_OK(sock)) { + if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval, &optvallen)) + return err; + if (optval) + return optval; + } + return err; +} +#endif /* defined(_WIN32) */ + +#if defined(_WIN32) +#define E(code, s) { code, (s " [" #code " ]") } +struct { int code; const char *msg; } windows_socket_errors[] = { + E(WSAEINTR, "Interrupted function call"), + E(WSAEACCES, "Permission denied"), + E(WSAEFAULT, "Bad address"), + E(WSAEINVAL, "Invalid argument"), + E(WSAEMFILE, "Too many open files"), + E(WSAEWOULDBLOCK, "Resource temporarily unavailable"), + E(WSAEINPROGRESS, "Operation now in progress"), + E(WSAEALREADY, "Operation already in progress"), + E(WSAENOTSOCK, "Socket operation on nonsocket"), + E(WSAEDESTADDRREQ, "Destination address required"), + E(WSAEMSGSIZE, "Message too long"), + E(WSAEPROTOTYPE, "Protocol wrong for socket"), + E(WSAENOPROTOOPT, "Bad protocol option"), + E(WSAEPROTONOSUPPORT, "Protocol not supported"), + E(WSAESOCKTNOSUPPORT, "Socket type not supported"), + /* What's the difference between NOTSUPP and NOSUPPORT? :) */ + E(WSAEOPNOTSUPP, "Operation not supported"), + E(WSAEPFNOSUPPORT, "Protocol family not supported"), + E(WSAEAFNOSUPPORT, "Address family not supported by protocol family"), + E(WSAEADDRINUSE, "Address already in use"), + E(WSAEADDRNOTAVAIL, "Cannot assign requested address"), + E(WSAENETDOWN, "Network is down"), + E(WSAENETUNREACH, "Network is unreachable"), + E(WSAENETRESET, "Network dropped connection on reset"), + E(WSAECONNABORTED, "Software caused connection abort"), + E(WSAECONNRESET, "Connection reset by peer"), + E(WSAENOBUFS, "No buffer space available"), + E(WSAEISCONN, "Socket is already connected"), + E(WSAENOTCONN, "Socket is not connected"), + E(WSAESHUTDOWN, "Cannot send after socket shutdown"), + E(WSAETIMEDOUT, "Connection timed out"), + E(WSAECONNREFUSED, "Connection refused"), + E(WSAEHOSTDOWN, "Host is down"), + E(WSAEHOSTUNREACH, "No route to host"), + E(WSAEPROCLIM, "Too many processes"), + /* Yes, some of these start with WSA, not WSAE. No, I don't know why. */ + E(WSASYSNOTREADY, "Network subsystem is unavailable"), + E(WSAVERNOTSUPPORTED, "Winsock.dll out of range"), + E(WSANOTINITIALISED, "Successful WSAStartup not yet performed"), + E(WSAEDISCON, "Graceful shutdown now in progress"), +#ifdef WSATYPE_NOT_FOUND + E(WSATYPE_NOT_FOUND, "Class type not found"), +#endif + E(WSAHOST_NOT_FOUND, "Host not found"), + E(WSATRY_AGAIN, "Nonauthoritative host not found"), + E(WSANO_RECOVERY, "This is a nonrecoverable error"), + E(WSANO_DATA, "Valid name, no data record of requested type)"), + + /* There are some more error codes whose numeric values are marked + * <b>OS dependent</b>. They start with WSA_, apparently for the same + * reason that practitioners of some craft traditions deliberately + * introduce imperfections into their baskets and rugs "to allow the + * evil spirits to escape." If we catch them, then our binaries + * might not report consistent results across versions of Windows. + * Thus, I'm going to let them all fall through. + */ + { -1, NULL }, +}; +/** There does not seem to be a strerror equivalent for Winsock errors. + * Naturally, we have to roll our own. + */ +const char * +tor_socket_strerror(int e) +{ + int i; + for (i=0; windows_socket_errors[i].code >= 0; ++i) { + if (e == windows_socket_errors[i].code) + return windows_socket_errors[i].msg; + } + return strerror(e); +} +#endif /* defined(_WIN32) */ |