From 7f1e1c7ffa8134927b072959ea6548e21eb0c3a4 Mon Sep 17 00:00:00 2001 From: Gurucharan Shetty Date: Fri, 23 May 2014 09:35:47 -0700 Subject: socket-util: Refactor unix specific code to a new file. Signed-off-by: Gurucharan Shetty Acked-by: Ben Pfaff --- lib/socket-util-unix.c | 400 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 400 insertions(+) create mode 100644 lib/socket-util-unix.c (limited to 'lib/socket-util-unix.c') diff --git a/lib/socket-util-unix.c b/lib/socket-util-unix.c new file mode 100644 index 000000000..6b451d4f9 --- /dev/null +++ b/lib/socket-util-unix.c @@ -0,0 +1,400 @@ +/* + * Copyright (c) 2014 Nicira, Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include +#include "socket-util.h" +#include +#include +#include +#include +#include +#include +#include +#include +#include "fatal-signal.h" +#include "random.h" +#include "util.h" +#include "vlog.h" + +VLOG_DEFINE_THIS_MODULE(socket_util_unix); + +/* #ifdefs make it a pain to maintain code: you have to try to build both ways. + * Thus, this file compiles all of the code regardless of the target, by + * writing "if (LINUX)" instead of "#ifdef __linux__". */ +#ifdef __linux__ +#define LINUX 1 +#else +#define LINUX 0 +#endif + +#ifndef O_DIRECTORY +#define O_DIRECTORY 0 +#endif + +/* Maximum length of the sun_path member in a struct sockaddr_un, excluding + * space for a null terminator. */ +#define MAX_UN_LEN (sizeof(((struct sockaddr_un *) 0)->sun_path) - 1) + +void +xpipe(int fds[2]) +{ + if (pipe(fds)) { + VLOG_FATAL("failed to create pipe (%s)", ovs_strerror(errno)); + } +} + +void +xpipe_nonblocking(int fds[2]) +{ + xpipe(fds); + xset_nonblocking(fds[0]); + xset_nonblocking(fds[1]); +} + +/* Drain all the data currently in the receive queue of a datagram socket (and + * possibly additional data). There is no way to know how many packets are in + * the receive queue, but we do know that the total number of bytes queued does + * not exceed the receive buffer size, so we pull packets until none are left + * or we've read that many bytes. */ +int +drain_rcvbuf(int fd) +{ + int rcvbuf; + + rcvbuf = get_socket_rcvbuf(fd); + if (rcvbuf < 0) { + return -rcvbuf; + } + + while (rcvbuf > 0) { + /* In Linux, specifying MSG_TRUNC in the flags argument causes the + * datagram length to be returned, even if that is longer than the + * buffer provided. Thus, we can use a 1-byte buffer to discard the + * incoming datagram and still be able to account how many bytes were + * removed from the receive buffer. + * + * On other Unix-like OSes, MSG_TRUNC has no effect in the flags + * argument. */ + char buffer[LINUX ? 1 : 2048]; + ssize_t n_bytes = recv(fd, buffer, sizeof buffer, + MSG_TRUNC | MSG_DONTWAIT); + if (n_bytes <= 0 || n_bytes >= rcvbuf) { + break; + } + rcvbuf -= n_bytes; + } + return 0; +} + +/* Attempts to shorten 'name' by opening a file descriptor for the directory + * part of the name and indirecting through /proc/self/fd//. + * On systems with Linux-like /proc, this works as long as isn't too + * long. + * + * On success, returns 0 and stores the short name in 'short_name' and a + * directory file descriptor to eventually be closed in '*dirfpd'. */ +static int +shorten_name_via_proc(const char *name, char short_name[MAX_UN_LEN + 1], + int *dirfdp) +{ + char *dir, *base; + int dirfd; + int len; + + if (!LINUX) { + return ENAMETOOLONG; + } + + dir = dir_name(name); + dirfd = open(dir, O_DIRECTORY | O_RDONLY); + if (dirfd < 0) { + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); + int error = errno; + + VLOG_WARN_RL(&rl, "%s: open failed (%s)", dir, ovs_strerror(error)); + free(dir); + + return error; + } + free(dir); + + base = base_name(name); + len = snprintf(short_name, MAX_UN_LEN + 1, + "/proc/self/fd/%d/%s", dirfd, base); + free(base); + + if (len >= 0 && len <= MAX_UN_LEN) { + *dirfdp = dirfd; + return 0; + } else { + close(dirfd); + return ENAMETOOLONG; + } +} + +/* Attempts to shorten 'name' by creating a symlink for the directory part of + * the name and indirecting through /. This works on + * systems that support symlinks, as long as isn't too long. + * + * On success, returns 0 and stores the short name in 'short_name' and the + * symbolic link to eventually delete in 'linkname'. */ +static int +shorten_name_via_symlink(const char *name, char short_name[MAX_UN_LEN + 1], + char linkname[MAX_UN_LEN + 1]) +{ + char *abs, *dir, *base; + const char *tmpdir; + int error; + int i; + + abs = abs_file_name(NULL, name); + dir = dir_name(abs); + base = base_name(abs); + free(abs); + + tmpdir = getenv("TMPDIR"); + if (tmpdir == NULL) { + tmpdir = "/tmp"; + } + + for (i = 0; i < 1000; i++) { + int len; + + len = snprintf(linkname, MAX_UN_LEN + 1, + "%s/ovs-un-c-%"PRIu32, tmpdir, random_uint32()); + error = (len < 0 || len > MAX_UN_LEN ? ENAMETOOLONG + : symlink(dir, linkname) ? errno + : 0); + if (error != EEXIST) { + break; + } + } + + if (!error) { + int len; + + fatal_signal_add_file_to_unlink(linkname); + + len = snprintf(short_name, MAX_UN_LEN + 1, "%s/%s", linkname, base); + if (len < 0 || len > MAX_UN_LEN) { + fatal_signal_unlink_file_now(linkname); + error = ENAMETOOLONG; + } + } + + if (error) { + linkname[0] = '\0'; + } + free(dir); + free(base); + + return error; +} + +/* Stores in '*un' a sockaddr_un that refers to file 'name'. Stores in + * '*un_len' the size of the sockaddr_un. + * + * Returns 0 on success, otherwise a positive errno value. + * + * Uses '*dirfdp' and 'linkname' to store references to data when the caller no + * longer needs to use 'un'. On success, freeing these references with + * free_sockaddr_un() is mandatory to avoid a leak; on failure, freeing them is + * unnecessary but harmless. */ +static int +make_sockaddr_un(const char *name, struct sockaddr_un *un, socklen_t *un_len, + int *dirfdp, char linkname[MAX_UN_LEN + 1]) +{ + char short_name[MAX_UN_LEN + 1]; + + *dirfdp = -1; + linkname[0] = '\0'; + if (strlen(name) > MAX_UN_LEN) { + /* 'name' is too long to fit in a sockaddr_un. Try a workaround. */ + int error = shorten_name_via_proc(name, short_name, dirfdp); + if (error == ENAMETOOLONG) { + error = shorten_name_via_symlink(name, short_name, linkname); + } + if (error) { + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1); + + VLOG_WARN_RL(&rl, "Unix socket name %s is longer than maximum " + "%"PRIuSIZE" bytes", name, MAX_UN_LEN); + return error; + } + + name = short_name; + } + + un->sun_family = AF_UNIX; + ovs_strzcpy(un->sun_path, name, sizeof un->sun_path); + *un_len = (offsetof(struct sockaddr_un, sun_path) + + strlen (un->sun_path) + 1); + return 0; +} + +/* Clean up after make_sockaddr_un(). */ +static void +free_sockaddr_un(int dirfd, const char *linkname) +{ + if (dirfd >= 0) { + close(dirfd); + } + if (linkname[0]) { + fatal_signal_unlink_file_now(linkname); + } +} + +/* Binds Unix domain socket 'fd' to a file with permissions 0700. */ +static int +bind_unix_socket(int fd, struct sockaddr *sun, socklen_t sun_len) +{ + /* According to _Unix Network Programming_, umask should affect bind(). */ + mode_t old_umask = umask(0077); + int error = bind(fd, sun, sun_len) ? errno : 0; + umask(old_umask); + return error; +} + +/* Creates a Unix domain socket in the given 'style' (either SOCK_DGRAM or + * SOCK_STREAM) that is bound to '*bind_path' (if 'bind_path' is non-null) and + * connected to '*connect_path' (if 'connect_path' is non-null). If 'nonblock' + * is true, the socket is made non-blocking. + * + * Returns the socket's fd if successful, otherwise a negative errno value. */ +int +make_unix_socket(int style, bool nonblock, + const char *bind_path, const char *connect_path) +{ + int error; + int fd; + + fd = socket(PF_UNIX, style, 0); + if (fd < 0) { + return -errno; + } + + /* Set nonblocking mode right away, if we want it. This prevents blocking + * in connect(), if connect_path != NULL. (In turn, that's a corner case: + * it will only happen if style is SOCK_STREAM or SOCK_SEQPACKET, and only + * if a backlog of un-accepted connections has built up in the kernel.) */ + if (nonblock) { + error = set_nonblocking(fd); + if (error) { + goto error; + } + } + + if (bind_path) { + char linkname[MAX_UN_LEN + 1]; + struct sockaddr_un un; + socklen_t un_len; + int dirfd; + + if (unlink(bind_path) && errno != ENOENT) { + VLOG_WARN("unlinking \"%s\": %s\n", + bind_path, ovs_strerror(errno)); + } + fatal_signal_add_file_to_unlink(bind_path); + + error = make_sockaddr_un(bind_path, &un, &un_len, &dirfd, linkname); + if (!error) { + error = bind_unix_socket(fd, (struct sockaddr *) &un, un_len); + } + free_sockaddr_un(dirfd, linkname); + + if (error) { + goto error; + } + } + + if (connect_path) { + char linkname[MAX_UN_LEN + 1]; + struct sockaddr_un un; + socklen_t un_len; + int dirfd; + + error = make_sockaddr_un(connect_path, &un, &un_len, &dirfd, linkname); + if (!error + && connect(fd, (struct sockaddr*) &un, un_len) + && errno != EINPROGRESS) { + error = errno; + } + free_sockaddr_un(dirfd, linkname); + + if (error) { + goto error; + } + } + + return fd; + +error: + if (error == EAGAIN) { + error = EPROTO; + } + if (bind_path) { + fatal_signal_unlink_file_now(bind_path); + } + close(fd); + return -error; +} + +int +get_unix_name_len(socklen_t sun_len) +{ + return (sun_len >= offsetof(struct sockaddr_un, sun_path) + ? sun_len - offsetof(struct sockaddr_un, sun_path) + : 0); +} + +/* Calls ioctl() on an AF_INET sock, passing the specified 'command' and + * 'arg'. Returns 0 if successful, otherwise a positive errno value. */ +int +af_inet_ioctl(unsigned long int command, const void *arg) +{ + static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER; + static int sock; + + if (ovsthread_once_start(&once)) { + sock = socket(AF_INET, SOCK_DGRAM, 0); + if (sock < 0) { + int error = sock_errno(); + VLOG_ERR("failed to create inet socket: %s", sock_strerror(error)); + sock = -error; + } + ovsthread_once_done(&once); + } + + return (sock < 0 ? -sock + : ioctl(sock, command, arg) == -1 ? errno + : 0); +} + +int +af_inet_ifreq_ioctl(const char *name, struct ifreq *ifr, unsigned long int cmd, + const char *cmd_name) +{ + int error; + + ovs_strzcpy(ifr->ifr_name, name, sizeof ifr->ifr_name); + error = af_inet_ioctl(cmd, ifr); + if (error) { + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20); + VLOG_DBG_RL(&rl, "%s: ioctl(%s) failed: %s", name, cmd_name, + ovs_strerror(error)); + } + return error; +} -- cgit v1.2.1