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/*
* UNIX SOCK_STREAM protocol layer (uxst)
*
* Copyright 2000-2010 Willy Tarreau <w@1wt.eu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <common/compat.h>
#include <common/config.h>
#include <common/debug.h>
#include <common/errors.h>
#include <common/mini-clist.h>
#include <common/standard.h>
#include <common/time.h>
#include <common/version.h>
#include <types/global.h>
#include <proto/fd.h>
#include <proto/log.h>
#include <proto/protocols.h>
#include <proto/proto_uxst.h>
#include <proto/task.h>
static int uxst_bind_listener(struct listener *listener, char *errmsg, int errlen);
static int uxst_bind_listeners(struct protocol *proto, char *errmsg, int errlen);
static int uxst_unbind_listeners(struct protocol *proto);
/* Note: must not be declared <const> as its list will be overwritten */
static struct protocol proto_unix = {
.name = "unix_stream",
.sock_domain = PF_UNIX,
.sock_type = SOCK_STREAM,
.sock_prot = 0,
.sock_family = AF_UNIX,
.sock_addrlen = sizeof(struct sockaddr_un),
.l3_addrlen = sizeof(((struct sockaddr_un*)0)->sun_path),/* path len */
.accept = &listener_accept,
.bind = uxst_bind_listener,
.bind_all = uxst_bind_listeners,
.unbind_all = uxst_unbind_listeners,
.enable_all = enable_all_listeners,
.disable_all = disable_all_listeners,
.get_src = uxst_get_src,
.get_dst = uxst_get_dst,
.listeners = LIST_HEAD_INIT(proto_unix.listeners),
.nb_listeners = 0,
};
/********************************
* 1) low-level socket functions
********************************/
/*
* Retrieves the source address for the socket <fd>, with <dir> indicating
* if we're a listener (=0) or an initiator (!=0). It returns 0 in case of
* success, -1 in case of error. The socket's source address is stored in
* <sa> for <salen> bytes.
*/
int uxst_get_src(int fd, struct sockaddr *sa, socklen_t salen, int dir)
{
if (dir)
return getsockname(fd, sa, &salen);
else
return getpeername(fd, sa, &salen);
}
/*
* Retrieves the original destination address for the socket <fd>, with <dir>
* indicating if we're a listener (=0) or an initiator (!=0). It returns 0 in
* case of success, -1 in case of error. The socket's source address is stored
* in <sa> for <salen> bytes.
*/
int uxst_get_dst(int fd, struct sockaddr *sa, socklen_t salen, int dir)
{
if (dir)
return getpeername(fd, sa, &salen);
else
return getsockname(fd, sa, &salen);
}
/* Tries to destroy the UNIX stream socket <path>. The socket must not be used
* anymore. It practises best effort, and no error is returned.
*/
static void destroy_uxst_socket(const char *path)
{
struct sockaddr_un addr;
int sock, ret;
/* We might have been chrooted, so we may not be able to access the
* socket. In order to avoid bothering the other end, we connect with a
* wrong protocol, namely SOCK_DGRAM. The return code from connect()
* is enough to know if the socket is still live or not. If it's live
* in mode SOCK_STREAM, we get EPROTOTYPE or anything else but not
* ECONNREFUSED. In this case, we do not touch it because it's used
* by some other process.
*/
sock = socket(PF_UNIX, SOCK_DGRAM, 0);
if (sock < 0)
return;
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, path, sizeof(addr.sun_path));
addr.sun_path[sizeof(addr.sun_path) - 1] = 0;
ret = connect(sock, (struct sockaddr *)&addr, sizeof(addr));
if (ret < 0 && errno == ECONNREFUSED) {
/* Connect failed: the socket still exists but is not used
* anymore. Let's remove this socket now.
*/
unlink(path);
}
close(sock);
}
/********************************
* 2) listener-oriented functions
********************************/
/* This function creates a UNIX socket associated to the listener. It changes
* the state from ASSIGNED to LISTEN. The socket is NOT enabled for polling.
* The return value is composed from ERR_NONE, ERR_RETRYABLE and ERR_FATAL.
*/
static int uxst_bind_listener(struct listener *listener, char *errmsg, int errlen)
{
int fd;
char tempname[MAXPATHLEN];
char backname[MAXPATHLEN];
struct sockaddr_un addr;
const char *msg = NULL;
const char *path;
int ret;
/* ensure we never return garbage */
if (errmsg && errlen)
*errmsg = 0;
if (listener->state != LI_ASSIGNED)
return ERR_NONE; /* already bound */
path = ((struct sockaddr_un *)&listener->addr)->sun_path;
/* 1. create socket names */
if (!path[0]) {
msg = "Invalid empty name for a UNIX socket";
goto err_return;
}
ret = snprintf(tempname, MAXPATHLEN, "%s.%d.tmp", path, pid);
if (ret < 0 || ret >= MAXPATHLEN) {
msg = "name too long for UNIX socket";
goto err_return;
}
ret = snprintf(backname, MAXPATHLEN, "%s.%d.bak", path, pid);
if (ret < 0 || ret >= MAXPATHLEN) {
msg = "name too long for UNIX socket";
goto err_return;
}
/* 2. clean existing orphaned entries */
if (unlink(tempname) < 0 && errno != ENOENT) {
msg = "error when trying to unlink previous UNIX socket";
goto err_return;
}
if (unlink(backname) < 0 && errno != ENOENT) {
msg = "error when trying to unlink previous UNIX socket";
goto err_return;
}
/* 3. backup existing socket */
if (link(path, backname) < 0 && errno != ENOENT) {
msg = "error when trying to preserve previous UNIX socket";
goto err_return;
}
/* 4. prepare new socket */
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, tempname, sizeof(addr.sun_path));
addr.sun_path[sizeof(addr.sun_path) - 1] = 0;
fd = socket(PF_UNIX, SOCK_STREAM, 0);
if (fd < 0) {
msg = "cannot create UNIX socket";
goto err_unlink_back;
}
if (fd >= global.maxsock) {
msg = "socket(): not enough free sockets, raise -n argument";
goto err_unlink_temp;
}
if (fcntl(fd, F_SETFL, O_NONBLOCK) == -1) {
msg = "cannot make UNIX socket non-blocking";
goto err_unlink_temp;
}
if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
/* note that bind() creates the socket <tempname> on the file system */
msg = "cannot bind UNIX socket";
goto err_unlink_temp;
}
/* <uid> and <gid> different of -1 will be used to change the socket owner.
* If <mode> is not 0, it will be used to restrict access to the socket.
* While it is known not to be portable on every OS, it's still useful
* where it works.
*/
if (((listener->perm.ux.uid != -1 || listener->perm.ux.gid != -1) &&
(chown(tempname, listener->perm.ux.uid, listener->perm.ux.gid) == -1)) ||
(listener->perm.ux.mode != 0 && chmod(tempname, listener->perm.ux.mode) == -1)) {
msg = "cannot change UNIX socket ownership";
goto err_unlink_temp;
}
if (listen(fd, listener->backlog ? listener->backlog : listener->maxconn) < 0) {
msg = "cannot listen to UNIX socket";
goto err_unlink_temp;
}
/* 5. install.
* Point of no return: we are ready, we'll switch the sockets. We don't
* fear loosing the socket <path> because we have a copy of it in
* backname.
*/
if (rename(tempname, path) < 0) {
msg = "cannot switch final and temporary UNIX sockets";
goto err_rename;
}
/* 6. cleanup */
unlink(backname); /* no need to keep this one either */
/* the socket is now listening */
listener->fd = fd;
listener->state = LI_LISTEN;
/* the function for the accept() event */
fd_insert(fd);
fdtab[fd].iocb = listener->proto->accept;
fdtab[fd].owner = listener; /* reference the listener instead of a task */
return ERR_NONE;
err_rename:
ret = rename(backname, path);
if (ret < 0 && errno == ENOENT)
unlink(path);
err_unlink_temp:
unlink(tempname);
close(fd);
err_unlink_back:
unlink(backname);
err_return:
if (msg && errlen)
snprintf(errmsg, errlen, "%s [%s]", msg, path);
return ERR_FATAL | ERR_ALERT;
}
/* This function closes the UNIX sockets for the specified listener.
* The listener enters the LI_ASSIGNED state. It always returns ERR_NONE.
*/
static int uxst_unbind_listener(struct listener *listener)
{
if (listener->state > LI_ASSIGNED) {
unbind_listener(listener);
destroy_uxst_socket(((struct sockaddr_un *)&listener->addr)->sun_path);
}
return ERR_NONE;
}
/* Add a listener to the list of unix stream listeners. The listener's state
* is automatically updated from LI_INIT to LI_ASSIGNED. The number of
* listeners is updated. This is the function to use to add a new listener.
*/
void uxst_add_listener(struct listener *listener)
{
if (listener->state != LI_INIT)
return;
listener->state = LI_ASSIGNED;
listener->proto = &proto_unix;
LIST_ADDQ(&proto_unix.listeners, &listener->proto_list);
proto_unix.nb_listeners++;
}
/********************************
* 3) protocol-oriented functions
********************************/
/* This function creates all UNIX sockets bound to the protocol entry <proto>.
* It is intended to be used as the protocol's bind_all() function.
* The sockets will be registered but not added to any fd_set, in order not to
* loose them across the fork(). A call to uxst_enable_listeners() is needed
* to complete initialization.
*
* The return value is composed from ERR_NONE, ERR_RETRYABLE and ERR_FATAL.
*/
static int uxst_bind_listeners(struct protocol *proto, char *errmsg, int errlen)
{
struct listener *listener;
int err = ERR_NONE;
list_for_each_entry(listener, &proto->listeners, proto_list) {
err |= uxst_bind_listener(listener, errmsg, errlen);
if (err & ERR_ABORT)
break;
}
return err;
}
/* This function stops all listening UNIX sockets bound to the protocol
* <proto>. It does not detaches them from the protocol.
* It always returns ERR_NONE.
*/
static int uxst_unbind_listeners(struct protocol *proto)
{
struct listener *listener;
list_for_each_entry(listener, &proto->listeners, proto_list)
uxst_unbind_listener(listener);
return ERR_NONE;
}
/********************************
* 4) high-level functions
********************************/
__attribute__((constructor))
static void __uxst_protocol_init(void)
{
protocol_register(&proto_unix);
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/