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/***************************************************************************
* libancillary - black magic on Unix domain sockets
* (C) Nicolas George
***************************************************************************/
/*
* fastd Android port
* Copyright (c) 2014-2015, Haofeng "Rick" Lei <ricklei@gmail.com>
* All rights reserved.
*/
/*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* libancillary code from:
* http://www.normalesup.org/~george/comp/libancillary/
* with minor indent/style adjusts to fit fastd project
*/
/* vim: set noexpandtab ts=8 sw=8 sts=8 */
/**
\file
Android specific methods for communicating with GUI
*/
#ifdef __ANDROID__
#include "fastd.h"
#include <sys/un.h>
/** declare a work buffer for sending/receiving \e n handles */
#define ANCIL_FD_BUFFER(n) \
struct { \
struct cmsghdr h; \
int fd[n]; \
}
/** receive \e n_fds handles from unix domain socket \e sock and store in \e fds */
static int ancil_recv_fds_with_buffer(int sock, int *fds, unsigned n_fds, void *buffer) {
struct msghdr msghdr;
char nothing;
struct iovec nothing_ptr;
struct cmsghdr *cmsg;
int i;
nothing_ptr.iov_base = ¬hing;
nothing_ptr.iov_len = 1;
msghdr.msg_name = NULL;
msghdr.msg_namelen = 0;
msghdr.msg_iov = ¬hing_ptr;
msghdr.msg_iovlen = 1;
msghdr.msg_flags = 0;
msghdr.msg_control = buffer;
msghdr.msg_controllen = sizeof(struct cmsghdr) + sizeof(int) * n_fds;
cmsg = CMSG_FIRSTHDR(&msghdr);
cmsg->cmsg_len = msghdr.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
for (i = 0; i < n_fds; i++) {
((int *)CMSG_DATA(cmsg))[i] = -1;
}
if (recvmsg(sock, &msghdr, 0) < 0) {
return(-1);
}
for (i = 0; i < n_fds; i++) {
fds[i] = ((int *)CMSG_DATA(cmsg))[i];
}
n_fds = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
return n_fds;
}
/** shortcut for receiving only one \e fd from \e sock */
static int ancil_recv_fd(int sock, int *fd) {
ANCIL_FD_BUFFER(1) buffer;
return ancil_recv_fds_with_buffer(sock, fd, 1, &buffer) == 1 ? 0 : -1;
}
/** send \e n_fds handles in \e fds to unix domain socket \e sock */
static int ancil_send_fds_with_buffer(int sock, const int *fds, unsigned n_fds, void *buffer) {
struct msghdr msghdr;
char nothing = '!';
struct iovec nothing_ptr;
struct cmsghdr *cmsg;
int i;
nothing_ptr.iov_base = ¬hing;
nothing_ptr.iov_len = 1;
msghdr.msg_name = NULL;
msghdr.msg_namelen = 0;
msghdr.msg_iov = ¬hing_ptr;
msghdr.msg_iovlen = 1;
msghdr.msg_flags = 0;
msghdr.msg_control = buffer;
msghdr.msg_controllen = sizeof(struct cmsghdr) + sizeof(int) * n_fds;
cmsg = CMSG_FIRSTHDR(&msghdr);
cmsg->cmsg_len = msghdr.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
for (i = 0; i < n_fds; i++) {
((int *)CMSG_DATA(cmsg))[i] = fds[i];
}
return sendmsg(sock, &msghdr, 0) >= 0 ? 0 : -1;
}
/** shortcut for sending only one \e fd to \e sock */
static int ancil_send_fd(int sock, int fd)
{
ANCIL_FD_BUFFER(1) buffer;
return ancil_send_fds_with_buffer(sock, &fd, 1, &buffer);
}
/*
* libancillary end
*/
/** name of unix domain socket for communication with Android FastdVpnService */
#define CTRL_SOCK_NAME "fastd_tun_sock"
/** message sent by Android FastdVpnService to indicate successful protection of socket */
#define PROTECT_OK 'X'
/** message sent by Android FastdVpnService when protecting socket failed */
#define PROTECT_ERROR 'E'
/** establish the unix domain socket with Android GUI */
static void init_ctrl_sock(void) {
/* Must keep consistent with FastdVpnService */
struct sockaddr_un addr;
if ((ctx.android_ctrl_sock_fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
exit_errno("could not create unix domain socket");
}
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
addr.sun_path[0] = 0; /* Linux's abstract unix domain socket name */
strncpy(addr.sun_path + 1, CTRL_SOCK_NAME, sizeof(addr.sun_path) - 2);
int socklen = offsetof(struct sockaddr_un, sun_path) + strlen(CTRL_SOCK_NAME) + 1;
if (connect(ctx.android_ctrl_sock_fd, (struct sockaddr*)&addr, socklen) == -1) {
exit_errno("could not connect to Android LocalServerSocket");
}
}
/** receive TUN fd from Android GUI; this is the only way to open TUN device on non-rooted Android */
int fastd_android_receive_tunfd(void) {
init_ctrl_sock();
int handle;
if (ancil_recv_fd(ctx.android_ctrl_sock_fd, &handle)) {
exit_errno("could not receive TUN handle from Android");
} else {
pr_debug("received fd: %u", handle);
}
return handle;
}
/** send fastd pid to Android GUI for later signal sending (HUP, TERM etc) */
void fastd_android_send_pid(void) {
char pid[20];
snprintf(pid, sizeof(pid), "%u", (unsigned)getpid());
if (write(ctx.android_ctrl_sock_fd, pid, strlen(pid)) != strlen(pid)) {
exit_errno("send pid");
}
}
/** report \e fd to Android GUI to be protected (i.e. not to be routed via TUN) */
bool fastd_android_protect_socket(int fd) {
if (!conf.android_integration) {
/* rooted/non-GUI mode */
return true;
}
pr_debug("sending fd to protect");
if (ancil_send_fd(ctx.android_ctrl_sock_fd, fd) == -1) {
exit_errno("could not send handle to Android for protecting");
}
char buf[20];
if (read(ctx.android_ctrl_sock_fd, buf, sizeof(buf)) == -1) {
exit_errno("read ack");
}
return buf[0] == PROTECT_OK;
}
#endif /* __ANDROID__ */
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