Rename android_ctrl_sock.c to android.c

1 files changed, 217 insertions, 0 deletions

diff --git a/src/android.c b/src/android.c
new file mode 100644
index 0000000..c0620c8
--- /dev/null
+++ b/src/android.c
@@ -0,0 +1,217 @@
+/***************************************************************************
+ * 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 = &nothing;
+	nothing_ptr.iov_len = 1;
+	msghdr.msg_name = NULL;
+	msghdr.msg_namelen = 0;
+	msghdr.msg_iov = &nothing_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 = &nothing;
+	nothing_ptr.iov_len = 1;
+	msghdr.msg_name = NULL;
+	msghdr.msg_namelen = 0;
+	msghdr.msg_iov = &nothing_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)) {
+		pr_error("could not receive TUN handle from Android");
+		return -1;
+	}
+
+	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__ */
+