include/cutils/sockets.h

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * 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.
 */

#ifndef __CUTILS_SOCKETS_H
#define __CUTILS_SOCKETS_H

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#ifdef HAVE_WINSOCK
#include <winsock2.h>
typedef int  socklen_t;
#elif HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#define ANDROID_SOCKET_ENV_PREFIX	"ANDROID_SOCKET_"
#define ANDROID_SOCKET_DIR		"/dev/socket"

#ifdef __cplusplus
extern "C" {
#endif

/*
 * android_get_control_socket - simple helper function to get the file
 * descriptor of our init-managed Unix domain socket. `name' is the name of the
 * socket, as given in init.rc. Returns -1 on error.
 *
 * This is inline and not in libcutils proper because we want to use this in
 * third-party daemons with minimal modification.
 */
static inline int android_get_control_socket(const char *name)
{
	char key[64] = ANDROID_SOCKET_ENV_PREFIX;
	const char *val;
	int fd;

	/* build our environment variable, counting cycles like a wolf ... */
#if HAVE_STRLCPY
	strlcpy(key + sizeof(ANDROID_SOCKET_ENV_PREFIX) - 1,
		name,
		sizeof(key) - sizeof(ANDROID_SOCKET_ENV_PREFIX));
#else	/* for the host, which may lack the almightly strncpy ... */
	strncpy(key + sizeof(ANDROID_SOCKET_ENV_PREFIX) - 1,
		name,
		sizeof(key) - sizeof(ANDROID_SOCKET_ENV_PREFIX));
	key[sizeof(key)-1] = '\0';
#endif

	val = getenv(key);
	if (!val)
		return -1;

	errno = 0;
	fd = strtol(val, NULL, 10);
	if (errno)
		return -1;

	return fd;
}

/*
 * See also android.os.LocalSocketAddress.Namespace
 */
// Linux "abstract" (non-filesystem) namespace
#define ANDROID_SOCKET_NAMESPACE_ABSTRACT 0
// Android "reserved" (/dev/socket) namespace
#define ANDROID_SOCKET_NAMESPACE_RESERVED 1
// Normal filesystem namespace
#define ANDROID_SOCKET_NAMESPACE_FILESYSTEM 2

extern int socket_loopback_client(int port, int type);
extern int socket_network_client(const char *host, int port, int type);
extern int socket_loopback_server(int port, int type);
extern int socket_local_server(const char *name, int namespaceId, int type);
extern int socket_local_server_bind(int s, const char *name, int namespaceId);
extern int socket_local_client_connect(int fd, 
        const char *name, int namespaceId, int type);
extern int socket_local_client(const char *name, int namespaceId, int type);
extern int socket_inaddr_any_server(int port, int type);

/*
 * socket_peer_is_trusted - Takes a socket which is presumed to be a
 * connected local socket (e.g. AF_LOCAL) and returns whether the peer
 * (the userid that owns the process on the other end of that socket)
 * is one of the two trusted userids, root or shell.
 *
 * Note: This only works as advertised on the Android OS and always
 * just returns true when called on other operating systems.
 */
extern bool socket_peer_is_trusted(int fd);

#ifdef __cplusplus
}
#endif

#endif /* __CUTILS_SOCKETS_H */