InterfaceController.cpp revision 2b8d1ead4ea2ff8cb5af1ce88033a8ea0d691402 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *	  http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <dirent.h>
18
19#define LOG_TAG "InterfaceController"
20#include <cutils/log.h>
21#include <logwrap/logwrap.h>
22
23#include "InterfaceController.h"
24#include "RouteController.h"
25
26const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";
27
28const char sys_net_path[] = "/sys/class/net";
29
30const char wl_util_path[] = "/system/xbin/wlutil";
31
32InterfaceController::InterfaceController() {
33	// Initial IPv6 settings.
34	// By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
35	// This causes RAs to work or not work based on whether forwarding is on, and causes routes
36	// learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
37	// by always setting accept_ra to 2.
38	setAcceptRA("2");
39
40	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);
41
42	// Enable optimistic DAD for IPv6 addresses on all interfaces.
43	setIPv6OptimisticMode("1");
44}
45
46InterfaceController::~InterfaceController() {
47}
48
49int InterfaceController::writeIPv6ProcPath(const char *interface, const char *setting, const char *value) {
50	char *path;
51	if (!isIfaceName(interface)) {
52		errno = ENOENT;
53		return -1;
54	}
55	asprintf(&path, "%s/%s/%s", ipv6_proc_path, interface, setting);
56	int success = writeFile(path, value, strlen(value));
57	free(path);
58	return success;
59}
60
61int InterfaceController::setEnableIPv6(const char *interface, const int on) {
62	// When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
63	// When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
64	// addresses and routes and disables IPv6 on the interface.
65	const char *disable_ipv6 = on ? "0" : "1";
66	return writeIPv6ProcPath(interface, "disable_ipv6", disable_ipv6);
67}
68
69int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
70	// 0: disable IPv6 privacy addresses
71	// 0: enable IPv6 privacy addresses and prefer them over non-privacy ones.
72	return writeIPv6ProcPath(interface, "use_tempaddr", on ? "2" : "0");
73}
74
75// Enables or disables IPv6 ND offload. This is useful for 464xlat on wifi, IPv6 tethering, and
76// generally implementing IPv6 neighbour discovery and duplicate address detection properly.
77// TODO: This should be implemented in wpa_supplicant via driver commands instead.
78int InterfaceController::setIPv6NdOffload(char* interface, const int on) {
79    // Only supported on Broadcom chipsets via wlutil for now.
80    if (access(wl_util_path, X_OK) == 0) {
81        const char *argv[] = {
82            wl_util_path,
83            "-a",
84            interface,
85            "ndoe",
86            on ? "1" : "0"
87        };
88        int ret = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL,
89                                      false, false);
90        ALOGD("%s ND offload on %s: %d (%s)",
91              (on ? "enabling" : "disabling"), interface, ret, strerror(errno));
92        return ret;
93    } else {
94        return 0;
95    }
96}
97
98int InterfaceController::isInterfaceName(const char *name) {
99	return strcmp(name, ".") &&
100		strcmp(name, "..") &&
101		strcmp(name, "default") &&
102		strcmp(name, "all");
103}
104
105void InterfaceController::setOnAllInterfaces(const char* filename, const char* value) {
106	// Set the default value, which is used by any interfaces that are created in the future.
107	writeIPv6ProcPath("default", filename, value);
108
109	// Set the value on all the interfaces that currently exist.
110	DIR* dir = opendir(ipv6_proc_path);
111	if (!dir) {
112		ALOGE("Can't list %s: %s", ipv6_proc_path, strerror(errno));
113		return;
114	}
115	dirent* d;
116	while ((d = readdir(dir))) {
117		if (d->d_type == DT_DIR && isInterfaceName(d->d_name)) {
118			writeIPv6ProcPath(d->d_name, filename, value);
119		}
120	}
121	closedir(dir);
122}
123
124void InterfaceController::setAcceptRA(const char *value) {
125	setOnAllInterfaces("accept_ra", value);
126}
127
128// |tableOrOffset| is interpreted as:
129//     If == 0: default. Routes go into RT6_TABLE_MAIN.
130//     If > 0: user set. Routes go into the specified table.
131//     If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
132//             ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
133//             table 1005, etc.
134void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
135	char* value;
136	asprintf(&value, "%d", tableOrOffset);
137	setOnAllInterfaces("accept_ra_rt_table", value);
138	free(value);
139}
140
141int InterfaceController::setMtu(const char *interface, const char *mtu)
142{
143	char *path;
144	if (!isIfaceName(interface)) {
145		errno = ENOENT;
146		return -1;
147	}
148	asprintf(&path, "%s/%s/mtu", sys_net_path, interface);
149	int success = writeFile(path, mtu, strlen(mtu));
150	free(path);
151	return success;
152}
153
154void InterfaceController::setIPv6OptimisticMode(const char *value) {
155	setOnAllInterfaces("optimistic_dad", value);
156	setOnAllInterfaces("use_optimistic", value);
157}
158