InterfaceController.cpp revision b67219a71d1d896bcb34c4a7a797824b88515b2c 
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#include <errno.h>
19#include <malloc.h>
20
21#define LOG_TAG "InterfaceController"
22#include <base/file.h>
23#include <base/stringprintf.h>
24#include <cutils/log.h>
25#include <logwrap/logwrap.h>
26
27#include "InterfaceController.h"
28#include "RouteController.h"
29
30using android::base::ReadFileToString;
31using android::base::StringPrintf;
32using android::base::WriteStringToFile;
33
34const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";
35
36const char sys_net_path[] = "/sys/class/net";
37
38const char wl_util_path[] = "/system/xbin/wlutil";
39
40InterfaceController::InterfaceController() {
41	// Initial IPv6 settings.
42	// By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
43	// This causes RAs to work or not work based on whether forwarding is on, and causes routes
44	// learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
45	// by always setting accept_ra to 2.
46	setAcceptRA("2");
47
48	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);
49
50	// Enable optimistic DAD for IPv6 addresses on all interfaces.
51	setIPv6OptimisticMode("1");
52}
53
54InterfaceController::~InterfaceController() {
55}
56
57int InterfaceController::writeIPv6ProcPath(const char *interface, const char *setting, const char *value) {
58	if (!isIfaceName(interface)) {
59		errno = ENOENT;
60		return -1;
61	}
62	std::string path(StringPrintf("%s/%s/%s", ipv6_proc_path, interface, setting));
63	return WriteStringToFile(value, path);
64}
65
66int InterfaceController::setEnableIPv6(const char *interface, const int on) {
67	// When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
68	// When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
69	// addresses and routes and disables IPv6 on the interface.
70	const char *disable_ipv6 = on ? "0" : "1";
71	return writeIPv6ProcPath(interface, "disable_ipv6", disable_ipv6);
72}
73
74int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
75	// 0: disable IPv6 privacy addresses
76	// 0: enable IPv6 privacy addresses and prefer them over non-privacy ones.
77	return writeIPv6ProcPath(interface, "use_tempaddr", on ? "2" : "0");
78}
79
80// Enables or disables IPv6 ND offload. This is useful for 464xlat on wifi, IPv6 tethering, and
81// generally implementing IPv6 neighbour discovery and duplicate address detection properly.
82// TODO: This should be implemented in wpa_supplicant via driver commands instead.
83int InterfaceController::setIPv6NdOffload(char* interface, const int on) {
84    // Only supported on Broadcom chipsets via wlutil for now.
85    if (access(wl_util_path, X_OK) == 0) {
86        const char *argv[] = {
87            wl_util_path,
88            "-a",
89            interface,
90            "ndoe",
91            on ? "1" : "0"
92        };
93        int ret = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL,
94                                      false, false);
95        ALOGD("%s ND offload on %s: %d (%s)",
96              (on ? "enabling" : "disabling"), interface, ret, strerror(errno));
97        return ret;
98    } else {
99        return 0;
100    }
101}
102
103int InterfaceController::isInterfaceName(const char *name) {
104	return strcmp(name, ".") &&
105		strcmp(name, "..") &&
106		strcmp(name, "default") &&
107		strcmp(name, "all");
108}
109
110void InterfaceController::setOnAllInterfaces(const char* filename, const char* value) {
111	// Set the default value, which is used by any interfaces that are created in the future.
112	writeIPv6ProcPath("default", filename, value);
113
114	// Set the value on all the interfaces that currently exist.
115	DIR* dir = opendir(ipv6_proc_path);
116	if (!dir) {
117		ALOGE("Can't list %s: %s", ipv6_proc_path, strerror(errno));
118		return;
119	}
120	dirent* d;
121	while ((d = readdir(dir))) {
122		if (d->d_type == DT_DIR && isInterfaceName(d->d_name)) {
123			writeIPv6ProcPath(d->d_name, filename, value);
124		}
125	}
126	closedir(dir);
127}
128
129void InterfaceController::setAcceptRA(const char *value) {
130	setOnAllInterfaces("accept_ra", value);
131}
132
133// |tableOrOffset| is interpreted as:
134//     If == 0: default. Routes go into RT6_TABLE_MAIN.
135//     If > 0: user set. Routes go into the specified table.
136//     If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
137//             ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
138//             table 1005, etc.
139void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
140	std::string value(StringPrintf("%d", tableOrOffset));
141	setOnAllInterfaces("accept_ra_rt_table", value.c_str());
142}
143
144int InterfaceController::setMtu(const char *interface, const char *mtu)
145{
146	if (!isIfaceName(interface)) {
147		errno = ENOENT;
148		return -1;
149	}
150	std::string path(StringPrintf("%s/%s/mtu", sys_net_path, interface));
151	return WriteStringToFile(mtu, path);
152}
153
154void InterfaceController::setIPv6OptimisticMode(const char *value) {
155	setOnAllInterfaces("optimistic_dad", value);
156	setOnAllInterfaces("use_optimistic", value);
157}
158