InterfaceController.cpp revision e1da484b30196cc6ec496407e32c67bcb5295bec 
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::StringPrintf;
31using android::base::WriteStringToFile;
32
33namespace {
34
35const char ipv6_proc_path[] = "/proc/sys/net/ipv6/conf";
36
37const char sys_net_path[] = "/sys/class/net";
38
39const char wl_util_path[] = "/system/xbin/wlutil";
40
41bool isInterfaceName(const char *name) {
42    return strcmp(name, ".") &&
43            strcmp(name, "..") &&
44            strcmp(name, "default") &&
45            strcmp(name, "all");
46}
47
48int writeValueToPath(
49        const char* dirname, const char* subdirname, const char* basename,
50        const char* value) {
51    std::string path(StringPrintf("%s/%s/%s", dirname, subdirname, basename));
52    return WriteStringToFile(value, path);
53}
54
55void setOnAllInterfaces(const char* dirname, const char* basename, const char* value) {
56    // Set the default value, which is used by any interfaces that are created in the future.
57    writeValueToPath(dirname, "default", basename, value);
58
59    // Set the value on all the interfaces that currently exist.
60    DIR* dir = opendir(dirname);
61    if (!dir) {
62        ALOGE("Can't list %s: %s", dirname, strerror(errno));
63        return;
64    }
65    dirent* d;
66    while ((d = readdir(dir))) {
67        if ((d->d_type != DT_DIR) || !isInterfaceName(d->d_name)) {
68            continue;
69        }
70        writeValueToPath(dirname, d->d_name, basename, value);
71    }
72    closedir(dir);
73}
74
75}  // namespace
76
77InterfaceController::InterfaceController() {
78	// Initial IPv6 settings.
79	// By default, accept_ra is set to 1 (accept RAs unless forwarding is on) on all interfaces.
80	// This causes RAs to work or not work based on whether forwarding is on, and causes routes
81	// learned from RAs to go away when forwarding is turned on. Make this behaviour predictable
82	// by always setting accept_ra to 2.
83	setAcceptRA("2");
84
85	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);
86
87	// Enable optimistic DAD for IPv6 addresses on all interfaces.
88	setIPv6OptimisticMode("1");
89}
90
91InterfaceController::~InterfaceController() {
92}
93
94int InterfaceController::setEnableIPv6(const char *interface, const int on) {
95    if (!isIfaceName(interface)) {
96        errno = ENOENT;
97        return -1;
98    }
99    // When disable_ipv6 changes from 1 to 0, the kernel starts autoconf.
100    // When disable_ipv6 changes from 0 to 1, the kernel clears all autoconf
101    // addresses and routes and disables IPv6 on the interface.
102    const char *disable_ipv6 = on ? "0" : "1";
103    return writeValueToPath(ipv6_proc_path, interface, "disable_ipv6", disable_ipv6);
104}
105
106int InterfaceController::setIPv6PrivacyExtensions(const char *interface, const int on) {
107    if (!isIfaceName(interface)) {
108        errno = ENOENT;
109        return -1;
110    }
111    // 0: disable IPv6 privacy addresses
112    // 0: enable IPv6 privacy addresses and prefer them over non-privacy ones.
113    return writeValueToPath(ipv6_proc_path, interface, "use_tempaddr", on ? "2" : "0");
114}
115
116// Enables or disables IPv6 ND offload. This is useful for 464xlat on wifi, IPv6 tethering, and
117// generally implementing IPv6 neighbour discovery and duplicate address detection properly.
118// TODO: This should be implemented in wpa_supplicant via driver commands instead.
119int InterfaceController::setIPv6NdOffload(char* interface, const int on) {
120    // Only supported on Broadcom chipsets via wlutil for now.
121    if (access(wl_util_path, X_OK) == 0) {
122        const char *argv[] = {
123            wl_util_path,
124            "-a",
125            interface,
126            "ndoe",
127            on ? "1" : "0"
128        };
129        int ret = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL,
130                                      false, false);
131        ALOGD("%s ND offload on %s: %d (%s)",
132              (on ? "enabling" : "disabling"), interface, ret, strerror(errno));
133        return ret;
134    } else {
135        return 0;
136    }
137}
138
139void InterfaceController::setAcceptRA(const char *value) {
140    setOnAllInterfaces(ipv6_proc_path, "accept_ra", value);
141}
142
143// |tableOrOffset| is interpreted as:
144//     If == 0: default. Routes go into RT6_TABLE_MAIN.
145//     If > 0: user set. Routes go into the specified table.
146//     If < 0: automatic. The absolute value is intepreted as an offset and added to the interface
147//             ID to get the table. If it's set to -1000, routes from interface ID 5 will go into
148//             table 1005, etc.
149void InterfaceController::setAcceptRARouteTable(int tableOrOffset) {
150    std::string value(StringPrintf("%d", tableOrOffset));
151    setOnAllInterfaces(ipv6_proc_path, "accept_ra_rt_table", value.c_str());
152}
153
154int InterfaceController::setMtu(const char *interface, const char *mtu)
155{
156    if (!isIfaceName(interface)) {
157        errno = ENOENT;
158        return -1;
159    }
160    return writeValueToPath(sys_net_path, interface, "mtu", mtu);
161}
162
163void InterfaceController::setIPv6OptimisticMode(const char *value) {
164    setOnAllInterfaces(ipv6_proc_path, "optimistic_dad", value);
165    setOnAllInterfaces(ipv6_proc_path, "use_optimistic", value);
166}
167