NetlinkEvent.cpp revision 381f70f52a282e6da780e4b686aaa9c230be2cdc 
1/*
2 * Copyright (C) 2008 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#include <stdlib.h>
17#include <string.h>
18
19#define LOG_TAG "NetlinkEvent"
20#include <cutils/log.h>
21
22#include <sysutils/NetlinkEvent.h>
23
24#include <sys/types.h>
25#include <sys/socket.h>
26#include <netinet/in.h>
27#include <arpa/inet.h>
28#include <net/if.h>
29
30#include <linux/if.h>
31#include <linux/netfilter/nfnetlink.h>
32#include <linux/netfilter_ipv4/ipt_ULOG.h>
33/* From kernel's net/netfilter/xt_quota2.c */
34const int QLOG_NL_EVENT  = 112;
35
36#include <linux/netlink.h>
37#include <linux/rtnetlink.h>
38
39const int NetlinkEvent::NlActionUnknown = 0;
40const int NetlinkEvent::NlActionAdd = 1;
41const int NetlinkEvent::NlActionRemove = 2;
42const int NetlinkEvent::NlActionChange = 3;
43const int NetlinkEvent::NlActionLinkUp = 4;
44const int NetlinkEvent::NlActionLinkDown = 5;
45
46NetlinkEvent::NetlinkEvent() {
47    mAction = NlActionUnknown;
48    memset(mParams, 0, sizeof(mParams));
49    mPath = NULL;
50    mSubsystem = NULL;
51}
52
53NetlinkEvent::~NetlinkEvent() {
54    int i;
55    if (mPath)
56        free(mPath);
57    if (mSubsystem)
58        free(mSubsystem);
59    for (i = 0; i < NL_PARAMS_MAX; i++) {
60        if (!mParams[i])
61            break;
62        free(mParams[i]);
63    }
64}
65
66void NetlinkEvent::dump() {
67    int i;
68
69    for (i = 0; i < NL_PARAMS_MAX; i++) {
70        if (!mParams[i])
71            break;
72        SLOGD("NL param '%s'\n", mParams[i]);
73    }
74}
75
76/*
77 * Decode a RTM_NEWADDR or RTM_DELADDR message.
78 */
79bool NetlinkEvent::parseIfAddrMessage(int type, struct ifaddrmsg *ifaddr,
80                                      int rtasize) {
81    struct rtattr *rta = IFA_RTA(ifaddr);
82    struct ifa_cacheinfo *cacheinfo = NULL;
83    char addrstr[INET6_ADDRSTRLEN] = "";
84
85    // Sanity check.
86    if (type != RTM_NEWADDR && type != RTM_DELADDR) {
87        SLOGE("parseIfAddrMessage on incorrect message type 0x%x\n", type);
88        return false;
89    }
90
91    // For log messages.
92    const char *msgtype = (type == RTM_NEWADDR) ? "RTM_NEWADDR" : "RTM_DELADDR";
93
94    while(RTA_OK(rta, rtasize)) {
95        if (rta->rta_type == IFA_ADDRESS) {
96            // Only look at the first address, because we only support notifying
97            // one change at a time.
98            if (*addrstr != '\0') {
99                SLOGE("Multiple IFA_ADDRESSes in %s, ignoring\n", msgtype);
100                continue;
101            }
102
103            // Convert the IP address to a string.
104            if (ifaddr->ifa_family == AF_INET) {
105                struct in_addr *addr4 = (struct in_addr *) RTA_DATA(rta);
106                if (RTA_PAYLOAD(rta) < sizeof(*addr4)) {
107                    SLOGE("Short IPv4 address (%d bytes) in %s",
108                          RTA_PAYLOAD(rta), msgtype);
109                    continue;
110                }
111                inet_ntop(AF_INET, addr4, addrstr, sizeof(addrstr));
112            } else if (ifaddr->ifa_family == AF_INET6) {
113                struct in6_addr *addr6 = (struct in6_addr *) RTA_DATA(rta);
114                if (RTA_PAYLOAD(rta) < sizeof(*addr6)) {
115                    SLOGE("Short IPv6 address (%d bytes) in %s",
116                          RTA_PAYLOAD(rta), msgtype);
117                    continue;
118                }
119                inet_ntop(AF_INET6, addr6, addrstr, sizeof(addrstr));
120            } else {
121                SLOGE("Unknown address family %d\n", ifaddr->ifa_family);
122                continue;
123            }
124
125            // Find the interface name.
126            char ifname[IFNAMSIZ + 1];
127            if (!if_indextoname(ifaddr->ifa_index, ifname)) {
128                SLOGE("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
129                return false;
130            }
131
132            // Fill in interface information.
133            mAction = (type == RTM_NEWADDR) ? NlActionAdd : NlActionRemove;
134            mSubsystem = strdup("address");
135            asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr,
136                     ifaddr->ifa_prefixlen);
137            asprintf(&mParams[1], "IFACE=%s", ifname);
138            asprintf(&mParams[2], "FLAGS=%u", ifaddr->ifa_flags);
139            asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope);
140        } else if (rta->rta_type == IFA_CACHEINFO) {
141            // Address lifetime information.
142            if (cacheinfo) {
143                // We only support one address.
144                SLOGE("Multiple IFA_CACHEINFOs in %s, ignoring\n", msgtype);
145                continue;
146            }
147
148            if (RTA_PAYLOAD(rta) < sizeof(*cacheinfo)) {
149                SLOGE("Short IFA_CACHEINFO (%d vs. %d bytes) in %s",
150                      RTA_PAYLOAD(rta), sizeof(cacheinfo), msgtype);
151                continue;
152            }
153
154            cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta);
155            asprintf(&mParams[4], "PREFERRED=%u", cacheinfo->ifa_prefered);
156            asprintf(&mParams[5], "VALID=%u", cacheinfo->ifa_valid);
157            asprintf(&mParams[6], "CSTAMP=%u", cacheinfo->cstamp);
158            asprintf(&mParams[7], "TSTAMP=%u", cacheinfo->tstamp);
159        }
160
161        rta = RTA_NEXT(rta, rtasize);
162    }
163
164    if (addrstr[0] == '\0') {
165        SLOGE("No IFA_ADDRESS in %s\n", msgtype);
166        return false;
167    }
168
169    return true;
170}
171
172/*
173 * Parse an binary message from a NETLINK_ROUTE netlink socket.
174 */
175bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
176    size_t sz = size;
177    const struct nlmsghdr *nh = (struct nlmsghdr *) buffer;
178
179    while (NLMSG_OK(nh, sz) && (nh->nlmsg_type != NLMSG_DONE)) {
180
181        if (nh->nlmsg_type == RTM_NEWLINK) {
182            int len = nh->nlmsg_len - sizeof(*nh);
183            struct ifinfomsg *ifi;
184
185            if (sizeof(*ifi) > (size_t) len) {
186                SLOGE("Got a short RTM_NEWLINK message\n");
187                continue;
188            }
189
190            ifi = (ifinfomsg *)NLMSG_DATA(nh);
191            if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) {
192                continue;
193            }
194
195            struct rtattr *rta = (struct rtattr *)
196              ((char *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
197            len = NLMSG_PAYLOAD(nh, sizeof(*ifi));
198
199            while(RTA_OK(rta, len)) {
200                switch(rta->rta_type) {
201                case IFLA_IFNAME:
202                    char buffer[16 + IFNAMSIZ];
203                    snprintf(buffer, sizeof(buffer), "INTERFACE=%s",
204                             (char *) RTA_DATA(rta));
205                    mParams[0] = strdup(buffer);
206                    mAction = (ifi->ifi_flags & IFF_LOWER_UP) ?
207                      NlActionLinkUp : NlActionLinkDown;
208                    mSubsystem = strdup("interface");
209                    break;
210                }
211
212                rta = RTA_NEXT(rta, len);
213            }
214
215        } else if (nh->nlmsg_type == QLOG_NL_EVENT) {
216            char *devname;
217            ulog_packet_msg_t *pm;
218            size_t len = nh->nlmsg_len - sizeof(*nh);
219            if (sizeof(*pm) > len) {
220                SLOGE("Got a short QLOG message\n");
221                continue;
222            }
223            pm = (ulog_packet_msg_t *)NLMSG_DATA(nh);
224            devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
225            asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
226            asprintf(&mParams[1], "INTERFACE=%s", devname);
227            mSubsystem = strdup("qlog");
228            mAction = NlActionChange;
229
230        } else if (nh->nlmsg_type == RTM_NEWADDR ||
231                   nh->nlmsg_type == RTM_DELADDR) {
232            int len = nh->nlmsg_len - sizeof(*nh);
233            struct ifaddrmsg *ifa;
234
235            if (sizeof(*ifa) > (size_t) len) {
236                SLOGE("Got a short RTM_xxxADDR message\n");
237                continue;
238            }
239
240            ifa = (ifaddrmsg *)NLMSG_DATA(nh);
241            size_t rtasize = IFA_PAYLOAD(nh);
242            if (!parseIfAddrMessage(nh->nlmsg_type, ifa, rtasize)) {
243                continue;
244            }
245        } else {
246                SLOGD("Unexpected netlink message. type=0x%x\n", nh->nlmsg_type);
247        }
248        nh = NLMSG_NEXT(nh, size);
249    }
250
251    return true;
252}
253
254/* If the string between 'str' and 'end' begins with 'prefixlen' characters
255 * from the 'prefix' array, then return 'str + prefixlen', otherwise return
256 * NULL.
257 */
258static const char*
259has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen)
260{
261    if ((end-str) >= (ptrdiff_t)prefixlen && !memcmp(str, prefix, prefixlen))
262        return str + prefixlen;
263    else
264        return NULL;
265}
266
267/* Same as strlen(x) for constant string literals ONLY */
268#define CONST_STRLEN(x)  (sizeof(x)-1)
269
270/* Convenience macro to call has_prefix with a constant string literal  */
271#define HAS_CONST_PREFIX(str,end,prefix)  has_prefix((str),(end),prefix,CONST_STRLEN(prefix))
272
273
274/*
275 * Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT
276 * netlink socket.
277 */
278bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) {
279    const char *s = buffer;
280    const char *end;
281    int param_idx = 0;
282    int i;
283    int first = 1;
284
285    if (size == 0)
286        return false;
287
288    /* Ensure the buffer is zero-terminated, the code below depends on this */
289    buffer[size-1] = '\0';
290
291    end = s + size;
292    while (s < end) {
293        if (first) {
294            const char *p;
295            /* buffer is 0-terminated, no need to check p < end */
296            for (p = s; *p != '@'; p++) {
297                if (!*p) { /* no '@', should not happen */
298                    return false;
299                }
300            }
301            mPath = strdup(p+1);
302            first = 0;
303        } else {
304            const char* a;
305            if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
306                if (!strcmp(a, "add"))
307                    mAction = NlActionAdd;
308                else if (!strcmp(a, "remove"))
309                    mAction = NlActionRemove;
310                else if (!strcmp(a, "change"))
311                    mAction = NlActionChange;
312            } else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
313                mSeq = atoi(a);
314            } else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
315                mSubsystem = strdup(a);
316            } else if (param_idx < NL_PARAMS_MAX) {
317                mParams[param_idx++] = strdup(s);
318            }
319        }
320        s += strlen(s) + 1;
321    }
322    return true;
323}
324
325bool NetlinkEvent::decode(char *buffer, int size, int format) {
326    if (format == NetlinkListener::NETLINK_FORMAT_BINARY) {
327        return parseBinaryNetlinkMessage(buffer, size);
328    } else {
329        return parseAsciiNetlinkMessage(buffer, size);
330    }
331}
332
333const char *NetlinkEvent::findParam(const char *paramName) {
334    size_t len = strlen(paramName);
335    for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != NULL; ++i) {
336        const char *ptr = mParams[i] + len;
337        if (!strncmp(mParams[i], paramName, len) && *ptr == '=')
338            return ++ptr;
339    }
340
341    SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName);
342    return NULL;
343}
344