NetlinkEvent.cpp revision b982bce73b7e2c824ffb50115ea382fe45c751a4 
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 <linux/if.h>
27#include <linux/netfilter/nfnetlink.h>
28#include <linux/netfilter_ipv4/ipt_ULOG.h>
29/* From kernel's net/netfilter/xt_quota2.c */
30const int QLOG_NL_EVENT  = 112;
31
32#include <linux/netlink.h>
33#include <linux/rtnetlink.h>
34
35const int NetlinkEvent::NlActionUnknown = 0;
36const int NetlinkEvent::NlActionAdd = 1;
37const int NetlinkEvent::NlActionRemove = 2;
38const int NetlinkEvent::NlActionChange = 3;
39const int NetlinkEvent::NlActionLinkUp = 4;
40const int NetlinkEvent::NlActionLinkDown = 5;
41
42NetlinkEvent::NetlinkEvent() {
43    mAction = NlActionUnknown;
44    memset(mParams, 0, sizeof(mParams));
45    mPath = NULL;
46    mSubsystem = NULL;
47}
48
49NetlinkEvent::~NetlinkEvent() {
50    int i;
51    if (mPath)
52        free(mPath);
53    if (mSubsystem)
54        free(mSubsystem);
55    for (i = 0; i < NL_PARAMS_MAX; i++) {
56        if (!mParams[i])
57            break;
58        free(mParams[i]);
59    }
60}
61
62void NetlinkEvent::dump() {
63    int i;
64
65    for (i = 0; i < NL_PARAMS_MAX; i++) {
66        if (!mParams[i])
67            break;
68        SLOGD("NL param '%s'\n", mParams[i]);
69    }
70}
71
72/*
73 * Parse an binary message from a NETLINK_ROUTE netlink socket.
74 */
75bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
76    size_t sz = size;
77    const struct nlmsghdr *nh = (struct nlmsghdr *) buffer;
78
79    while (NLMSG_OK(nh, sz) && (nh->nlmsg_type != NLMSG_DONE)) {
80
81        if (nh->nlmsg_type == RTM_NEWLINK) {
82            int len = nh->nlmsg_len - sizeof(*nh);
83            struct ifinfomsg *ifi;
84
85            if (sizeof(*ifi) > (size_t) len) {
86                SLOGE("Got a short RTM_NEWLINK message\n");
87                continue;
88            }
89
90            ifi = (ifinfomsg *)NLMSG_DATA(nh);
91            if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) {
92                continue;
93            }
94
95            struct rtattr *rta = (struct rtattr *)
96              ((char *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
97            len = NLMSG_PAYLOAD(nh, sizeof(*ifi));
98
99            while(RTA_OK(rta, len)) {
100                switch(rta->rta_type) {
101                case IFLA_IFNAME:
102                    char buffer[16 + IFNAMSIZ];
103                    snprintf(buffer, sizeof(buffer), "INTERFACE=%s",
104                             (char *) RTA_DATA(rta));
105                    mParams[0] = strdup(buffer);
106                    mAction = (ifi->ifi_flags & IFF_LOWER_UP) ?
107                      NlActionLinkUp : NlActionLinkDown;
108                    mSubsystem = strdup("net");
109                    break;
110                }
111
112                rta = RTA_NEXT(rta, len);
113            }
114
115        } else if (nh->nlmsg_type == QLOG_NL_EVENT) {
116            char *devname;
117            ulog_packet_msg_t *pm;
118            size_t len = nh->nlmsg_len - sizeof(*nh);
119            if (sizeof(*pm) > len) {
120                SLOGE("Got a short QLOG message\n");
121                continue;
122            }
123            pm = (ulog_packet_msg_t *)NLMSG_DATA(nh);
124            devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
125            asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
126            asprintf(&mParams[1], "INTERFACE=%s", devname);
127            mSubsystem = strdup("qlog");
128            mAction = NlActionChange;
129
130        } else {
131                SLOGD("Unexpected netlink message. type=0x%x\n", nh->nlmsg_type);
132        }
133        nh = NLMSG_NEXT(nh, size);
134    }
135
136    return true;
137}
138
139/* If the string between 'str' and 'end' begins with 'prefixlen' characters
140 * from the 'prefix' array, then return 'str + prefixlen', otherwise return
141 * NULL.
142 */
143static const char*
144has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen)
145{
146    if ((end-str) >= (ptrdiff_t)prefixlen && !memcmp(str, prefix, prefixlen))
147        return str + prefixlen;
148    else
149        return NULL;
150}
151
152/* Same as strlen(x) for constant string literals ONLY */
153#define CONST_STRLEN(x)  (sizeof(x)-1)
154
155/* Convenience macro to call has_prefix with a constant string literal  */
156#define HAS_CONST_PREFIX(str,end,prefix)  has_prefix((str),(end),prefix,CONST_STRLEN(prefix))
157
158
159/*
160 * Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT
161 * netlink socket.
162 */
163bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) {
164    const char *s = buffer;
165    const char *end;
166    int param_idx = 0;
167    int i;
168    int first = 1;
169
170    if (size == 0)
171        return false;
172
173    /* Ensure the buffer is zero-terminated, the code below depends on this */
174    buffer[size-1] = '\0';
175
176    end = s + size;
177    while (s < end) {
178        if (first) {
179            const char *p;
180            /* buffer is 0-terminated, no need to check p < end */
181            for (p = s; *p != '@'; p++) {
182                if (!*p) { /* no '@', should not happen */
183                    return false;
184                }
185            }
186            mPath = strdup(p+1);
187            first = 0;
188        } else {
189            const char* a;
190            if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
191                if (!strcmp(a, "add"))
192                    mAction = NlActionAdd;
193                else if (!strcmp(a, "remove"))
194                    mAction = NlActionRemove;
195                else if (!strcmp(a, "change"))
196                    mAction = NlActionChange;
197            } else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
198                mSeq = atoi(a);
199            } else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
200                mSubsystem = strdup(a);
201            } else if (param_idx < NL_PARAMS_MAX) {
202                mParams[param_idx++] = strdup(s);
203            }
204        }
205        s += strlen(s) + 1;
206    }
207    return true;
208}
209
210bool NetlinkEvent::decode(char *buffer, int size, int format) {
211    if (format == NetlinkListener::NETLINK_FORMAT_BINARY) {
212        return parseBinaryNetlinkMessage(buffer, size);
213    } else {
214        return parseAsciiNetlinkMessage(buffer, size);
215    }
216}
217
218const char *NetlinkEvent::findParam(const char *paramName) {
219    size_t len = strlen(paramName);
220    for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != NULL; ++i) {
221        const char *ptr = mParams[i] + len;
222        if (!strncmp(mParams[i], paramName, len) && *ptr == '=')
223            return ++ptr;
224    }
225
226    SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName);
227    return NULL;
228}
229