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      1 /*
      2  * Copyright (C) 2010 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 <arpa/inet.h>
     18 #include <dirent.h>
     19 #include <errno.h>
     20 #include <linux/if.h>
     21 #include <math.h>
     22 #include <netdb.h>
     23 #include <netinet/in.h>
     24 #include <stdlib.h>
     25 #include <sys/socket.h>
     26 #include <sys/types.h>
     27 #include <string.h>
     28 #include <pthread.h>
     29 #include <resolv_netid.h>
     30 #include <net/if.h>
     31 
     32 #define LOG_TAG "DnsProxyListener"
     33 #define DBG 0
     34 #define VDBG 0
     35 
     36 #include <chrono>
     37 
     38 #include <cutils/log.h>
     39 #include <binder/IServiceManager.h>
     40 #include <utils/String16.h>
     41 #include <sysutils/SocketClient.h>
     42 
     43 #include "Fwmark.h"
     44 #include "DnsProxyListener.h"
     45 #include "NetdConstants.h"
     46 #include "NetworkController.h"
     47 #include "ResponseCode.h"
     48 #include "android/net/metrics/IDnsEventListener.h"
     49 
     50 using android::String16;
     51 using android::interface_cast;
     52 using android::net::metrics::IDnsEventListener;
     53 
     54 DnsProxyListener::DnsProxyListener(const NetworkController* netCtrl) :
     55         FrameworkListener("dnsproxyd"), mNetCtrl(netCtrl) {
     56     registerCmd(new GetAddrInfoCmd(this));
     57     registerCmd(new GetHostByAddrCmd(this));
     58     registerCmd(new GetHostByNameCmd(this));
     59 }
     60 
     61 DnsProxyListener::GetAddrInfoHandler::GetAddrInfoHandler(
     62         SocketClient *c, char* host, char* service, struct addrinfo* hints,
     63         const struct android_net_context& netcontext,
     64         const android::sp<android::net::metrics::IDnsEventListener>& dnsEventListener)
     65         : mClient(c),
     66           mHost(host),
     67           mService(service),
     68           mHints(hints),
     69           mNetContext(netcontext),
     70           mDnsEventListener(dnsEventListener) {
     71 }
     72 
     73 DnsProxyListener::GetAddrInfoHandler::~GetAddrInfoHandler() {
     74     free(mHost);
     75     free(mService);
     76     free(mHints);
     77 }
     78 
     79 void DnsProxyListener::GetAddrInfoHandler::start() {
     80     pthread_t thread;
     81     pthread_create(&thread, NULL,
     82                    DnsProxyListener::GetAddrInfoHandler::threadStart, this);
     83     pthread_detach(thread);
     84 }
     85 
     86 void* DnsProxyListener::GetAddrInfoHandler::threadStart(void* obj) {
     87     GetAddrInfoHandler* handler = reinterpret_cast<GetAddrInfoHandler*>(obj);
     88     handler->run();
     89     delete handler;
     90     pthread_exit(NULL);
     91     return NULL;
     92 }
     93 
     94 android::sp<IDnsEventListener> DnsProxyListener::getDnsEventListener() {
     95     if (mDnsEventListener == nullptr) {
     96         // Use checkService instead of getService because getService waits for 5 seconds for the
     97         // service to become available. The DNS resolver inside netd is started much earlier in the
     98         // boot sequence than the framework DNS listener, and we don't want to delay all DNS lookups
     99         // for 5 seconds until the DNS listener starts up.
    100         android::sp<android::IBinder> b = android::defaultServiceManager()->checkService(
    101                 android::String16("dns_listener"));
    102         if (b != nullptr) {
    103             mDnsEventListener = interface_cast<IDnsEventListener>(b);
    104         }
    105     }
    106     // If the DNS listener service is dead, the binder call will just return an error, which should
    107     // be fine because the only impact is that we can't log DNS events. In any case, this should
    108     // only happen if the system server is going down, which means it will shortly be taking us down
    109     // with it.
    110     return mDnsEventListener;
    111 }
    112 
    113 static bool sendBE32(SocketClient* c, uint32_t data) {
    114     uint32_t be_data = htonl(data);
    115     return c->sendData(&be_data, sizeof(be_data)) == 0;
    116 }
    117 
    118 // Sends 4 bytes of big-endian length, followed by the data.
    119 // Returns true on success.
    120 static bool sendLenAndData(SocketClient* c, const int len, const void* data) {
    121     return sendBE32(c, len) && (len == 0 || c->sendData(data, len) == 0);
    122 }
    123 
    124 // Returns true on success
    125 static bool sendhostent(SocketClient *c, struct hostent *hp) {
    126     bool success = true;
    127     int i;
    128     if (hp->h_name != NULL) {
    129         success &= sendLenAndData(c, strlen(hp->h_name)+1, hp->h_name);
    130     } else {
    131         success &= sendLenAndData(c, 0, "") == 0;
    132     }
    133 
    134     for (i=0; hp->h_aliases[i] != NULL; i++) {
    135         success &= sendLenAndData(c, strlen(hp->h_aliases[i])+1, hp->h_aliases[i]);
    136     }
    137     success &= sendLenAndData(c, 0, ""); // null to indicate we're done
    138 
    139     uint32_t buf = htonl(hp->h_addrtype);
    140     success &= c->sendData(&buf, sizeof(buf)) == 0;
    141 
    142     buf = htonl(hp->h_length);
    143     success &= c->sendData(&buf, sizeof(buf)) == 0;
    144 
    145     for (i=0; hp->h_addr_list[i] != NULL; i++) {
    146         success &= sendLenAndData(c, 16, hp->h_addr_list[i]);
    147     }
    148     success &= sendLenAndData(c, 0, ""); // null to indicate we're done
    149     return success;
    150 }
    151 
    152 static bool sendaddrinfo(SocketClient* c, struct addrinfo* ai) {
    153     // struct addrinfo {
    154     //      int     ai_flags;       /* AI_PASSIVE, AI_CANONNAME, AI_NUMERICHOST */
    155     //      int     ai_family;      /* PF_xxx */
    156     //      int     ai_socktype;    /* SOCK_xxx */
    157     //      int     ai_protocol;    /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
    158     //      socklen_t ai_addrlen;   /* length of ai_addr */
    159     //      char    *ai_canonname;  /* canonical name for hostname */
    160     //      struct  sockaddr *ai_addr;      /* binary address */
    161     //      struct  addrinfo *ai_next;      /* next structure in linked list */
    162     // };
    163 
    164     // Write the struct piece by piece because we might be a 64-bit netd
    165     // talking to a 32-bit process.
    166     bool success =
    167             sendBE32(c, ai->ai_flags) &&
    168             sendBE32(c, ai->ai_family) &&
    169             sendBE32(c, ai->ai_socktype) &&
    170             sendBE32(c, ai->ai_protocol);
    171     if (!success) {
    172         return false;
    173     }
    174 
    175     // ai_addrlen and ai_addr.
    176     if (!sendLenAndData(c, ai->ai_addrlen, ai->ai_addr)) {
    177         return false;
    178     }
    179 
    180     // strlen(ai_canonname) and ai_canonname.
    181     if (!sendLenAndData(c, ai->ai_canonname ? strlen(ai->ai_canonname) + 1 : 0, ai->ai_canonname)) {
    182         return false;
    183     }
    184 
    185     return true;
    186 }
    187 
    188 void DnsProxyListener::GetAddrInfoHandler::run() {
    189     if (DBG) {
    190         ALOGD("GetAddrInfoHandler, now for %s / %s / {%u,%u,%u,%u,%u}", mHost, mService,
    191                 mNetContext.app_netid, mNetContext.app_mark,
    192                 mNetContext.dns_netid, mNetContext.dns_mark,
    193                 mNetContext.uid);
    194     }
    195 
    196     struct addrinfo* result = NULL;
    197     Stopwatch s;
    198     uint32_t rv = android_getaddrinfofornetcontext(mHost, mService, mHints, &mNetContext, &result);
    199     const int latencyMs = lround(s.timeTaken());
    200 
    201     if (rv) {
    202         // getaddrinfo failed
    203         mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, &rv, sizeof(rv));
    204     } else {
    205         bool success = !mClient->sendCode(ResponseCode::DnsProxyQueryResult);
    206         struct addrinfo* ai = result;
    207         while (ai && success) {
    208             success = sendBE32(mClient, 1) && sendaddrinfo(mClient, ai);
    209             ai = ai->ai_next;
    210         }
    211         success = success && sendBE32(mClient, 0);
    212         if (!success) {
    213             ALOGW("Error writing DNS result to client");
    214         }
    215     }
    216     if (result) {
    217         freeaddrinfo(result);
    218     }
    219     mClient->decRef();
    220     if (mDnsEventListener != nullptr) {
    221         mDnsEventListener->onDnsEvent(mNetContext.dns_netid, IDnsEventListener::EVENT_GETADDRINFO,
    222                                       (int32_t) rv, latencyMs);
    223     }
    224 }
    225 
    226 DnsProxyListener::GetAddrInfoCmd::GetAddrInfoCmd(DnsProxyListener* dnsProxyListener) :
    227     NetdCommand("getaddrinfo"),
    228     mDnsProxyListener(dnsProxyListener) {
    229 }
    230 
    231 int DnsProxyListener::GetAddrInfoCmd::runCommand(SocketClient *cli,
    232                                             int argc, char **argv) {
    233     if (DBG) {
    234         for (int i = 0; i < argc; i++) {
    235             ALOGD("argv[%i]=%s", i, argv[i]);
    236         }
    237     }
    238     if (argc != 8) {
    239         char* msg = NULL;
    240         asprintf( &msg, "Invalid number of arguments to getaddrinfo: %i", argc);
    241         ALOGW("%s", msg);
    242         cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
    243         free(msg);
    244         return -1;
    245     }
    246 
    247     char* name = argv[1];
    248     if (strcmp("^", name) == 0) {
    249         name = NULL;
    250     } else {
    251         name = strdup(name);
    252     }
    253 
    254     char* service = argv[2];
    255     if (strcmp("^", service) == 0) {
    256         service = NULL;
    257     } else {
    258         service = strdup(service);
    259     }
    260 
    261     struct addrinfo* hints = NULL;
    262     int ai_flags = atoi(argv[3]);
    263     int ai_family = atoi(argv[4]);
    264     int ai_socktype = atoi(argv[5]);
    265     int ai_protocol = atoi(argv[6]);
    266     unsigned netId = strtoul(argv[7], NULL, 10);
    267     uid_t uid = cli->getUid();
    268 
    269     struct android_net_context netcontext;
    270     mDnsProxyListener->mNetCtrl->getNetworkContext(netId, uid, &netcontext);
    271 
    272     if (ai_flags != -1 || ai_family != -1 ||
    273         ai_socktype != -1 || ai_protocol != -1) {
    274         hints = (struct addrinfo*) calloc(1, sizeof(struct addrinfo));
    275         hints->ai_flags = ai_flags;
    276         hints->ai_family = ai_family;
    277         hints->ai_socktype = ai_socktype;
    278         hints->ai_protocol = ai_protocol;
    279     }
    280 
    281     if (DBG) {
    282         ALOGD("GetAddrInfoHandler for %s / %s / {%u,%u,%u,%u,%u}",
    283              name ? name : "[nullhost]",
    284              service ? service : "[nullservice]",
    285              netcontext.app_netid, netcontext.app_mark,
    286              netcontext.dns_netid, netcontext.dns_mark,
    287              netcontext.uid);
    288     }
    289 
    290     cli->incRef();
    291     DnsProxyListener::GetAddrInfoHandler* handler =
    292             new DnsProxyListener::GetAddrInfoHandler(cli, name, service, hints, netcontext,
    293                                                      mDnsProxyListener->getDnsEventListener());
    294     handler->start();
    295 
    296     return 0;
    297 }
    298 
    299 /*******************************************************
    300  *                  GetHostByName                      *
    301  *******************************************************/
    302 DnsProxyListener::GetHostByNameCmd::GetHostByNameCmd(DnsProxyListener* dnsProxyListener) :
    303       NetdCommand("gethostbyname"),
    304       mDnsProxyListener(dnsProxyListener) {
    305 }
    306 
    307 int DnsProxyListener::GetHostByNameCmd::runCommand(SocketClient *cli,
    308                                             int argc, char **argv) {
    309     if (DBG) {
    310         for (int i = 0; i < argc; i++) {
    311             ALOGD("argv[%i]=%s", i, argv[i]);
    312         }
    313     }
    314     if (argc != 4) {
    315         char* msg = NULL;
    316         asprintf(&msg, "Invalid number of arguments to gethostbyname: %i", argc);
    317         ALOGW("%s", msg);
    318         cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
    319         free(msg);
    320         return -1;
    321     }
    322 
    323     uid_t uid = cli->getUid();
    324     unsigned netId = strtoul(argv[1], NULL, 10);
    325     char* name = argv[2];
    326     int af = atoi(argv[3]);
    327 
    328     if (strcmp(name, "^") == 0) {
    329         name = NULL;
    330     } else {
    331         name = strdup(name);
    332     }
    333 
    334     uint32_t mark = mDnsProxyListener->mNetCtrl->getNetworkForDns(&netId, uid);
    335 
    336     cli->incRef();
    337     DnsProxyListener::GetHostByNameHandler* handler =
    338             new DnsProxyListener::GetHostByNameHandler(cli, name, af, netId, mark,
    339                                                        mDnsProxyListener->getDnsEventListener());
    340     handler->start();
    341 
    342     return 0;
    343 }
    344 
    345 DnsProxyListener::GetHostByNameHandler::GetHostByNameHandler(
    346         SocketClient* c, char* name, int af, unsigned netId, uint32_t mark,
    347         const android::sp<android::net::metrics::IDnsEventListener>& dnsEventListener)
    348         : mClient(c),
    349           mName(name),
    350           mAf(af),
    351           mNetId(netId),
    352           mMark(mark),
    353           mDnsEventListener(dnsEventListener) {
    354 }
    355 
    356 DnsProxyListener::GetHostByNameHandler::~GetHostByNameHandler() {
    357     free(mName);
    358 }
    359 
    360 void DnsProxyListener::GetHostByNameHandler::start() {
    361     pthread_t thread;
    362     pthread_create(&thread, NULL,
    363             DnsProxyListener::GetHostByNameHandler::threadStart, this);
    364     pthread_detach(thread);
    365 }
    366 
    367 void* DnsProxyListener::GetHostByNameHandler::threadStart(void* obj) {
    368     GetHostByNameHandler* handler = reinterpret_cast<GetHostByNameHandler*>(obj);
    369     handler->run();
    370     delete handler;
    371     pthread_exit(NULL);
    372     return NULL;
    373 }
    374 
    375 void DnsProxyListener::GetHostByNameHandler::run() {
    376     if (DBG) {
    377         ALOGD("DnsProxyListener::GetHostByNameHandler::run\n");
    378     }
    379 
    380     Stopwatch s;
    381     struct hostent* hp = android_gethostbynamefornet(mName, mAf, mNetId, mMark);
    382     const int latencyMs = lround(s.timeTaken());
    383 
    384     if (DBG) {
    385         ALOGD("GetHostByNameHandler::run gethostbyname errno: %s hp->h_name = %s, name_len = %zu\n",
    386                 hp ? "success" : strerror(errno),
    387                 (hp && hp->h_name) ? hp->h_name : "null",
    388                 (hp && hp->h_name) ? strlen(hp->h_name) + 1 : 0);
    389     }
    390 
    391     bool success = true;
    392     if (hp) {
    393         success = mClient->sendCode(ResponseCode::DnsProxyQueryResult) == 0;
    394         success &= sendhostent(mClient, hp);
    395     } else {
    396         success = mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, NULL, 0) == 0;
    397     }
    398 
    399     if (!success) {
    400         ALOGW("GetHostByNameHandler: Error writing DNS result to client\n");
    401     }
    402     mClient->decRef();
    403 
    404     if (mDnsEventListener != nullptr) {
    405         mDnsEventListener->onDnsEvent(mNetId, IDnsEventListener::EVENT_GETHOSTBYNAME,
    406                                       h_errno, latencyMs);
    407     }
    408 }
    409 
    410 
    411 /*******************************************************
    412  *                  GetHostByAddr                      *
    413  *******************************************************/
    414 DnsProxyListener::GetHostByAddrCmd::GetHostByAddrCmd(const DnsProxyListener* dnsProxyListener) :
    415         NetdCommand("gethostbyaddr"),
    416         mDnsProxyListener(dnsProxyListener) {
    417 }
    418 
    419 int DnsProxyListener::GetHostByAddrCmd::runCommand(SocketClient *cli,
    420                                             int argc, char **argv) {
    421     if (DBG) {
    422         for (int i = 0; i < argc; i++) {
    423             ALOGD("argv[%i]=%s", i, argv[i]);
    424         }
    425     }
    426     if (argc != 5) {
    427         char* msg = NULL;
    428         asprintf(&msg, "Invalid number of arguments to gethostbyaddr: %i", argc);
    429         ALOGW("%s", msg);
    430         cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
    431         free(msg);
    432         return -1;
    433     }
    434 
    435     char* addrStr = argv[1];
    436     int addrLen = atoi(argv[2]);
    437     int addrFamily = atoi(argv[3]);
    438     uid_t uid = cli->getUid();
    439     unsigned netId = strtoul(argv[4], NULL, 10);
    440 
    441     void* addr = malloc(sizeof(struct in6_addr));
    442     errno = 0;
    443     int result = inet_pton(addrFamily, addrStr, addr);
    444     if (result <= 0) {
    445         char* msg = NULL;
    446         asprintf(&msg, "inet_pton(\"%s\") failed %s", addrStr, strerror(errno));
    447         ALOGW("%s", msg);
    448         cli->sendMsg(ResponseCode::OperationFailed, msg, false);
    449         free(addr);
    450         free(msg);
    451         return -1;
    452     }
    453 
    454     uint32_t mark = mDnsProxyListener->mNetCtrl->getNetworkForDns(&netId, uid);
    455 
    456     cli->incRef();
    457     DnsProxyListener::GetHostByAddrHandler* handler =
    458             new DnsProxyListener::GetHostByAddrHandler(cli, addr, addrLen, addrFamily, netId, mark);
    459     handler->start();
    460 
    461     return 0;
    462 }
    463 
    464 DnsProxyListener::GetHostByAddrHandler::GetHostByAddrHandler(SocketClient* c,
    465                                                              void* address,
    466                                                              int   addressLen,
    467                                                              int   addressFamily,
    468                                                              unsigned netId,
    469                                                              uint32_t mark)
    470         : mClient(c),
    471           mAddress(address),
    472           mAddressLen(addressLen),
    473           mAddressFamily(addressFamily),
    474           mNetId(netId),
    475           mMark(mark) {
    476 }
    477 
    478 DnsProxyListener::GetHostByAddrHandler::~GetHostByAddrHandler() {
    479     free(mAddress);
    480 }
    481 
    482 void DnsProxyListener::GetHostByAddrHandler::start() {
    483     pthread_t thread;
    484     pthread_create(&thread, NULL,
    485                    DnsProxyListener::GetHostByAddrHandler::threadStart, this);
    486     pthread_detach(thread);
    487 }
    488 
    489 void* DnsProxyListener::GetHostByAddrHandler::threadStart(void* obj) {
    490     GetHostByAddrHandler* handler = reinterpret_cast<GetHostByAddrHandler*>(obj);
    491     handler->run();
    492     delete handler;
    493     pthread_exit(NULL);
    494     return NULL;
    495 }
    496 
    497 void DnsProxyListener::GetHostByAddrHandler::run() {
    498     if (DBG) {
    499         ALOGD("DnsProxyListener::GetHostByAddrHandler::run\n");
    500     }
    501     struct hostent* hp;
    502 
    503     // NOTE gethostbyaddr should take a void* but bionic thinks it should be char*
    504     hp = android_gethostbyaddrfornet((char*)mAddress, mAddressLen, mAddressFamily, mNetId, mMark);
    505 
    506     if (DBG) {
    507         ALOGD("GetHostByAddrHandler::run gethostbyaddr errno: %s hp->h_name = %s, name_len = %zu\n",
    508                 hp ? "success" : strerror(errno),
    509                 (hp && hp->h_name) ? hp->h_name : "null",
    510                 (hp && hp->h_name) ? strlen(hp->h_name) + 1 : 0);
    511     }
    512 
    513     bool success = true;
    514     if (hp) {
    515         success = mClient->sendCode(ResponseCode::DnsProxyQueryResult) == 0;
    516         success &= sendhostent(mClient, hp);
    517     } else {
    518         success = mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, NULL, 0) == 0;
    519     }
    520 
    521     if (!success) {
    522         ALOGW("GetHostByAddrHandler: Error writing DNS result to client\n");
    523     }
    524     mClient->decRef();
    525 }
    526