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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 <netdb.h>
     22 #include <netinet/in.h>
     23 #include <stdlib.h>
     24 #include <sys/socket.h>
     25 #include <sys/types.h>
     26 #include <string.h>
     27 
     28 #define LOG_TAG "DnsProxyListener"
     29 #define DBG 0
     30 
     31 #include <cutils/log.h>
     32 #include <sysutils/SocketClient.h>
     33 
     34 #include "DnsProxyListener.h"
     35 
     36 DnsProxyListener::DnsProxyListener() :
     37                  FrameworkListener("dnsproxyd") {
     38     registerCmd(new GetAddrInfoCmd());
     39     registerCmd(new GetHostByAddrCmd());
     40 }
     41 
     42 DnsProxyListener::GetAddrInfoHandler::~GetAddrInfoHandler() {
     43     free(mHost);
     44     free(mService);
     45     free(mHints);
     46 }
     47 
     48 void DnsProxyListener::GetAddrInfoHandler::start() {
     49     pthread_create(&mThread, NULL,
     50                    DnsProxyListener::GetAddrInfoHandler::threadStart, this);
     51 }
     52 
     53 void* DnsProxyListener::GetAddrInfoHandler::threadStart(void* obj) {
     54     GetAddrInfoHandler* handler = reinterpret_cast<GetAddrInfoHandler*>(obj);
     55     handler->run();
     56     delete handler;
     57     pthread_exit(NULL);
     58     return NULL;
     59 }
     60 
     61 // Sends 4 bytes of big-endian length, followed by the data.
     62 // Returns true on success.
     63 static bool sendLenAndData(SocketClient *c, const int len, const void* data) {
     64     uint32_t len_be = htonl(len);
     65     return c->sendData(&len_be, 4) == 0 &&
     66         (len == 0 || c->sendData(data, len) == 0);
     67 }
     68 
     69 void DnsProxyListener::GetAddrInfoHandler::run() {
     70     if (DBG) {
     71         LOGD("GetAddrInfoHandler, now for %s / %s", mHost, mService);
     72     }
     73 
     74     struct addrinfo* result = NULL;
     75     int rv = getaddrinfo(mHost, mService, mHints, &result);
     76     bool success = (mClient->sendData(&rv, sizeof(rv)) == 0);
     77     if (rv == 0) {
     78         struct addrinfo* ai = result;
     79         while (ai && success) {
     80             success = sendLenAndData(mClient, sizeof(struct addrinfo), ai)
     81                 && sendLenAndData(mClient, ai->ai_addrlen, ai->ai_addr)
     82                 && sendLenAndData(mClient,
     83                                   ai->ai_canonname ? strlen(ai->ai_canonname) + 1 : 0,
     84                                   ai->ai_canonname);
     85             ai = ai->ai_next;
     86         }
     87         success = success && sendLenAndData(mClient, 0, "");
     88     }
     89     if (result) {
     90         freeaddrinfo(result);
     91     }
     92     if (!success) {
     93         LOGW("Error writing DNS result to client");
     94     }
     95     mClient->decRef();
     96 }
     97 
     98 DnsProxyListener::GetAddrInfoCmd::GetAddrInfoCmd() :
     99     NetdCommand("getaddrinfo") {
    100 }
    101 
    102 int DnsProxyListener::GetAddrInfoCmd::runCommand(SocketClient *cli,
    103                                             int argc, char **argv) {
    104     if (DBG) {
    105         for (int i = 0; i < argc; i++) {
    106             LOGD("argv[%i]=%s", i, argv[i]);
    107         }
    108     }
    109     if (argc != 7) {
    110         LOGW("Invalid number of arguments to getaddrinfo: %i", argc);
    111         sendLenAndData(cli, 0, NULL);
    112         return -1;
    113     }
    114 
    115     char* name = argv[1];
    116     if (strcmp("^", name) == 0) {
    117         name = NULL;
    118     } else {
    119         name = strdup(name);
    120     }
    121 
    122     char* service = argv[2];
    123     if (strcmp("^", service) == 0) {
    124         service = NULL;
    125     } else {
    126         service = strdup(service);
    127     }
    128 
    129     struct addrinfo* hints = NULL;
    130     int ai_flags = atoi(argv[3]);
    131     int ai_family = atoi(argv[4]);
    132     int ai_socktype = atoi(argv[5]);
    133     int ai_protocol = atoi(argv[6]);
    134     if (ai_flags != -1 || ai_family != -1 ||
    135         ai_socktype != -1 || ai_protocol != -1) {
    136         hints = (struct addrinfo*) calloc(1, sizeof(struct addrinfo));
    137         hints->ai_flags = ai_flags;
    138         hints->ai_family = ai_family;
    139         hints->ai_socktype = ai_socktype;
    140         hints->ai_protocol = ai_protocol;
    141     }
    142 
    143     if (DBG) {
    144         LOGD("GetAddrInfoHandler for %s / %s",
    145              name ? name : "[nullhost]",
    146              service ? service : "[nullservice]");
    147     }
    148 
    149     cli->incRef();
    150     DnsProxyListener::GetAddrInfoHandler* handler =
    151         new DnsProxyListener::GetAddrInfoHandler(cli, name, service, hints);
    152     handler->start();
    153 
    154     return 0;
    155 }
    156 
    157 /*******************************************************
    158  *                  GetHostByAddr                       *
    159  *******************************************************/
    160 DnsProxyListener::GetHostByAddrCmd::GetHostByAddrCmd() :
    161         NetdCommand("gethostbyaddr") {
    162 }
    163 
    164 int DnsProxyListener::GetHostByAddrCmd::runCommand(SocketClient *cli,
    165                                             int argc, char **argv) {
    166     if (DBG) {
    167         for (int i = 0; i < argc; i++) {
    168             LOGD("argv[%i]=%s", i, argv[i]);
    169         }
    170     }
    171     if (argc != 4) {
    172         LOGW("Invalid number of arguments to gethostbyaddr: %i", argc);
    173         sendLenAndData(cli, 0, NULL);
    174         return -1;
    175     }
    176 
    177     char* addrStr = argv[1];
    178     int addrLen = atoi(argv[2]);
    179     int addrFamily = atoi(argv[3]);
    180 
    181     void* addr = malloc(sizeof(struct in6_addr));
    182     errno = 0;
    183     int result = inet_pton(addrFamily, addrStr, addr);
    184     if (result <= 0) {
    185         LOGW("inet_pton(\"%s\") failed %s", addrStr, strerror(errno));
    186         free(addr);
    187         sendLenAndData(cli, 0, NULL);
    188         return -1;
    189     }
    190 
    191     cli->incRef();
    192     DnsProxyListener::GetHostByAddrHandler* handler =
    193             new DnsProxyListener::GetHostByAddrHandler(cli, addr, addrLen, addrFamily);
    194     handler->start();
    195 
    196     return 0;
    197 }
    198 
    199 DnsProxyListener::GetHostByAddrHandler::~GetHostByAddrHandler() {
    200     free(mAddress);
    201 }
    202 
    203 void DnsProxyListener::GetHostByAddrHandler::start() {
    204     pthread_create(&mThread, NULL,
    205                    DnsProxyListener::GetHostByAddrHandler::threadStart, this);
    206 }
    207 
    208 void* DnsProxyListener::GetHostByAddrHandler::threadStart(void* obj) {
    209     GetHostByAddrHandler* handler = reinterpret_cast<GetHostByAddrHandler*>(obj);
    210     handler->run();
    211     delete handler;
    212     pthread_exit(NULL);
    213     return NULL;
    214 }
    215 
    216 void DnsProxyListener::GetHostByAddrHandler::run() {
    217     if (DBG) {
    218         LOGD("DnsProxyListener::GetHostByAddrHandler::run\n");
    219     }
    220 
    221     struct hostent* hp;
    222 
    223     // NOTE gethostbyaddr should take a void* but bionic thinks it should be char*
    224     hp = gethostbyaddr((char*)mAddress, mAddressLen, mAddressFamily);
    225 
    226     if (DBG) {
    227         LOGD("GetHostByAddrHandler::run gethostbyaddr errno: %s hp->h_name = %s, name_len = %d\n",
    228                 hp ? "success" : strerror(errno),
    229                 (hp && hp->h_name) ? hp->h_name: "null",
    230                 (hp && hp->h_name) ? strlen(hp->h_name)+ 1 : 0);
    231     }
    232 
    233     bool success = sendLenAndData(mClient, (hp && hp->h_name) ? strlen(hp->h_name)+ 1 : 0,
    234             (hp && hp->h_name) ? hp->h_name : "");
    235 
    236     if (!success) {
    237         LOGW("GetHostByAddrHandler: Error writing DNS result to client\n");
    238     }
    239     mClient->decRef();
    240 }
    241