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      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 
     17 #include <stdio.h>
     18 #include <stdlib.h>
     19 #include <signal.h>
     20 #include <errno.h>
     21 #include <string.h>
     22 #include <sys/stat.h>
     23 #include <sys/types.h>
     24 #include <sys/wait.h>
     25 
     26 #include <fcntl.h>
     27 #include <dirent.h>
     28 
     29 #define LOG_TAG "Netd"
     30 
     31 #include "cutils/log.h"
     32 
     33 #include "CommandListener.h"
     34 #include "NetlinkManager.h"
     35 #include "DnsProxyListener.h"
     36 #include "MDnsSdListener.h"
     37 #include "FwmarkServer.h"
     38 
     39 static void blockSigpipe();
     40 static void remove_pid_file();
     41 static bool write_pid_file();
     42 
     43 const char* const PID_FILE_PATH = "/data/misc/net/netd_pid";
     44 const int PID_FILE_FLAGS = O_CREAT | O_TRUNC | O_WRONLY | O_NOFOLLOW | O_CLOEXEC;
     45 const mode_t PID_FILE_MODE = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;  // mode 0644, rw-r--r--
     46 
     47 int main() {
     48 
     49     CommandListener *cl;
     50     NetlinkManager *nm;
     51     DnsProxyListener *dpl;
     52     MDnsSdListener *mdnsl;
     53     FwmarkServer* fwmarkServer;
     54 
     55     ALOGI("Netd 1.0 starting");
     56     remove_pid_file();
     57 
     58     blockSigpipe();
     59 
     60     if (!(nm = NetlinkManager::Instance())) {
     61         ALOGE("Unable to create NetlinkManager");
     62         exit(1);
     63     };
     64 
     65     cl = new CommandListener();
     66     nm->setBroadcaster((SocketListener *) cl);
     67 
     68     if (nm->start()) {
     69         ALOGE("Unable to start NetlinkManager (%s)", strerror(errno));
     70         exit(1);
     71     }
     72 
     73     // Set local DNS mode, to prevent bionic from proxying
     74     // back to this service, recursively.
     75     setenv("ANDROID_DNS_MODE", "local", 1);
     76     dpl = new DnsProxyListener(CommandListener::sNetCtrl);
     77     if (dpl->startListener()) {
     78         ALOGE("Unable to start DnsProxyListener (%s)", strerror(errno));
     79         exit(1);
     80     }
     81 
     82     mdnsl = new MDnsSdListener();
     83     if (mdnsl->startListener()) {
     84         ALOGE("Unable to start MDnsSdListener (%s)", strerror(errno));
     85         exit(1);
     86     }
     87 
     88     fwmarkServer = new FwmarkServer(CommandListener::sNetCtrl);
     89     if (fwmarkServer->startListener()) {
     90         ALOGE("Unable to start FwmarkServer (%s)", strerror(errno));
     91         exit(1);
     92     }
     93 
     94     /*
     95      * Now that we're up, we can respond to commands
     96      */
     97     if (cl->startListener()) {
     98         ALOGE("Unable to start CommandListener (%s)", strerror(errno));
     99         exit(1);
    100     }
    101 
    102     bool wrote_pid = write_pid_file();
    103 
    104     while(1) {
    105         sleep(30); // 30 sec
    106         if (!wrote_pid) {
    107             wrote_pid = write_pid_file();
    108         }
    109     }
    110 
    111     ALOGI("Netd exiting");
    112     remove_pid_file();
    113     exit(0);
    114 }
    115 
    116 static bool write_pid_file() {
    117     char pid_buf[20];  // current pid_max is 32768, so plenty of room
    118     snprintf(pid_buf, sizeof(pid_buf), "%ld\n", (long)getpid());
    119 
    120     int fd = open(PID_FILE_PATH, PID_FILE_FLAGS, PID_FILE_MODE);
    121     if (fd == -1) {
    122         ALOGE("Unable to create pid file (%s)", strerror(errno));
    123         return false;
    124     }
    125 
    126     // File creation is affected by umask, so make sure the right mode bits are set.
    127     if (fchmod(fd, PID_FILE_MODE) == -1) {
    128         ALOGE("failed to set mode 0%o on %s (%s)", PID_FILE_MODE, PID_FILE_PATH, strerror(errno));
    129         close(fd);
    130         remove_pid_file();
    131         return false;
    132     }
    133 
    134     if (write(fd, pid_buf, strlen(pid_buf)) != (ssize_t)strlen(pid_buf)) {
    135         ALOGE("Unable to write to pid file (%s)", strerror(errno));
    136         close(fd);
    137         remove_pid_file();
    138         return false;
    139     }
    140     close(fd);
    141     return true;
    142 }
    143 
    144 static void remove_pid_file() {
    145     unlink(PID_FILE_PATH);
    146 }
    147 
    148 static void blockSigpipe()
    149 {
    150     sigset_t mask;
    151 
    152     sigemptyset(&mask);
    153     sigaddset(&mask, SIGPIPE);
    154     if (sigprocmask(SIG_BLOCK, &mask, NULL) != 0)
    155         ALOGW("WARNING: SIGPIPE not blocked\n");
    156 }
    157