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      1 /*
      2  * Copyright (C) 2014 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 "FwmarkClient.h"
     18 
     19 #include "FwmarkCommand.h"
     20 
     21 #include <errno.h>
     22 #include <stdlib.h>
     23 #include <string.h>
     24 #include <sys/socket.h>
     25 #include <sys/un.h>
     26 #include <unistd.h>
     27 
     28 namespace {
     29 
     30 const sockaddr_un FWMARK_SERVER_PATH = {AF_UNIX, "/dev/socket/fwmarkd"};
     31 
     32 }  // namespace
     33 
     34 bool FwmarkClient::shouldSetFwmark(int family) {
     35     return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
     36 }
     37 
     38 FwmarkClient::FwmarkClient() : mChannel(-1) {
     39 }
     40 
     41 FwmarkClient::~FwmarkClient() {
     42     if (mChannel >= 0) {
     43         close(mChannel);
     44     }
     45 }
     46 
     47 int FwmarkClient::send(FwmarkCommand* data, int fd) {
     48     mChannel = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
     49     if (mChannel == -1) {
     50         return -errno;
     51     }
     52 
     53     if (TEMP_FAILURE_RETRY(connect(mChannel, reinterpret_cast<const sockaddr*>(&FWMARK_SERVER_PATH),
     54                                    sizeof(FWMARK_SERVER_PATH))) == -1) {
     55         // If we are unable to connect to the fwmark server, assume there's no error. This protects
     56         // against future changes if the fwmark server goes away.
     57         return 0;
     58     }
     59 
     60     iovec iov;
     61     iov.iov_base = data;
     62     iov.iov_len = sizeof(*data);
     63 
     64     msghdr message;
     65     memset(&message, 0, sizeof(message));
     66     message.msg_iov = &iov;
     67     message.msg_iovlen = 1;
     68 
     69     union {
     70         cmsghdr cmh;
     71         char cmsg[CMSG_SPACE(sizeof(fd))];
     72     } cmsgu;
     73 
     74     if (data->cmdId != FwmarkCommand::QUERY_USER_ACCESS) {
     75         memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
     76         message.msg_control = cmsgu.cmsg;
     77         message.msg_controllen = sizeof(cmsgu.cmsg);
     78 
     79         cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
     80         cmsgh->cmsg_len = CMSG_LEN(sizeof(fd));
     81         cmsgh->cmsg_level = SOL_SOCKET;
     82         cmsgh->cmsg_type = SCM_RIGHTS;
     83         memcpy(CMSG_DATA(cmsgh), &fd, sizeof(fd));
     84     }
     85 
     86     if (TEMP_FAILURE_RETRY(sendmsg(mChannel, &message, 0)) == -1) {
     87         return -errno;
     88     }
     89 
     90     int error = 0;
     91 
     92     if (TEMP_FAILURE_RETRY(recv(mChannel, &error, sizeof(error), 0)) == -1) {
     93         return -errno;
     94     }
     95 
     96     return error;
     97 }
     98