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