FwmarkClient.cpp revision bb881e28e62bc5048f4a62d21104aa25da13b0f1 
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 <errno.h>
20#include <stdlib.h>
21#include <string.h>
22#include <sys/socket.h>
23#include <sys/un.h>
24#include <unistd.h>
25
26namespace {
27
28const sockaddr_un FWMARK_SERVER_PATH = {AF_UNIX, "/dev/socket/fwmarkd"};
29
30}  // namespace
31
32bool FwmarkClient::shouldSetFwmark(int family) {
33    return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
34}
35
36FwmarkClient::FwmarkClient() : mChannel(-1) {
37}
38
39FwmarkClient::~FwmarkClient() {
40    if (mChannel >= 0) {
41        close(mChannel);
42    }
43}
44
45int FwmarkClient::send(void* data, size_t len, int fd) {
46    mChannel = socket(AF_UNIX, SOCK_STREAM, 0);
47    if (mChannel == -1) {
48        return -errno;
49    }
50
51    if (TEMP_FAILURE_RETRY(connect(mChannel, reinterpret_cast<const sockaddr*>(&FWMARK_SERVER_PATH),
52                                   sizeof(FWMARK_SERVER_PATH))) == -1) {
53        // If we are unable to connect to the fwmark server, assume there's no error. This protects
54        // against future changes if the fwmark server goes away.
55        return 0;
56    }
57
58    iovec iov;
59    iov.iov_base = data;
60    iov.iov_len = len;
61
62    msghdr message;
63    memset(&message, 0, sizeof(message));
64    message.msg_iov = &iov;
65    message.msg_iovlen = 1;
66
67    union {
68        cmsghdr cmh;
69        char cmsg[CMSG_SPACE(sizeof(fd))];
70    } cmsgu;
71
72    memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
73    message.msg_control = cmsgu.cmsg;
74    message.msg_controllen = sizeof(cmsgu.cmsg);
75
76    cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
77    cmsgh->cmsg_len = CMSG_LEN(sizeof(fd));
78    cmsgh->cmsg_level = SOL_SOCKET;
79    cmsgh->cmsg_type = SCM_RIGHTS;
80    memcpy(CMSG_DATA(cmsgh), &fd, sizeof(fd));
81
82    if (TEMP_FAILURE_RETRY(sendmsg(mChannel, &message, 0)) == -1) {
83        return -errno;
84    }
85
86    int error = 0;
87
88    if (TEMP_FAILURE_RETRY(recv(mChannel, &error, sizeof(error), 0)) == -1) {
89        return -errno;
90    }
91
92    return error;
93}
94