FwmarkClient.cpp revision 5fc275794ab41d110abbdb7683ed9db45918985f 
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
24namespace {
25
26const sockaddr_un FWMARK_SERVER_PATH = {AF_UNIX, "/dev/socket/fwmarkd"};
27
28}  // namespace
29
30bool FwmarkClient::shouldSetFwmark(int family) {
31    return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
32}
33
34FwmarkClient::FwmarkClient() : mChannel(-1) {
35}
36
37FwmarkClient::~FwmarkClient() {
38    if (mChannel >= 0) {
39        // We don't care about errors while closing the channel, so restore any previous error.
40        int error = errno;
41        close(mChannel);
42        errno = error;
43    }
44}
45
46bool FwmarkClient::send(void* data, size_t len, int fd) {
47    mChannel = socket(AF_UNIX, SOCK_STREAM, 0);
48    if (mChannel == -1) {
49        return false;
50    }
51
52    if (TEMP_FAILURE_RETRY(connect(mChannel, reinterpret_cast<const sockaddr*>(&FWMARK_SERVER_PATH),
53                                   sizeof(FWMARK_SERVER_PATH))) == -1) {
54        // If we are unable to connect to the fwmark server, assume there's no error. This protects
55        // against future changes if the fwmark server goes away.
56        errno = 0;
57        return true;
58    }
59
60    iovec iov;
61    iov.iov_base = data;
62    iov.iov_len = len;
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    memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
75    message.msg_control = cmsgu.cmsg;
76    message.msg_controllen = sizeof(cmsgu.cmsg);
77
78    cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
79    cmsgh->cmsg_len = CMSG_LEN(sizeof(fd));
80    cmsgh->cmsg_level = SOL_SOCKET;
81    cmsgh->cmsg_type = SCM_RIGHTS;
82    memcpy(CMSG_DATA(cmsgh), &fd, sizeof(fd));
83
84    if (TEMP_FAILURE_RETRY(sendmsg(mChannel, &message, 0)) == -1) {
85        return false;
86    }
87
88    int error = 0;
89    if (TEMP_FAILURE_RETRY(recv(mChannel, &error, sizeof(error), 0)) == -1) {
90        return false;
91    }
92
93    errno = error;
94    return !error;
95}
96