FwmarkClient.cpp revision 27aacc0d49dbc5c3721ae5ca6f6033be6537c4c3 
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 <sys/socket.h>
22#include <sys/un.h>
23#include <unistd.h>
24
25namespace {
26
27const sockaddr_un FWMARK_SERVER_PATH = {AF_UNIX, "/dev/socket/fwmarkd"};
28
29}  // namespace
30
31bool FwmarkClient::shouldSetFwmark(int family) {
32    return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
33}
34
35FwmarkClient::FwmarkClient() : mChannel(-1) {
36}
37
38FwmarkClient::~FwmarkClient() {
39    if (mChannel >= 0) {
40        close(mChannel);
41    }
42}
43
44int FwmarkClient::send(void* data, size_t len, int fd) {
45    mChannel = socket(AF_UNIX, SOCK_STREAM, 0);
46    if (mChannel == -1) {
47        return -errno;
48    }
49
50    if (TEMP_FAILURE_RETRY(connect(mChannel, reinterpret_cast<const sockaddr*>(&FWMARK_SERVER_PATH),
51                                   sizeof(FWMARK_SERVER_PATH))) == -1) {
52        // If we are unable to connect to the fwmark server, assume there's no error. This protects
53        // against future changes if the fwmark server goes away.
54        return 0;
55    }
56
57    iovec iov;
58    iov.iov_base = data;
59    iov.iov_len = len;
60
61    msghdr message;
62    memset(&message, 0, sizeof(message));
63    message.msg_iov = &iov;
64    message.msg_iovlen = 1;
65
66    union {
67        cmsghdr cmh;
68        char cmsg[CMSG_SPACE(sizeof(fd))];
69    } cmsgu;
70
71    memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
72    message.msg_control = cmsgu.cmsg;
73    message.msg_controllen = sizeof(cmsgu.cmsg);
74
75    cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
76    cmsgh->cmsg_len = CMSG_LEN(sizeof(fd));
77    cmsgh->cmsg_level = SOL_SOCKET;
78    cmsgh->cmsg_type = SCM_RIGHTS;
79    memcpy(CMSG_DATA(cmsgh), &fd, sizeof(fd));
80
81    if (TEMP_FAILURE_RETRY(sendmsg(mChannel, &message, 0)) == -1) {
82        return -errno;
83    }
84
85    int error = 0;
86
87    if (TEMP_FAILURE_RETRY(recv(mChannel, &error, sizeof(error), 0)) == -1) {
88        return -errno;
89    }
90
91    return error;
92}
93