1 /*
2 * Copyright (C) 2019 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 "adbconnection/server.h"
18
19 #include <sys/epoll.h>
20 #include <sys/socket.h>
21 #include <sys/un.h>
22 #include <unistd.h>
23
24 #include <algorithm>
25 #include <array>
26 #include <vector>
27
28 #include <android-base/logging.h>
29 #include <android-base/unique_fd.h>
30
31 using android::base::unique_fd;
32
33 #define JDWP_CONTROL_NAME "\0jdwp-control"
34 #define JDWP_CONTROL_NAME_LEN (sizeof(JDWP_CONTROL_NAME) - 1)
35
36 static_assert(JDWP_CONTROL_NAME_LEN <= sizeof(reinterpret_cast<sockaddr_un*>(0)->sun_path));
37
38 // Listen for incoming jdwp clients forever.
adbconnection_listen(void (* callback)(int fd,pid_t pid))39 void adbconnection_listen(void (*callback)(int fd, pid_t pid)) {
40 sockaddr_un addr = {};
41 socklen_t addrlen = JDWP_CONTROL_NAME_LEN + sizeof(addr.sun_family);
42
43 addr.sun_family = AF_UNIX;
44 memcpy(addr.sun_path, JDWP_CONTROL_NAME, JDWP_CONTROL_NAME_LEN);
45
46 unique_fd s(socket(AF_UNIX, SOCK_SEQPACKET | SOCK_NONBLOCK | SOCK_CLOEXEC, 0));
47 if (s < 0) {
48 PLOG(ERROR) << "failed to create JDWP control socket";
49 return;
50 }
51
52 if (bind(s.get(), reinterpret_cast<sockaddr*>(&addr), addrlen) < 0) {
53 PLOG(ERROR) << "failed to bind JDWP control socket";
54 return;
55 }
56
57 if (listen(s.get(), 4) < 0) {
58 PLOG(ERROR) << "failed to listen on JDWP control socket";
59 return;
60 }
61
62 std::vector<unique_fd> pending_connections;
63
64 unique_fd epfd(epoll_create1(EPOLL_CLOEXEC));
65 std::array<epoll_event, 16> events;
66
67 events[0].events = EPOLLIN;
68 events[0].data.fd = -1;
69 if (epoll_ctl(epfd.get(), EPOLL_CTL_ADD, s.get(), &events[0]) != 0) {
70 LOG(FATAL) << "failed to register event with epoll fd";
71 }
72
73 while (true) {
74 int epoll_rc = TEMP_FAILURE_RETRY(epoll_wait(epfd.get(), events.data(), events.size(), -1));
75 if (epoll_rc == -1) {
76 PLOG(FATAL) << "epoll_wait failed";
77 }
78
79 for (int i = 0; i < epoll_rc; ++i) {
80 const epoll_event& event = events[i];
81 if (event.data.fd == -1) {
82 unique_fd client(
83 TEMP_FAILURE_RETRY(accept4(s.get(), nullptr, nullptr, SOCK_NONBLOCK | SOCK_CLOEXEC)));
84
85 if (client == -1) {
86 PLOG(WARNING) << "failed to accept client on JDWP control socket";
87 continue;
88 }
89
90 epoll_event register_event;
91 register_event.events = EPOLLIN;
92 register_event.data.fd = client.get();
93
94 if (epoll_ctl(epfd.get(), EPOLL_CTL_ADD, client.get(), ®ister_event) != 0) {
95 PLOG(FATAL) << "failed to register JDWP client with epoll";
96 }
97
98 pending_connections.emplace_back(std::move(client));
99 } else {
100 // n^2, but the backlog should be short.
101 auto it = std::find_if(pending_connections.begin(), pending_connections.end(),
102 [&](const unique_fd& fd) { return fd.get() == event.data.fd; });
103
104 if (it == pending_connections.end()) {
105 LOG(FATAL) << "failed to find JDWP client (" << event.data.fd
106 << ") in pending connections";
107 }
108
109 // Massively oversized buffer: we're expecting an int32_t from the other end.
110 char buf[32];
111 int rc = TEMP_FAILURE_RETRY(recv(it->get(), buf, sizeof(buf), MSG_DONTWAIT));
112 if (rc != 4) {
113 LOG(ERROR) << "received data of incorrect size from JDWP client: read " << rc
114 << ", expected 4";
115 } else {
116 int32_t pid;
117 memcpy(&pid, buf, sizeof(pid));
118 callback(it->release(), static_cast<pid_t>(pid));
119 }
120
121 if (epoll_ctl(epfd.get(), EPOLL_CTL_DEL, event.data.fd, nullptr) != 0) {
122 LOG(FATAL) << "failed to delete fd from JDWP epoll fd";
123 }
124
125 pending_connections.erase(it);
126 }
127 }
128 }
129 }
130