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