1 /*
2  * Copyright (C) 2015 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 #define TRACE_TAG RWX
18 
19 #include "adb_io.h"
20 
21 #include <unistd.h>
22 
23 #if !ADB_HOST
24 #include <sys/socket.h>
25 #include <sys/un.h>
26 #endif
27 
28 #include <thread>
29 
30 #include <android-base/stringprintf.h>
31 
32 #include "adb.h"
33 #include "adb_trace.h"
34 #include "adb_utils.h"
35 #include "sysdeps.h"
36 
37 bool SendProtocolString(borrowed_fd fd, std::string_view s) {
38     unsigned int length = s.size();
39     if (length > MAX_PAYLOAD - 4) {
40         errno = EMSGSIZE;
41         return false;
42     }
43 
44     // The cost of sending two strings outweighs the cost of formatting.
45     // "adb sync" performance is affected by this.
46     auto str = android::base::StringPrintf("%04x", length).append(s);
47     return WriteFdExactly(fd, str);
48 }
49 
50 bool ReadProtocolString(borrowed_fd fd, std::string* s, std::string* error) {
51     char buf[5];
52     if (!ReadFdExactly(fd, buf, 4)) {
53         *error = perror_str("protocol fault (couldn't read status length)");
54         return false;
55     }
56     buf[4] = 0;
57 
58     unsigned long len = strtoul(buf, nullptr, 16);
59     s->resize(len, '\0');
60     if (!ReadFdExactly(fd, &(*s)[0], len)) {
61         *error = perror_str("protocol fault (couldn't read status message)");
62         return false;
63     }
64 
65     return true;
66 }
67 
68 bool SendOkay(borrowed_fd fd) {
69     return WriteFdExactly(fd, "OKAY", 4);
70 }
71 
72 bool SendFail(borrowed_fd fd, std::string_view reason) {
73     return WriteFdExactly(fd, "FAIL", 4) && SendProtocolString(fd, reason);
74 }
75 
76 bool ReadFdExactly(borrowed_fd fd, void* buf, size_t len) {
77     char* p = reinterpret_cast<char*>(buf);
78 
79     size_t len0 = len;
80 
81     D("readx: fd=%d wanted=%zu", fd.get(), len);
82     while (len > 0) {
83         int r = adb_read(fd, p, len);
84         if (r > 0) {
85             len -= r;
86             p += r;
87         } else if (r == -1) {
88             D("readx: fd=%d error %d: %s", fd.get(), errno, strerror(errno));
89             return false;
90         } else {
91             D("readx: fd=%d disconnected", fd.get());
92             errno = 0;
93             return false;
94         }
95     }
96 
97     VLOG(RWX) << "readx: fd=" << fd.get() << " wanted=" << len0 << " got=" << (len0 - len) << " "
98               << dump_hex(reinterpret_cast<const unsigned char*>(buf), len0);
99 
100     return true;
101 }
102 
103 bool WriteFdExactly(borrowed_fd fd, const void* buf, size_t len) {
104     const char* p = reinterpret_cast<const char*>(buf);
105     int r;
106 
107     VLOG(RWX) << "writex: fd=" << fd.get() << " len=" << len << " "
108               << dump_hex(reinterpret_cast<const unsigned char*>(buf), len);
109 
110     while (len > 0) {
111         r = adb_write(fd, p, len);
112         if (r == -1) {
113             D("writex: fd=%d error %d: %s", fd.get(), errno, strerror(errno));
114             if (errno == EAGAIN) {
115                 std::this_thread::yield();
116                 continue;
117             } else if (errno == EPIPE) {
118                 D("writex: fd=%d disconnected", fd.get());
119                 errno = 0;
120                 return false;
121             } else {
122                 return false;
123             }
124         } else {
125             len -= r;
126             p += r;
127         }
128     }
129     return true;
130 }
131 
132 bool WriteFdExactly(borrowed_fd fd, const char* str) {
133     return WriteFdExactly(fd, str, strlen(str));
134 }
135 
136 bool WriteFdExactly(borrowed_fd fd, const std::string& str) {
137     return WriteFdExactly(fd, str.c_str(), str.size());
138 }
139 
140 bool WriteFdFmt(borrowed_fd fd, const char* fmt, ...) {
141     std::string str;
142 
143     va_list ap;
144     va_start(ap, fmt);
145     android::base::StringAppendV(&str, fmt, ap);
146     va_end(ap);
147 
148     return WriteFdExactly(fd, str);
149 }
150 
151 bool ReadOrderlyShutdown(borrowed_fd fd) {
152     char buf[16];
153 
154     // Only call this function if you're sure that the peer does
155     // orderly/graceful shutdown of the socket, closing the socket so that
156     // adb_read() will return 0. If the peer keeps the socket open, adb_read()
157     // will never return.
158     int result = adb_read(fd, buf, sizeof(buf));
159     if (result == -1) {
160         // If errno is EAGAIN, that means this function was called on a
161         // nonblocking socket and it would have blocked (which would be bad
162         // because we'd probably block the main thread where nonblocking IO is
163         // done). Don't do that. If you have a nonblocking socket, use the
164         // fdevent APIs to get called on FDE_READ, and then call this function
165         // if you really need to, but it shouldn't be needed for server sockets.
166         CHECK_NE(errno, EAGAIN);
167 
168         // Note that on Windows, orderly shutdown sometimes causes
169         // recv() == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET. That
170         // can be ignored.
171         return false;
172     } else if (result == 0) {
173         // Peer has performed an orderly/graceful shutdown.
174         return true;
175     } else {
176         // Unexpectedly received data. This is essentially a protocol error
177         // because you should not call this function unless you expect no more
178         // data. We don't repeatedly call adb_read() until we get zero because
179         // we don't know how long that would take, but we do know that the
180         // caller wants to close the socket soon.
181         VLOG(RWX) << "ReadOrderlyShutdown(" << fd.get() << ") unexpectedly read "
182                   << dump_hex(buf, result);
183         // Shutdown the socket to prevent the caller from reading or writing to
184         // it which doesn't make sense if we just read and discarded some data.
185         adb_shutdown(fd);
186         errno = EINVAL;
187         return false;
188     }
189 }
190