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#include <android-base/stringprintf.h>
24
25#include "adb.h"
26#include "adb_trace.h"
27#include "adb_utils.h"
28#include "sysdeps.h"
29
30bool SendProtocolString(int fd, const std::string& s) {
31    unsigned int length = s.size();
32    if (length > MAX_PAYLOAD_V1 - 4) {
33        errno = EMSGSIZE;
34        return false;
35    }
36
37    // The cost of sending two strings outweighs the cost of formatting.
38    // "adb sync" performance is affected by this.
39    return WriteFdFmt(fd, "%04x%.*s", length, length, s.c_str());
40}
41
42bool ReadProtocolString(int fd, std::string* s, std::string* error) {
43    char buf[5];
44    if (!ReadFdExactly(fd, buf, 4)) {
45        *error = perror_str("protocol fault (couldn't read status length)");
46        return false;
47    }
48    buf[4] = 0;
49
50    unsigned long len = strtoul(buf, 0, 16);
51    s->resize(len, '\0');
52    if (!ReadFdExactly(fd, &(*s)[0], len)) {
53        *error = perror_str("protocol fault (couldn't read status message)");
54        return false;
55    }
56
57    return true;
58}
59
60bool SendOkay(int fd) {
61    return WriteFdExactly(fd, "OKAY", 4);
62}
63
64bool SendFail(int fd, const std::string& reason) {
65    return WriteFdExactly(fd, "FAIL", 4) && SendProtocolString(fd, reason);
66}
67
68bool ReadFdExactly(int fd, void* buf, size_t len) {
69    char* p = reinterpret_cast<char*>(buf);
70
71    size_t len0 = len;
72
73    D("readx: fd=%d wanted=%zu", fd, len);
74    while (len > 0) {
75        int r = adb_read(fd, p, len);
76        if (r > 0) {
77            len -= r;
78            p += r;
79        } else if (r == -1) {
80            D("readx: fd=%d error %d: %s", fd, errno, strerror(errno));
81            return false;
82        } else {
83            D("readx: fd=%d disconnected", fd);
84            errno = 0;
85            return false;
86        }
87    }
88
89    VLOG(RWX) << "readx: fd=" << fd << " wanted=" << len0 << " got=" << (len0 - len)
90              << " " << dump_hex(reinterpret_cast<const unsigned char*>(buf), len0);
91
92    return true;
93}
94
95bool WriteFdExactly(int fd, const void* buf, size_t len) {
96    const char* p = reinterpret_cast<const char*>(buf);
97    int r;
98
99    VLOG(RWX) << "writex: fd=" << fd << " len=" << len
100              << " " << dump_hex(reinterpret_cast<const unsigned char*>(buf), len);
101
102    while (len > 0) {
103        r = adb_write(fd, p, len);
104        if (r == -1) {
105            D("writex: fd=%d error %d: %s", fd, errno, strerror(errno));
106            if (errno == EAGAIN) {
107                adb_sleep_ms(1); // just yield some cpu time
108                continue;
109            } else if (errno == EPIPE) {
110                D("writex: fd=%d disconnected", fd);
111                errno = 0;
112                return false;
113            } else {
114                return false;
115            }
116        } else {
117            len -= r;
118            p += r;
119        }
120    }
121    return true;
122}
123
124bool WriteFdExactly(int fd, const char* str) {
125    return WriteFdExactly(fd, str, strlen(str));
126}
127
128bool WriteFdExactly(int fd, const std::string& str) {
129    return WriteFdExactly(fd, str.c_str(), str.size());
130}
131
132bool WriteFdFmt(int fd, const char* fmt, ...) {
133    std::string str;
134
135    va_list ap;
136    va_start(ap, fmt);
137    android::base::StringAppendV(&str, fmt, ap);
138    va_end(ap);
139
140    return WriteFdExactly(fd, str);
141}
142
143bool ReadOrderlyShutdown(int fd) {
144    char buf[16];
145
146    // Only call this function if you're sure that the peer does
147    // orderly/graceful shutdown of the socket, closing the socket so that
148    // adb_read() will return 0. If the peer keeps the socket open, adb_read()
149    // will never return.
150    int result = adb_read(fd, buf, sizeof(buf));
151    if (result == -1) {
152        // If errno is EAGAIN, that means this function was called on a
153        // nonblocking socket and it would have blocked (which would be bad
154        // because we'd probably block the main thread where nonblocking IO is
155        // done). Don't do that. If you have a nonblocking socket, use the
156        // fdevent APIs to get called on FDE_READ, and then call this function
157        // if you really need to, but it shouldn't be needed for server sockets.
158        CHECK_NE(errno, EAGAIN);
159
160        // Note that on Windows, orderly shutdown sometimes causes
161        // recv() == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET. That
162        // can be ignored.
163        return false;
164    } else if (result == 0) {
165        // Peer has performed an orderly/graceful shutdown.
166        return true;
167    } else {
168        // Unexpectedly received data. This is essentially a protocol error
169        // because you should not call this function unless you expect no more
170        // data. We don't repeatedly call adb_read() until we get zero because
171        // we don't know how long that would take, but we do know that the
172        // caller wants to close the socket soon.
173        VLOG(RWX) << "ReadOrderlyShutdown(" << fd << ") unexpectedly read "
174                  << dump_hex(buf, result);
175        // Shutdown the socket to prevent the caller from reading or writing to
176        // it which doesn't make sense if we just read and discarded some data.
177        adb_shutdown(fd);
178        errno = EINVAL;
179        return false;
180    }
181}
182