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