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1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "remoting/host/setup/native_messaging_writer.h" | |
6 | |
7 #include <string> | |
8 | |
9 #include "base/basictypes.h" | |
10 #include "base/json/json_writer.h" | |
11 | |
12 namespace { | |
13 | |
14 // 4-byte type used for the message header. | |
15 typedef uint32 MessageLengthType; | |
16 | |
17 // Defined as an int, for passing to APIs that take an int, to avoid | |
18 // signed/unsigned warnings about implicit cast. | |
19 const int kMessageHeaderSize = sizeof(MessageLengthType); | |
20 | |
21 // Limit the size of sent messages, since Chrome will not accept messages | |
22 // larger than 1MB, and this helps deal with the problem of integer overflow | |
23 // when passing sizes to net::FileStream APIs that take |int| parameters. | |
24 // This is defined as size_t (unsigned type) so it can be compared with the | |
25 // result of std::string::length() without compiler warnings. | |
26 const size_t kMaximumMessageSize = 1024 * 1024; | |
27 | |
28 // Performs the same task as FileStream::WriteSync(), but ensures that exactly | |
29 // |buffer_length| bytes are written. Unlike WriteSync(), a partial write may | |
30 // only occur as a result of end-of-file or fatal error. Returns the number of | |
31 // bytes written (buffer_length) or an error-code <= 0. | |
32 // | |
33 // TODO(lambroslambrou): Add this method to net::FileStream, with unit-tests. | |
34 // See http://crbug.com/232202. | |
35 int WriteUntilComplete(net::FileStream* out, | |
36 const char* buffer, int buffer_length) { | |
37 int written = 0; | |
38 while (written < buffer_length) { | |
39 int result = out->WriteSync(buffer + written, buffer_length - written); | |
40 if (result <= 0) { | |
41 return result; | |
42 } | |
43 DCHECK_LE(result, buffer_length - written); | |
44 written += result; | |
45 } | |
46 return written; | |
47 } | |
48 | |
49 } // namespace | |
50 | |
51 namespace remoting { | |
52 | |
53 NativeMessagingWriter::NativeMessagingWriter(base::PlatformFile handle) | |
54 : write_stream_(handle, base::PLATFORM_FILE_WRITE, NULL), | |
55 fail_(false) { | |
56 } | |
57 | |
58 NativeMessagingWriter::~NativeMessagingWriter() { | |
59 } | |
60 | |
61 bool NativeMessagingWriter::WriteMessage(const base::Value& message) { | |
62 if (fail_) { | |
63 LOG(ERROR) << "Stream marked as corrupt."; | |
64 return false; | |
65 } | |
66 | |
67 std::string message_json; | |
68 base::JSONWriter::Write(&message, &message_json); | |
69 | |
70 CHECK_LE(message_json.length(), kMaximumMessageSize); | |
71 | |
72 // Cast from size_t to the proper header type. The check above ensures this | |
73 // won't overflow. | |
74 MessageLengthType message_length = | |
75 static_cast<MessageLengthType>(message_json.length()); | |
76 | |
77 int result = WriteUntilComplete( | |
78 &write_stream_, reinterpret_cast<char*>(&message_length), | |
79 kMessageHeaderSize); | |
80 if (result != kMessageHeaderSize) { | |
81 LOG(ERROR) << "Failed to send message header, write returned " << result; | |
82 fail_ = true; | |
83 return false; | |
84 } | |
85 | |
86 // The length check above ensures that the cast won't overflow a signed | |
87 // 32-bit int. | |
88 int message_length_as_int = message_length; | |
89 | |
90 // CHECK needed since data() is undefined on an empty std::string. | |
91 CHECK(!message_json.empty()); | |
92 result = WriteUntilComplete(&write_stream_, message_json.data(), | |
93 message_length_as_int); | |
94 if (result != message_length_as_int) { | |
95 LOG(ERROR) << "Failed to send message body, write returned " << result; | |
96 fail_ = true; | |
97 return false; | |
98 } | |
99 | |
100 return true; | |
101 } | |
102 | |
103 } // namespace remoting | |
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