Transport.java revision 96c5af40d639d629267794f4f0338a267ff94ce5 
1/*
2 * Copyright (C) 2008 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
17package com.android.email.mail;
18
19import java.io.IOException;
20import java.io.InputStream;
21import java.io.OutputStream;
22import java.net.SocketException;
23import java.net.URI;
24
25/**
26 * This interface defines a "transport", which is defined here as being one layer below the
27 * specific wire protocols such as POP3, IMAP, or SMTP.
28 *
29 * Practically speaking, it provides a definition of the common functionality between them
30 * (dealing with sockets & streams, SSL, logging, and so forth), and provides a seam just below
31 * the individual protocols to enable better testing.
32 *
33 * The following features are supported and presumed to be common:
34 *
35 *  Interpretation of URI
36 *  Support for SSL and TLS wireline security
37 */
38public interface Transport {
39
40    /**
41     * Connection security options for transport that supports SSL and/or TLS
42     */
43    public static final int CONNECTION_SECURITY_NONE = 0;
44    public static final int CONNECTION_SECURITY_TLS_OPTIONAL = 1;
45    public static final int CONNECTION_SECURITY_TLS_REQUIRED = 2;
46    public static final int CONNECTION_SECURITY_SSL_REQUIRED = 3;
47    public static final int CONNECTION_SECURITY_SSL_OPTIONAL = 4;
48
49    /**
50     * Get a new transport, using an existing one as a model.  The new transport is configured as if
51     * setUri() and setSecurity() have been called, but not opened or connected in any way.
52     * @return a new Transport ready to open()
53     */
54    public Transport newInstanceWithConfiguration();
55
56    /**
57     * Set the Uri for the connection.
58     *
59     * @param uri The Uri for the connection
60     * @param defaultPort If the Uri does not include an explicit port, this value will be used.
61     */
62    public void setUri(URI uri, int defaultPort);
63
64    /**
65     * @return Returns the host part of the Uri
66     */
67    public String getHost();
68
69    /**
70     * @return Returns the port (either from the Uri or from the default)
71     */
72    public int getPort();
73
74    /**
75     * Returns the user info parts of the Uri, if any were supplied.  Typically, [0] is the user
76     * and [1] is the password.
77     * @return Returns the user info parts of the Uri.  Null if none were supplied.
78     */
79    public String[] getUserInfoParts();
80
81    /**
82     * Set the desired security mode for this connection.
83     * @param connectionSecurity A value indicating the desired security mode.
84     */
85    public void setSecurity(int connectionSecurity);
86
87    /**
88     * @return Returns the desired security mode for this connection.
89     */
90    public int getSecurity();
91
92    /**
93     * @return true if the security mode indicates that SSL is possible (optional or required)
94     */
95    public boolean canTrySslSecurity();
96
97    /**
98     * @return true if the security mode indicates that TLS is possible (optional or required)
99     */
100    public boolean canTryTlsSecurity();
101
102    /**
103     * Set the socket timeout.
104     * @param timeoutMilliseconds the read timeout value if greater than {@code 0}, or
105     *            {@code 0} for an infinite timeout.
106     */
107    public void setSoTimeout(int timeoutMilliseconds) throws SocketException;
108
109        /**
110     * Attempts to open the connection using the supplied parameters, and using SSL if indicated.
111     */
112    public void open() throws MessagingException, CertificateValidationException;
113
114    /**
115     * Attempts to reopen the connection using TLS.
116     */
117    public void reopenTls() throws MessagingException;
118
119    /**
120     * @return true if the connection is open
121     */
122    public boolean isOpen();
123
124    /**
125     * Closes the connection.  Does not send any closure messages, simply closes the socket and the
126     * associated streams.  Best effort only.  Catches all exceptions and always returns.
127     *
128     * MUST NOT throw any exceptions.
129     */
130    public void close();
131
132    /**
133     * @return returns the active input stream
134     */
135    public InputStream getInputStream();
136
137    /**
138     * @return returns the active output stream
139     */
140    public OutputStream getOutputStream();
141
142    /**
143     * Write a single line to the server, and may generate a log entry (if enabled).
144     * @param s The text to send to the server.
145     * @param sensitiveReplacement If the command includes sensitive data (e.g. authentication)
146     * please pass a replacement string here (for logging).  Most callers simply pass null,
147     */
148    void writeLine(String s, String sensitiveReplacement) throws IOException;
149
150    /**
151     * Reads a single line from the server.  Any delimiter characters will not be included in the
152     * result.  May generate a log entry, if enabled.
153     * @return Returns the string from the server.
154     * @throws IOException
155     */
156    String readLine() throws IOException;
157
158}
159