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      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 
     17 package com.android.email.mail;
     18 
     19 import java.io.IOException;
     20 import java.io.InputStream;
     21 import java.io.OutputStream;
     22 import java.net.InetAddress;
     23 import java.net.SocketException;
     24 import java.net.URI;
     25 
     26 /**
     27  * This interface defines a "transport", which is defined here as being one layer below the
     28  * specific wire protocols such as POP3, IMAP, or SMTP.
     29  *
     30  * Practically speaking, it provides a definition of the common functionality between them
     31  * (dealing with sockets & streams, SSL, logging, and so forth), and provides a seam just below
     32  * the individual protocols to enable better testing.
     33  *
     34  * The following features are supported and presumed to be common:
     35  *
     36  *  Interpretation of URI
     37  *  Support for SSL and TLS wireline security
     38  */
     39 public interface Transport {
     40 
     41     /**
     42      * Connection security options for transport that supports SSL and/or TLS
     43      */
     44     public static final int CONNECTION_SECURITY_NONE = 0;
     45     public static final int CONNECTION_SECURITY_SSL = 1;
     46     public static final int CONNECTION_SECURITY_TLS = 2;
     47 
     48     /**
     49      * Get a new transport, using an existing one as a model.  The new transport is configured as if
     50      * setUri() and setSecurity() have been called, but not opened or connected in any way.
     51      * @return a new Transport ready to open()
     52      */
     53     public Transport newInstanceWithConfiguration();
     54 
     55     /**
     56      * Set the Uri for the connection.
     57      *
     58      * @param uri The Uri for the connection
     59      * @param defaultPort If the Uri does not include an explicit port, this value will be used.
     60      */
     61     public void setUri(URI uri, int defaultPort);
     62 
     63     /**
     64      * @return Returns the host part of the Uri
     65      */
     66     public String getHost();
     67 
     68     /**
     69      * @return Returns the port (either from the Uri or from the default)
     70      */
     71     public int getPort();
     72 
     73     /**
     74      * Returns the user info parts of the Uri, if any were supplied.  Typically, [0] is the user
     75      * and [1] is the password.
     76      * @return Returns the user info parts of the Uri.  Null if none were supplied.
     77      */
     78     public String[] getUserInfoParts();
     79 
     80     /**
     81      * Set the desired security mode for this connection.
     82      * @param connectionSecurity A value indicating the desired security mode.
     83      * @param trustAllCertificates true to allow unverifiable certificates to be used
     84      */
     85     public void setSecurity(int connectionSecurity, boolean trustAllCertificates);
     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
     94      */
     95     public boolean canTrySslSecurity();
     96 
     97     /**
     98      * @return true if the security mode indicates that TLS is possible
     99      */
    100     public boolean canTryTlsSecurity();
    101 
    102     /**
    103      * @return true if the security mode indicates that all certificates can be trusted
    104      */
    105     public boolean canTrustAllCertificates();
    106 
    107     /**
    108      * Set the socket timeout.
    109      * @param timeoutMilliseconds the read timeout value if greater than {@code 0}, or
    110      *            {@code 0} for an infinite timeout.
    111      */
    112     public void setSoTimeout(int timeoutMilliseconds) throws SocketException;
    113 
    114         /**
    115      * Attempts to open the connection using the supplied parameters, and using SSL if indicated.
    116      */
    117     public void open() throws MessagingException, CertificateValidationException;
    118 
    119     /**
    120      * Attempts to reopen the connection using TLS.
    121      */
    122     public void reopenTls() throws MessagingException;
    123 
    124     /**
    125      * @return true if the connection is open
    126      */
    127     public boolean isOpen();
    128 
    129     /**
    130      * Closes the connection.  Does not send any closure messages, simply closes the socket and the
    131      * associated streams.  Best effort only.  Catches all exceptions and always returns.
    132      *
    133      * MUST NOT throw any exceptions.
    134      */
    135     public void close();
    136 
    137     /**
    138      * @return returns the active input stream
    139      */
    140     public InputStream getInputStream();
    141 
    142     /**
    143      * @return returns the active output stream
    144      */
    145     public OutputStream getOutputStream();
    146 
    147     /**
    148      * Write a single line to the server, and may generate a log entry (if enabled).
    149      * @param s The text to send to the server.
    150      * @param sensitiveReplacement If the command includes sensitive data (e.g. authentication)
    151      * please pass a replacement string here (for logging).  Most callers simply pass null,
    152      */
    153     void writeLine(String s, String sensitiveReplacement) throws IOException;
    154 
    155     /**
    156      * Reads a single line from the server.  Any delimiter characters will not be included in the
    157      * result.  May generate a log entry, if enabled.
    158      * @return Returns the string from the server.
    159      * @throws IOException
    160      */
    161     String readLine() throws IOException;
    162 
    163     /**
    164      * @return The local address.  If we have an open socket, get the local address from this.
    165      *     Otherwise simply use {@link InetAddress#getLocalHost}.
    166      */
    167     InetAddress getLocalAddress() throws IOException;
    168 }
    169