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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.SocketException;
     23 import 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  */
     38 public 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_SSL = 1;
     45     public static final int CONNECTION_SECURITY_TLS = 2;
     46 
     47     /**
     48      * Get a new transport, using an existing one as a model.  The new transport is configured as if
     49      * setUri() and setSecurity() have been called, but not opened or connected in any way.
     50      * @return a new Transport ready to open()
     51      */
     52     public Transport newInstanceWithConfiguration();
     53 
     54     /**
     55      * Set the Uri for the connection.
     56      *
     57      * @param uri The Uri for the connection
     58      * @param defaultPort If the Uri does not include an explicit port, this value will be used.
     59      */
     60     public void setUri(URI uri, int defaultPort);
     61 
     62     /**
     63      * @return Returns the host part of the Uri
     64      */
     65     public String getHost();
     66 
     67     /**
     68      * @return Returns the port (either from the Uri or from the default)
     69      */
     70     public int getPort();
     71 
     72     /**
     73      * Returns the user info parts of the Uri, if any were supplied.  Typically, [0] is the user
     74      * and [1] is the password.
     75      * @return Returns the user info parts of the Uri.  Null if none were supplied.
     76      */
     77     public String[] getUserInfoParts();
     78 
     79     /**
     80      * Set the desired security mode for this connection.
     81      * @param connectionSecurity A value indicating the desired security mode.
     82      * @param trustAllCertificates true to allow unverifiable certificates to be used
     83      */
     84     public void setSecurity(int connectionSecurity, boolean trustAllCertificates);
     85 
     86     /**
     87      * @return Returns the desired security mode for this connection.
     88      */
     89     public int getSecurity();
     90 
     91     /**
     92      * @return true if the security mode indicates that SSL is possible
     93      */
     94     public boolean canTrySslSecurity();
     95 
     96     /**
     97      * @return true if the security mode indicates that TLS is possible
     98      */
     99     public boolean canTryTlsSecurity();
    100 
    101     /**
    102      * @return true if the security mode indicates that all certificates can be trusted
    103      */
    104     public boolean canTrustAllCertificates();
    105 
    106     /**
    107      * Set the socket timeout.
    108      * @param timeoutMilliseconds the read timeout value if greater than {@code 0}, or
    109      *            {@code 0} for an infinite timeout.
    110      */
    111     public void setSoTimeout(int timeoutMilliseconds) throws SocketException;
    112 
    113         /**
    114      * Attempts to open the connection using the supplied parameters, and using SSL if indicated.
    115      */
    116     public void open() throws MessagingException, CertificateValidationException;
    117 
    118     /**
    119      * Attempts to reopen the connection using TLS.
    120      */
    121     public void reopenTls() throws MessagingException;
    122 
    123     /**
    124      * @return true if the connection is open
    125      */
    126     public boolean isOpen();
    127 
    128     /**
    129      * Closes the connection.  Does not send any closure messages, simply closes the socket and the
    130      * associated streams.  Best effort only.  Catches all exceptions and always returns.
    131      *
    132      * MUST NOT throw any exceptions.
    133      */
    134     public void close();
    135 
    136     /**
    137      * @return returns the active input stream
    138      */
    139     public InputStream getInputStream();
    140 
    141     /**
    142      * @return returns the active output stream
    143      */
    144     public OutputStream getOutputStream();
    145 
    146     /**
    147      * Write a single line to the server, and may generate a log entry (if enabled).
    148      * @param s The text to send to the server.
    149      * @param sensitiveReplacement If the command includes sensitive data (e.g. authentication)
    150      * please pass a replacement string here (for logging).  Most callers simply pass null,
    151      */
    152     void writeLine(String s, String sensitiveReplacement) throws IOException;
    153 
    154     /**
    155      * Reads a single line from the server.  Any delimiter characters will not be included in the
    156      * result.  May generate a log entry, if enabled.
    157      * @return Returns the string from the server.
    158      * @throws IOException
    159      */
    160     String readLine() throws IOException;
    161 
    162 }
    163