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| author |   hongbotian <hongbo.tianhongbo@huawei.com> | 2015-11-30 02:41:33 -0500 |
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| committer | hongbotian <hongbo.tianhongbo@huawei.com> | 2015-11-30 02:43:36 -0500 |
| commit | 9401f816dd0d9d550fe98a8507224bde51c4b847 (patch) | |
| tree | 94f2d7a7893a787bafdca8b5ef063ea316938874 /rubbos/app/tomcat-connectors-1.2.32-src/docs/ajp/ajpv13a.html | |
| parent | e8ec7aa8e38a93f5b034ac74cebce5de23710317 (diff) | |
upload tomcat
JIRA: BOTTLENECK-7
Change-Id: I875d474869efd76ca203c30b60ebc0c3ee606d0e
Signed-off-by: hongbotian <hongbo.tianhongbo@huawei.com>
Diffstat (limited to 'rubbos/app/tomcat-connectors-1.2.32-src/docs/ajp/ajpv13a.html')
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diff --git a/rubbos/app/tomcat-connectors-1.2.32-src/docs/ajp/ajpv13a.html b/rubbos/app/tomcat-connectors-1.2.32-src/docs/ajp/ajpv13a.html new file mode 100644 index 00000000..58056035 --- /dev/null +++ b/rubbos/app/tomcat-connectors-1.2.32-src/docs/ajp/ajpv13a.html @@ -0,0 +1,654 @@ +<html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>The Apache Tomcat Connector - AJP Protocol Reference - AJPv13</title><meta name="author" value="danmil@shore.net"><meta name="email" value="danmil@shore.net"><meta name="author" value="Jean-Frederic Clere"><meta name="email" value="jfrederic.clere@fujitsu-siemens.com"><link href="../style.css" type="text/css" rel="stylesheet"></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="4"><!--PAGE HEADER--><tr><td colspan="2"><!--TOMCAT LOGO--><a href="http://tomcat.apache.org/"><img src="../images/tomcat.gif" align="left" alt="Apache Tomcat" border="0"></a><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="http://www.apache.org/images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap="true"><p><strong>Links</strong></p><ul><li><a href="../index.html">Docs Home</a></li></ul><p><strong>Reference Guide</strong></p><ul><li><a href="../reference/workers.html">workers.properties</a></li><li><a href="../reference/uriworkermap.html">uriworkermap.properties</a></li><li><a href="../reference/status.html">Status Worker</a></li><li><a href="../reference/apache.html">Apache HTTP Server</a></li><li><a href="../reference/iis.html">IIS</a></li></ul><p><strong>Generic HowTo</strong></p><ul><li><a href="../generic_howto/quick.html">For the impatient</a></li><li><a href="../generic_howto/workers.html">All about workers</a></li><li><a href="../generic_howto/timeouts.html">Timeouts</a></li><li><a href="../generic_howto/loadbalancers.html">Load Balancing</a></li><li><a href="../generic_howto/proxy.html">Reverse Proxy</a></li></ul><p><strong>Webserver HowTo</strong></p><ul><li><a href="../webserver_howto/apache.html">Apache HTTP Server</a></li><li><a href="../webserver_howto/iis.html">IIS</a></li><li><a href="../webserver_howto/nes.html">Netscape/SunOne/Sun</a></li></ul><p><strong>AJP Protocol Reference</strong></p><ul><li><a href="../ajp/ajpv13a.html">AJPv13</a></li><li><a href="../ajp/ajpv13ext.html">AJPv13 Extension Proposal</a></li></ul><p><strong>Miscellaneous Documentation</strong></p><ul><li><a href="../miscellaneous/faq.html">Frequently asked questions</a></li><li><a href="../miscellaneous/changelog.html">Changelog</a></li><li><a href="http://issues.apache.org/bugzilla/buglist.cgi?query_format=advanced&short_desc_type=allwordssubstr&short_desc=&product=Tomcat+Connectors&long_desc_type=substring&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&keywords_type=allwords&keywords=&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&emailassigned_to1=1&emailtype1=substring&email1=&emailassigned_to2=1&emailreporter2=1&emailcc2=1&emailtype2=substring&email2=&bugidtype=include&bug_id=&votes=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&order=Reuse+same+sort+as+last+time&field0-0-0=noop&type0-0-0=noop&value0-0-0=">Current Tomcat Connectors bugs</a></li><li><a href="../miscellaneous/doccontrib.html">Contribute documentation</a></li><li><a href="../miscellaneous/jkstatustasks.html">JK Status Ant Tasks</a></li><li><a href="../miscellaneous/reporttools.html">Reporting Tools</a></li><li><a href="http://tomcat.apache.org/connectors-doc-archive/jk2/index.html">Old JK/JK2 documentation</a></li></ul><p><strong>News</strong></p><ul><li><a href="../news/20110701.html">2011</a></li><li><a href="../news/20100101.html">2010</a></li><li><a href="../news/20090301.html">2009</a></li><li><a href="../news/20081001.html">2008</a></li><li><a href="../news/20070301.html">2007</a></li><li><a href="../news/20060101.html">2006</a></li><li><a href="../news/20050101.html">2005</a></li><li><a href="../news/20041100.html">2004</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left"><table border="0" width="100%" cellspacing="4"><tr><td align="left" valign="top"><h1>The Apache Tomcat Connector - AJP Protocol Reference</h1><h2>AJPv13</h2></td><td align="right" valign="top" nowrap="true"><small><a href="printer/ajpv13a.html"><img src="../images/printer.gif" border="0" alt="Printer Friendly Version"><br>print-friendly<br>version + </a></small></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Intro"><strong>Intro</strong></a></font></td></tr><tr><td><blockquote> + +<p> +The original document was written by +Dan Milstein, <author email="danmil@shore.net">danmil@shore.net</author> +on December 2000. The present document is generated out of an xml file +to allow a more easy integration in the Tomcat documentation. + +</p> + +<p> +This describes the Apache JServ Protocol version 1.3 (hereafter +<b>ajp13</b>). There is, apparently, no current documentation of how the +protocol works. This document is an attempt to remedy that, in order to +make life easier for maintainers of JK, and for anyone who wants to +port the protocol somewhere (into jakarta 4.x, for example). +</p> + +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="author"><strong>author</strong></a></font></td></tr><tr><td><blockquote> + +<p> +I am not one of the designers of this protocol -- I believe that Gal +Shachor was the original designer. Everything in this document is derived +from the actual implementation I found in the tomcat 3.x code. I hope it +is useful, but I can't make any grand claims to perfect accuracy. I also +don't know why certain design decisions were made. Where I was able, I've +offered some possible justifications for certain choices, but those are +only my guesses. In general, the C code which Shachor wrote is very clean +and comprehensible (if almost totally undocumented). I've cleaned up the +Java code, and I think it's reasonably readable. +</p> +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Design Goals"><strong>Design Goals</strong></a></font></td></tr><tr><td><blockquote> + +<p> +According to email from Gal Shachor to the jakarta-dev mailing list, +the original goals of <b>JK</b> (and thus <b>ajp13</b>) were to extend +<b>mod_jserv</b> and <b>ajp12</b> by (I am only including the goals which +relate to communication between the web server and the servlet container): + +<ul> + <li> Increasing performance (speed, specifically). </li> + + <li> Adding support for SSL, so that <b class="code">isSecure()</b> and + <b class="code">getScheme()</b> will function correctly within the servlet + container. The client certificates and cipher suite will be + available to servlets as request attributes. </li> + +</ul> +</p> +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Overview of the protocol"><strong>Overview of the protocol</strong></a></font></td></tr><tr><td><blockquote> + +<p> +The <b>ajp13</b> protocol is packet-oriented. A binary format was +presumably chosen over the more readable plain text for reasons of +performance. The web server communicates with the servlet container over +TCP connections. To cut down on the expensive process of socket creation, +the web server will attempt to maintain persistent TCP connections to the +servlet container, and to reuse a connection for multiple request/response +cycles. +</p><p> +Once a connection is assigned to a particular request, it will not be +used for any others until the request-handling cycle has terminated. In +other words, requests are not multiplexed over connections. This makes +for much simpler code at either end of the connection, although it does +cause more connections to be open at once. +</p><p> +Once the web server has opened a connection to the servlet container, +the connection can be in one of the following states: +</p><p> +<ul> + <li> Idle <br> No request is being handled over this connection. </li> + <li> Assigned <br> The connecton is handling a specific request.</li> +</ul> + +</p><p> +Once a connection is assigned to handle a particular request, the basic +request informaton (e.g. HTTP headers, etc) is sent over the connection in +a highly condensed form (e.g. common strings are encoded as integers). +Details of that format are below in Request Packet Structure. If there is a +body to the request (content-length > 0), that is sent in a separate +packet immediately after. +</p><p> +At this point, the servlet container is presumably ready to start +processing the request. As it does so, it can send the +following messages back to the web server: + +<ul> + <li>SEND_HEADERS <br>Send a set of headers back to the browser.</li> + + <li>SEND_BODY_CHUNK <br>Send a chunk of body data back to the browser.</li> + + <li>GET_BODY_CHUNK <br>Get further data from the request if it hasn't all + been transferred yet. This is necessary because the packets have a fixed + maximum size and arbitrary amounts of data can be included the body of a + request (for uploaded files, for example). (Note: this is unrelated to + HTTP chunked tranfer).</li> + + <li>END_RESPONSE <br> Finish the request-handling cycle.</li> +</ul> +</p><p> + +Each message is accompanied by a differently formatted packet of data. See +Response Packet Structures below for details. +</p> +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Basic Packet Structure"><strong>Basic Packet Structure</strong></a></font></td></tr><tr><td><blockquote> + +<p> +There is a bit of an XDR heritage to this protocol, but it differs in +lots of ways (no 4 byte alignment, for example). +</p><p> +Byte order: I am not clear about the endian-ness of the individual +bytes. I'm guessing the bytes are little-endian, because that's what XDR +specifies, and I'm guessing that sys/socket library is magically making +that so (on the C side). If anyone with a better knowledge of socket calls +can step in, that would be great. +</p><p> +There are four data types in the protocol: bytes, booleans, integers and +strings. + +<dl> + <dt><b>Byte</b></dt> + <dd>A single byte.</dd> + + <dt><b>Boolean</b></dt> + <dd>A single byte, 1 = true, 0 = false. Using other non-zero values as + true (i.e. C-style) may work in some places, but it won't in + others.</dd> + + <dt><b>Integer</b></dt> + <dd>A number in the range of 0 to 2^16 (32768). Stored in 2 bytes with + the high-order byte first.</dd> + + <dt><b>String</b></dt> + <dd>A variable-sized string (length bounded by 2^16). Encoded with the + length packed into two bytes first, followed by the string (including the + terminating '\0'). Note that the encoded length does <b>not</b> include + the trailing '\0' -- it is like <b class="code">strlen</b>. This is a touch + confusing on the Java side, which is littered with odd autoincrement + statements to skip over these terminators. I believe the reason this was + done was to allow the C code to be extra efficient when reading strings + which the servlet container is sending back -- with the terminating \0 + character, the C code can pass around references into a single buffer, + without copying. If the \0 was missing, the C code would have to copy + things out in order to get its notion of a string. Note a size of -1 + (65535) indicates a null string and no data follow the length in this + case.</dd> +</dl> +</p> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Packet Size"><strong>Packet Size</strong></a></font></td></tr><tr><td><blockquote> +<p> +According to much of the code, the max packet +size is 8 * 1024 bytes (8K). The actual length of the packet is encoded in the +header. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Packet Headers"><strong>Packet Headers</strong></a></font></td></tr><tr><td><blockquote> +<p> +Packets sent from the server to the container begin with +<b class="code">0x1234</b>. Packets sent from the container to the server begin +with <b class="code">AB</b> (that's the ASCII code for A followed by the ASCII +code for B). After those first two bytes, there is an integer (encoded as +above) with the length of the payload. Although this might suggest that +the maximum payload could be as large as 2^16, in fact, the code sets the +maximum to be 8K. + + +<table> + <tr> + <th colspan="6">Packet Format (Server->Container)</th> + </tr> + + <tr> + <th>Byte</th> + <td>0</td> + <td>1</td> + <td>2</td> + <td>3</td> + <td>4...(n+3)</td> + </tr> + + <tr> + <th>Contents</th> + <td>0x12</td> + <td>0x34</td> + <td colspan="2">Data Length (n)</td> + <td>Data</td> + </tr> +</table> + +<table> + <tr> + <th colspan="6"><b>Packet Format (Container->Server)</b></th> + </tr> + + <tr> + <th>Byte</th> + <td>0</td> + <td>1</td> + <td>2</td> + <td>3</td> + <td>4...(n+3)</td> + </tr> + + <tr> + <th>Contents</th> + <td>A</td> + <td>B</td> + <td colspan="2">Data Length (n)</td> + <td>Data</td> + </tr> +</table> +</p> +<p> +<A NAME="prefix-codes"></A> For most packets, the first byte of the +payload encodes the type of message. The exception is for request body +packets sent from the server to the container -- they are sent with a +standard packet header (0x1234 and then length of the packet), but without +any prefix code after that (this seems like a mistake to me). +</p><p> +The web server can send the following messages to the servlet container: + +<table> + <tr> + <th>Code</th> + <th>Type of Packet</th> + <th>Meaning</th> + </tr> + <tr> + <td>2</td> + <td>Forward Request</td> + <td>Begin the request-processing cycle with the following data</td> + </tr> + <tr> + <td>7</td> + <td>Shutdown</td> + <td>The web server asks the container to shut itself down.</td> + </tr> + <tr> + <td>8</td> + <td>Ping</td> + <td>The web server asks the container to take control (secure login phase).</td> + </tr> + <tr> + <td>10</td> + <td>CPing</td> + <td>The web server asks the container to respond quickly with a CPong.</td> + </tr> + <tr> + <td>none</td> + <td>Data</td> + <td>Size (2 bytes) and corresponding body data.</td> + </tr> +</table> +</p> +<p> +To ensure some +basic security, the container will only actually do the <b class="code">Shutdown</b> if the +request comes from the same machine on which it's hosted. +</p> +<p> +The first <b class="code">Data</b> packet is send immediatly after the <b class="code">Forward Request</b> by the web server. +</p> + +<p>The servlet container can send the following types of messages to the web +server: +<table> + <tr> + <th>Code</th> + <th>Type of Packet</th> + <th>Meaning</th> + </tr> + <tr> + <td>3</td> + <td>Send Body Chunk</td> + <td>Send a chunk of the body from the servlet container to the web + server (and presumably, onto the browser). </td> + </tr> + <tr> + <td>4</td> + <td>Send Headers</td> + <td>Send the response headers from the servlet container to the web + server (and presumably, onto the browser).</td> + </tr> + <tr> + <td>5</td> + <td>End Response</td> + <td>Marks the end of the response (and thus the request-handling cycle).</td> + </tr> + <tr> + <td>6</td> + <td>Get Body Chunk</td> + <td>Get further data from the request if it hasn't all been transferred + yet.</td> + </tr> + <tr> + <td>9</td> + <td>CPong Reply</td> + <td>The reply to a CPing request</td> + </tr> +</table> +</p> +<p> +Each of the above messages has a different internal structure, detailed below. +</p> +</blockquote></td></tr></table> +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Request Packet Structure"><strong>Request Packet Structure</strong></a></font></td></tr><tr><td><blockquote> + +<p> +For messages from the server to the container of type "Forward Request": +</p><p> +<div class="example"><pre> +AJP13_FORWARD_REQUEST := + prefix_code (byte) 0x02 = JK_AJP13_FORWARD_REQUEST + method (byte) + protocol (string) + req_uri (string) + remote_addr (string) + remote_host (string) + server_name (string) + server_port (integer) + is_ssl (boolean) + num_headers (integer) + request_headers *(req_header_name req_header_value) + attributes *(attribut_name attribute_value) + request_terminator (byte) OxFF +</pre></div> +</p><p> +The <b class="code">request_headers</b> have the following structure: +</p><p> +<div class="example"><pre> +req_header_name := + sc_req_header_name | (string) [see below for how this is parsed] + +sc_req_header_name := 0xA0xx (integer) + +req_header_value := (string) +</pre></div> +</p><p> + +The <b class="code">attributes</b> are optional and have the following structure: +</p><p> +<div class="example"><pre> +attribute_name := sc_a_name | (sc_a_req_attribute string) + +attribute_value := (string) + +</pre></div> +</p><p> +Not that the all-important header is "content-length', because it +determines whether or not the container looks for another packet +immediately. +</p><p> +Detailed description of the elements of Forward Request. +</p> +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="request_prefix"><strong>request_prefix</strong></a></font></td></tr><tr><td><blockquote> +<p> +For all requests, this will be 2. +See above for details on other <A HREF="#prefix-codes">prefix codes</A>. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="method"><strong>method</strong></a></font></td></tr><tr><td><blockquote> +<p> +The HTTP method, encoded as a single byte: +</p> + +<p> +<table> + <tr><th>Command Name</th><th>Code</th></tr> + <tr><td>OPTIONS</td><td>1</td></tr> + <tr><td>GET</td><td>2</td></tr> + <tr><td>HEAD</td><td>3</td></tr> + <tr><td>POST</td><td>4</td></tr> + <tr><td>PUT</td><td>5</td></tr> + <tr><td>DELETE</td><td>6</td></tr> + <tr><td>TRACE</td><td>7</td></tr> + <tr><td>PROPFIND</td><td>8</td></tr> + <tr><td>PROPPATCH</td><td>9</td></tr> + <tr><td>MKCOL</td><td>10</td></tr> + <tr><td>COPY</td><td>11</td></tr> + <tr><td>MOVE</td><td>12</td></tr> + <tr><td>LOCK</td><td>13</td></tr> + <tr><td>UNLOCK</td><td>14</td></tr> + <tr><td>ACL</td><td>15</td></tr> + <tr><td>REPORT</td><td>16</td></tr> + <tr><td>VERSION-CONTROL</td><td>17</td></tr> + <tr><td>CHECKIN</td><td>18</td></tr> + <tr><td>CHECKOUT</td><td>19</td></tr> + <tr><td>UNCHECKOUT</td><td>20</td></tr> + <tr><td>SEARCH</td><td>21</td></tr> + <tr><td>MKWORKSPACE</td><td>22</td></tr> + <tr><td>UPDATE</td><td>23</td></tr> + <tr><td>LABEL</td><td>24</td></tr> + <tr><td>MERGE</td><td>25</td></tr> + <tr><td>BASELINE_CONTROL</td><td>26</td></tr> + <tr><td>MKACTIVITY</td><td>27</td></tr> +</table> +</p> + +<p>Later version of ajp13, when used with mod_jk2, will transport +additional methods, even if they are not in this list. +</p> + +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="protocol, req_uri, remote_addr, remote_host, server_name, server_port, is_ssl"><strong>protocol, req_uri, remote_addr, remote_host, server_name, server_port, is_ssl</strong></a></font></td></tr><tr><td><blockquote> +<p> + These are all fairly self-explanatory. Each of these is required, and + will be sent for every request. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Headers"><strong>Headers</strong></a></font></td></tr><tr><td><blockquote> +<p> + The structure of <b class="code">request_headers</b> is the following: + First, the number of headers <b class="code">num_headers</b> is encoded. + Then, a series of header name <b class="code">req_header_name</b> / value + <b class="code">req_header_value</b> pairs follows. + Common header names are encoded as integers, + to save space. If the header name is not in the list of basic headers, + it is encoded normally (as a string, with prefixed length). The list of + common headers <b class="code">sc_req_header_name</b>and their codes + is as follows (all are case-sensitive): +</p><p> +<table> + <tr><th>Name</th><th>Code value</th><th>Code name</th></tr> + <tr><td>accept</td><td>0xA001</td><td>SC_REQ_ACCEPT</td></tr> + <tr><td>accept-charset</td><td>0xA002</td><td>SC_REQ_ACCEPT_CHARSET</td></tr> + <tr><td>accept-encoding</td><td>0xA003</td><td>SC_REQ_ACCEPT_ENCODING</td></tr> + <tr><td>accept-language</td><td>0xA004</td><td>SC_REQ_ACCEPT_LANGUAGE</td></tr> + <tr><td>authorization</td><td>0xA005</td><td>SC_REQ_AUTHORIZATION</td></tr> + <tr><td>connection</td><td>0xA006</td><td>SC_REQ_CONNECTION</td></tr> + <tr><td>content-type</td><td>0xA007</td><td>SC_REQ_CONTENT_TYPE</td></tr> + <tr><td>content-length</td><td>0xA008</td><td>SC_REQ_CONTENT_LENGTH</td></tr> + <tr><td>cookie</td><td>0xA009</td><td>SC_REQ_COOKIE</td></tr> + <tr><td>cookie2</td><td>0xA00A</td><td>SC_REQ_COOKIE2</td></tr> + <tr><td>host</td><td>0xA00B</td><td>SC_REQ_HOST</td></tr> + <tr><td>pragma</td><td>0xA00C</td><td>SC_REQ_PRAGMA</td></tr> + <tr><td>referer</td><td>0xA00D</td><td>SC_REQ_REFERER</td></tr> + <tr><td>user-agent</td><td>0xA00E</td><td>SC_REQ_USER_AGENT</td></tr> +</table> +</p><p> + The Java code that reads this grabs the first two-byte integer and if + it sees an <b class="code">'0xA0'</b> in the most significant + byte, it uses the integer in the second byte as an index into an array of + header names. If the first byte is not '0xA0', it assumes that the + two-byte integer is the length of a string, which is then read in. +</p><p> + This works on the assumption that no header names will have length + greater than 0x9999 (==0xA000 - 1), which is perfectly reasonable, though + somewhat arbitrary. (If you, like me, started to think about the cookie + spec here, and about how long headers can get, fear not -- this limit is + on header <b>names</b> not header <b>values</b>. It seems unlikely that + unmanageably huge header names will be showing up in the HTTP spec any time + soon). +</p><p> + <b>Note:</b> The <b class="code">content-length</b> header is extremely + important. If it is present and non-zero, the container assumes that + the request has a body (a POST request, for example), and immediately + reads a separate packet off the input stream to get that body. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Attributes"><strong>Attributes</strong></a></font></td></tr><tr><td><blockquote> +<p> + + The attributes prefixed with a <b class="code">?</b> + (e.g. <b class="code">?context</b>) are all optional. For each, there is a + single byte code to indicate the type of attribute, and then a string to + give its value. They can be sent in any order (thogh the C code always + sends them in the order listed below). A special terminating code is + sent to signal the end of the list of optional attributes. The list of + byte codes is: +</p><p> + +<table> + <tr><th>Information</th><th>Code Value</th><th>Note</th></tr> + <tr><td>?context</td><td>0x01</td><td>Not currently implemented</td></tr> + <tr><td>?servlet_path</td><td>0x02</td><td>Not currently implemented</td></tr> + <tr><td>?remote_user</td><td>0x03</td><td></td></tr> + <tr><td>?auth_type</td><td>0x04</td><td></td></tr> + <tr><td>?query_string</td><td>0x05</td><td></td></tr> + <tr><td>?route</td><td>0x06</td><td></td></tr> + <tr><td>?ssl_cert</td><td>0x07</td><td></td></tr> + <tr><td>?ssl_cipher</td><td>0x08</td><td></td></tr> + <tr><td>?ssl_session</td><td>0x09</td><td></td></tr> + <tr><td>?req_attribute</td><td>0x0A</td><td>Name (the name of the attribut follows)</td></tr> + <tr><td>?ssl_key_size</td><td>0x0B</td><td></td></tr> + <tr><td>?secret</td><td>0x0C</td><td></td></tr> + <tr><td>?stored_method</td><td>0x0D</td><td></td></tr> + <tr><td>are_done</td><td>0xFF</td><td>request_terminator</td></tr> +</table> + +</p><p> + + The <b class="code">context</b> and <b class="code">servlet_path</b> are not currently + set by the C code, and most of the Java code completely ignores whatever + is sent over for those fields (and some of it will actually break if a + string is sent along after one of those codes). I don't know if this is + a bug or an unimplemented feature or just vestigial code, but it's + missing from both sides of the connection. +</p><p> + The <b class="code">remote_user</b> and <b class="code">auth_type</b> presumably refer + to HTTP-level authentication, and communicate the remote user's username + and the type of authentication used to establish their identity (e.g. Basic, + Digest). I'm not clear on why the password isn't also sent, but I don't + know HTTP authentication inside and out. +</p><p> + The <b class="code">query_string</b>, <b class="code">ssl_cert</b>, + <b class="code">ssl_cipher</b>, and <b class="code">ssl_session</b> refer to the + corresponding pieces of HTTP and HTTPS. +</p><p> + The <b class="code">route</b>, as I understand it, is used to support sticky + sessions -- associating a user's sesson with a particular Tomcat instance + in the presence of multiple, load-balancing servers. I don't know the + details. +</p><p> + Beyond this list of basic attributes, any number of other attributes can + be sent via the <b class="code">req_attribute</b> code (0x0A). A pair of strings + to represent the attribute name and value are sent immediately after each + instance of that code. Environment values are passed in via this method. +</p><p> + Finally, after all the attributes have been sent, the attribute terminator, + 0xFF, is sent. This signals both the end of the list of attributes and + also then end of the Request Packet. +</p> +</blockquote></td></tr></table> + +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Response Packet Structure"><strong>Response Packet Structure</strong></a></font></td></tr><tr><td><blockquote> + +<p> +For messages which the container can send back to the server. + +<div class="example"><pre> +AJP13_SEND_BODY_CHUNK := + prefix_code 3 + chunk_length (integer) + chunk *(byte) + + +AJP13_SEND_HEADERS := + prefix_code 4 + http_status_code (integer) + http_status_msg (string) + num_headers (integer) + response_headers *(res_header_name header_value) + +res_header_name := + sc_res_header_name | (string) [see below for how this is parsed] + +sc_res_header_name := 0xA0 (byte) + +header_value := (string) + +AJP13_END_RESPONSE := + prefix_code 5 + reuse (boolean) + + +AJP13_GET_BODY_CHUNK := + prefix_code 6 + requested_length (integer) +</pre></div> + +</p> +<p> +Details: +</p> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Send Body Chunk"><strong>Send Body Chunk</strong></a></font></td></tr><tr><td><blockquote> +<p> + The chunk is basically binary data, and is sent directly back to the browser. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Send Headers"><strong>Send Headers</strong></a></font></td></tr><tr><td><blockquote> +<p> + The status code and message are the usual HTTP things (e.g. "200" and "OK"). + The response header names are encoded the same way the request header names are. + See <A HREF="#header_encoding">above</A> for details about how the the + codes are distinguished from the strings. The codes for common headers are: +</p> + +<p> +<table> + <tr><th>Name</th><th>Code value</th></tr> + <tr><td>Content-Type</td><td>0xA001</td></tr> + <tr><td>Content-Language</td><td>0xA002</td></tr> + <tr><td>Content-Length</td><td>0xA003</td></tr> + <tr><td>Date</td><td>0xA004</td></tr> + <tr><td>Last-Modified</td><td>0xA005</td></tr> + <tr><td>Location</td><td>0xA006</td></tr> + <tr><td>Set-Cookie</td><td>0xA007</td></tr> + <tr><td>Set-Cookie2</td><td>0xA008</td></tr> + <tr><td>Servlet-Engine</td><td>0xA009</td></tr> + <tr><td>Status</td><td>0xA00A</td></tr> + <tr><td>WWW-Authenticate</td><td>0xA00B</td></tr> +</table> + +</p> + +<p> + After the code or the string header name, the header value is immediately + encoded. +</p> + +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="End Response"><strong>End Response</strong></a></font></td></tr><tr><td><blockquote> +<p> + Signals the end of this request-handling cycle. If the + <b class="code">reuse</b> flag is true (==1), this TCP connection can now be used to + handle new incoming requests. If <b class="code">reuse</b> is false (anything + other than 1 in the actual C code), the connection should be closed. +</p> +</blockquote></td></tr></table> + +<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Get Body Chunk"><strong>Get Body Chunk</strong></a></font></td></tr><tr><td><blockquote> +<p> + The container asks for more data from the request (If the body was + too large to fit in the first packet sent over or when the request is + chuncked). + The server will send a body packet back with an amount of data which is + the minimum of the <b class="code">request_length</b>, + the maximum send body size (8186 (8 Kbytes - 6)), and the + number of bytes actually left to send from the request body. +<br> + If there is no more data in the body (i.e. the servlet container is + trying to read past the end of the body), the server will send back an + "empty" packet, which is a body packet with a payload length of 0. + (0x12,0x34,0x00,0x00) +</p> +</blockquote></td></tr></table> +</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Questions I Have"><strong>Questions I Have</strong></a></font></td></tr><tr><td><blockquote> + +<p> What happens if the request headers > max packet size? There is no +provision to send a second packet of request headers in case there are more +than 8K (I think this is correctly handled for response headers, though I'm +not certain). I don't know if there is a way to get more than 8K worth of +data into that initial set of request headers, but I'll bet there is +(combine long cookies with long ssl information and a lot of environment +variables, and you should hit 8K easily). I think the connector would just +fail before trying to send any headers in this case, but I'm not certain.</p> + +<p> What about authentication? There doesn't seem to be any authentication +of the connection between the web server and the container. This strikes +me as potentially dangerous.</p> + +</blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font color="#525D76" size="-1"><em> + Copyright © 1999-2011, Apache Software Foundation + </em></font></div></td></tr></table></body></html>
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