public final class CGIServlet extends HttpServlet
Note: This code compiles and even works for simple CGI cases. Exhaustive testing has not been done. Please consider it beta quality. Feedback is appreciated to the author (see below).
Example:
If an instance of this servlet was mapped (using
<web-app>/WEB-INF/web.xml) to:
<web-app>/cgi-bin/*
then the following request:
http://localhost:8080/<web-app>/cgi-bin/dir1/script/pathinfo1
would result in the execution of the script
<web-app-root>/WEB-INF/cgi/dir1/script
with the script's PATH_INFO set to /pathinfo1.
Recommendation: House all your CGI scripts under
<webapp>/WEB-INF/cgi. This will ensure that you do not
accidentally expose your cgi scripts' code to the outside world and that
your cgis will be cleanly ensconced underneath the WEB-INF (i.e.,
non-content) area.
The default CGI location is mentioned above. You have the flexibility to put CGIs wherever you want, however:
The CGI search path will start at webAppRootDir + File.separator + cgiPathPrefix (or webAppRootDir alone if cgiPathPrefix is null).
cgiPathPrefix is defined by setting this servlet's cgiPathPrefix init parameter
CGI Specification:
derived from
http://cgi-spec.golux.com.
A work-in-progress & expired Internet Draft. Note no actual RFC describing
the CGI specification exists. Where the behavior of this servlet differs
from the specification cited above, it is either documented here, a bug,
or an instance where the specification cited differs from Best
Community Practice (BCP).
Such instances should be well-documented here. Please email the
Tomcat group
with amendments.
Canonical metavariables:
The CGI specification defines the following canonical metavariables:
[excerpt from CGI specification]
AUTH_TYPE CONTENT_LENGTH CONTENT_TYPE GATEWAY_INTERFACE PATH_INFO PATH_TRANSLATED QUERY_STRING REMOTE_ADDR REMOTE_HOST REMOTE_IDENT REMOTE_USER REQUEST_METHOD SCRIPT_NAME SERVER_NAME SERVER_PORT SERVER_PROTOCOL SERVER_SOFTWARE
Metavariables with names beginning with the protocol name (e.g., "HTTP_ACCEPT") are also canonical in their description of request header fields. The number and meaning of these fields may change independently of this specification. (See also section 6.1.5 [of the CGI specification].)
[end excerpt]
standard input handling: If your script accepts standard input,
then the client must start sending input within a certain timeout period,
otherwise the servlet will assume no input is coming and carry on running
the script. The script's the standard input will be closed and handling of
any further input from the client is undefined. Most likely it will be
ignored. If this behavior becomes undesirable, then this servlet needs
to be enhanced to handle threading of the spawned process' stdin, stdout,
and stderr (which should not be too hard).
If you find your cgi scripts are timing out receiving input, you can set
the init parameter stderrTimeout of your webapps' cgi-handling
servlet.
Metavariable Values: According to the CGI specification, implementations may choose to represent both null or missing values in an implementation-specific manner, but must define that manner. This implementation chooses to always define all required metavariables, but set the value to "" for all metavariables whose value is either null or undefined. PATH_TRANSLATED is the sole exception to this rule, as per the CGI Specification.
NPH -- Non-parsed-header implementation: This implementation does not support the CGI NPH concept, whereby server ensures that the data supplied to the script are precisely as supplied by the client and unaltered by the server.
The function of a servlet container (including Tomcat) is specifically designed to parse and possible alter CGI-specific variables, and as such makes NPH functionality difficult to support.
The CGI specification states that compliant servers MAY support NPH output. It does not state servers MUST support NPH output to be unconditionally compliant. Thus, this implementation maintains unconditional compliance with the specification though NPH support is not present.
The CGI specification is located at http://cgi-spec.golux.com.
| Modifier and Type | Class and Description |
|---|---|
protected class |
CGIServlet.CGIEnvironment
Encapsulates the CGI environment and rules to derive
that environment from the servlet container and request information.
|
protected class |
CGIServlet.CGIRunner
Encapsulates the knowledge of how to run a CGI script, given the
script's desired environment and (optionally) input/output streams
Exposes a
run method used to actually invoke the
CGI. |
protected static class |
CGIServlet.HTTPHeaderInputStream
This is an input stream specifically for reading HTTP headers.
|
| Constructor and Description |
|---|
CGIServlet() |
| Modifier and Type | Method and Description |
|---|---|
protected void |
doGet(HttpServletRequest req,
HttpServletResponse res)
Provides CGI Gateway service.
|
protected void |
doOptions(HttpServletRequest req,
HttpServletResponse res)
Called by the server (via the
service method)
to allow a servlet to handle an OPTIONS request. |
void |
init(ServletConfig config)
Sets instance variables.
|
protected void |
printServletEnvironment(ServletOutputStream out,
HttpServletRequest req,
HttpServletResponse res)
Deprecated.
Use
printServletEnvironment(HttpServletRequest).
This will be removed in Tomcat 8.5.X onwards |
protected void |
service(HttpServletRequest req,
HttpServletResponse res)
Receives standard HTTP requests from the public
service method and dispatches
them to the doMethod methods defined in
this class. |
doDelete, doHead, doPost, doPut, doTrace, getLastModified, servicedestroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, logpublic void init(ServletConfig config) throws ServletException
Modified from Craig R. McClanahan's InvokerServlet
init in interface Servletinit in class GenericServletconfig - a ServletConfig object
containing the servlet's
configuration and initialization
parametersServletException - if an exception has occurred that
interferes with the servlet's normal
operationUnavailableException@Deprecated protected void printServletEnvironment(ServletOutputStream out, HttpServletRequest req, HttpServletResponse res) throws IOException
printServletEnvironment(HttpServletRequest).
This will be removed in Tomcat 8.5.X onwardsCopied from SnoopAllServlet by Craig R. McClanahan
out - Unusedreq - HttpServletRequest object used as source of informationres - UnusedIOException - if a write operation exception occursprotected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
HttpServletservice method and dispatches
them to the doMethod methods defined in
this class. This method is an HTTP-specific version of the
Servlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse) method. There's no
need to override this method.service in class HttpServletreq - the HttpServletRequest object that
contains the request the client made of
the servletres - the HttpServletResponse object that
contains the response the servlet returns
to the clientServletException - if the HTTP request
cannot be handledIOException - if an input or output error occurs
while the servlet is handling the
HTTP requestServlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
doGet in class HttpServletreq - HttpServletRequest passed in by servlet containerres - HttpServletResponse passed in by servlet containerServletException - if a servlet-specific exception occursIOException - if a read/write exception occursServletResponse.setContentType(java.lang.String)protected void doOptions(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
HttpServletservice method)
to allow a servlet to handle an OPTIONS request.
The OPTIONS request determines which HTTP methods
the server supports and
returns an appropriate header. For example, if a servlet
overrides doGet, this method returns the
following header:
Allow: GET, HEAD, TRACE, OPTIONS
There's no need to override this method unless the servlet implements new HTTP methods, beyond those implemented by HTTP 1.1.
doOptions in class HttpServletreq - the HttpServletRequest object that
contains the request the client made of
the servletres - the HttpServletResponse object that
contains the response the servlet returns
to the clientServletException - if the request for the
OPTIONS cannot be handledIOException - if an input or output error occurs
while the servlet is handling the
OPTIONS requestCopyright © 2000-2021 Apache Software Foundation. All Rights Reserved.