NAME
CGI::Tiny - Common Gateway Interface, with no frills
SYNOPSIS
#!/usr/bin/perl
use strict;
use warnings;
use utf8;
use CGI::Tiny;
cgi {
my $cgi = $_;
$cgi->set_error_handler(sub {
my ($cgi, $error, $rendered) = @_;
warn $error;
unless ($rendered) {
if ($cgi->response_status_code == 413) {
$cgi->render(json => {error => 'Request body limit exceeded'});
} elsif ($cgi->response_status_code == 400) {
$cgi->render(json => {error => 'Bad request'});
} else {
$cgi->render(json => {error => 'Internal server error'});
}
}
});
my $method = $cgi->method;
my $fribble;
if ($method eq 'GET' or $method eq 'HEAD') {
$fribble = $cgi->query_param('fribble');
} elsif ($method eq 'POST') {
$fribble = $cgi->body_param('fribble');
} else {
$cgi->set_response_status(405)->render;
exit;
}
die "Invalid fribble parameter" unless length $fribble;
if ($cgi->param('download')) {
$cgi->set_response_disposition(attachment => 'fribble.json');
}
$cgi->render(json => {fribble => $fribble});
};
DESCRIPTION
CGI::Tiny provides a modern interface to write CGI
<https://en.wikipedia.org/wiki/Common_Gateway_Interface> scripts to
dynamically respond to HTTP requests as defined in RFC 3875
<https://tools.ietf.org/html/rfc3875>. It is intended to be:
* Minimal
CGI::Tiny contains a small amount of code and (on modern Perls) no
non-core requirements. No framework needed.
* Simple
CGI::Tiny is straightforward to use, avoids anything magical or
surprising, and provides easy access to the most commonly needed
features.
* Robust
CGI::Tiny's interface is designed to help the developer follow best
practices and avoid common pitfalls and vulnerabilities by default.
* Lazy
CGI::Tiny only loads code or processes information once it is needed,
so simple requests can be handled without unnecessary overhead.
* Restrained
CGI::Tiny is designed for the CGI protocol which executes the program
again for every request. It is not suitable for persistent protocols
like FastCGI or PSGI.
* Flexible
CGI::Tiny can be used with other modules to handle tasks like routing
and templating, and doesn't impose unnecessary constraints to reading
input or rendering output.
Most applications are better written in a PSGI-compatible framework
(e.g. Dancer2 or Mojolicious) and deployed in a persistent application
server so that the application does not have to start up again every
time it receives a request. CGI::Tiny, and the CGI protocol in general,
is only suited for restricted deployment environments that can only run
CGI scripts, or applications that don't need to scale.
See "COMPARISON TO CGI.PM".
USAGE
CGI::Tiny's interface is the cgi block.
use CGI::Tiny;
cgi {
my $cgi = $_;
# set up error handling on $cgi
# inspect request data via $cgi
# set response headers if needed via $cgi
# render response with $cgi->render or $cgi->render_chunk
};
The block is immediately run with $_ set to a CGI::Tiny object, which
"METHODS" can be called on to read request information and render a
response.
If an exception is thrown within the block, or the block does not
render a response, it will run the handler set by "set_error_handler"
if any, or by default emit the error as a warning and (if nothing has
been rendered yet) render a 500 Internal Server Error. The default
server error will also be rendered if the process ends abnormally
between importing from CGI::Tiny and the start of the cgi block.
Note that the cgi block's current implementation as a regular exported
subroutine is an implementation detail, and future implementations
reserve the right to provide it as an XSUB or keyword for performance
reasons. Don't call it as CGI::Tiny::cgi, don't rely on @_ being set,
and don't use return to exit the block; use exit to end a CGI script
early after rendering a response.
See CGI::Tiny::Cookbook for advanced usage examples.
DATA SAFETY
CGI::Tiny does not provide any special affordances for taint mode as it
is overeager, imprecise, and can significantly impact performance. Web
developers should instead proactively take care not to use any request
data (including request headers, form fields, or other request content)
directly in an unsafe manner, as it can make the program vulnerable to
injections that cause undesired or dangerous behavior. The most common
risks to watch out for include:
* System commands
Do not interpolate arbitrary data into a shell command, such as with
system or backticks. Data can be safely passed as command arguments
using methods that bypass the shell, such as the list form of system,
or modules like IPC::System::Simple, IPC::ReadpipeX, and IPC::Run3.
If shell features are needed, data can be escaped for bourne-style
shells with String::ShellQuote.
* Database queries
Do not interpolate arbitrary data into database queries. Data can be
safely passed to database queries using placeholders
<https://metacpan.org/pod/DBI#Placeholders-and-Bind-Values>.
* Regex
Do not interpolate arbitrary data into regular expressions, such as
the m// or s/// operators, or the first argument to split. Data can
be safely included in a regex to match it as an exact string by
escaping it with the quotemeta function or equivalent \Q escape
sequence.
* HTML
Do not interpolate arbitrary data into HTML. Data can be safely
included in HTML by escaping it with "escape_html", or passing it to
an HTML template engine with an auto-escape feature; see
"Templating".
METHODS
The following methods can be called on the CGI::Tiny object provided to
the cgi block.
Setup
set_error_handler
$cgi = $cgi->set_error_handler(sub {
my ($cgi, $error, $rendered) = @_;
...
});
Sets an error handler to run in the event of an exception or if the
script ends without rendering a response. The handler will be called
with the CGI::Tiny object, the error value, and a boolean indicating
whether response headers have been rendered yet.
The error value can be any exception thrown by Perl or user code. It
should generally not be included in any response rendered to the
client, but instead warned or logged.
Exceptions may occur before or after response headers have been
rendered. If response headers have not been rendered, error handlers
may inspect "response_status_code" and/or render some error response.
The response status code will be set to 500 when this handler is called
if it has not been set to a specific 400- or 500-level error status.
If the error handler itself throws an exception, that error and the
original error will be emitted as a warning. If no response has been
rendered after the error handler completes or dies, a default error
response will be rendered.
Note that the error handler is only meant for logging and customization
of the final error response in a failed request dispatch; to handle
exceptions within standard application flow without causing an error
response, use an exception handling mechanism such as
Syntax::Keyword::Try or Feature::Compat::Try (which will use the new
try feature if available).
set_request_body_buffer
$cgi = $cgi->set_request_body_buffer(256*1024);
Sets the buffer size (number of bytes to read at once) for reading the
request body. Defaults to the value of the CGI_TINY_REQUEST_BODY_BUFFER
environment variable or 262144 (256 KiB). A value of 0 will use the
default value.
set_request_body_limit
$cgi = $cgi->set_request_body_limit(16*1024*1024);
Sets the limit in bytes for the request body. Defaults to the value of
the CGI_TINY_REQUEST_BODY_LIMIT environment variable or 16777216 (16
MiB). A value of 0 will remove the limit (not recommended unless you
have other safeguards on memory usage).
Since the request body is not parsed until needed, methods that parse
the request body like "body" or "upload" will set the response status
to 413 Payload Too Large and throw an exception if the content length
is over the limit. Files uploaded through a multipart/form-data request
body also count toward this limit, though they are streamed to
temporary files when parsed.
set_multipart_form_options
$cgi = $cgi->set_multipart_form_options({discard_files => 1, tempfile_args => [SUFFIX => '.dat']});
Set a hash reference of options to pass when parsing a
multipart/form-data request body with "parse_multipart_form_data" in
CGI::Tiny::Multipart. No effect after the form data has been parsed
such as by calling "body_params" or "uploads" for the first time.
Note that options like parse_as_files and on_file_buffer can alter the
content and file keys of the form field structure returned by
"body_parts". Thus "uploads" may not contain file and may instead
contain content, and "body_params" text field values may be read from
file, which will be expected to be a seekable filehandle if present.
set_multipart_form_charset
$cgi = $cgi->set_multipart_form_charset('UTF-8');
Sets the default charset for decoding multipart/form-data forms,
defaults to UTF-8. Parameter and upload field names, upload filenames,
and text parameter values that don't specify a charset will be decoded
from this charset. Set to an empty string to disable this decoding,
effectively interpreting such values in ISO-8859-1.
set_input_handle
$cgi = $cgi->set_input_handle($fh);
Sets the input handle to read the request body from. If not set, reads
from STDIN. The handle will have binmode applied before reading to
remove any translation layers.
set_output_handle
$cgi = $cgi->set_output_handle($fh);
Sets the output handle to print the response to. If not set, prints to
STDOUT. The handle will have binmode applied before printing to remove
any translation layers.
Request Environment
CGI::Tiny provides direct access to CGI request meta-variables
<https://tools.ietf.org/html/rfc3875#section-4.1> via methods that map
to the equivalent uppercase names (and a few short aliases). Since CGI
does not distinguish between missing and empty values, missing values
will be normalized to an empty string.
auth_type
# AUTH_TYPE="Basic"
my $auth_type = $cgi->auth_type;
The authentication scheme used in the Authorization HTTP request header
if any.
content_length
# CONTENT_LENGTH="42"
my $content_length = $cgi->content_length;
The size in bytes of the request body content if any.
content_type
# CONTENT_TYPE="text/plain;charset=UTF-8"
my $content_type = $cgi->content_type;
The MIME type of the request body content if any.
gateway_interface
# GATEWAY_INTERFACE="CGI/1.1"
my $gateway_inteface = $cgi->gateway_interface;
The CGI version used for communication with the CGI server.
path_info
path
# PATH_INFO="/foo/42"
my $path = $cgi->path_info;
my $path = $cgi->path;
The URL path following the SCRIPT_NAME in the request URL if any.
path_translated
# PATH_TRANSLATED="/var/www/html/foo/42"
my $path_translated = $cgi->path_translated;
A local file path derived from PATH_INFO by the CGI server, as if it
were a request to the document root, if it chooses to provide it.
query_string
query
# QUERY_STRING="foo=bar"
my $query = $cgi->query_string;
my $query = $cgi->query;
The query string component of the request URL.
remote_addr
# REMOTE_ADDR="8.8.8.8"
my $remote_addr = $cgi->remote_addr;
The IPv4 or IPv6 address of the requesting client.
remote_host
# REMOTE_HOST="example.com"
my $remote_host = $cgi->remote_host;
The domain name of the requesting client if available, or REMOTE_ADDR.
remote_ident
# REMOTE_IDENT="someuser"
my $remote_ident = $cgi->remote_ident;
The identity of the client reported by an RFC 1413 ident request if
available.
remote_user
# REMOTE_USER="someuser"
my $remote_user = $cgi->remote_user;
The user identity provided as part of an AUTH_TYPE authenticated
request.
request_method
method
# REQUEST_METHOD="GET"
my $method = $cgi->request_method;
my $method = $cgi->method;
The HTTP request method verb.
script_name
# SCRIPT_NAME="/cgi-bin/script.cgi"
my $script_name = $cgi->script_name;
The host-relative URL path to the CGI script.
server_name
# SERVER_NAME="example.com"
my $server_name = $cgi->server_name;
The hostname of the server as the target of the request, such as from
the Host HTTP request header.
server_port
# SERVER_PORT="443"
my $server_port = $cgi->server_port;
The TCP port on which the server received the request.
server_protocol
# SERVER_PROTOCOL="HTTP/1.1"
my $server_protocol = $cgi->server_protocol;
The HTTP protocol version of the request.
server_software
# SERVER_SOFTWARE="Apache\/2.4.37 (centos)"
my $server_software = $cgi->server_software;
The name and version of the CGI server.
Request Parsing
headers
my $hashref = $cgi->headers;
Hash reference of available request header names and values. Header
names are represented in lowercase.
header
my $value = $cgi->header('Accept-Language');
Retrieve the value of a request header by name (case insensitive). CGI
request headers can only contain a single value, which may be combined
from multiple values.
cookies
my $pairs = $cgi->cookies;
Retrieve request cookies as an ordered array reference of name/value
pairs, represented as two-element array references.
cookie_names
my $arrayref = $cgi->cookie_names;
Retrieve request cookie names as an ordered array reference, without
duplication.
cookie
my $value = $cgi->cookie('foo');
Retrieve the value of a request cookie by name. If multiple cookies
were passed with the same name, returns the last value. Use
"cookie_array" to get multiple values of a cookie name.
cookie_array
my $arrayref = $cgi->cookie_array('foo');
Retrieve values of a request cookie name as an ordered array reference.
params
my $pairs = $cgi->params;
Retrieve URL query string parameters and
application/x-www-form-urlencoded or multipart/form-data body
parameters as an ordered array reference of name/value pairs,
represented as two-element array references. Names and values are
decoded to Unicode characters.
Query parameters are returned first, followed by body parameters. Use
"query_params" or "body_params" to retrieve query or body parameters
separately.
Note that this will read the text form fields into memory as in
"body_params".
param_names
my $arrayref = $cgi->param_names;
Retrieve URL query string parameter names and
application/x-www-form-urlencoded or multipart/form-data body parameter
names, decoded to Unicode characters, as an ordered array reference,
without duplication.
Query parameter names are returned first, followed by body parameter
names. Use "query_param_names" or "body_param_names" to retrieve query
or body parameter names separately.
Note that this will read the text form fields into memory as in
"body_params".
param
my $value = $cgi->param('foo');
Retrieve value of a named URL query string parameter or
application/x-www-form-urlencoded or multipart/form-data body
parameter, decoded to Unicode characters.
If the parameter name was passed multiple times, returns the last body
parameter value if any, otherwise the last query parameter value. Use
"param_array" to get multiple values of a parameter, or "query_param"
or "body_param" to retrieve the last query or body parameter value
specifically.
Note that this will read the text form fields into memory as in
"body_params".
param_array
my $arrayref = $cgi->param_array('foo');
Retrieve values of a named URL query string parameter or
application/x-www-form-urlencoded or multipart/form-data body
parameter, decoded to Unicode characters, as an ordered array
reference.
Query parameter values will be returned first, followed by body
parameter values. Use "query_param_array" or "body_param_array" to
retrieve query or body parameter values separately.
Note that this will read the text form fields into memory as in
"body_params".
query_params
my $pairs = $cgi->query_params;
Retrieve URL query string parameters as an ordered array reference of
name/value pairs, represented as two-element array references. Names
and values are decoded to Unicode characters.
query_param_names
my $arrayref = $cgi->query_param_names;
Retrieve URL query string parameter names, decoded to Unicode
characters, as an ordered array reference, without duplication.
query_param
my $value = $cgi->query_param('foo');
Retrieve value of a named URL query string parameter, decoded to
Unicode characters.
If the parameter name was passed multiple times, returns the last
value. Use "query_param_array" to get multiple values of a parameter.
query_param_array
my $arrayref = $cgi->query_param_array('foo');
Retrieve values of a named URL query string parameter, decoded to
Unicode characters, as an ordered array reference.
body
my $bytes = $cgi->body;
Retrieve the request body as bytes.
Note that this will read the whole request body into memory, so make
sure the "set_request_body_limit" can fit well within the available
memory.
Not available after calling "body_parts", "body_params", or "uploads"
(or related accessors) on a multipart/form-data request, since this
type of request body is not retained in memory after parsing.
body_json
my $data = $cgi->body_json;
Decode an application/json request body from UTF-8-encoded JSON.
Note that this will read the whole request body into memory, so make
sure the "set_request_body_limit" can fit well within the available
memory.
body_params
my $pairs = $cgi->body_params;
Retrieve application/x-www-form-urlencoded or multipart/form-data body
parameters as an ordered array reference of name/value pairs,
represented as two-element array references. Names and values are
decoded to Unicode characters.
Note that this will read the text form fields into memory, so make sure
the "set_request_body_limit" can fit well within the available memory.
multipart/form-data file uploads will be streamed to temporary files
accessible via "uploads" and related methods.
body_param_names
my $arrayref = $cgi->body_param_names;
Retrieve application/x-www-form-urlencoded or multipart/form-data body
parameter names, decoded to Unicode characters, as an ordered array
reference, without duplication.
Note that this will read the text form fields into memory as in
"body_params".
body_param
my $value = $cgi->body_param('foo');
Retrieve value of a named application/x-www-form-urlencoded or
multipart/form-data body parameter, decoded to Unicode characters.
If the parameter name was passed multiple times, returns the last
value. Use "body_param_array" to get multiple values of a parameter.
Note that this will read the text form fields into memory as in
"body_params".
body_param_array
my $arrayref = $cgi->body_param_array('foo');
Retrieve values of a named application/x-www-form-urlencoded or
multipart/form-data body parameter, decoded to Unicode characters, as
an ordered array reference.
Note that this will read the text form fields into memory as in
"body_params".
body_parts
my $parts = $cgi->body_parts;
Retrieve multipart/form-data request body parts as an ordered array
reference using "parse_multipart_form_data" in CGI::Tiny::Multipart.
Most applications should retrieve multipart form data through
"body_params" and "uploads" (or related accessors) instead.
Note that this will read the text form fields into memory, so make sure
the "set_request_body_limit" can fit well within the available memory.
File uploads will be streamed to temporary files.
uploads
my $pairs = $cgi->uploads;
Retrieve multipart/form-data file uploads as an ordered array reference
of name/upload pairs, represented as two-element array references.
Names are decoded to Unicode characters.
Note that this will read the text form fields into memory, so make sure
the "set_request_body_limit" can fit well within the available memory.
File uploads are represented as a hash reference containing the
following keys:
filename
Original filename supplied to file input. An empty filename may
indicate that no file was submitted.
content_type
Content-Type of uploaded file, undef if unspecified.
size
File size in bytes.
file
File::Temp object storing the file contents in a temporary file,
which will be cleaned up when the CGI script ends by default. The
filehandle will be open with the seek pointer at the start of the
file for reading.
upload_names
my $arrayref = $cgi->upload_names;
Retrieve multipart/form-data file upload names, decoded to Unicode
characters, as an ordered array reference, without duplication.
Note that this will read the text form fields into memory as in
"uploads".
upload
my $upload = $cgi->upload('foo');
Retrieve a named multipart/form-data file upload. If the upload name
was passed multiple times, returns the last value. Use "upload_array"
to get multiple uploads with the same name.
See "uploads" for details on the representation of the upload.
Note that this will read the text form fields into memory as in
"uploads".
upload_array
my $arrayref = $cgi->upload_array('foo');
Retrieve all multipart/form-data file uploads of the specified name as
an ordered array reference.
See "uploads" for details on the representation of the uploads.
Note that this will read the text form fields into memory as in
"uploads".
Response
set_nph
$cgi = $cgi->set_nph;
$cgi = $cgi->set_nph(1);
If set to a true value or called without a value before rendering
response headers, CGI::Tiny will act as a NPH (Non-Parsed Header)
<https://tools.ietf.org/html/rfc3875#section-5> script and render full
HTTP response headers. This may be required for some CGI servers, or
enable unbuffered responses or HTTP extensions not supported by the CGI
server.
No effect after response headers have been rendered.
set_response_body_buffer
$cgi = $cgi->set_response_body_buffer(128*1024);
Sets the buffer size (number of bytes to read at once) for streaming a
file or handle response body with "render" or "render_chunk". Defaults
to the value of the CGI_TINY_RESPONSE_BODY_BUFFER environment variable
or 131072 (128 KiB). A value of 0 will use the default value.
set_response_status
$cgi = $cgi->set_response_status(404);
$cgi = $cgi->set_response_status('500 Internal Server Error');
Sets the response HTTP status code. A full status string including a
human-readable message will be used as-is. A bare status code must be a
known HTTP status code
<https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml>
and will have the standard human-readable message appended.
No effect after response headers have been rendered.
The CGI protocol assumes a status of 200 OK if no response status is
set.
set_response_disposition
$cgi = $cgi->set_response_disposition('attachment');
$cgi = $cgi->set_response_disposition(attachment => $filename);
$cgi = $cgi->set_response_disposition('inline'); # default behavior
$cgi = $cgi->set_response_disposition(inline => $filename);
Sets the response Content-Disposition header to indicate how the client
should present the response, with an optional filename specified in
Unicode characters. attachment suggests to download the content as a
file, and inline suggests to display the content inline (the default
behavior). No effect after response headers have been rendered.
set_response_type
$cgi = $cgi->set_response_type('application/xml');
Sets the response Content-Type header, to override autodetection in
"render" or "render_chunk". undef will remove the override. No effect
after response headers have been rendered.
set_response_charset
$cgi = $cgi->set_response_charset('UTF-8');
Set charset to use when rendering text, html, or xml response content,
defaults to UTF-8.
add_response_header
$cgi = $cgi->add_response_header('Content-Language' => 'en');
Adds a custom response header. No effect after response headers have
been rendered.
Note that header names are case insensitive and CGI::Tiny does not
attempt to deduplicate or munge headers that have been added manually.
Headers are printed in the response in the same order added, and adding
the same header multiple times will result in multiple instances of
that response header.
add_response_cookie
$cgi = $cgi->add_response_cookie($name => $value,
Expires => 'Sun, 06 Nov 1994 08:49:37 GMT',
HttpOnly => 1,
'Max-Age' => 3600,
Path => '/foo',
SameSite => 'Strict',
Secure => 1,
);
Adds a Set-Cookie response header. No effect after response headers
have been rendered.
Note that cookie values should only consist of ASCII characters and may
not contain any control characters, space characters, or the characters
",;\. More complex values can be encoded to UTF-8 and base64 for
transport.
use Unicode::UTF8 'encode_utf8';
use MIME::Base64 'encode_base64';
my $encoded_value = encode_base64 encode_utf8($value), '';
$cgi->add_response_cookie(foo => $encoded_value, %attrs);
use Unicode::UTF8 'decode_utf8';
use MIME::Base64 'decode_base64';
my $value = decode_utf8 decode_base64 $cgi->cookie('foo');
Data structures can be encoded to JSON and base64 for transport.
use Cpanel::JSON::XS 'encode_json';
use MIME::Base64 'encode_base64';
my $encoded_value = encode_base64 encode_json(\%hash), '';
$cgi->add_response_cookie(foo => $encoded_value, %attrs);
use Cpanel::JSON::XS 'decode_json';
use MIME::Base64 'decode_base64';
my $hashref = decode_json decode_base64 $cgi->cookie('foo');
Optional cookie attributes are specified in key-value pairs after the
cookie name and value. Cookie attribute names are case-insensitive.
Domain
Domain for which cookie is valid.
Expires
Expiration date string for cookie. "epoch_to_date" can be used to
generate the appropriate date string format.
HttpOnly
If set to a true value, the cookie will be restricted from
client-side scripts.
Max-Age
Max age of cookie before it expires, in seconds, as an alternative to
specifying Expires.
Path
URL path for which cookie is valid.
SameSite
Strict to restrict the cookie to requests from the same site, Lax to
allow it additionally in certain cross-site requests. This attribute
is currently part of a draft specification so its handling may
change, but it is supported by most browsers.
Secure
If set to a true value, the cookie will be restricted to HTTPS
requests.
reset_response_headers
$cgi = $cgi->reset_response_headers;
Remove any pending response headers set by "add_response_header" or
"add_response_cookie". No effect after response headers have been
rendered.
response_status_code
my $code = $cgi->response_status_code;
Numerical response HTTP status code that will be sent when headers are
rendered, as set by "set_response_status" or an error occurring.
Defaults to 200.
render
$cgi = $cgi->render; # default Content-Type:
$cgi = $cgi->render(text => $text); # text/plain;charset=$charset
$cgi = $cgi->render(html => $html); # text/html;charset=$charset
$cgi = $cgi->render(xml => $xml); # application/xml;charset=$charset
$cgi = $cgi->render(json => $ref); # application/json;charset=UTF-8
$cgi = $cgi->render(data => $bytes); # application/octet-stream
$cgi = $cgi->render(file => $filepath); # application/octet-stream
$cgi = $cgi->render(redirect => $url);
Renders response headers and then fixed-length response content of a
type indicated by the first parameter, if any. A Content-Length header
will be set to the length of the encoded response content, and further
calls to render or "render_chunk" will throw an exception. Use
"render_chunk" instead to render without a Content-Length header.
The Content-Type response header will be set according to
"set_response_type", or autodetected depending on the data type of any
non-empty response content passed.
The Date response header will be set to the current time as an HTTP
date string if not set manually.
If the "request_method" is HEAD, any provided response content will be
ignored (other than redirect URLs) and Content-Length will be set to 0.
text, html, or xml data is expected to be decoded Unicode characters,
and will be encoded according to "set_response_charset" (UTF-8 by
default). Unicode::UTF8 will be used for efficient UTF-8 encoding if
available.
json data structures will be encoded to JSON and UTF-8.
data or file will render bytes from a string or local file path
respectively. A handle, or a file whose size cannot be determined
accurately from the filesystem, must be rendered using "render_chunk"
since its Content-Length cannot be determined beforehand.
redirect will set a Location header to redirect the client to another
URL. The response status will be set to 302 Found unless a different
300-level status has been set with "set_response_status". It will set a
Content-Length of 0, and it will not set a Content-Type response
header.
render_chunk
$cgi = $cgi->render_chunk; # default Content-Type:
$cgi = $cgi->render_chunk(text => $text); # text/plain;charset=$charset
$cgi = $cgi->render_chunk(html => $html); # text/html;charset=$charset
$cgi = $cgi->render_chunk(xml => $xml); # application/xml;charset=$charset
$cgi = $cgi->render_chunk(json => $ref); # application/json;charset=UTF-8
$cgi = $cgi->render_chunk(data => $bytes); # application/octet-stream
$cgi = $cgi->render_chunk(file => $filepath); # application/octet-stream
$cgi = $cgi->render_chunk(handle => $filehandle); # application/octet-stream
Renders response headers the first time it is called, and then chunked
response content of a type indicated by the first parameter, if any. No
Content-Length header will be set, and render_chunk may be called
additional times with more response content.
render_chunk does not impose a chunked response, it simply does not
generate a Content-Length header. For content where the total encoded
content length is known in advance but the content can't be passed to a
single "render" call, a Content-Length header can be set manually with
"add_response_header", and then render_chunk may be used to render each
part.
The Content-Type response header will be set according to
"set_response_type", or autodetected depending on the data type passed
in the first call to render_chunk, or to application/octet-stream if
there is no more appropriate value. It will be set even if no content
is passed to the first render_chunk call, in case content is rendered
in subsequent calls.
The Date response header will be set to the current time as an HTTP
date string if not set manually.
If the "request_method" is HEAD, any provided response content will be
ignored.
text, html, or xml data is expected to be decoded Unicode characters,
and will be encoded according to "set_response_charset" (UTF-8 by
default). Unicode::UTF8 will be used for efficient UTF-8 encoding if
available.
json data structures will be encoded to JSON and UTF-8.
data, file, or handle will render bytes from a string, local file path,
or open filehandle respectively. A handle will have binmode applied to
remove any translation layers, and its contents will be streamed until
EOF.
redirect responses must be rendered with "render".
FUNCTIONS
The following convenience functions are provided but not exported.
epoch_to_date
my $date = CGI::Tiny::epoch_to_date $epoch;
Convert a Unix epoch timestamp, such as returned by time, to a RFC 1123
HTTP date string suitable for use in HTTP headers such as Date and
Expires.
date_to_epoch
my $epoch = CGI::Tiny::date_to_epoch $date;
Parse a RFC 1123 HTTP date string to a Unix epoch timestamp. For
compatibility as required by RFC 7231
<https://tools.ietf.org/html/rfc7231#section-7.1.1.1>, legacy RFC 850
and ANSI C asctime date formats are also recognized. Returns undef if
the string does not parse as any of these formats.
# RFC 1123
my $epoch = CGI::Tiny::date_to_epoch 'Sun, 06 Nov 1994 08:49:37 GMT';
# RFC 850
my $epoch = CGI::Tiny::date_to_epoch 'Sunday, 06-Nov-94 08:49:37 GMT';
# asctime
my $epoch = CGI::Tiny::date_to_epoch 'Sun Nov 6 08:49:37 1994';
escape_html
my $escaped = CGI::Tiny::escape_html $text;
Escapes characters that are unsafe for embedding in HTML text. The
characters &<>"' will each be replaced with the corresponding HTML
character reference (HTML entity).
This functionality is built into most HTML template engines; see
"Templating". For more general HTML entity escaping and unescaping use
HTML::Entities.
ENVIRONMENT
CGI::Tiny recognizes the following environment variables, in addition
to the standard CGI environment variables.
CGI_TINY_REQUEST_BODY_BUFFER
Default value for "set_request_body_buffer".
CGI_TINY_REQUEST_BODY_LIMIT
Default value for "set_request_body_limit".
CGI_TINY_RESPONSE_BODY_BUFFER
Default value for "set_response_body_buffer".
DEBUGGING COMMANDS
CGI::Tiny scripts can be executed from the commandline for debugging
purposes. A command can be passed as the first argument to help set up
the CGI environment.
These commands are considered a development interface and come with no
stability guarantee.
$ ./script.cgi get '/?foo=bar'
$ ./script.cgi head
$ ./script.cgi post '/form' -C 'one=value' -C 'two=value' --content='foo=bar+baz'
-H 'Content-Type: application/x-www-form-urlencoded'
$ ./script.cgi put -H "Content-Length: $(stat --printf='%s' foo.dat)"
-H "Content-Type: $(file -bi foo.dat)" <foo.dat
$ ./script.cgi delete -v '/item/42'
The get, head, post, put, and delete commands will emulate a request of
the specified "request_method". A following URL parameter will be
passed as the "path_info" and "query_string" if present.
Request content may be provided through STDIN but the Content-Length
request header must be set to the size of the input as required by the
CGI spec.
The response will be printed to STDOUT as normal. You may wish to
redirect the output of the command to a file or hexdump program if the
response is expected not to be printable text in the character encoding
of your terminal.
Options may follow the command:
--content=<string>, -c <string>
Passes the string value as request body content and sets the
Content-Length request header to its size.
--cookie=<string>, -C <string>
String values of the form name=value will be passed as request
cookies. Can appear multiple times.
--header=<string>, -H <string>
String values of the form Name: value will be passed as request
headers. Can appear multiple times. If the same header name is
provided multiple times, the values will be joined with commas, which
is only valid for certain headers.
--verbose, -v
Includes response CGI headers (or HTTP headers in NPH mode) in the
output before response content. Enabled automatically for head.
COMPARISON TO CGI.PM
Traditionally, the CGI module (referred to as CGI.pm to differentiate
it from the CGI protocol) has been used to write Perl CGI scripts. This
module fills a similar need but has a number of interface differences
to be aware of.
* There is no CGI::Tiny object constructor; the object is accessible
within the cgi block, only reads request data from the environment
once it is accessed, and ensures that a valid response is rendered to
avoid gateway errors even in the event of an exception or premature
exit.
* Instead of global variables like $CGI::POST_MAX, global behavior
settings are applied to the CGI::Tiny object inside the cgi block.
* Exceptions within the cgi block are handled by default by rendering
a server error response and emitting the error as a warning. This can
be customized with "set_error_handler".
* Request parameter accessors in CGI::Tiny are not context sensitive,
as context sensitivity can lead to surprising behavior and
vulnerabilities
<https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-1572>.
"param", "query_param", "body_param", and "upload" always return a
single value; "param_array", "query_param_array", "body_param_array",
and "upload_array" must be used to retrieve multi-value parameters.
* CGI::Tiny's "param" accessor is also not method-sensitive; it
accesses either query or body request parameters with the same
behavior regardless of request method, and query and body request
parameters can be accessed separately with "query_param" and
"body_param" respectively.
* CGI::Tiny's "param" accessor only retrieves text parameters;
uploaded files and their metadata are accessed with "upload" and
related methods.
* CGI::Tiny decodes request parameters to Unicode characters
automatically, and "render"/"render_chunk" provide methods to encode
response content from Unicode characters to UTF-8 by default.
* In CGI.pm, response headers must be printed manually before any
response content is printed to avoid malformed responses. In
CGI::Tiny, the "render" or "render_chunk" methods are used to print
response content, and automatically print response headers when first
called. redirect responses are also handled by "render".
* In CGI::Tiny, a custom response status is set by calling
"set_response_status" before the first "render" or "render_chunk",
which only requires the status code and will add the appropriate
human-readable status message itself.
* Response setters are distinct methods from request accessors in
CGI::Tiny. "content_type", "header", and "cookie" are used to access
request data, and "set_response_type", "add_response_header", and
"add_response_cookie" are used to set response headers for the
pending response before the first call to "render" or "render_chunk".
* CGI::Tiny does not provide any HTML generation helpers, as this
functionality is much better implemented by other robust
implementations on CPAN; see "Templating".
* CGI::Tiny does not do any implicit encoding of cookie values or the
Expires header or cookie attribute. The "epoch_to_date" convenience
function is provided to render appropriate Expires date values.
There are a number of alternatives to CGI.pm but they do not
sufficiently address the design issues; primarily, none of them
gracefully handle exceptions or failure to render a response, and
several of them have no features for rendering responses.
* CGI::Simple shares all of the interface design problems of CGI.pm,
though it does not reimplement the HTML generation helpers.
* CGI::Thin is ancient and only implements parsing of request query
or body parameters, without decoding them to Unicode characters.
* CGI::Minimal has context-sensitive parameter accessors, and only
implements parsing of request query/body parameters (without decoding
them to Unicode characters) and uploads.
* CGI::Lite has context-sensitive parameter accessors, and only
implements parsing of request query/body parameters (without decoding
them to Unicode characters), uploads, and cookies.
* CGI::Easy has a robust interface, but pre-parses all request
information.
CAVEATS
CGI is an extremely simplistic protocol and relies particularly on the
global state of environment variables and the STDIN and STDOUT standard
filehandles. CGI::Tiny does not prevent you from messing with these
interfaces directly, but it may result in confusion.
CGI::Tiny eschews certain sanity checking for performance reasons. For
example, Content-Type and other header values set for the response
should only contain ASCII text with no control characters, but
CGI::Tiny does not verify this (though it does verify they do not
contain newline characters to protect against HTTP response splitting).
Field names and filenames in multipart/form-data requests do not have a
well-defined escape mechanism for special characters, so CGI::Tiny will
not attempt to decode these names from however the client passes them
aside from "set_multipart_form_charset". For best compatibility, form
field names should be ASCII without double quotes or semicolons.
BUGS
Report any issues on the public bugtracker.
AUTHOR
Dan Book <dbook@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2021 by Dan Book.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
SEE ALSO
CGI::Alternatives, Mojolicious, Dancer2