/usr/share/doc/libbobcat4-dev/man/cgi.3.html

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<h1 id="title">FBB::CGI</h1>
<h2 id="author">libbobcat-dev_4.04.00-x.tar.gz</h2>
<h2 id="date">2005-2016</h2>

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<title>FBB::CGI(3bobcat)</title>
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<h1 id="title">FBB::CGI(3bobcat)</h1>
<h2 id="author">libbobcat-dev_4.04.00-x.tar.gz CGI interface</h2>
<h2 id="date">2005-2016</h2>


<p>
<h2 >NAME</h2>FBB::CGI - handles GET and POST submitted form data
<p>
<h2 >SYNOPSIS</h2>
    <strong >#include &lt;bobcat/cgi&gt;</strong><br/>
    Linking option: <em >-lbobcat</em> 
<p>
<h2 >DESCRIPTION</h2>
<p>
The class <em >CGI</em> offers an interface to data submitted by web-forms. The
data is sent to a script handling the data using a <em >&lt;form
action="/path/to/form/script"&gt;</em> stanza. Very often this is indeed a script,
like a Perl script, but there is no need to use a scripting language. The
class <em >CGI</em> allows <strong >C++</strong> programmers to process the form by an executable
usually resulting in faster processing and in construction time benefits from
the type safety offered by <strong >C++</strong>. The class <em >CGI</em> automatically handles
data submitted using the <em >GET</em> method as well as data submitted using the
<em >POST</em> method.
<p>
By default the class's constructor writes the customary <em >Content-type</em>
header lines to the standard output stream. Additional (html) output of a
reply page must be provided by other code. Therefore, a program processing an
uploaded form will have an organization comparable to the following basic
setup:
        <pre>

    // assume includes and namespace std/FBB were defined
    int main()
    {
        CGI cgi;
        cout &lt;&lt; "&lt;html&gt;&lt;body&gt;\n";
        if (parametersOK(cgi))
        {
            process(cgi);     
            generateReplyPage();
        }
        else
            generateErrorPage();
        cout &lt;&lt; "&lt;/body&gt;&lt;/html&gt;\n;
    }
        
</pre>

<p>
When errors in the received form-data are detected an error message is
written to the standard output stream and an <em >FBB::Exception</em> exception is
thrown.
<p>
<h2 >NAMESPACE</h2>
    <strong >FBB</strong><br/>
    All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace <strong >FBB</strong>.
<p>
<h2 >INHERITS FROM</h2>
    -
<p>
<h2 >TYPEDEF</h2>
    <ul>
    <li> <strong >CGI::MapStringVector</strong>:<br/> 
       A shorthand for <em >std::unordered_map&lt;std::string, 
        std::vector&lt;std::string&gt; &gt;</em>,
        which is the data type in which form-variables are stored. 
    </ul>
<p>
<h2 >ENUMERATIONS</h2>
    The <em >CGI::Method</em> enumeration specifies values indicating the way the
        form's data were submitted:
    <ul>
    <li> <strong >CGI::UNDETERMINED</strong>:<br/>
       Used internally indicating that the form's method was neither <em >GET</em>
        nor <em >POST</em>.
    <li> <strong >CGI::GET</strong>:<br/>
       Indicates that the <em >GET</em> method was used when submitting the form's
        data;
    <li> <strong >CGI::POST</strong>:<br/>
       Indicates that the <em >POST</em> method was used when submitting the form's
        data.
    </ul>
<p>
The <em >CGI::Create</em> enumeration is used to request or suppress creation of
        the directory to contain any file uploaded by a form:
    <ul>
    <li> <strong >CGI::DONT_CREATE_PATH</strong>:<br/>
       When uploading files, the destination directory must exist;
    <li> <strong >CGI::CREATE_PATH</strong>:<br/>
       When uploading files, the destination directory will be created.
    </ul>
<p>
<h2 >CONSTRUCTORS</h2>
    <ul>
    <li> <strong >CGI(bool defaultEscape = true, 
            char const *header = "Content-type: text/html", 
            std::ostream &amp;out = std::cout)</strong>:<br/>
        The default constructor writes the standard content type header to the
standard output stream and will use <em >std::cout</em> for output. Specifying <em >0</em>
as header suppresses outputting the <em >Content-type</em> line. Otherwise the
content type line is also followed by two <em >\r\n</em> character combinations. By
default all characters in retrieved form-variables are escaped. The overloaded
insertion operators (see below) can be used to modify the default set of
characters to escape. The backslash is used as the escape character. The
escape-prefix is not used if the <em >defaultEscape</em> value is specified as
<em >false</em> and if no insertions into the <strong >CGI</strong> object were performed.
    </ul>
    The copy and move constructors are available.
<p>
<h2 >OERLOADED OPERATORS</h2>
<p>
<strong >Note:</strong> the following three insertion operators, defining sets of
characters that should be escaped, can only be used before calling any of the
<em >param, begin</em> or <em >end</em> members. As soon as one of these latter three
members has been called the set of characters to be escaped is fixed and
attempts to modify that set is silently ignored.
<p>
<ul>
    <li> <strong >char const *operator[](std::string const &amp;key) const</strong>:<br/>
        The index operator returns the value of the environment variable
        specified as the index. 0 is returned if the variable
        specified at <em >key</em> is not defined.
<p>
<li> <strong >CGI &amp;operator&lt;&lt;(std::string const &amp;accept)</strong>:<br/>
       This member's actions are suppressed once <em >param, begin</em> or
        <em >end</em> (see below) has been called.
<p>
The insertion operator can be used to fine-tune the set of characters
        that are escaped in strings returned by <em >param</em> (see
        below). Depending on the value of the constructor's <em >defaultEscape</em>
        parameter characters inserted into the <em >CGI</em> object will or will not
        be escaped by a backslash. 
<p>
If the constructor's <em >defaultEscape</em> parameter was specified as
        <em >true</em> then the insertion operator can be used to define a set of
        characters that are <em >not</em> escaped. 
<p>
If <em >defaultEscape</em> was specified as <em >false</em> then the insertion
        operator will define a set of characters that <em >will</em> be
        escaped. 
<p>
The backlash itself is always escaped and a request to use it
        unescaped is silently ignored. 
<p>
The <em >accept</em> string can be specified as a regular expression
        character set, without the usual surrounding square brackets. E.g., an
        insertion like <em >cgi &lt;&lt; "-a-z0-9"</em> defines the set consisting of the
        dash, the lower case letters and the digits.
<p>
Individual characters, character ranges (using the dash to specify a
        range) and all standard character classes (<em >[:alnum:], [:alpha:],
        [:cntrl:], [:digit:], [:graph:], [:lower:], [:print:], [:punct:],
        [:space:], [:upper:]</em>, and <em >[:xdigit:]</em>) can be used to specify a
        set of characters. In addition to these standard character classes the
        class <em >[:cgi:]</em> can be used to define the set consisting of the
        characters <em >" ' ` ;</em> and <em >\</em>.  
<p>
Note that standard and <em >[:cgi:]</em> character classes <em >do</em> require
        square brackets. 
<p>
When a series of insertions are performed then the union of the sets
        defined by these insertions are used. 
<p>
<strong >Note</strong>: using unescaped single quotes, the double quotes, backtick
        characters and semicolons in CGI-programs might be risky and is not
        advised.
<p>
<li> <strong >CGI &amp;operator&lt;&lt;(int c)</strong>:<br/>
       This member's actions are suppressed once <em >param, begin</em> or
        <em >end</em> (see below) has been called.
<p>
This insertion operator is used to change the default escape handling
        of a single character <em >c</em>. The <em >int</em> parameter is cast internally
        to a <em >char</em>.
<p>
<li> <strong >CGI &amp;operator&lt;&lt;(std::pair&lt;char, char&gt; range)</strong>:<br/>
       This member's actions are suppressed once <em >param, begin</em> or
        <em >end</em> (see below) has been called.
<p>
This insertion operator can be used to change the default escape
        handling of a range of characters. The pair's second character must be
        equal to or exceed the position of the pair's first character in the
        ASCII collating sequence or the member will have no effect.
<p>
<li> <strong >std::ostream &amp;std::operator&lt;&lt;(std::ostream &amp;out, CGI const &amp;cgi)</strong>:<br/>
       <em >CGI</em> objects can be inserted into <em >ostreams</em> to display the
        characters that will appear escaped in strings returned by the 
        <em >param()</em> member function. Each character for which <em >isprint()</em>
        returns <em >true</em> will be displayed as character, surrounded by single
        quotes. For all other characters their ASCII values are displayed.
        Each character is displayed on a line by itself.
<p>
</ul>
<p>
The copy and move assignment operators are available. 
<p>
<h2 >MEMBER FUNCTIONS</h2>
    <ul>
    <li> <strong >CGI::MapStringVector::const_iterator begin()</strong>:<br/>
       Returns the begin iterator of the form's parameter map. Iterator values
        unequal to <em >end</em> (see below) point to a pair of values, the first of
        which is the name of a field defined by the form, the second is a
        vector of strings containing the field's value(s). See also the
        description of the <em >param</em> member below.
<p>
<li> <strong >CGI::MapStringVector::const_iterator end()</strong>:<br/>
       Returns the end iterator of the form's parameter map.
<p>
<li> <strong >unsigned long long maxUploadSize() const</strong>:<br/>
       Returns the current maximum file upload size in bytes.
<p>
<li> <strong >CGI::Method method() const</strong>:<br/> 
       Returns the method that was used when the form was submitted (either
        <em >CGI::GET</em> or <em >CGI::POST</em>).
<p>
<li> <strong >std::vector&lt;std::string&gt; const &amp;param(std::string const &amp;variable)</strong>:<br/>
       Returns the value of the form-variable specified by the function's
        argument. An empty vector is returned if the variable was not provided
        by the form's data. 
<p>
If the same variable was specified multiple times or if its value
        extends over multiple lines (only with <em >multipart/form-data</em>) then
        the vector contains multiple strings. 
<p>
With <em >GET</em> and <em >POST</em> methods not using <em >multipart/form-data</em>
        input fields extending over multiple lines are stored in one string,
        using <em >\r\n</em> combinations between those lines.
<p>
When files are uploaded the vectors contain sets of four
        strings. The first string provides the path nme of the uploaded file;
        the second string provides the file name specified in the form itself
        (so it is the name of the file at the remote location); the third
        string shows the content type specified by the remote browser (e.g.,
        <em >application/octet-stream</em>), the fourth string contains <em >OK</em> if
        the file was successfully uploaded and <em >truncated</em> if the file was
        truncated. Existing files will not be overwritten. When uploading a
        file a usable filename must be found within 100 trials.
<p>
<li> <strong >std::string param1(std::string const &amp;variable) const</strong>:<br/>
       Returns the first element of the <em >vector&lt;string&gt;</em> returned by the
        <em >param</em> member or an empty string if <em >variable</em> was not defined by
        the received form.
<p>
<li> <strong >std::string const &amp;query() const</strong>:<br/> 
       Returns the query-string submitted with <em >CGI::GET</em> or <em >CGI::POST</em>
        forms (if the <em >POST</em>ed form specified
        <em >ENCTYPE="multipart/form-data"</em> the query string is empty). 
<p>
<li> <strong >report()</strong>:<br/>
        The <em >report</em> member silently returns if no errors were encountered
        while processing form-data. Otherwise, the <em >html</em> file generated by
        the <em >CGI</em> program displays a line starting with <em >FBB::CGI</em>,
        followed by the status report. 
<p>
The following status report messages are presently defined:
<p>
<em >Content-Disposition not recognized in:</em>, which is followed by the
        line where the <em >Content-Disposition</em> was expected. This may occur
        when processing <em >multipart/form</em> data.
<p>
<em >Invalid multipart/form-data</em>. This message can be generated when
        readling lines while processing <em >multipart/form</em> data.
<p>
<em >GET/POST REQUEST_METHOD not found</em>. This message is shown if the
        program couldn't find the form's <em >REQUEST_METHOD</em> type (i.e.,
        <em >GET</em> or <em >POST</em>).
<p>
<em >Invalid CONTENT_LENGHT in POSTed form</em>. This message is shown if
        the content-length header has an incorrect value.
<p>
<em >Content-Type not found for file-field</em>, followed by the file's
        field name. This message is shown if no <em >Content-Type</em> specification
        was found in an uploaded form.
<p>
<em >Can't open a file to write an uploaded file</em>. This message
        indicates that the CGI program was unable to open a file to write an
        uploaded file to. This can be caused by an overfull disk or partition
        or by incorrect write-permissions.
<p>
<em >multipart/form-data: no end-boundary found</em>. This message is shown
        if the end-boundary was missing in a <em >multipart/form-data</em> form.
<p>
<li> <strong >void setFileDestination(std::string const &amp;path, 
                                std::string const &amp;prefix = "",
                                Create create = CREATE_PATH)</strong>:<br/>
       This member is used to specify the path and prefix of uploaded
        files. Uploaded files will be stored at <em >path/prefixNr</em> where <em >Nr</em>
        is an internally used number starting at one. When <em >CREATE_PATH</em> is
        specified <em >path</em> must be available or the <strong >CGI</strong> object must be
        able to create the path. If <em >DONT_CREATE_PATH</em> is specified the
        specified path must be available. If not, an <em >FBB::Exception</em>
        exception will be thrown.
<p>
<li> <strong >void setMaxUploadSize(size_t maxSize, int unit = 'M')</strong>:<br/>
       This member can be used to change the maximum size of uploaded
        files. Its default value is 100Mb. The <em >unit</em> can be one of <em >b</em>
        (bytes, the default), <em >K</em> (Kbytes), <em >M</em> (Mbytes) or <em >G</em>
        (Gbytes). Unit-specifiers are interpreted case insensitively. File
        uploads will continue until the maximum upload size is exceeded,
        followed by discarding any remainder.
    </ul>
    The first time one of the <em >param(), begin()</em> or <em >end()</em> members is
called these members may detect errors in the the received form data. If so,
an error message is written to the standard output stream and an
<em >FBB::Exception</em> exception will be thrown.
<p>
<h2 >STATIC MEMBERS</h2>
    <ul>
    <li> <strong >std::string dos2unix(std::string const &amp;text)</strong>:<br/>
        This member converts all <em >\r\n</em> character combinations in <em >text</em>
        into plain <em >\n</em> characters, returning the converted text.
<p>
<li> <strong >std::string unPercent(std::string const &amp;text)</strong>:<br/> This member converts
        all <em >%xx</em> encoded characters into their corresponding ASCII
        values. Also, <em >+</em> characters are converted to single blank
        spaces. The converted string is returned.
    </ul>    
<p>
<h2 >EXAMPLE</h2>
<p>
<pre >
#include "main.ih"

void showParam(CGI::MapStringVector::value_type const &amp;mapValue)
{
    cout &lt;&lt; "Param: " &lt;&lt; mapValue.first &lt;&lt; '\n';

    for (auto &amp;str: mapValue.second)
        cout &lt;&lt; "    " &lt;&lt; CGI::dos2unix(str) &lt;&lt; "\n"
            "    ";

    cout &lt;&lt; '\n';
}

int main(int argc, char **argv)
try
{
    Arg &amp;arg = Arg::initialize("evhm:", argc, argv);

    // usage and version are in the source archive in .../cgi/driver
    // arg.versionHelp(usage, version, 2);

    ifstream in(arg[0]);
    string line;
    while (getline(in, line))
    {
        size_t pos = line.find('=');

        if (pos == string::npos)
            continue;
                            // set environment vars simulating
                            // a GET form
        if (setenv(line.substr(0, pos).c_str(),     
               line.substr(pos + 1).c_str(), true) == 0)
        {
            if (arg.option('e'))
                cout &lt;&lt; line.substr(0, pos).c_str() &lt;&lt; '=' &lt;&lt;
                       line.substr(pos + 1).c_str() &lt;&lt; '\n';
        }
        else
            cout &lt;&lt; "FAILED: setenv " &lt;&lt; line &lt;&lt; '\n';
    }

    CGI cgi(false);             // chars are not escaped

    cgi &lt;&lt; arg[1];

    if (arg.option(&amp;line, 'm'))
        cgi.setMaxUploadSize(A2x(line), *line.rbegin());

    cout &lt;&lt; "Max upload size (b): " &lt;&lt; cgi.maxUploadSize() &lt;&lt; '\n';

    CGI::Method method = cgi.method();

    cout &lt;&lt; "To escape:\n" &lt;&lt; 
            cgi &lt;&lt; "\n"
            "Method: " &lt;&lt; (method == CGI::GET ? "GET" : "POST") &lt;&lt; 
            '\n';

    cout &lt;&lt; "Query string: " &lt;&lt; cgi.query() &lt;&lt; '\n';

    cout &lt;&lt; "Submit string: `" &lt;&lt; cgi.param1("submit") &lt;&lt; "'\n";

    for (auto &amp;mapElement: cgi)
        showParam(mapElement);

    cout &lt;&lt; "END OF PROGRAM\n";
}
catch (exception const &amp;err)
{
    cout &lt;&lt; err.what() &lt;&lt; '\n';
    return 1;
}
catch (...)
{
    return 1;
}




</pre>

<p>
To test the program's <em >get</em> form processing, call it as <em >driver get
'[:cgi:]'</em>, with the file <em >get</em> containing:
    <pre >
INFO=This is an abbreviated set of environment variables
SERVER_ADMIN=f.b.brokken@rug.nl
GATEWAY_INTERFACE=CGI/1.1
SERVER_PROTOCOL=HTTP/1.1
REQUEST_METHOD=GET
QUERY_STRING=hidden=hidval&amp;submit=Submit+%20Query
</pre>

<p>
To test the program's <em >post</em> form processing, call it as <em >driver post1
'[:cgi:]'</em>, using <em >post1</em> and <em >post1.cin</em> found in Bobcat's source archive
under <em >../cgi/driver</em>.
<p>
<h2 >FILES</h2>
    <em >bobcat/cgi</em> - defines the class interface
<p>
<h2 >SEE ALSO</h2>
    <strong >bobcat</strong>(7)
<p>
<h2 >BUGS</h2>
    None Reported.
<p>

<h2 >DISTRIBUTION FILES</h2>
    <ul>
    <li> <em >bobcat_4.04.00-x.dsc</em>: detached signature;
    <li> <em >bobcat_4.04.00-x.tar.gz</em>: source archive;
    <li> <em >bobcat_4.04.00-x_i386.changes</em>: change log;
    <li> <em >libbobcat1_4.04.00-x_*.deb</em>: debian package holding the
            libraries;
    <li> <em >libbobcat1-dev_4.04.00-x_*.deb</em>: debian package holding the
            libraries, headers and manual pages;
    <li> <em >http://sourceforge.net/projects/bobcat</em>: public archive location;
    </ul>
<p>
<h2 >BOBCAT</h2>
    Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
<p>
<h2 >COPYRIGHT</h2>
    This is free software, distributed under the terms of the 
    GNU General Public License (GPL).
<p>
<h2 >AUTHOR</h2>
    Frank B. Brokken (<strong >f.b.brokken@rug.nl</strong>).
<p>
libbobcat-dev 4.04.00-1 / usr / share / doc / libbobcat4-dev / man / cgi.3.html
