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<!-- Copyright (C) 2003 Red Hat, Inc. -->
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>Support Functions and Macros</TITLE
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><H1
CLASS="SECT1"
><A
NAME="NET-HTTPD-HTML">Support Functions and Macros</H1
><P
>The emphasis of this server is on dynamically generated content,
rather than fetching it from a filesystem. To do this the handler
functions make calls to <TT
CLASS="FUNCTION"
>fprintf()</TT
> and
<TT
CLASS="FUNCTION"
>fputs()</TT
>. Such handler functions would end up a
mass of print calls, with the actual structure of the HTML page hidden
in the format strings and arguments, making maintenance and debugging
very difficult. Such an approach would also result in the definition
of many, often only slightly different, format strings, leading to
unnecessary bloat.</P
><P
>In an effort to expose the structure of the HTML in the structure of
the C code, and to maximize the sharing of string constants, the
<TT
CLASS="FILENAME"
>cyg/httpd/httpd.h</TT
> header file defines a set of
helper functions and macros. Most of these are wrappers for predefined
print calls on the <TT
CLASS="PARAMETER"
><I
>client</I
></TT
> stream passed to the
hander function. For examples of their use, see the System Monitor
example.</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>All arguments to macros are pointers to strings, unless otherwise
stated. In general, wherever a function or macro has an
<TT
CLASS="PARAMETER"
><I
>attr</I
></TT
> or <TT
CLASS="PARAMETER"
><I
>__attr</I
></TT
>
parameter, then the contents of this string will be inserted into the
tag being defined as HTML attributes. If it is a NULL or empty string
it will be ignored.</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN15305">HTTP Support</H2
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>void cyg_http_start( FILE *client, char *content_type, int content_length );
void cyg_http_finish( FILE *client );
#define html_begin(__client)
#define html_end( __client )</PRE
></TD
></TR
></TABLE
><P
>The function <TT
CLASS="FUNCTION"
>cyg_http_start()</TT
> generates a simple
HTTP response header containing the value of
<TT
CLASS="LITERAL"
>CYGDAT_HTTPD_SERVER_ID</TT
> in the "Server" field, and the
values of <TT
CLASS="PARAMETER"
><I
>content_type</I
></TT
> and
<TT
CLASS="PARAMETER"
><I
>content_length</I
></TT
> in the "Content-type"
and "Content-length" field respectively. The function
<TT
CLASS="FUNCTION"
>cyg_http_finish()</TT
> just adds an extra newline to
the end of the output and then flushes it to force the data out to the
client.</P
><P
>The macro <TT
CLASS="LITERAL"
>html_begin()</TT
> generates an HTTP header
with a "text/html" content type followed by an opening
"<html>" tag. <TT
CLASS="LITERAL"
>html_end()</TT
> generates
a closing "</html>" tag and calls
<TT
CLASS="FUNCTION"
>cyg_http_finish()</TT
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN15318">General HTML Support</H2
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>void cyg_html_tag_begin( FILE *client, char *tag, char *attr );
void cyg_html_tag_end( FILE *client, char *tag );
#define html_tag_begin( __client, __tag, __attr )
#define html_tag_end( __client, __tag )
#define html_head( __client, __title, __meta )
#define html_body_begin( __client, __attr )
#define html_body_end( __client )
#define html_heading( __client, __level, __heading )
#define html_para_begin( __client, __attr )
#define html_url( __client, __text, __link )
#define html_image( __client, __source, __alt, __attr )</PRE
></TD
></TR
></TABLE
><P
>The function <TT
CLASS="FUNCTION"
>cyg_html_tag_begin()</TT
> generates an
opening tag with the given name. The function
<TT
CLASS="FUNCTION"
>cyg_html_tag_end()</TT
> generates a closing tag with
the given name. The macros <TT
CLASS="LITERAL"
>html_tag_begin()</TT
> and
<TT
CLASS="LITERAL"
>html_tag_end</TT
> are just wrappers for these functions.</P
><P
>The macro <TT
CLASS="LITERAL"
>html_head()</TT
> generates an HTML header
section with <TT
CLASS="PARAMETER"
><I
>__title</I
></TT
> as the title. The
<TT
CLASS="PARAMETER"
><I
>__meta</I
></TT
> argument defines any meta tags that will
be inserted into the header. <TT
CLASS="LITERAL"
>html_body_begin()</TT
> and
<TT
CLASS="LITERAL"
>html_body_end</TT
> generate HTML body begin and end
tags.</P
><P
><TT
CLASS="LITERAL"
>html_heading()</TT
> generates a complete HTML header
where <TT
CLASS="PARAMETER"
><I
>__level</I
></TT
> is a numerical level, between 1
and 6, and <TT
CLASS="PARAMETER"
><I
>__heading</I
></TT
> is the heading
text. <TT
CLASS="LITERAL"
>html_para_begin()</TT
> generates a paragraph
break.</P
><P
><TT
CLASS="LITERAL"
>html_url()</TT
> inserts a URL where
<TT
CLASS="PARAMETER"
><I
>__text</I
></TT
> is the displayed text and
<TT
CLASS="PARAMETER"
><I
>__link</I
></TT
> is the URL of the linked
page. <TT
CLASS="LITERAL"
>html_image()</TT
> inserts an image tag where
<TT
CLASS="PARAMETER"
><I
>__source</I
></TT
> is the URL of the image to be
included and <TT
CLASS="PARAMETER"
><I
>__alt</I
></TT
> is the alternative text for
when the image is not displayed.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN15344">Table Support</H2
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>#define html_table_begin( __client, __attr )
#define html_table_end( __client )
#define html_table_header( __client, __content, __attr )
#define html_table_row_begin( __client, __attr )
#define html_table_row_end( __client )
#define html_table_data_begin( __client, __attr )
#define html_table_data_end( __client ) </PRE
></TD
></TR
></TABLE
><P
><TT
CLASS="LITERAL"
>html_table_begin()</TT
> starts a table and
<TT
CLASS="LITERAL"
>html_table_end()</TT
> end
it. <TT
CLASS="LITERAL"
>html_table_header()</TT
> generates a simple table
column header containg the string <TT
CLASS="PARAMETER"
><I
>__content</I
></TT
>. </P
><P
><TT
CLASS="LITERAL"
>html_table_row_begin()</TT
> and
<TT
CLASS="LITERAL"
>html_table_row_end()</TT
> begin and end a table row,
and similarly <TT
CLASS="LITERAL"
>html_table_data_begin()</TT
> and
<TT
CLASS="LITERAL"
>html_table_data_end()</TT
> begin and end a table
entry. </P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN15357">Forms Support</H2
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>#define html_form_begin( __client, __url, __attr )
#define html_form_end( __client )
#define html_form_input( __client, __type, __name, __value, __attr )
#define html_form_input_radio( __client, __name, __value, __checked )
#define html_form_input_checkbox( __client, __name, __value, __checked )
#define html_form_input_hidden( __client, __name, __value )
#define html_form_select_begin( __client, __name, __attr )
#define html_form_option( __client, __value, __label, __selected )
#define html_form_select_end( __client )
void cyg_formdata_parse( char *data, char *list[], int size );
char *cyg_formlist_find( char *list[], char *name );</PRE
></TD
></TR
></TABLE
><P
><TT
CLASS="LITERAL"
>html_form_begin()</TT
> begins a form, the
<TT
CLASS="PARAMETER"
><I
>__url</I
></TT
> argument is the value for the
<TT
CLASS="LITERAL"
>action</TT
>
attribute. <TT
CLASS="LITERAL"
>html_form_end()</TT
> ends the form.</P
><P
><TT
CLASS="LITERAL"
>html_form_input()</TT
> defines a general form input
element with the given type, name and
value. <TT
CLASS="LITERAL"
>html_form_input_radio</TT
> creates a radio button
with the given name and value; the <TT
CLASS="PARAMETER"
><I
>__checked</I
></TT
>
argument is a boolean expression that is used to determine whether the
<TT
CLASS="LITERAL"
>checked</TT
> attribute is added to the tag. Similarly
<TT
CLASS="LITERAL"
>html_form_input_checkbox()</TT
> defines a checkbox
element. <TT
CLASS="LITERAL"
>html_form_input_hidden()</TT
> defines a hidden
form element with the given name and value.</P
><P
><TT
CLASS="LITERAL"
>html_form_select_begin()</TT
> begins a multiple choice
menu with the given name. <TT
CLASS="LITERAL"
>html_form_select_end()</TT
>
end it. <TT
CLASS="LITERAL"
>html_form_option()</TT
> defines a menu entry
with the given value and label; the <TT
CLASS="PARAMETER"
><I
>__selected</I
></TT
>
argument is a boolean expression controlling whether the
<TT
CLASS="LITERAL"
>selected</TT
> attribute is added to the tag.</P
><P
><TT
CLASS="FUNCTION"
>cyg_formdata_parse()</TT
> converts a form response
string into an <TT
CLASS="LITERAL"
>NULL</TT
>-terminated array of
"name=value" entries. The <TT
CLASS="PARAMETER"
><I
>data</I
></TT
>
argument is the string as passed to the handler function; note that
this string is not copied and will be updated in place to form the
list entries. <TT
CLASS="PARAMETER"
><I
>list</I
></TT
> is a pointer to an array of
character pointers, and is <TT
CLASS="PARAMETER"
><I
>size</I
></TT
> elements long.
<TT
CLASS="FUNCTION"
>cyg_formlist_find()</TT
> searches a list generated by
<TT
CLASS="FUNCTION"
>cyg_formdata_parse()</TT
> and returns a pointer to the
value part of the string whose name part matches
<TT
CLASS="PARAMETER"
><I
>name</I
></TT
>; if there is no match it will return
<TT
CLASS="LITERAL"
>NULL</TT
>.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN15388">Predefined Handlers</H2
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
> int cyg_httpd_send_html( FILE *client, char *filename, char *request, void *arg );
typedef struct
{
char *content_type;
cyg_uint32 content_length;
cyg_uint8 *data;
} cyg_httpd_data;
#define CYG_HTTPD_DATA( __name, __type, __length, __data )
int cyg_httpd_send_data( FILE *client, char *filename, char *request, void *arg ); </PRE
></TD
></TR
></TABLE
><P
>The HTTP server defines a couple of predefined handers to make it
easier to deliver simple, static content.</P
><P
><TT
CLASS="FUNCTION"
>cyg_httpd_send_html()</TT
> takes a
<TT
CLASS="LITERAL"
>NULL</TT
>-terminated string as the argument and sends it
to the client with an HTTP header indicating that it is HTML. The
following is an example of its use:</P
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
> char cyg_html_message[] = "<head><title>Welcome</title></head>\n"
"<body><h2>Welcome to my Web Page</h2></body>\n"
CYG_HTTPD_TABLE_ENTRY( cyg_html_message_entry,
"/message.html",
cyg_httpd_send_html,
cyg_html_message ); </PRE
></TD
></TR
></TABLE
><P
><TT
CLASS="FUNCTION"
>cyg_httpd_send_data()</TT
> Sends arbitrary data to the
client. The argument is a pointer to a <SPAN
CLASS="TYPE"
>cyg_httpd_data</SPAN
>
structure that defines the content type and length of the data, and a
pointer to the data itself. The <TT
CLASS="LITERAL"
>CYG_HTTPD_DATA()</TT
>
macro automates the definition of the structure. Here is a typical
example of its use:</P
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
> static cyg_uint8 ecos_logo_gif[] = {
...
};
CYG_HTTPD_DATA( cyg_monitor_ecos_logo_data,
"image/gif",
sizeof(ecos_logo_gif),
ecos_logo_gif );
CYG_HTTPD_TABLE_ENTRY( cyg_monitor_ecos_logo,
"/monitor/ecos.gif",
cyg_httpd_send_data,
&cyg_monitor_ecos_logo_data ); </PRE
></TD
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