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/*$T httpd.c GC 1.138 07/23/05 13:10:49 */

/*
 * \defgroup httpd Web server @{ The uIP web server is a very simplistic
 * implementation of an HTTP server. It can serve web pages and files from a
 * read-only ROM filesystem, and provides a very small scripting language. The
 * script language is very simple and works as follows. Each script line starts
 * with a command character, either "i", "t", "c", "#" or ".". The "i" command
 * tells the script interpreter to "include" a file from the virtual file system
 * and output it to the web browser. The "t" command should be followed by a line
 * of text that is to be output to the browser. The "c" command is used to call
 * one of the C functions from the httpd-cgi.c file. A line that starts with a "#"
 * is ignored (i.e., the "#" denotes a comment), and the "." denotes the last
 * script line. The script that produces the file statistics page looks somewhat
 * like this: \code i /header.html t <h1>File statistics</h1><br><table
 * width="100%"> t <tr><td><a href="/index.html">/index.html</a></td><td> c a
 * /index.html t </td></tr> <tr><td><a href="/cgi/files">/cgi/files</a></td><td> c
 * a /cgi/files t </td></tr> <tr><td><a href="/cgi/tcp">/cgi/tcp</a></td><td> c a
 * /cgi/tcp t </td></tr> <tr><td><a href="/404.html">/404.html</a></td><td> c a
 * Copyright (c) 2001, Adam Dunkels. All rights reserved. Redistribution and use
 * in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: 1. Redistributions of source
 * code must retain the above copyright notice, this list of conditions and the
 * following disclaimer. 2. Redistributions in binary form must reproduce the
 * above copyright notice, this list of conditions and the following disclaimer in
 * the documentation and/or other materials provided with the distribution. 3. The
 * name of the author may not be used to endorse or promote products derived from
 * this software without specific prior written permission. THIS SOFTWARE IS
 * PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * This file is part of the uIP TCP/IP stack. $Id: httpd.c,v 1.28.2.6 2003/10/07
 * 13:22:27 adam Exp $
 */
#include "uip.h"
#include "httpd.h"
#include "fs.h"
#include "fsdata.h"
#include "cgi.h"

#define NULL    ( void * ) 0

/* The HTTP server states: */
#define HTTP_NOGET  0
#define HTTP_FILE   1
#define HTTP_TEXT   2
#define HTTP_FUNC   3
#define HTTP_END    4

#ifdef DEBUG
#include <stdio.h>
#define PRINT( x )
#define PRINTLN( x )
#else /* DEBUG */
#define PRINT( x )
#define PRINTLN( x )
#endif /* DEBUG */

struct httpd_state              *hs;

extern const struct fsdata_file file_index_html;
extern const struct fsdata_file file_404_html;

static void                     next_scriptline( void );
static void                     next_scriptstate( void );

#define ISO_G       0x47
#define ISO_E       0x45
#define ISO_T       0x54
#define ISO_slash   0x2f
#define ISO_c       0x63
#define ISO_g       0x67
#define ISO_i       0x69
#define ISO_space   0x20
#define ISO_nl      0x0a
#define ISO_cr      0x0d
#define ISO_a       0x61
#define ISO_t       0x74
#define ISO_hash    0x23
#define ISO_period  0x2e

#define httpPORT    80

/*
 =======================================================================================================================
    Initialize the web server. Starts to listen for incoming connection requests on TCP port 80.
 =======================================================================================================================
 */
void httpd_init( void )
{
    fs_init();

    /* Listen to port 80. */
    uip_listen( HTONS( httpPORT ) );
}

/*
 =======================================================================================================================
 =======================================================================================================================
 */
void httpd_appcall( void )
{
    /*~~~~~~~~~~~~~~~~~~~*/
    struct fs_file  fsfile;
    u8_t            i;
    /*~~~~~~~~~~~~~~~~~~~*/

    switch( uip_conn->lport )
    {
    /* This is the web server: */
    case HTONS( httpPORT ):
        /* Pick out the application state from the uip_conn structure. */
        hs = ( struct httpd_state * ) ( uip_conn->appstate );

        /*
         * We use the uip_ test functions to deduce why we were called. If uip_connected()
         * is non-zero, we were called because a remote host has connected to us. If
         * uip_newdata() is non-zero, we were called because the remote host has sent us
         * new data, and if uip_acked() is non-zero, the remote host has acknowledged the
         * data we previously sent to it.
         */
        if( uip_connected() )
        {
            /*
             * Since we have just been connected with the remote host, we reset the state for
             * this connection. The ->count variable contains the amount of data that is yet
             * to be sent to the remote host, and the ->state is set to HTTP_NOGET to signal
             * that we haven't received any HTTP GET request for this connection yet.
             */
            hs->state = HTTP_NOGET;
            hs->count = 0;
            return;
        }
        else if( uip_poll() )
        {
            /*
             * If we are polled ten times, we abort the connection. This is because we don't
             * want connections lingering indefinately in the system.
             */
            if( hs->count++ >= 10 )
            {
                uip_abort();
            }

            return;
        }
        else if( uip_newdata() && hs->state == HTTP_NOGET )
        {
            /*
             * Check for GET.
             */
            if
            (
                uip_appdata[0] != ISO_G
            ||  uip_appdata[1] != ISO_E
            ||  uip_appdata[2] != ISO_T
            ||  uip_appdata[3] != ISO_space
            )
            {
                /* If it isn't a GET, we abort the connection. */
                uip_abort();
                return;
            }

            /* Find the file we are looking for. */
            for( i = 4; i < 40; ++i )
            {
                if( uip_appdata[i] == ISO_space || uip_appdata[i] == ISO_cr || uip_appdata[i] == ISO_nl )
                {
                    uip_appdata[i] = 0;
                    break;
                }
            }

            PRINT( "request for file " );
            PRINTLN( &uip_appdata[4] );

            /* Check for a request for "/". */
            if( uip_appdata[4] == ISO_slash && uip_appdata[5] == 0 )
            {
                fs_open( file_index_html.name, &fsfile );
            }
            else
            {
                if( !fs_open( ( const char * ) &uip_appdata[4], &fsfile ) )
                {
                    PRINTLN( "couldn't open file" );
                    fs_open( file_404_html.name, &fsfile );
                }
            }

            if
            (
                uip_appdata[4] == ISO_slash
            &&  uip_appdata[5] == ISO_c
            &&  uip_appdata[6] == ISO_g
            &&  uip_appdata[7] == ISO_i
            &&  uip_appdata[8] == ISO_slash
            )
            {
                /*
                 * If the request is for a file that starts with "/cgi/", we prepare for invoking
                 * a script.
                 */
                hs->script = fsfile.data;
                next_scriptstate();
            }
            else
            {
                hs->script = NULL;

                /*
                 * The web server is now no longer in the HTTP_NOGET state, but in the HTTP_FILE
                 * state since is has now got the GET from the client and will start transmitting
                 * the file.
                 */
                hs->state = HTTP_FILE;

                /*
                 * Point the file pointers in the connection state to point to the first byte of
                 * the file.
                 */
                hs->dataptr = fsfile.data;
                hs->count = fsfile.len;
            }
        }

        if( hs->state != HTTP_FUNC )
        {
            /*
             * Check if the client (remote end) has acknowledged any data that we've
             * previously sent. If so, we move the file pointer further into the file and send
             * back more data. If we are out of data to send, we close the connection.
             */
            if( uip_acked() )
            {
                if( hs->count >= uip_conn->len )
                {
                    hs->count -= uip_conn->len;
                    hs->dataptr += uip_conn->len;
                }
                else
                {
                    hs->count = 0;
                }

                if( hs->count == 0 )
                {
                    if( hs->script != NULL )
                    {
                        next_scriptline();
                        next_scriptstate();
                    }
                    else
                    {
                        uip_close();
                    }
                }
            }
        }
        else
        {
            /* Call the CGI function. */
            if( cgitab[hs->script[2] - ISO_a](uip_acked()) )
            {
                /* If the function returns non-zero, we jump to the next line in the script. */
                next_scriptline();
                next_scriptstate();
            }
        }

        if( hs->state != HTTP_FUNC && !uip_poll() )
        {
            /* Send a piece of data, but not more than the MSS of the connection. */
            uip_send( ( void * ) hs->dataptr, hs->count );
        }

        /* Finally, return to uIP. Our outgoing packet will soon be on its way... */
        return;

    default:
        /* Should never happen. */
        uip_abort();
        break;
    }
}

/*
 =======================================================================================================================
    next_scriptline(): Reads the script until it finds a newline.
 =======================================================================================================================
 */
static void next_scriptline( void )
{
    /* Loop until we find a newline character. */
    do
    {
        ++( hs->script );
    } while( hs->script[0] != ISO_nl );

    /* Eat up the newline as well. */
    ++( hs->script );
}

/*
 =======================================================================================================================
    next_sciptstate: Reads one line of script and decides what to do next.
 =======================================================================================================================
 */
static void next_scriptstate( void )
{
    /*~~~~~~~~~~~~~~~~~~~*/
    struct fs_file  fsfile;
    u8_t            i;
    /*~~~~~~~~~~~~~~~~~~~*/

again:
    switch( hs->script[0] )
    {
    case ISO_t:
        /* Send a text string. */
        hs->state = HTTP_TEXT;
        hs->dataptr = &hs->script[2];

        /* Calculate length of string. */
        for( i = 0; hs->dataptr[i] != ISO_nl; ++i );
        hs->count = i;
        break;

    case ISO_c:
        /* Call a function. */
        hs->state = HTTP_FUNC;
        hs->dataptr = NULL;
        hs->count = 0;
        cgitab[hs->script[2] - ISO_a]( 0 );
        break;

    case ISO_i:
        /* Include a file. */
        hs->state = HTTP_FILE;
        if( !fs_open( &hs->script[2], &fsfile ) )
        {
            uip_abort();
        }

        hs->dataptr = fsfile.data;
        hs->count = fsfile.len;
        break;

    case ISO_hash:
        /* Comment line. */
        next_scriptline();
        goto again;

    case ISO_period:
        /* End of script. */
        hs->state = HTTP_END;
        uip_close();
        break;

    default:
        uip_abort();
        break;
    }
}

/*
 * @}
 */