12-8-Protocol, request, response, canvas (verification code production)

Fwrite (file handle, write content) return value is the length of bytes written to the file

fopen (file path, open mode) This is the file handle.

Fclose (file handle) Close file handle

After the file handle is opened, you can read and write to the file, and closing the file handle will no longer read and write to the file.

Copy (copied file path, file path after copying) copying files

Store location to include file name

Unlink (file path) Delete file

Filemtime (file path) returns the time when the file was last modified and a timestamp was obtained

FileSize (file path) returns the size of the file, in bytes

Request protocol Package for http:

1, Request line (Request-line)

Request mode-Request path-protocol version

Requires a separate row, the path does not include the domain name

2, request header (Request-line)

The collection of all protocol entries that are required for this request

Host: Indicates the hostname (domain name) of the requesting server

Accept-encoding:gzip indicates the type of file compression encoding supported by the browser

Accept_charset: Browser-supported character set

Referer which URL this request came from

Accept-language: Acceptable language types

Cookie: Cookie Data If there are no expired cookies on the site

User-agent: Kernel information for the browser

Accept: Data types acceptable to the browser

3, empty line

Used to separate the request header from the request data, the table name request header to this end

4, request data (Request-line)

The requested data is stored here, such as personal information entered when registering an account.

Use Telnet to send a request to the server

In cmd: 1,telnet 192.168.148.10 80

2,ctrl+] The echo of the data

3, enter request line, request header, blank line

Each Telnet send request can only be a single time, re-use need to turn on Telnet

About the appropriate protocol package for http:

1, Response line (status line)

Protocol version, Status code (404: Request resource does not exist), status description

Common Status Codes:

OK: Request successful

302 found: Redirect, with the response header location used, the server requires the browser to re-initiate a request

404 Not Found: Request resource does not exist

403 Forbidden: No access to the resource

Server Internet Error: Internal errors, not responding properly

Exclusive row

2, response header (also a collection of some protocols)

A collection of protocols

Protocol Name: Value

Server: Servers information

Date: Response time

Last-modified: File Last Modified

Content-length: Length of response body (bytes)

Content-type: The data type of the corresponding content-text/html image/png

Location: Redirect, browser encounters this option to jump immediately, will not parse the later content

Refresh: Redirect, browser encountered this option will be ready to jump, time will jump, continue to parse down

Content-encodeing: File Encoding format

Cache-control: Cache control, no-cached-do not cache

3, empty line

4, Response body (corresponding data)

PHP Analog HTTP response

Through the header () function

Header ("Protocol Name: Protocol value");

Header ("Content-type:text/html;charset=utf-8"); Set file encoding

Header ("Location: New URL or uri"); Set jump, the browser accesses to the row to jump (inside the station with the URI)

Header ("Refresh: The time the wait is refreshed; Url=url or URI") during the wait process, the following code will continue to execute

Verification Code

PHP default does not handle the function of the picture, so to load the GD library (image processing extension)

Php.ini--extension=php_gd2.dll

Canvas: Imagecreate (width,height); (256 colors)

Imagecreatetruecolor (Width,height); (24-bit True color) (general use)

Color handle: Imagecolorallocate (Img,red,green,blue);

IMG: Canvas Resource

Draw text: imagestring (img,size,x,y,sting,color);

Size: Text sizes

X, y: Starting coordinates (the origin is the upper-left corner)

String: Text content

Color: Handles to Colors

Image<png|jpeg|gif> (canvas resource [, save path])

The output is to use the header function to set the corresponding header information, tell the browser this is a picture

Clean up data buffers with Ob_clean () before output

1, fill background

A) Imagefill (Img,x,y,color); Fills the area with the same color and continuous field.

IMG: Canvas Resource

X, y: Coordinate points

Color: Handles to Colors

2, add interference line

A) imageline (Img,x1,y1,x2,y2,color);

3, add noise (interference point)

A) Imagesetpixel (Img,x,y,color);

Code implementation:

1. img = Imagecreatetruecolor (170,40);

2. BackColor = Imagecolorallocate ($img, Mt_rand (180,255), Mt_rand (0,255), Mt_rand (180,255));

3. Imaggefill ($img, 0,0, $backcolor);

4. $arr = Array_merge (range (' A ', ' Z '), rang (' A ', ' Z '), Range (0,9));

5. Shuffle ($arr);

6. $rand _keys = Arr_rand ($arr, 4);

7. $str = ";

8. foreach ($rand _key as $value) {

$str. = $arr [$value];

}

9. $span = Ceil (170/(4+1));

for ($i =1; $i <=4; $i + +) {

$strcolor = Imagecolorallocate ($img, Mt_rand (0,100), Mt_rand (0,100), Mt_rand (0,100));

Imagestring ($img, 5, $i * $span, ten, $str [$i-1], $strcolor);

}

One. for ($i =1; $i <=6; $i + +) {

$linecolor = Imagecolorallocate ($img, Mt_rand (5,100), Mt_rand (50,100), Mt_rand (0,100));

Imageline ($img, Mt_rand (0,169), Mt_rand (0,39), Mt_rand (0,169), Mt_rand (0,39), $linecolor);

}

for ($i =1; $i <=170*40*0.03; $i + +) {

$pxcolor = Imagecolorallocate ($img, Mt_rand (0,255), Mt_rand (0,255), Mt_rand (0,255)

Imagesetpixel ($img, Mt_rand (0,169), Mt_rand (0,39), $pxcolor);

}

Header ("Content-type:image/png");

Ob_clean ();

Imagepng ($IMG);

12-8-Protocol, request, response, canvas (verification code production)