Bit's World

There are two modules that can limit the bandwidth for apache, one is "Bandwidth Module", Version 0.5rc1， Bandwidth and Connection control per Virtual Host or Directory， Last Updated January 28th, 2005，http://www.ivn.cl/apache/
another is the "mod_cband"，Version 0.9，A virtual host bandwidth-limiting module provided to solve the problem of limiting virtualhosts bandwidth usage，Last Updated September 07th, 2005，http://cband.linux.pl/

There also two modules that can limit cocurrent connections:
mod_vhost_limit，v0.1，
Restrict the number of simultaneous connections per vhost，
Last Modified : 2004.02.26，http://www.ivn.cl/apache/
mod_limitipconn，Version 0.22，Limit the number of simultaneous connections from a single client IP
address. Contains rudimentary support for detection of proxy clients，Last Updated July 22nd, 2003，
http://dominia.org/djao/limitipconn2.html

ASCII:

U-00000000 - U-0000007F: 0xxxxxxx  

UTF8的编码方式：

U-00000000 - U-0000007F: 0xxxxxxx  

U-00000080 - U-000007FF: 110xxxxx 10xxxxxx  

U-00000800 - U-0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx  

U-00010000 - U-001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx  

U-00200000 - U-03FFFFFF: 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx  

U-04000000 - U-7FFFFFFF: 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

 

GB2312

范围： 0xA1A1 - 0xFEFE

 

GBK

范围： 0×8140 - 0xFEFE

GB18030:

编码是变长的，其二字节部分与GBK兼容；四字节部分是扩充的字形、字位，其编码范围是首字节0×81-0xfe、二字节0×30-0×39、三字节0×81-0xfe、四字节0×30-0×39。



（ GB18030 > GBK > GB2312 ）

BIG5

范围： 0xA140 - 0xF9FE, 0xA1A1 - 0xF9FE

可以看到：

各种编码方式都是以 >0x80的字符开头的，所以strstr不会有问题， 但是strchr会有问题，因为GB/BIG5在编码的第二字节用到了<0x80部分，而UTF8没有这个问题。



关于编码方式的检测如果单纯基于纯二进制内容参考下面的文章，基本是基于概率来检测的：

http://www.mozilla.org/projects/intl/UniversalCharsetDetection.html