key words:自動腳本 代理腳本 代理 沖出窗子
本文獻給那些對自動代理腳本有興趣、想自己寫的朋友。
1、什么是代理腳本(PAC)
?一個PAC文件其實就是一個文本文件，最簡單的格式就是包含一個叫FindProxyForURL的
?JScript函數，IE通過傳入兩個變量來調用這個函數，一個是用戶瀏覽的地址URL全路經，
?一個是這個URL中的主機名部分(host)。這個FindProxyForURL函數有三種可能的字符串
?返回值，一是"DIRECT"，就是直接連接，不通過代理；二是"PROXY?proxyaddr:port"，
?其中proxyaddr和port分別是代理的地址和代理的端口；三是"SOCKS?socksaddr:port"，
?其中socksaddr和port分別是socks代理的地址和端口，一個自動代理文件可以是多個
?選擇的組合，其中用分號(;)隔開，如：
???
???function?FindProxyForURL(url,host)
???{
?????if?(host?==?"www.mydomain.com")
?????????return?"DIRECT";
?
?????????return?"PROXY?myproxy:80;
?????????????????PROXY?myotherproxy:8080;?
?????????????????DIRECT";
???}
???
???
2、下面是代理腳本可能用到的函數和說明：
PAC?Helper?Functions
dnsDomainIs(host,?domain)??????????????Returns?true?if?the?host?is?part?of?the
???????????????????????????????????????specified?domain,?false?otherwise.
?
isInNet(hostname,??????????????????????Resolves?the?hostname?and?subnet?IP,
???????????????????????????????????????subnet?mask)?returns?true?if?the
???????????????????????????????????????hostname?is?within?the?subnet?specified
???????????????????????????????????????by?the?IP?address?and?the?subnet?mask,
???????????????????????????????????????false?otherwise.
?
isPlainHostName(host)??????????????????Returns?true?if?there?are?no?dots?in?the
???????????????????????????????????????hostname,?false?otherwise.
?
isResolvable(host)?????????????????????Internet?Explorer?tries?to?resolve?the
???????????????????????????????????????hostname?through?DNS?and?returns?true?if
???????????????????????????????????????successful,?false?otherwise.
?
localHostOrDomainIs????????????????????Returns?true?if?the?host?matches?(host,
???????????????????????????????????????domain)?the?host?portion?of?the?domain,
???????????????????????????????????????or?if?the?host?matches?the?host?and
???????????????????????????????????????domain?portions?of?the?domain,?false
???????????????????????????????????????otherwise.?(Executed?only?for?URLs?in
???????????????????????????????????????the?local?domain.)
?
dnsDomainLevels(host)??????????????????Returns?the?number?of?dots?in?the
???????????????????????????????????????hostname.
?
dnsResolve(host)???????????????????????Returns?a?string?containing?the?IP
???????????????????????????????????????address?of?the?specified?host.
?
myIPAddress(?)?????????????????????????Returns?a?string?containing?the?local
???????????????????????????????????????machine’s?IP?address.
?
shExpMatch(url,?shexp)?????????????????Returns?true?if?the?supplied?URL?matches
???????????????????????????????????????the?specified?shell?expression,?false
???????????????????????????????????????otherwise.?
?
dateRange(parmList)????????????????????Returns?true?if?the?current?date?falls
???????????????????????????????????????within?the?dates?specified?in?parmList,
???????????????????????????????????????false?otherwise.?
?
timeRange(parmList)????????????????????Returns?true?if?the?current?time?falls
???????????????????????????????????????within?the?times?specified?in?parmList,
???????????????????????????????????????false?otherwise.?
?
weekdayRange(parmList)?????????????????Returns?true?if?today?is?within?the?days
???????????????????????????????????????of?the?week?specified?in?parmList,?false
???????????????????????????????????????otherwise.?
3、下面是各個函數應用的例子：
??a、isPlainHostName(host)，本例演示判斷是否為本地主機，如http://myservername/
??的方式訪問，如果是直接連接，否則使用代理
??function?FindProxyForURL(url,?host)
??{
????if?(isPlainHostName(host))
??????return?"DIRECT";
????else
??????return?"PROXY?proxy:80";
??}
??
??b、dnsDomainIs(host,?"")、localHostOrDomainIs(host,?"")，本例演示判斷訪問主機
??是否屬于某個域和某個域名，如果屬于.company.com域的主機名，而域名不是
??www.company.com和home.company.com的直接連接，否則使用代理訪問。
??function?FindProxyForURL(url,?host)
??{
????if?((isPlainHostName(host)?||
???????dnsDomainIs(host,?".company.com"))?&&
??????!localHostOrDomainIs(host,?"www.company.com")?&&
??????!localHostOrDomainIs(host,?"home.company.com"))
??????return?"DIRECT";
????else
??????return?"PROXY?proxy:80";
??}
??
??c、isResolvable(host)，本例演示主機名能否被dns服務器解析，如果能直接訪問，否
??則就通過代理訪問。
??function?FindProxyForURL(url,?host)
??{
????if?(isResolvable(host))
??????return?"DIRECT";
????else
??????return?"PROXY?proxy:80";
??}
??
??d、isInNet(host,?"",?"")，本例演示訪問IP是否在某個子網內，如果是就直接訪問，
??否則就通過代理，例子演示訪問清華IP段的主頁不用代理。
??function?FindProxyForURL(url,?host)
??{
????if?(isInNet(host,?"166.111.0.0",?"255.255.0.0"))
??????return?"DIRECT";
????else
??????return?"PROXY?proxy:80";
??}
??
?e、shExpMatch(host,?"")，本例演示根據主機域名來改變連接類型，本地主機、*.edu、
??*.com分別用不同的連接方式。
??function?FindProxyForURL(url,?host)
??{
????if?(isPlainHostName(host))
??????return?"DIRECT";
????else?if?(shExpMatch(host,?"*.com"))
??????return?"PROXY?comproxy:80";
????else?if?(shExpMatch(host,?"*.edu"))
??????return?"PROXY?eduproxy:80";
????else
??????return?"PROXY?proxy:80";
??}
??
?f、url.substring()，本例演示根據不同的協議來選擇不同的代理，http、https、ftp、
??gopher分別使用不同的代理。
??function?FindProxyForURL(url,?host)
??{
??????if?(url.substring(0,?5)?==?"http:")?{
????????return?"PROXY?proxy:80";
??????}
??????else?if?(url.substring(0,?4)?==?"ftp:")?{
????????return?"PROXY?fproxy:80";
??????}
??????else?if?(url.substring(0,?7)?==?"gopher:")?{
????????return?"PROXY?gproxy";
??????}
??????else?if?(url.substring(0,?6)?==?"https:")?{
????????return?"PROXY?secproxy:8080";
??????}
??????else?{
????????return?"DIRECT";
??????}
??}
??
??g、dnsResolve(host)，本例演示判斷訪問主機是否某個IP，如果是就使用代理，否則直
??接連接。
??unction?FindProxyForURL(url,?host)
??{
??????if?(dnsResolve(host)?==?"166.111.8.237")?{
????????return?"PROXY?secproxy:8080";
??????}
??????else?{
????????return?"PROXY?proxy:80";
??????}
??}
??
??h、myIpAddress()，本例演示判斷本地IP是否某個IP，如果是就使用代理，否則直接使
??用連接。
??function?FindProxyForURL(url,?host)
??{
??????if?(myIpAddress()?==?"166.111.8.238")?{?
????????return?"PROXY?proxy:80";
??????}
??????else?{
????????return?"DIRECT";
??????}
??}
??
??i、dnsDomainLevels(host)，本例演示訪問主機的域名級數是幾級，就是域名有幾個點
??如果域名中有點，就通過代理訪問，否則直接連接。
??function?FindProxyForURL(url,?host)
??{
??????if?(dnsDomainLevels(host)?>?0)?{?//?if?number?of?dots?in?host?>?0
????????return?"PROXY?proxy:80";
??????}
????????return?"DIRECT";
??}
??
??j、weekdayRange()，本例演示當前日期的范圍來改變使用代理，如果是GMT時間周三
??到周六，使用代理連接，否則直接連接。
??function?FindProxyForURL(url,?host)
??{
????if(weekdayRange("WED",?"SAT",?"GMT"))?
?????return?"PROXY?proxy:80";
????else?
?????return?"DIRECT";
??}
??
??k、最后一個例子是演示隨機使用代理，這樣可以好好利用代理服務器。
?function?FindProxyForURL(url,host)
?{
??????return?randomProxy();
?}
?
?function?randomProxy()
?{
?????switch(?Math.floor(?Math.random()?*?5?)?)
?????{
?????????case?0:
?????????????return?"PROXY?proxy1:80";
?????????????break;
?????????case?1:
?????????????return?"PROXY?proxy2:80";?
?????????????break;
?????????case?2:
?????????????return?"PROXY?proxy3:80";
?????????????break;
?????????case?3:
?????????????return?"PROXY?proxy4:80";
?????????????break;
?????????case?4:
?????????????return?"PROXY?proxy5:80";
?????????????break;
?????}????
?}
?
利用上面的函數和例子說明，大家就可以寫出比較復雜有效的自動代理腳本。