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发信人: cycker (空), 信区: Internet
标 题: Navigator Proxy Auto-Config File Format
发信站: 荔园晨风BBS站 (Fri Jul 2 22:04:55 2004), 站内信件
http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html
Documentation
Navigator Proxy Auto-Config File Format
March 1996
(There are several examples and tips in the end of this document)
The proxy autoconfig file is written in JavaScript. The file must defin
e the function:
function FindProxyForURL(url, host)
{
...
}
which will be called by the Navigator in the following way for every UR
L that is retrieved by it:
ret = FindProxyForURL(url, host);
where:
url
the full URL being accessed.
host
the hostname extracted from the URL. This is only for convenience,
it is the exact same string as between :// and the first : or / after th
at. The port number is not included in this parameter. It can be extract
ed from the URL when necessary.
ret
(the return value) a string describing the configuration. The forma
t of this string is defined below.
Saving the Auto-Config File
Setting the MIME Type
1. You should save the JavaScript function to file with a .pac filen
ame extension; for example:
proxy.pac
Note 1: You should save the JavaScript function by itself, not em
bed it in HTML.
Note 2: The examples in the end of this document are complete, th
ere is no additional syntax needed to save it into a file and use it (of
course, the JavaScripts have to be edited to reflect your site's domain
name and/or subnets).
2. Next, you should configure your server to map the .pac filename e
xtension to the MIME type:
application/x-ns-proxy-autoconfig
If using a Netscape server, edit the mime.types file in the confi
g directory. If using Apache, CERN or NCSA servers, use the AddType dire
ctive.
Return Value Format
The JavaScript function returns a single string.
If the string is null, no proxies should be used.
The string can contain any number of the following building blocks, sep
arated by a semicolon:
DIRECT
Connections should be made directly, without any proxies.
PROXY host:port
The specified proxy should be used.
SOCKS host:port
The specified SOCKS server should be used.
If there are multiple semicolon-separated settings, the left-most setti
ng will be used, until the Navigator fails to establish the connection t
o the proxy. In that case the next value will be used, etc.
The Navigator will automatically retry a previously unresponsive proxy
after 30 minutes, then after 1 hour from the previous try (always adding
an extra 30 minutes).
If all proxies are down, and there was no DIRECT option specified, the
Navigator will ask if proxies should be temporarily ignored, and direct
connections attempted. The Navigator will ask if proxies should be retri
ed after 20 minutes has passed (then the next time 40 minutes from the p
revious question, always adding 20 minutes).
Examples:
PROXY w3proxy.netscape.com:8080; PROXY mozilla.netscape.com:8081
Primary proxy is w3proxy:8080; if that goes down start using mozill
a:8081 until the primary proxy comes up again.
PROXY w3proxy.netscape.com:8080; PROXY mozilla.netscape.com:8081; DIREC
T
Same as above, but if both proxies go down, automatically start mak
ing direct connections. (In the first example above, Netscape will ask u
ser confirmation about making direct connections; in this third case, th
ere is no user intervention.)
PROXY w3proxy.netscape.com:8080; SOCKS socks:1080
Use SOCKS if the primary proxy goes down.
Predefined Functions and Environment for the JavaScript Function
* Hostname based conditions:
o isPlainHostName()
o dnsDomainIs()
o localHostOrDomainIs()
o isResolvable()
o isInNet()
* Related utility functions:
o dnsResolve()
o myIpAddress()
o dnsDomainLevels()
* URL/hostname based conditions:
o shExpMatch()
* Time based conditions:
o weekdayRange()
o dateRange()
o timeRange()
* There is one associative array already defined (because a JavaScr
ipt currently cannot define them on its own):
o ProxyConfig.bindings
isPlainHostName(host)
host
the hostname from the URL (excluding port number).
True iff there is no domain name in the hostname (no dots).
Examples:
isPlainHostName("www")
is true.
isPlainHostName("www.netscape.com")
is false.
dnsDomainIs(host, domain)
host
is the hostname from the URL.
domain
is the domain name to test the hostname against.
Returns true iff the domain of hostname matches.
Examples:
dnsDomainIs("www.netscape.com", ".netscape.com")
is true.
dnsDomainIs("www", ".netscape.com")
is false.
dnsDomainIs("www.mcom.com", ".netscape.com")
is false.
localHostOrDomainIs(host, hostdom)
host
the hostname from the URL.
hostdom
fully qualified hostname to match against.
Is true if the hostname matches exactly the specified hostname, or if t
here is no domain name part in the hostname, but the unqualified hostnam
e matches.
Examples:
localHostOrDomainIs("www.netscape.com", "www.netscape.com")
is true (exact match).
localHostOrDomainIs("www", "www.netscape.com")
is true (hostname match, domain not specified).
localHostOrDomainIs("www.mcom.com", "www.netscape.com")
is false (domain name mismatch).
localHostOrDomainIs("home.netscape.com", "www.netscape.com")
is false (hostname mismatch).
isResolvable(host)
host
is the hostname from the URL.
Tries to resolve the hostname. Returns true if succeeds.
Examples:
isResolvable("www.netscape.com")
is true (unless DNS fails to resolve it due to a firewall or some o
ther reason).
isResolvable("bogus.domain.foobar")
is false.
isInNet(host, pattern, mask)
host
a DNS hostname, or IP address. If a hostname is passed, it will be
resoved into an IP address by this function.
pattern
an IP address pattern in the dot-separated format
mask
mask for the IP address pattern informing which parts of the IP add
ress should be matched against. 0 means ignore, 255 means match.
True iff the IP address of the host matches the specified IP address pa
ttern.
Pattern and mask specification is done the same way as for SOCKS config
uration.
Examples:
isInNet(host, "198.95.249.79", "255.255.255.255")
is true iff the IP address of host matches exactly 198.95.249.79.
isInNet(host, "198.95.0.0", "255.255.0.0")
is true iff the IP address of the host matches 198.95.*.*.
dnsResolve(host)
host
hostname to resolve
Resolves the given DNS hostname into an IP address, and returns it in t
he dot separated format as a string.
Example:
dnsResolve("home.netscape.com")
returns the string "198.95.249.79".
myIpAddress()
Returns the IP address of the host that the Navigator is running on, as
a string in the dot-separated integer format.
Example:
myIpAddress()
would return the string "198.95.249.79" if you were running the Nav
igator on that host.
dnsDomainLevels(host)
host
is the hostname from the URL.
Returns the number (integer) of DNS domain levels (number of dots) in t
he hostname.
Examples:
dnsDomainLevels("www")
returns 0.
dnsDomainLevels("www.netscape.com")
returns 2.
shExpMatch(str, shexp)
str
is any string to compare (e.g. the URL, or the hostname).
shexp
is a shell expression to compare against.
Returns true if the string matches the specified shell expression.
Actually, currently the patterns are shell expressions, not regular exp
ressions.
Examples:
shExpMatch("http://home.netscape.com/people/ari/index.html", "*/ari/*")
is true.
shExpMatch("http://home.netscape.com/people/montulli/index.html", "*/ar
i/*")
is false.
weekdayRange(wd1, wd2, gmt)
wd1
and
wd2
are one of the weekday strings:
SUN MON TUE WED THU FRI SAT
gmt
is either the string: GMT or is left out.
Only the first parameter is mandatory. Either the second, the third, or
both may be left out.
If only one parameter is present, the function yeilds a true value on t
he weekday that the parameter represents. If the string "GMT" is specifi
ed as a second parameter, times are taken to be in GMT, otherwise in loc
al timezone.
If both wd1 and wd1 are defined, the condition is true if the current w
eekday is in between those two weekdays. Bounds are inclusive. If the "G
MT" parameter is specified, times are taken to be in GMT, otherwise the
local timezone is used.
Examples:
weekdayRange("MON", "FRI")
true Monday trhough Friday (local timezone).
weekdayRange("MON", "FRI", "GMT")
same as above, but GMT timezone.
weekdayRange("SAT")
true on Saturdays local time.
weekdayRange("SAT", "GMT")
true on Saturdays GMT time.
weekdayRange("FRI", "MON")
true Friday through Monday (note, order does matter!).
dateRange(day)
dateRange(day1, day2)
dateRange(mon)
dateRange(month1, month2)
dateRange(year)
dateRange(year1, year2)
dateRange(day1, month1, day2, month2)
dateRange(month1, year1, month2, year2)
dateRange(day1, month1, year1, day2, month2, year2)
dateRange(day1, month1, year1, day2, month2, year2, gmt)
day
is the day of month between 1 and 31 (as an integer).
month
is one of the month strings:
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
year
is the full year number, for example 1995 (but not 95). Integer.
gmt
is either the string "GMT", which makes time comparison occur in GM
T timezone; if left unspecified, times are taken to be in the local time
zone.
Even though the above examples don't show, the "GMT" parameter can be s
pecified in any of the 9 different call profiles, always as the last par
ameter.
If only a single value is specified (from each category: day, month, ye
ar), the function returns a true value only on days that match that spec
ification. If both values are specified, the result is true between thos
e times, including bounds.
Examples:
dateRange(1)
true on the first day of each month, local timezone.
dateRange(1, "GMT")
true on the first day of each month, GMT timezone.
dateRange(1, 15)
true on the first half of each month.
dateRange(24, "DEC")
true on 24th of December each year.
dateRange(24, "DEC", 1995)
true on 24th of December, 1995.
dateRange("JAN", "MAR")
true on the first quarter of the year.
dateRange(1, "JUN", 15, "AUG")
true from June 1st until August 15th, each year (including June 1st
and August 15th).
dateRange(1, "JUN", 15, 1995, "AUG", 1995)
true from June 1st, 1995, until August 15th, same year.
dateRange("OCT", 1995, "MAR", 1996)
true from October 1995 until March 1996 (including the entire month
of October 1995 and March 1996).
dateRange(1995)
true during the entire year 1995.
dateRange(1995, 1997)
true from beginning of year 1995 until the end of year 1997.
timeRange(hour)
timeRange(hour1, hour2)
timeRange(hour1, min1, hour2, min2)
timeRange(hour1, min1, sec1, hour2, min2, sec2)
timeRange(hour1, min1, sec1, hour2, min2, sec2, gmt)
hour
is the hour from 0 to 23. (0 is midnight, 23 is 11 pm.)
min
minutes from 0 to 59.
sec
seconds from 0 to 59.
gmt
either the string "GMT" for GMT timezone, or not specified, for loc
al timezone. Again, even though the above list doesn't show it, this par
ameter may be present in each of the different parameter profiles, alway
s as the last parameter.
True during (or between) the specified time(s).
Examples:
timerange(12)
true from noon to 1pm.
timerange(12, 13)
same as above.
timerange(12, "GMT")
true from noon to 1pm, in GMT timezone.
timerange(9, 17)
true from 9am to 5pm.
timerange(8, 30, 17, 00)
true from 8:30am to 5:00pm.
timerange(0, 0, 0, 0, 0, 30)
true between midnight and 30 seconds past midnight.
Example #1: Use proxy for everything except local hosts
This would work in Netscape's environment. All hosts which aren't fully
qualified, or the ones that are in local domain, will be connected to d
irectly. Everything else will go through w3proxy:8080. If the proxy goes
down, connections become automatically direct.
function FindProxyForURL(url, host)
{
if (isPlainHostName(host) ||
dnsDomainIs(host, ".netscape.com"))
return "DIRECT";
else
return "PROXY w3proxy.netscape.com:8080; DIRECT";
}
Note: This is the simplest and most efficient autoconfig file for cases
where there's only one proxy.
Example #1b: As above, but use proxy for local servers which are outsid
e the firewall
If there are hosts (such as the main Web server) that belong to the loc
al domain but are outside the firewall, and are only reachable through t
he proxy server, those exceptions can be handled using the localHostOrDo
mainIs() function:
function FindProxyForURL(url, host)
{
if ((isPlainHostName(host) ||
dnsDomainIs(host, ".netscape.com")) &&
!localHostOrDomainIs(host, "www.netscape.com") &&
!localHostOrDoaminIs(host, "merchant.netscape.com"))
return "DIRECT";
else
return "PROXY w3proxy.netscape.com:8080; DIRECT";
}
The above will use the proxy for everything else except local hosts in
the netscape.com domain, with the further exception that hosts www.netsc
ape.com and merchant.netscape.com will go through the proxy.
Note the order of the above exceptions for efficiency: localHostOrDomai
nIs() functions only get executed for URLs that are in local domain, not
for every URL. Be careful to note the parentheses around the or express
ion before the and expression to achieve the abovementioned efficient be
haviour.
Example #2: Use proxy only if cannot resolve host
This example would work in an environment where internal DNS is set up
so that it can only resolve internal host names, and the goal is to use
a proxy only for hosts which aren't resolvable:
function FindProxyForURL(url, host)
{
if (isResolvable(host))
return "DIRECT";
else
return "PROXY proxy.mydomain.com:8080";
}
The above requires consulting the DNS every time; it can be grouped sma
rtly with other rules so that DNS is consulted only if other rules do no
t yield a result:
function FindProxyForURL(url, host)
{
if (isPlainHostName(host) ||
dnsDomainIs(host, ".mydomain.com") ||
isResolvable(host))
return "DIRECT";
else
return "PROXY proxy.mydomain.com:8080";
}
Example #3: Subnet based decisions
In this example all the hosts in a given subnet are connected to direct
ly, others through the proxy.
function FindProxyForURL(url, host)
{
if (isInNet(host, "198.95.0.0", "255.255.0.0"))
return "DIRECT";
else
return "PROXY proxy.mydomain.com:8080";
}
Again, use of DNS in the above can be minimized by adding redundant rul
es in the beginning:
function FindProxyForURL(url, host)
{
if (isPlainHostName(host) ||
dnsDomainIs(host, ".mydomain.com") ||
isInNet(host, "198.95.0.0", "255.255.0.0"))
return "DIRECT";
else
return "PROXY proxy.mydomain.com:8080";
}
Example #4: Load balancing/routing based on URL patterns
This example is more sophisticated. There are four (4) proxy servers; o
ne of them is a hot stand-by for all of the other ones, so if any of the
remaining three goes down, the fourth one will take over.
Furthermore, the three remaining proxy servers share the load based on
URL patterns, which makes their caching more effective (there is only on
e copy of any document on the three servers -- as opposed to one copy on
each of them). The load is distributed like this:
Proxy Purpose
#1 .com domain
#2 .edu domain
#3 all other domains
#4 hot stand-by
All local accesses are desired to be direct. All proxy servers run on t
he port 8080 (they wouldn't need to). Note how strings can be concatenat
ed by the + operator in JavaScript.
function FindProxyForURL(url, host)
{
if (isPlainHostName(host) || dnsDomainIs(host, ".mydomain.com")
)
return "DIRECT";
else if (shExpMatch(host, "*.com"))
return "PROXY proxy1.mydomain.com:8080; " +
"PROXY proxy4.mydomain.com:8080";
else if (shExpMatch(host, "*.edu"))
return "PROXY proxy2.mydomain.com:8080; " +
"PROXY proxy4.mydomain.com:8080";
else
return "PROXY proxy3.mydomain.com:8080; " +
"PROXY proxy4.mydomain.com:8080";
}
Example #5: Setting a proxy for a specific protocol
Most of the standard JavaScript functionality is available for use in t
he FindProxyForURL() function. As an example, to set different proxies b
ased on the protocol, the substring() function can be used:
function FindProxyForURL(url, host)
{
if (url.substring(0, 5) == "http:") {
return "PROXY http-proxy.mydomain.com:8080";
}
else if (url.substring(0, 4) == "ftp:") {
return "PROXY ftp-proxy.mydomain.com:8080";
}
else if (url.substring(0, 7) == "gopher:") {
return "PROXY gopher-proxy.mydomain.com:8080";
}
else if (url.substring(0, 6) == "https:" ||
url.substring(0, 6) == "snews:") {
return "PROXY security-proxy.mydomain.com:8080";
}
else {
return "DIRECT";
}
}
Note: The same can be accomplished using the shExpMatch() function desc
ribed earlier; for example:
...
if (shExpMatch(url, "http:*")) {
return "PROXY http-proxy.mydomain.com:8080;
}
...
Tips
* The autoconfig file can be output by a CGI script. This is useful
e.g. when making the autoconfig file act differently based on the clien
t IP address (the REMOTE_ADDR environment variable in CGI).
* Use of isInNet(), isResolvable() and dnsResolve() functions shoul
d be carefully considered, as they require DNS server to be consulted (w
hereas all other autoconfig related functions are mere string matching f
unctions). If a proxy is used, the proxy will perform its own DNS lookup
which would double the impact on the DNS server. Most of the time these
functions are not necessary to achieve the desired result.
March 1996
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