Provided by: varnish_5.2.1-1ubuntu0.1_amd64 
NAME
vmod_std - Varnish Standard Module
SYNOPSIS
import std [from "path"] ;
CONTENTS
• STRING toupper(STRING)
• STRING tolower(STRING)
• VOID set_ip_tos(INT)
• REAL random(REAL, REAL)
• VOID log(STRING)
• VOID syslog(INT, STRING)
• STRING fileread(PRIV_CALL, STRING)
• BOOL file_exists(STRING)
• VOID collect(HEADER, STRING)
• DURATION duration(STRING, DURATION)
• INT integer(STRING, INT)
• IP ip(STRING, IP)
• REAL real(STRING, REAL)
• INT real2integer(REAL, INT)
• TIME real2time(REAL, TIME)
• INT time2integer(TIME, INT)
• REAL time2real(TIME, REAL)
• BOOL healthy(BACKEND)
• INT port(IP)
• VOID rollback(HTTP)
• VOID timestamp(STRING)
• STRING querysort(STRING)
• BOOL cache_req_body(BYTES)
• STRING strstr(STRING, STRING)
• TIME time(STRING, TIME)
• STRING getenv(STRING)
• VOID late_100_continue(BOOL)
DESCRIPTION
vmod_std contains basic functions which are part and parcel of Varnish, but which for reasons of
architecture fit better in a VMOD.
One particular class of functions in vmod_std is the conversions functions which all have the form:
TYPE type(STRING, TYPE)
These functions attempt to convert STRING to the TYPE, and if that fails, they return the second
argument, which must have the given TYPE.
toupper
STRING toupper(STRING s)
Description
Converts the string s to uppercase.
Example
set beresp.http.scream = std.toupper("yes!");
tolower
STRING tolower(STRING s)
Description
Converts the string s to lowercase.
Example
set beresp.http.nice = std.tolower("VerY");
set_ip_tos
VOID set_ip_tos(INT tos)
Description
Sets the IP type-of-service (TOS) field for the current session to tos. Please note that the TOS
field is not removed by the end of the request so probably want to set it on every request should
you utilize it.
Example
if (req.url ~ "^/slow/") {
std.set_ip_tos(0);
}
random
REAL random(REAL lo, REAL hi)
Description
Returns a random real number between lo and hi. This function uses the "testable" random
generator in varnishd which enables determinstic tests to be run (See m00002.vtc). This function
should not be used for cryptographic applications.
Example
set beresp.http.random-number = std.random(1, 100);
log
VOID log(STRING s)
Description
Logs the string s to the shared memory log, using VSL tag SLT_VCL_Log.
Example
std.log("Something fishy is going on with the vhost " + req.http.host);
syslog
VOID syslog(INT priority, STRING s)
Description
Logs the string s to syslog tagged with priority. priority is formed by ORing the facility and
level values. See your system's syslog.h file for possible values.
Example
std.syslog(9, "Something is wrong");
This will send a message to syslog using LOG_USER | LOG_ALERT.
fileread
STRING fileread(PRIV_CALL, STRING)
Description
Reads a file and returns a string with the content. Please note that it is not recommended to send
variables to this function the caching in the function doesn't take this into account. Also, files
are not re-read.
Example
set beresp.http.served-by = std.fileread("/etc/hostname");
file_exists
BOOL file_exists(STRING path)
Description
Returns true if path or the file pointed to by path exists, false otherwise.
Example
if (std.file_exists("/etc/return_503")) {
return (synth(503, "Varnish is in maintenance"));
}
collect
VOID collect(HEADER hdr, STRING sep=", ")
Description
Collapses multiple hdr headers into one long header. The default separator sep is the standard
comma separator to use when collapsing headers, with an additional whitespace for pretty
printing.
Care should be taken when collapsing headers. In particular collapsing Set-Cookie will lead to
unexpected results on the browser side.
Examples
std.collect(req.http.accept);
std.collect(req.http.cookie, "; ");
duration
DURATION duration(STRING s, DURATION fallback)
Description
Converts the string s to seconds. s must be quantified with ms (milliseconds), s (seconds), m
(minutes), h (hours), d (days), w (weeks) or y (years) units. If conversion fails, fallback will
be returned.
Example
set beresp.ttl = std.duration("1w", 3600s);
integer
INT integer(STRING s, INT fallback)
Description
Converts the string s to an integer. If conversion fails, fallback will be returned.
Example
if (std.integer(req.http.foo, 0) > 5) {
...
}
ip
IP ip(STRING s, IP fallback)
Description
Converts the string s to the first IP number returned by the system library function
getaddrinfo(3). If conversion fails, fallback will be returned.
Example
if (std.ip(req.http.X-forwarded-for, "0.0.0.0") ~ my_acl) {
...
}
real
REAL real(STRING s, REAL fallback)
Description
Converts the string s to a real. If conversion fails, fallback will be returned.
Example
if (std.real(req.http.foo, 0.0) > 5.5) {
...
}
real2integer
INT real2integer(REAL r, INT fallback)
Description
Converts the real r to an integer. If conversion fails, fallback will be returned.
Example
set req.http.integer = std.real2integer(1140618699.00, 0);
real2time
TIME real2time(REAL r, TIME fallback)
Description
Converts the real r to a time. If conversion fails, fallback will be returned.
Example
set req.http.time = std.real2time(1140618699.00, now);
time2integer
INT time2integer(TIME t, INT fallback)
Description
Converts the time t to a integer. If conversion fails, fallback will be returned.
Example
set req.http.int = std.time2integer(now, 0);
time2real
REAL time2real(TIME t, REAL fallback)
Description
Converts the time t to a real. If conversion fails, fallback will be returned.
Example
set req.http.real = std.time2real(now, 1.0);
healthy
BOOL healthy(BACKEND be)
Description
Returns true if the backend be is healthy.
port
INT port(IP ip)
Description
Returns the port number of the IP address ip.
rollback
VOID rollback(HTTP h)
Description
Restores the h HTTP headers to their original state.
Example
std.rollback(bereq);
timestamp
VOID timestamp(STRING s)
Description
Introduces a timestamp in the log with the current time, using the string s as the label. This is
useful to time the execution of lengthy VCL procedures, and makes the timestamps inserted
automatically by Varnish more accurate.
Example
std.timestamp("curl-request");
querysort
STRING querysort(STRING)
Description
Sorts the query string for cache normalization purposes.
Example
set req.url = std.querysort(req.url);
cache_req_body
BOOL cache_req_body(BYTES size)
Description
Caches the request body if it is smaller than size. Returns true if the body was cached, false
otherwise.
Normally the request body is not available after sending it to the backend. By caching it is
possible to retry pass operations, e.g. POST and PUT.
Example
if (std.cache_req_body(1KB)) {
...
}
strstr
STRING strstr(STRING s1, STRING s2)
Description
Returns a string beginning at the first occurrence of the string s2 in the string s1, or an empty
string if s2 is not found.
Note that the comparison is case sensitive.
Example
if (std.strstr(req.url, req.http.restrict)) {
...
}
This will check if the content of req.http.restrict occurs anywhere in req.url.
time
TIME time(STRING s, TIME fallback)
Description
Converts the string s to a time. If conversion fails, fallback will be returned.
Supported formats:
"Sun, 06 Nov 1994 08:49:37 GMT"
"Sunday, 06-Nov-94 08:49:37 GMT"
"Sun Nov 6 08:49:37 1994"
"1994-11-06T08:49:37"
"784111777.00"
"784111777"
Example
if (std.time(resp.http.last-modified, now) < now - 1w) {
...
}
getenv
STRING getenv(STRING name)
Description
Return environment variable name or the empty string.
See getenv(3)
Example
set req.http.My-Env = std.getenv("MY_ENV");
late_100_continue
VOID late_100_continue(BOOL late)
Description
Controls when varnish reacts to an Expect: 100-continue client request header.
Varnish always generates a 100 Continue response if requested by the client trough the Expect:
100-continue header when waiting for request body data.
But, by default, the 100 Continue response is already generated immediately after vcl_recv returns
to reduce latencies under the assumption that the request body will be read eventually.
Calling std.late_100_continue(true) in vcl_recv will cause the 100 Continue response to only be
sent when needed. This may cause additional latencies for processing request bodies, but is the
correct behavior by strict interpretation of RFC7231.
This function has no effect outside vcl_recv and after calling std.cache_req_body() or any other
function consuming the request body.
Example
vcl_recv {
std.late_100_continue(true);
if (req.method == "POST") {
std.late_100_continue(false);
return (pass);
}
...
}
SEE ALSO
• varnishd(1) • vsl(7)
COPYRIGHT
Copyright (c) 2010-2017 Varnish Software AS
All rights reserved.
Author: Poul-Henning Kamp <phk@FreeBSD.org>
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.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
VMOD_STD(3)