mirror of
https://github.com/schollz/cowyo.git
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241 lines
7.7 KiB
Go
241 lines
7.7 KiB
Go
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// Copyright (c) 2014, David Kitchen <david@buro9.com>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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//
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// * Neither the name of the organisation (Microcosm) nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package bluemonday_test
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import (
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"fmt"
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"regexp"
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"strings"
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"github.com/microcosm-cc/bluemonday"
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)
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func Example() {
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// Create a new policy
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p := bluemonday.NewPolicy()
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// Add elements to a policy without attributes
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p.AllowElements("b", "strong")
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// Add elements as a virtue of adding an attribute
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p.AllowAttrs("nowrap").OnElements("td", "th")
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// Attributes can either be added to all elements
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p.AllowAttrs("dir").Globally()
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//Or attributes can be added to specific elements
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p.AllowAttrs("value").OnElements("li")
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// It is ALWAYS recommended that an attribute be made to match a pattern
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// XSS in HTML attributes is a very easy attack vector
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// \p{L} matches unicode letters, \p{N} matches unicode numbers
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p.AllowAttrs("title").Matching(regexp.MustCompile(`[\p{L}\p{N}\s\-_',:\[\]!\./\\\(\)&]*`)).Globally()
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// You can stop at any time and call .Sanitize()
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// Assumes that string htmlIn was passed in from a HTTP POST and contains
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// untrusted user generated content
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htmlIn := `untrusted user generated content <body onload="alert('XSS')">`
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fmt.Println(p.Sanitize(htmlIn))
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// And you can take any existing policy and extend it
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p = bluemonday.UGCPolicy()
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p.AllowElements("fieldset", "select", "option")
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// Links are complex beasts and one of the biggest attack vectors for
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// malicious content so we have included features specifically to help here.
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// This is not recommended:
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p = bluemonday.NewPolicy()
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p.AllowAttrs("href").Matching(regexp.MustCompile(`(?i)mailto|https?`)).OnElements("a")
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// The regexp is insufficient in this case to have prevented a malformed
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// value doing something unexpected.
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// This will ensure that URLs are not considered invalid by Go's net/url
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// package.
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p.RequireParseableURLs(true)
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// If you have enabled parseable URLs then the following option will allow
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// relative URLs. By default this is disabled and will prevent all local and
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// schema relative URLs (i.e. `href="//www.google.com"` is schema relative).
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p.AllowRelativeURLs(true)
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// If you have enabled parseable URLs then you can whitelist the schemas
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// that are permitted. Bear in mind that allowing relative URLs in the above
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// option allows for blank schemas.
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p.AllowURLSchemes("mailto", "http", "https")
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// Regardless of whether you have enabled parseable URLs, you can force all
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// URLs to have a rel="nofollow" attribute. This will be added if it does
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// not exist.
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// This applies to "a" "area" "link" elements that have a "href" attribute
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p.RequireNoFollowOnLinks(true)
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// We provide a convenience function that applies all of the above, but you
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// will still need to whitelist the linkable elements:
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p = bluemonday.NewPolicy()
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p.AllowStandardURLs()
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p.AllowAttrs("cite").OnElements("blockquote")
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p.AllowAttrs("href").OnElements("a", "area")
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p.AllowAttrs("src").OnElements("img")
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// Policy Building Helpers
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// If you've got this far and you're bored already, we also bundle some
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// other convenience functions
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p = bluemonday.NewPolicy()
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p.AllowStandardAttributes()
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p.AllowImages()
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p.AllowLists()
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p.AllowTables()
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}
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func ExampleNewPolicy() {
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// NewPolicy is a blank policy and we need to explicitly whitelist anything
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// that we wish to allow through
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p := bluemonday.NewPolicy()
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// We ensure any URLs are parseable and have rel="nofollow" where applicable
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p.AllowStandardURLs()
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// AllowStandardURLs already ensures that the href will be valid, and so we
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// can skip the .Matching()
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p.AllowAttrs("href").OnElements("a")
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// We allow paragraphs too
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p.AllowElements("p")
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html := p.Sanitize(
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`<p><a onblur="alert(secret)" href="http://www.google.com">Google</a></p>`,
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)
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fmt.Println(html)
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// Output:
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//<p><a href="http://www.google.com" rel="nofollow">Google</a></p>
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}
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func ExampleStrictPolicy() {
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// StrictPolicy is equivalent to NewPolicy and as nothing else is declared
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// we are stripping all elements (and their attributes)
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p := bluemonday.StrictPolicy()
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html := p.Sanitize(
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`Goodbye <a onblur="alert(secret)" href="http://en.wikipedia.org/wiki/Goodbye_Cruel_World_(Pink_Floyd_song)">Cruel</a> World`,
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)
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fmt.Println(html)
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// Output:
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//Goodbye Cruel World
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}
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func ExampleUGCPolicy() {
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// UGCPolicy is a convenience policy for user generated content.
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p := bluemonday.UGCPolicy()
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html := p.Sanitize(
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`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`,
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)
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fmt.Println(html)
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// Output:
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//<a href="http://www.google.com" rel="nofollow">Google</a>
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}
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func ExamplePolicy_AllowAttrs() {
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p := bluemonday.NewPolicy()
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// Allow the 'title' attribute on every HTML element that has been
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// whitelisted
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p.AllowAttrs("title").Matching(bluemonday.Paragraph).Globally()
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// Allow the 'abbr' attribute on only the 'td' and 'th' elements.
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p.AllowAttrs("abbr").Matching(bluemonday.Paragraph).OnElements("td", "th")
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// Allow the 'colspan' and 'rowspan' attributes, matching a positive integer
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// pattern, on only the 'td' and 'th' elements.
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p.AllowAttrs("colspan", "rowspan").Matching(
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bluemonday.Integer,
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).OnElements("td", "th")
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}
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func ExamplePolicy_AllowElements() {
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p := bluemonday.NewPolicy()
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// Allow styling elements without attributes
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p.AllowElements("br", "div", "hr", "p", "span")
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}
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func ExamplePolicy_Sanitize() {
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// UGCPolicy is a convenience policy for user generated content.
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p := bluemonday.UGCPolicy()
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// string in, string out
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html := p.Sanitize(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
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fmt.Println(html)
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// Output:
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//<a href="http://www.google.com" rel="nofollow">Google</a>
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}
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func ExamplePolicy_SanitizeBytes() {
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// UGCPolicy is a convenience policy for user generated content.
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p := bluemonday.UGCPolicy()
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// []byte in, []byte out
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b := []byte(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
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b = p.SanitizeBytes(b)
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fmt.Println(string(b))
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// Output:
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//<a href="http://www.google.com" rel="nofollow">Google</a>
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}
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func ExamplePolicy_SanitizeReader() {
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// UGCPolicy is a convenience policy for user generated content.
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p := bluemonday.UGCPolicy()
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// io.Reader in, bytes.Buffer out
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r := strings.NewReader(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
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buf := p.SanitizeReader(r)
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fmt.Println(buf.String())
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// Output:
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//<a href="http://www.google.com" rel="nofollow">Google</a>
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}
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