aboutsummaryrefslogtreecommitdiffstats
path: root/vendor/github.com/google/safehtml/template/error.go
diff options
context:
space:
mode:
authorTaras Madan <tarasmadan@google.com>2023-02-22 22:16:50 +0100
committerTaras Madan <tarasmadan@google.com>2023-02-24 12:47:23 +0100
commit4165372ec8fd142475a4e35fd0cf4f8042132208 (patch)
tree21cd62211b4dd80bee469054c5b65db77342333c /vendor/github.com/google/safehtml/template/error.go
parent2b3ed821a493b8936c8bacfa6f8b4f1c90a00855 (diff)
dependencies: update
set go min requirements to 1.19 update dependencies update vendor
Diffstat (limited to 'vendor/github.com/google/safehtml/template/error.go')
-rw-r--r--vendor/github.com/google/safehtml/template/error.go280
1 files changed, 280 insertions, 0 deletions
diff --git a/vendor/github.com/google/safehtml/template/error.go b/vendor/github.com/google/safehtml/template/error.go
new file mode 100644
index 000000000..fe7821433
--- /dev/null
+++ b/vendor/github.com/google/safehtml/template/error.go
@@ -0,0 +1,280 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package template
+
+import (
+ "fmt"
+ "text/template/parse"
+)
+
+// Error describes a problem encountered during template Escaping.
+type Error struct {
+ // ErrorCode describes the kind of error.
+ ErrorCode ErrorCode
+ // Node is the node that caused the problem, if known.
+ // If not nil, it overrides Name and Line.
+ Node parse.Node
+ // Name is the name of the template in which the error was encountered.
+ Name string
+ // Line is the line number of the error in the template source or 0.
+ Line int
+ // Description is a human-readable description of the problem.
+ Description string
+}
+
+// ErrorCode is a code for a kind of error.
+type ErrorCode int
+
+// We define codes for each error that manifests while escaping templates, but
+// escaped templates may also fail at runtime.
+//
+// Output: "ZgotmplZ"
+// Example:
+// <img src="{{.X}}">
+// where {{.X}} evaluates to `javascript:...`
+// Discussion:
+// "ZgotmplZ" is a special value that indicates that unsafe content reached a
+// CSS or URL context at runtime. The output of the example will be
+// <img src="#ZgotmplZ">
+// If the data comes from a trusted source, use content types to exempt it
+// from filtering: URL(`javascript:...`).
+const (
+ // OK indicates the lack of an error.
+ OK ErrorCode = iota
+
+ // ErrAmbigContext: "... appears in an ambiguous context within a URL"
+ // Example:
+ // <a href="
+ // {{if .C}}
+ // /path/
+ // {{else}}
+ // /search?q=
+ // {{end}}
+ // {{.X}}
+ // ">
+ // Discussion:
+ // {{.X}} is in an ambiguous URL context since, depending on {{.C}},
+ // it may be either a URL suffix or a query parameter.
+ // Moving {{.X}} into the condition removes the ambiguity:
+ // <a href="{{if .C}}/path/{{.X}}{{else}}/search?q={{.X}}">
+ ErrAmbigContext
+
+ // ErrBadHTML: "expected space, attr name, or end of tag, but got ...",
+ // "... in unquoted attr", "... in attribute name"
+ // Example:
+ // <a href = /search?q=foo>
+ // <href=foo>
+ // <form na<e=...>
+ // <option selected<
+ // Discussion:
+ // This is often due to a typo in an HTML element, but some runes
+ // are banned in tag names, attribute names, and unquoted attribute
+ // values because they can tickle parser ambiguities.
+ // Quoting all attributes is the best policy.
+ ErrBadHTML
+
+ // ErrBranchEnd: "{{if}} branches end in different contexts"
+ // Example:
+ // {{if .C}}<a href="{{end}}{{.X}}
+ // Discussion:
+ // Package html/template statically examines each path through an
+ // {{if}}, {{range}}, or {{with}} to escape any following pipelines.
+ // The example is ambiguous since {{.X}} might be an HTML text node,
+ // or a URL prefix in an HTML attribute. The context of {{.X}} is
+ // used to figure out how to escape it, but that context depends on
+ // the run-time value of {{.C}} which is not statically known.
+ //
+ // The problem is usually something like missing quotes or angle
+ // brackets, or can be avoided by refactoring to put the two contexts
+ // into different branches of an if, range or with. If the problem
+ // is in a {{range}} over a collection that should never be empty,
+ // adding a dummy {{else}} can help.
+ ErrBranchEnd
+
+ // ErrEndContext: "... ends in a non-text context: ..."
+ // Examples:
+ // <div
+ // <div title="no close quote>
+ // <script>f()
+ // Discussion:
+ // Executed templates should produce a DocumentFragment of HTML.
+ // Templates that end without closing tags will trigger this error.
+ // Templates that should not be used in an HTML context or that
+ // produce incomplete Fragments should not be executed directly.
+ //
+ // {{define "main"}} <script>{{template "helper"}}</script> {{end}}
+ // {{define "helper"}} document.write(' <div title=" ') {{end}}
+ //
+ // "helper" does not produce a valid document fragment, so should
+ // not be Executed directly.
+ ErrEndContext
+
+ // ErrNoSuchTemplate: "no such template ..."
+ // Examples:
+ // {{define "main"}}<div {{template "attrs"}}>{{end}}
+ // {{define "attrs"}}href="{{.URL}}"{{end}}
+ // Discussion:
+ // Package html/template looks through template calls to compute the
+ // context.
+ // Here the {{.URL}} in "attrs" must be treated as a URL when called
+ // from "main", but you will get this error if "attrs" is not defined
+ // when "main" is parsed.
+ ErrNoSuchTemplate
+
+ // ErrOutputContext: "cannot compute output context for template ..."
+ // Examples:
+ // {{define "t"}}{{if .T}}{{template "t" .T}}{{end}}{{.H}}",{{end}}
+ // Discussion:
+ // A recursive template does not end in the same context in which it
+ // starts, and a reliable output context cannot be computed.
+ // Look for typos in the named template.
+ // If the template should not be called in the named start context,
+ // look for calls to that template in unexpected contexts.
+ // Maybe refactor recursive templates to not be recursive.
+ ErrOutputContext
+
+ // ErrPartialCharset: "unfinished JS regexp charset in ..."
+ // Example:
+ // <script>var pattern = /foo[{{.Chars}}]/</script>
+ // Discussion:
+ // Package html/template does not support interpolation into regular
+ // expression literal character sets.
+ ErrPartialCharset
+
+ // ErrPartialEscape: "unfinished escape sequence in ..."
+ // Example:
+ // <script>alert("\{{.X}}")</script>
+ // Discussion:
+ // Package html/template does not support actions following a
+ // backslash.
+ // This is usually an error and there are better solutions; for
+ // example
+ // <script>alert("{{.X}}")</script>
+ // should work, and if {{.X}} is a partial escape sequence such as
+ // "xA0", mark the whole sequence as safe content: JSStr(`\xA0`)
+ ErrPartialEscape
+
+ // ErrRangeLoopReentry: "on range loop re-entry: ..."
+ // Example:
+ // <script>var x = [{{range .}}'{{.}},{{end}}]</script>
+ // Discussion:
+ // If an iteration through a range would cause it to end in a
+ // different context than an earlier pass, there is no single context.
+ // In the example, there is missing a quote, so it is not clear
+ // whether {{.}} is meant to be inside a JS string or in a JS value
+ // context. The second iteration would produce something like
+ //
+ // <script>var x = ['firstValue,'secondValue]</script>
+ ErrRangeLoopReentry
+
+ // ErrSlashAmbig: '/' could start a division or regexp.
+ // Example:
+ // <script>
+ // {{if .C}}var x = 1{{end}}
+ // /-{{.N}}/i.test(x) ? doThis : doThat();
+ // </script>
+ // Discussion:
+ // The example above could produce `var x = 1/-2/i.test(s)...`
+ // in which the first '/' is a mathematical division operator or it
+ // could produce `/-2/i.test(s)` in which the first '/' starts a
+ // regexp literal.
+ // Look for missing semicolons inside branches, and maybe add
+ // parentheses to make it clear which interpretation you intend.
+ ErrSlashAmbig
+
+ // ErrPredefinedEscaper: "predefined escaper ... disallowed in template"
+ // Example:
+ // <div class={{. | html}}>Hello<div>
+ // Discussion:
+ // Package html/template already contextually escapes all pipelines to
+ // produce HTML output safe against code injection. Manually escaping
+ // pipeline output using the predefined escapers "html" or "urlquery" is
+ // unnecessary, and may affect the correctness or safety of the escaped
+ // pipeline output in Go 1.8 and earlier.
+ //
+ // In most cases, such as the given example, this error can be resolved by
+ // simply removing the predefined escaper from the pipeline and letting the
+ // contextual autoescaper handle the escaping of the pipeline. In other
+ // instances, where the predefined escaper occurs in the middle of a
+ // pipeline where subsequent commands expect escaped input, e.g.
+ // {{.X | html | makeALink}}
+ // where makeALink does
+ // return `<a href="`+input+`">link</a>`
+ // consider refactoring the surrounding template to make use of the
+ // contextual autoescaper, i.e.
+ // <a href="{{.X}}">link</a>
+ //
+ // To ease migration to Go 1.9 and beyond, "html" and "urlquery" will
+ // continue to be allowed as the last command in a pipeline. However, if the
+ // pipeline occurs in an unquoted attribute value context, "html" is
+ // disallowed. Avoid using "html" and "urlquery" entirely in new templates.
+ ErrPredefinedEscaper
+
+ // ErrEscapeAction: "cannot escape action ..."
+ // Discussion:
+ // Error returned while escaping an action using EscaperForContext.
+ // Refer to error message for more details.
+ // TODO: remove this error type and replace it with more informative sanitization errors.
+ ErrEscapeAction
+
+ // ErrCSPCompatibility: `"javascript:" URI disallowed for CSP compatibility`,
+ // "inline event handler ... is disallowed for CSP compatibility
+ // Examples:
+ // <span onclick="doThings();">A thing.</span>
+ // <a href="javascript:linkClicked()">foo</a>
+ // Discussion:
+ // Inline event handlers (onclick="...", onerror="...") and
+ // <a href="javascript:..."> links can be used to run scripts,
+ // so an attacker who finds an XSS bug could inject such HTML
+ // and execute malicious JavaScript. These patterns must be
+ // refactored into safer alternatives for compatibility with
+ // Content Security Policy (CSP).
+ //
+ // For example, the following HTML that contains an inline event handler:
+ // <script> function doThings() { ... } </script>
+ // <span onclick="doThings();">A thing.</span>
+ // can be refactored into:
+ // <span id="things">A thing.</span>
+ // <script nonce="${nonce}">
+ // document.addEventListener('DOMContentLoaded', function () {
+ // document.getElementById('things')
+ // .addEventListener('click', function doThings() { ... });
+ // });
+ // </script>
+ //
+ // Likewise, the following HTML containng a javascript: URI:
+ // <a href="javascript:linkClicked()">foo</a>
+ // can be refactored into:
+ // <a id="foo">foo</a>
+ // <script nonce="${nonce}">
+ // document.addEventListener('DOMContentLoaded', function () {
+ // document.getElementById('foo')
+ // .addEventListener('click', linkClicked);
+ // });
+ // </script>
+ ErrCSPCompatibility
+ // All JS templates inside script literals have to be balanced; otherwise a concatenation such as
+ // <script>alert(`x{{.data}}`</script> can contain XSS if data contains user-controlled escaped strings (e.g. as JSON).
+ ErrUnbalancedJsTemplate
+)
+
+func (e *Error) Error() string {
+ switch {
+ case e.Node != nil:
+ loc, _ := (*parse.Tree)(nil).ErrorContext(e.Node)
+ return fmt.Sprintf("html/template:%s: %s", loc, e.Description)
+ case e.Line != 0:
+ return fmt.Sprintf("html/template:%s:%d: %s", e.Name, e.Line, e.Description)
+ case e.Name != "":
+ return fmt.Sprintf("html/template:%s: %s", e.Name, e.Description)
+ }
+ return "html/template: " + e.Description
+}
+
+// errorf creates an error given a format string f and args.
+// The template Name still needs to be supplied.
+func errorf(k ErrorCode, node parse.Node, line int, f string, args ...interface{}) *Error {
+ return &Error{k, node, "", line, fmt.Sprintf(f, args...)}
+}