231 lines
7.7 KiB
Go
231 lines
7.7 KiB
Go
// This file is part of the happyDomain (R) project.
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// Copyright (c) 2020-2026 happyDomain
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// Authors: Pierre-Olivier Mercier, et al.
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package checker
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import (
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"context"
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"fmt"
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"strings"
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sdk "git.happydns.org/checker-sdk-go/checker"
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)
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func init() {
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RegisterRule(&hstsRule{})
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RegisterRule(&cspRule{})
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RegisterRule(&xFrameOptionsRule{})
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RegisterRule(&xXSSProtectionRule{})
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}
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// hstsRule checks the Strict-Transport-Security header on HTTPS responses.
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type hstsRule struct{}
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func (r *hstsRule) Name() string { return "http.hsts" }
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func (r *hstsRule) Description() string {
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return "Verifies the presence and quality of the Strict-Transport-Security header on HTTPS responses."
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}
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func (r *hstsRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
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data, errSt := loadHTTPData(ctx, obs)
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if errSt != nil {
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return []sdk.CheckState{*errSt}
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}
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require := sdk.GetBoolOption(opts, OptionRequireHSTS, true)
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minDays := sdk.GetIntOption(opts, OptionMinHSTSMaxAgeDays, DefaultMinHSTSMaxAge)
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minSeconds := int64(minDays) * 86400
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return EvalPerHTTPS(data, "http.hsts", func(p HTTPProbe) sdk.CheckState {
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h := ParseHSTS(p.Headers["strict-transport-security"])
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if h == nil {
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status := sdk.StatusWarn
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if !require {
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status = sdk.StatusInfo
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}
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return sdk.CheckState{
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Status: status,
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Code: "http.hsts.missing",
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Subject: p.Address,
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Message: "Strict-Transport-Security header is missing.",
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Meta: map[string]any{"fix": "Send `Strict-Transport-Security: max-age=15552000; includeSubDomains` from HTTPS responses."},
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}
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}
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if h.MaxAge < minSeconds {
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return sdk.CheckState{
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Status: sdk.StatusWarn,
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Code: "http.hsts.short_max_age",
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Subject: p.Address,
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Message: fmt.Sprintf("HSTS max-age=%d is below the recommended %d seconds (%d days).", h.MaxAge, minSeconds, minDays),
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}
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}
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return sdk.CheckState{
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Status: sdk.StatusOK,
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Code: "http.hsts.ok",
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Subject: p.Address,
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Message: fmt.Sprintf("HSTS present (max-age=%d, includeSubDomains=%v, preload=%v).", h.MaxAge, h.IncludeSub, h.Preload),
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}
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})
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}
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// cspRule checks for the presence of a Content-Security-Policy header.
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type cspRule struct{}
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func (r *cspRule) Name() string { return "http.csp" }
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func (r *cspRule) Description() string {
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return "Verifies the presence of a Content-Security-Policy header on HTTPS responses."
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}
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func (r *cspRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
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data, errSt := loadHTTPData(ctx, obs)
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if errSt != nil {
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return []sdk.CheckState{*errSt}
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}
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require := sdk.GetBoolOption(opts, OptionRequireCSP, false)
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return EvalPerHTTPS(data, "http.csp", func(p HTTPProbe) sdk.CheckState {
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csp := ParseCSP(p.Headers["content-security-policy"])
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if csp == nil {
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status := sdk.StatusInfo
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if require {
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status = sdk.StatusWarn
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}
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return sdk.CheckState{
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Status: status,
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Code: "http.csp.missing",
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Subject: p.Address,
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Message: "Content-Security-Policy header is missing.",
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Meta: map[string]any{"fix": "Define a CSP appropriate for your application (e.g. default-src 'self')."},
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}
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}
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if csp.HasUnsafe() {
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return sdk.CheckState{
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Status: sdk.StatusWarn,
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Code: "http.csp.unsafe",
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Subject: p.Address,
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Message: "Content-Security-Policy uses 'unsafe-inline' or 'unsafe-eval'.",
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}
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}
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return sdk.CheckState{
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Status: sdk.StatusOK,
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Code: "http.csp.ok",
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Subject: p.Address,
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Message: "Content-Security-Policy is set.",
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}
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})
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}
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// xFrameOptionsRule checks X-Frame-Options (or frame-ancestors in CSP as
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// an acceptable substitute).
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type xFrameOptionsRule struct{}
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func (r *xFrameOptionsRule) Name() string { return "http.x_frame_options" }
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func (r *xFrameOptionsRule) Description() string {
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return "Verifies that responses set X-Frame-Options or a CSP frame-ancestors directive."
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}
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func (r *xFrameOptionsRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
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data, errSt := loadHTTPData(ctx, obs)
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if errSt != nil {
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return []sdk.CheckState{*errSt}
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}
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return EvalPerHTTPS(data, "http.x_frame_options", func(p HTTPProbe) sdk.CheckState {
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xfo := strings.ToUpper(strings.TrimSpace(p.Headers["x-frame-options"]))
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hasFrameAncestors := ParseCSP(p.Headers["content-security-policy"]).HasDirective("frame-ancestors")
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switch {
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case xfo == "DENY" || xfo == "SAMEORIGIN" || hasFrameAncestors:
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return sdk.CheckState{
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Status: sdk.StatusOK,
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Code: "http.x_frame_options.ok",
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Subject: p.Address,
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Message: "Clickjacking protection is in place.",
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}
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case xfo != "":
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return sdk.CheckState{
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Status: sdk.StatusWarn,
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Code: "http.x_frame_options.invalid",
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Subject: p.Address,
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Message: "X-Frame-Options has an unrecognised value: " + xfo,
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}
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default:
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return sdk.CheckState{
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Status: sdk.StatusWarn,
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Code: "http.x_frame_options.missing",
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Subject: p.Address,
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Message: "Neither X-Frame-Options nor CSP frame-ancestors is set.",
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Meta: map[string]any{"fix": "Send `X-Frame-Options: DENY` (or SAMEORIGIN) or use CSP frame-ancestors."},
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}
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}
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})
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}
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func init() {
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// Showcase: a rule expressed entirely as a HeaderRuleSpec. Compare
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// with the hand-rolled rules above — the boilerplate vanishes once
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// the only logic is "is this header present and well-formed?".
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RegisterRule(HeaderRule(HeaderRuleSpec{
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Code: "http.x_content_type_options",
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Description: "Verifies that responses set X-Content-Type-Options: nosniff.",
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Header: "X-Content-Type-Options",
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Required: true,
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FixHint: "Add `X-Content-Type-Options: nosniff` to all responses.",
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Validate: func(v string) (sdk.Status, string) {
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if strings.EqualFold(v, "nosniff") {
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return sdk.StatusOK, "X-Content-Type-Options: nosniff is set."
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}
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return sdk.StatusWarn, "X-Content-Type-Options has an unexpected value: " + strings.ToLower(v)
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},
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}))
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}
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// xXSSProtectionRule checks the legacy X-XSS-Protection header. Modern
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// browsers ignore it, but if present we want it to be sane.
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type xXSSProtectionRule struct{}
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func (r *xXSSProtectionRule) Name() string { return "http.x_xss_protection" }
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func (r *xXSSProtectionRule) Description() string {
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return "Reports the value of the legacy X-XSS-Protection header (disabled is preferred on modern browsers; CSP is the proper replacement)."
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}
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func (r *xXSSProtectionRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
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data, errSt := loadHTTPData(ctx, obs)
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if errSt != nil {
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return []sdk.CheckState{*errSt}
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}
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return EvalPerHTTPS(data, "http.x_xss_protection", func(p HTTPProbe) sdk.CheckState {
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v := strings.TrimSpace(p.Headers["x-xss-protection"])
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switch {
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case v == "":
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return sdk.CheckState{
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Status: sdk.StatusInfo,
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Code: "http.x_xss_protection.absent",
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Subject: p.Address,
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Message: "X-XSS-Protection is not set; CSP is the recommended replacement.",
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}
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case strings.HasPrefix(v, "0"):
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return sdk.CheckState{
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Status: sdk.StatusOK,
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Code: "http.x_xss_protection.disabled",
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Subject: p.Address,
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Message: "X-XSS-Protection is explicitly disabled (recommended).",
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}
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case strings.Contains(strings.ToLower(v), "mode=block"):
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return sdk.CheckState{
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Status: sdk.StatusInfo,
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Code: "http.x_xss_protection.enabled",
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Subject: p.Address,
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Message: "X-XSS-Protection is set to the historically recommended `1; mode=block`. Modern browsers ignore this header; CSP is the proper replacement.",
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}
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default:
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return sdk.CheckState{
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Status: sdk.StatusInfo,
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Code: "http.x_xss_protection.enabled",
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Subject: p.Address,
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Message: "X-XSS-Protection is enabled. Modern browsers ignore this header; CSP is the proper replacement.",
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}
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}
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})
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}
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