From 2c2382e1fdcd193508f777acfca1d8dc39b6bbda Mon Sep 17 00:00:00 2001
From: Gunir <134402102+gunir@users.noreply.github.com>
Date: Sat, 13 Dec 2025 15:55:06 +0700
Subject: [PATCH 1/3] Create csp.go - Implementing $csp from uBlockOrigin

This PR implement a missing piece $csp modifier from uBO: https://github.com/gorhill/uBlock/wiki/Static-filter-syntax#csp

Signed-off-by: Gunir <134402102+gunir@users.noreply.github.com>
---
 networkrules/rulemodifiers/csp.go | 44 +++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 networkrules/rulemodifiers/csp.go

diff --git a/networkrules/rulemodifiers/csp.go b/networkrules/rulemodifiers/csp.go
new file mode 100644
index 0000000..150a21e
--- /dev/null
+++ b/networkrules/rulemodifiers/csp.go
@@ -0,0 +1,44 @@
+package rulemodifiers
+
+import (
+	"errors"
+	"net/http"
+	"strings"
+)
+
+type CSPModifier struct {
+	policy string
+}
+
+var _ ModifyingModifier = (*CSPModifier)(nil)
+
+func (m *CSPModifier) Parse(modifier string) error {
+	if !strings.HasPrefix(modifier, "csp=") {
+		return errors.New("invalid csp modifier")
+	}
+	m.policy = strings.TrimPrefix(modifier, "csp=")
+	if m.policy == "" {
+		return errors.New("empty csp policy")
+	}
+	return nil
+}
+
+func (m *CSPModifier) ModifyReq(req *http.Request) bool {
+	// CSP is a response header, so we do nothing to the request.
+	return false
+}
+
+func (m *CSPModifier) ModifyRes(res *http.Response) (bool, error) {
+	// We use Add() instead of Set() because if the site already has a CSP,
+	// browsers enforce the "intersection" of all policies (most restrictive wins).
+	res.Header.Add("Content-Security-Policy", m.policy)
+	return true, nil
+}
+
+func (m *CSPModifier) Cancels(modifier Modifier) bool {
+	other, ok := modifier.(*CSPModifier)
+	if !ok {
+		return false
+	}
+	return m.policy == other.policy
+}

From 104dd41eb973decdd1573b95cbd4677d9cf9f7af Mon Sep 17 00:00:00 2001
From: Gunir <134402102+gunir@users.noreply.github.com>
Date: Sat, 13 Dec 2025 15:55:51 +0700
Subject: [PATCH 2/3] Update rule.go - Register csp modifier

Signed-off-by: Gunir <134402102+gunir@users.noreply.github.com>
---
 networkrules/rule/rule.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/networkrules/rule/rule.go b/networkrules/rule/rule.go
index 66e123f..d3998b9 100644
--- a/networkrules/rule/rule.go
+++ b/networkrules/rule/rule.go
@@ -83,6 +83,9 @@ func (rm *Rule) ParseModifiers(modifiers []string) error {
 			modifier = &rulemodifiers.ScrambleJSModifier{}
 		case isKind("jsonprune"):
 			modifier = &rulemodifiers.JSONPruneModifier{}
+		// [NEW] Register the CSP Modifier
+		case isKind("csp"):
+			modifier = &rulemodifiers.CSPModifier{}
 		case isKind("all"):
 			// TODO: should act as "popup" modifier once it gets implemented
 			continue

From 1b8c81b679555c070402fe1c8857ee64e82ec29b Mon Sep 17 00:00:00 2001
From: Gunir <134402102+gunir@users.noreply.github.com>
Date: Sat, 17 Jan 2026 10:19:47 +0700
Subject: [PATCH 3/3] Update networkrules/rule/rule.go

Co-authored-by: Ansar Smagul <ansar@anfragment.net>
Signed-off-by: Gunir <134402102+gunir@users.noreply.github.com>
---
 networkrules/rule/rule.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/networkrules/rule/rule.go b/networkrules/rule/rule.go
index d3998b9..6a6c1f4 100644
--- a/networkrules/rule/rule.go
+++ b/networkrules/rule/rule.go
@@ -83,7 +83,6 @@ func (rm *Rule) ParseModifiers(modifiers []string) error {
 			modifier = &rulemodifiers.ScrambleJSModifier{}
 		case isKind("jsonprune"):
 			modifier = &rulemodifiers.JSONPruneModifier{}
-		// [NEW] Register the CSP Modifier
 		case isKind("csp"):
 			modifier = &rulemodifiers.CSPModifier{}
 		case isKind("all"):