Add response poisoning

lib/poison.go

@@ -0,0 +1,26 @@
+package lib
+
+import (
+	go_away "git.gammaspectra.live/git/go-away"
+	"io"
+	"path"
+	"slices"
+	"strings"
+)
+
+var poisonEncodings = []string{"br", "zstd", "gzip"}
+
+func (state *State) getPoison(mime string, encodings []string) (r io.ReadCloser, encoding string) {
+	for _, encoding = range poisonEncodings {
+		if !slices.Contains(encodings, encoding) {
+			continue
+		}
+
+		p := path.Join("poison", strings.ReplaceAll(mime, "/", "_")+"."+encoding+".poison")
+		f, err := go_away.PoisonFs.Open(p)
+		if err == nil {
+			return f, encoding
+		}
+	}
+	return nil, ""
+}