evil.gno

 1// Package evil is the adversarial engine of spike (a). It behaves during
 2// registration and misbehaves afterwards, selected by a mode it controls.
 3// Every mode is a question for the acceptance table in ../README.md.
 4package evil
 5
 6import (
 7	"strings"
 8
 9	"gno.land/r/g19dzk54hhsdc3gllpksuj6gu4a3e6fl8cr6rn4w/minhwa/spike/registry"
10)
11
12// The modes. Render chooses its behaviour from the seed so that each attack
13// can be triggered by a plain qeval without changing evil's state.
14const (
15	SeedWrite  = "write"  // write through a pointer into registry state
16	SeedBump   = "bump"   // call registry's non-crossing mutator
17	SeedPanic  = "panic"  // abort the read
18	SeedLoop   = "loop"   // burn the query gas
19	SeedHuge   = "huge"   // return an oversized output
20	SeedScript = "script" // return active SVG content
21)
22
23type impl struct{}
24
25// mutated flips Render's output for the sample seed after registration, to
26// show that a public engine realm with state can change its art (the
27// fingerprint check is the only on-chain detector).
28var mutated bool
29
30func (impl) Name() string { return "spike-evil" }
31
32func (impl) Render(seed string) string {
33	switch seed {
34	case registry.SampleSeed:
35		if mutated {
36			return "<svg>changed</svg>"
37		}
38		return "<svg>sample</svg>"
39	case SeedWrite:
40		registry.SharedBoard().Count = 999
41		return "<svg>wrote</svg>"
42	case SeedBump:
43		registry.UnsafeBump()
44		return "<svg>bumped</svg>"
45	case SeedPanic:
46		panic("evil: render refused")
47	case SeedLoop:
48		for {
49		}
50	case SeedHuge:
51		return "<svg>" + strings.Repeat("A", 1<<20) + "</svg>"
52	case SeedScript:
53		return `<svg xmlns="http://www.w3.org/2000/svg"><script>alert(1)</script></svg>`
54	}
55	return "<svg>" + seed + "</svg>"
56}
57
58func Register(cur realm) string {
59	return registry.Register(cross(cur), impl{})
60}
61
62// Mutate changes the sample output after registration (evil's own state).
63func Mutate(cur realm) {
64	mutated = true
65}