gnotif.gno

  1// Package gnotif is a registry of notification triggers. Each trigger names
  2// a realm and an event type to watch, and the text of the notification that
  3// gnotif servers send when a matching event lands on chain.
  4package gnotif
  5
  6import (
  7	"chain"
  8	"strconv"
  9	"strings"
 10
 11	"gno.land/p/nt/avl/v0"
 12	"gno.land/p/nt/seqid/v0"
 13)
 14
 15// Trigger is one declared notification rule. Filter holds comma-separated
 16// key=value pairs; Title, Body and Link are templates where {key} stands for
 17// the value of the event's attribute key.
 18type Trigger struct {
 19	ID, Target, Event, Filter, Param, Title, Body, Link string
 20	Declarer address
 21	Verified bool
 22}
 23
 24const (
 25	targetPrefix   = "gno.land/r/"
 26	maxTarget      = 256
 27	maxName        = 64
 28	maxFilterPairs = 8
 29	maxBody        = 255
 30	maxLink        = 256
 31)
 32
 33var (
 34	triggers avl.Tree // id → *Trigger
 35	lastID   seqid.ID
 36)
 37
 38// Declare stores a trigger and returns its id. The trigger is verified when
 39// its caller is the target realm itself.
 40func Declare(cur realm, target, event, filter, param, title, body, link string) string {
 41	validate(target, event, filter, param, title, body, link)
 42	caller := cur.Previous()
 43	tr := &Trigger{
 44		ID:       lastID.Next().String(),
 45		Target:   target,
 46		Event:    event,
 47		Filter:   filter,
 48		Param:    param,
 49		Title:    title,
 50		Body:     body,
 51		Link:     link,
 52		Declarer: caller.Address(),
 53		Verified: caller.IsCode() && caller.PkgPath() == target,
 54	}
 55	triggers.Set(tr.ID, tr)
 56	chain.Emit("TriggerDeclared",
 57		"id", tr.ID,
 58		"target", tr.Target,
 59		"event", tr.Event,
 60		"filter", tr.Filter,
 61		"param", tr.Param,
 62		"title", tr.Title,
 63		"body", tr.Body,
 64		"link", tr.Link,
 65		"declarer", tr.Declarer.String(),
 66		"verified", strconv.FormatBool(tr.Verified),
 67	)
 68	return tr.ID
 69}
 70
 71// Remove deletes a trigger. Only its declarer may remove it.
 72func Remove(cur realm, id string) {
 73	v := triggers.Get(id)
 74	if v == nil {
 75		panic("unknown trigger")
 76	}
 77	if v.(*Trigger).Declarer != cur.Previous().Address() {
 78		panic("not the declarer")
 79	}
 80	triggers.Remove(id)
 81	chain.Emit("TriggerRemoved", "id", id)
 82}
 83
 84func validate(target, event, filter, param, title, body, link string) {
 85	switch {
 86	case !strings.HasPrefix(target, targetPrefix) || len(target) > maxTarget:
 87		panic("invalid target")
 88	case !sized(event, 1, maxName):
 89		panic("invalid event")
 90	case !validFilter(filter):
 91		panic("invalid filter")
 92	case !sized(param, 0, maxName):
 93		panic("invalid param")
 94	case !sized(title, 1, maxName):
 95		panic("invalid title")
 96	case !sized(body, 0, maxBody):
 97		panic("invalid body")
 98	case !validLink(link):
 99		panic("invalid link")
100	}
101}
102
103func sized(s string, lo, hi int) bool {
104	return len(s) >= lo && len(s) <= hi
105}
106
107func validFilter(filter string) bool {
108	if filter == "" {
109		return true
110	}
111	pairs := strings.Split(filter, ",")
112	if len(pairs) > maxFilterPairs {
113		return false
114	}
115	for _, pair := range pairs {
116		key, value, ok := strings.Cut(pair, "=")
117		if !ok || !sized(key, 1, maxName) || !sized(value, 1, maxName) || strings.Contains(value, "=") {
118			return false
119		}
120	}
121	return true
122}
123
124// validLink accepts only a path, so a click always stays on the dapp's origin.
125// "//host" and "/\host" start with a slash yet resolve to another host.
126func validLink(link string) bool {
127	return sized(link, 1, maxLink) &&
128		strings.HasPrefix(link, "/") &&
129		!strings.HasPrefix(link, "//") &&
130		!strings.HasPrefix(link, "/\\")
131}