From f96b6b93dae4e865b3322d7a84d6bc345fd7c3c9 Mon Sep 17 00:00:00 2001
From: Henrique Dias <mail@hacdias.com>
Date: Mon, 19 Feb 2024 16:06:14 +0100
Subject: [PATCH] feat: ipns max cache ttl

---
 docs/environment-variables.md | 10 +++++++++-
 main.go                       |  7 +++++++
 setup.go                      |  7 ++++++-
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/docs/environment-variables.md b/docs/environment-variables.md
index 3baca0a..315d84f 100644
--- a/docs/environment-variables.md
+++ b/docs/environment-variables.md
@@ -8,6 +8,7 @@
   - [`RAINBOW_TRUSTLESS_GATEWAY_DOMAINS`](#rainbow_trustless_gateway_domains)
   - [`RAINBOW_GC_INTERVAL`](#rainbow_gc_interval)
   - [`RAINBOW_GC_THRESHOLD`](#rainbow_gc_threshold)
+  - [`RAINBOW_IPNS_MAX_CACHE_TTL`](#rainbow_ipns_max_cache_ttl)
   - [`KUBO_RPC_URL`](#kubo_rpc_url)
 - [Logging](#logging)
   - [`GOLOG_LOG_LEVEL`](#golog_log_level)
@@ -67,7 +68,6 @@ Default: none (`Host` is ignored and gateway at `127.0.0.1` supports both deseri
 
 The interval at which the garbage collector will be called. This is given as a string that corresponds to the duration of the interval. Set 0 to disable.
 
-
 Default: `60m`
 
 ## `RAINBOW_GC_THRESHOLD`
@@ -78,6 +78,14 @@ When the periodic GC runs, it checks for the total and available space on disk.
 
 Default: `0.3` (always keep 30% of the disk available)
 
+## `RAINBOW_IPNS_MAX_CACHE_TTL`
+
+The maximum duration which entries are valid in the name system cache. They are applied to everything under the `/ipns/` namespace, and allows you to cap the [Time-To-Live (TTL)](https://specs.ipfs.tech/ipns/ipns-record/#ttl-uint64) of [IPNS Records](https://specs.ipfs.tech/ipns/ipns-record/).
+
+When `RAINBOW_IPNS_MAX_CACHE_TTL` is set, it defines the upper bound limit of how long a [IPNS Name](https://specs.ipfs.tech/ipns/ipns-record/#ipns-name) lookup result will be cached and read from cache before checking for updates.
+
+Default: No upper bound, [TTL from IPNS Record](https://specs.ipfs.tech/ipns/ipns-record/#ttl-uint64)
+
 ### `KUBO_RPC_URL`
 
 Single URL or a comma separated list of RPC endpoints that provide legacy `/api/v0` from Kubo.
diff --git a/main.go b/main.go
index ad0607b..7e7d748 100644
--- a/main.go
+++ b/main.go
@@ -198,6 +198,12 @@ Generate an identity seed and launch a gateway:
 			EnvVars: []string{"RAINBOW_BLOCKSTORE"},
 			Usage:   "Type of blockstore to use, such as flatfs or badger. See https://github.com/ipfs/rainbow/blockstore.md for more details",
 		},
+		&cli.DurationFlag{
+			Name:    "ipns-max-cache-ttl",
+			Value:   0,
+			EnvVars: []string{"RAINBOW_IPNS_MAX_CACHE_TTL"},
+			Usage:   "The maximum duration IPNS entries are valid in the cache. Set 0 to disable.",
+		},
 	}
 
 	app.Commands = []*cli.Command{
@@ -296,6 +302,7 @@ share the same seed as long as the indexes are different.
 			RoutingV1:               cctx.String("routing"),
 			KuboRPCURLs:             getEnvs(EnvKuboRPC, DefaultKuboRPC),
 			DHTSharedHost:           cctx.Bool("dht-shared-host"),
+			IpnsMaxCacheTTL:         cctx.Duration("ipns-max-cache-ttl"),
 			DenylistSubs:            getCommaSeparatedList(cctx.String("denylists")),
 			Peering:                 peeringAddrs,
 			GCInterval:              cctx.Duration("gc-interval"),
diff --git a/setup.go b/setup.go
index fa3224d..4217f34 100644
--- a/setup.go
+++ b/setup.go
@@ -101,6 +101,7 @@ type Config struct {
 	RoutingV1               string
 	KuboRPCURLs             []string
 	DHTSharedHost           bool
+	IpnsMaxCacheTTL         time.Duration
 
 	DenylistSubs []string
 	Peering      []peer.AddrInfo
@@ -346,7 +347,11 @@ func Setup(ctx context.Context, cfg Config, key crypto.PrivKey, dnsCache *cached
 	if err != nil {
 		return nil, err
 	}
-	ns, err := namesys.NewNameSystem(vs, namesys.WithDNSResolver(dns))
+	nsOptions := []namesys.Option{namesys.WithDNSResolver(dns)}
+	if cfg.IpnsMaxCacheTTL > 0 {
+		nsOptions = append(nsOptions, namesys.WithMaxCacheTTL(cfg.IpnsMaxCacheTTL))
+	}
+	ns, err := namesys.NewNameSystem(vs, nsOptions...)
 	if err != nil {
 		return nil, err
 	}