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feat: DNS.MaxCacheTTL for DNS-over-HTTPS resolvers #8615

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merged 6 commits into from
Feb 10, 2022
Merged

feat: DNS.MaxCacheTTL for DNS-over-HTTPS resolvers #8615

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e7c4b48
feat: Add MaxCacheTTL option for DNS-over-HTTPS resolvers
thibmeu Dec 15, 2021
a31c284
Update libp2p/go-doh-resolver dependencies to support Options
thibmeu Dec 15, 2021
9906198
feat: Add `DNS.MaxCacheTTL` config documentation
thibmeu Dec 16, 2021
7f7f096
docs: DNS.MaxCacheTTL
lidel Jan 20, 2022
c9aa772
chore: [email protected]
lidel Jan 25, 2022
d5dc09b
docs: apply suggestions from review
lidel Feb 10, 2022
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13 changes: 10 additions & 3 deletions core/node/dns.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,9 @@ package node

import (
"fmt"
"math"
"strings"
"time"

config "github.com/ipfs/go-ipfs-config"
doh "github.com/libp2p/go-doh-resolver"
Expand All @@ -16,18 +18,23 @@ var defaultResolvers = map[string]string{
"crypto.": "https://resolver.cloudflare-eth.com/dns-query",
}

func newResolver(url string) (madns.BasicResolver, error) {
func newResolver(url string, opts ...doh.Option) (madns.BasicResolver, error) {
if !strings.HasPrefix(url, "https://") {
return nil, fmt.Errorf("invalid resolver url: %s", url)
}

return doh.NewResolver(url), nil
return doh.NewResolver(url, opts...)
}

func DNSResolver(cfg *config.Config) (*madns.Resolver, error) {
var opts []madns.Option
var err error

var dohOpts []doh.Option
if !cfg.DNS.MaxCacheTTL.IsDefault() {
dohOpts = append(dohOpts, doh.WithMaxCacheTTL(cfg.DNS.MaxCacheTTL.WithDefault(time.Duration(math.MaxUint32)*time.Second)))
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}

domains := make(map[string]struct{}) // to track overridden default resolvers
rslvrs := make(map[string]madns.BasicResolver) // to reuse resolvers for the same URL

Expand All @@ -44,7 +51,7 @@ func DNSResolver(cfg *config.Config) (*madns.Resolver, error) {

rslv, ok := rslvrs[url]
if !ok {
rslv, err = newResolver(url)
rslv, err = newResolver(url, dohOpts...)
if err != nil {
return nil, fmt.Errorf("bad resolver for %s: %w", domain, err)
}
Expand Down
26 changes: 22 additions & 4 deletions docs/config.md
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Original file line number Diff line number Diff line change
Expand Up @@ -140,7 +140,8 @@ config file at runtime.
- [`Swarm.Transports.Multiplexers.Yamux`](#swarmtransportsmultiplexersyamux)
- [`Swarm.Transports.Multiplexers.Mplex`](#swarmtransportsmultiplexersmplex)
- [`DNS`](#dns)
- [`DNS.Resolvers`](#dnsresolvers)
- [`DNS.Resolvers`](#dnsresolvers)
- [`DNS.MaxCacheTTL`](#dnsmaxcachettl)



Expand Down Expand Up @@ -1757,7 +1758,7 @@ Type: `priority`

Options for configuring DNS resolution for [DNSLink](https://docs.ipfs.io/concepts/dnslink/) and `/dns*` [Multiaddrs](https://github.com/multiformats/multiaddr/).

## `DNS.Resolvers`
### `DNS.Resolvers`

Map of [FQDNs](https://en.wikipedia.org/wiki/Fully_qualified_domain_name) to custom resolver URLs.

Expand All @@ -1772,7 +1773,7 @@ Example:
"eth.": "https://eth.link/dns-query",
"crypto.": "https://resolver.unstoppable.io/dns-query",
"libre.": "https://ns1.iriseden.fr/dns-query",
".": "https://doh-ch.blahdns.com:4443/dns-query"
".": "https://cloudflare-dns.com/dns-query"
}
}
}
Expand All @@ -1785,11 +1786,28 @@ Be mindful that:
```json
{
"eth.": "https://resolver.cloudflare-eth.com/dns-query",
"crypto.": "https://resolver.cloudflare-eth.com/dns-query
"crypto.": "https://resolver.cloudflare-eth.com/dns-query"
}
```
To get all the benefits of a decentralized naming system we strongly suggest setting DoH endpoint to an empty string and running own decentralized resolver as catch-all one on localhost.

Default: `{}`

Type: `object[string -> string]`

### `DNS.MaxCacheTTL`

Maximum duration entries are valid in the DoH cache.
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This allows to cap the Time-To-Live suggested by the DNS response ([RFC2181](https://datatracker.ietf.org/doc/html/rfc2181#section-8)).
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If present, the upper bound is applied to DoH resolvers in [`DNS.Resolvers`](#dnsresolvers).

Note: This does NOT work with OS-level resolver. To make this a global setting, add `.` entry to `DNS.Resolvers` first.
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**Examples:**
* `"5m"` DNS entries are kept for 5 minutes or less.
* `"0s"` DNS entries expire as soon as they are retrieved.

Default: Respect DNS Response TTL

Type: `optionalDuration`
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@guseggert guseggert Feb 3, 2022 •
edited
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For completeness, can we add optionalDuration to the Types section?

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Good idea, but opened #8729 to not block this PR.

4 changes: 2 additions & 2 deletions go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ require (
github.com/ipfs/go-ipfs-blockstore v1.1.2
github.com/ipfs/go-ipfs-chunker v0.0.5
github.com/ipfs/go-ipfs-cmds v0.6.0
github.com/ipfs/go-ipfs-config v0.18.0
github.com/ipfs/go-ipfs-config v0.19.0
github.com/ipfs/go-ipfs-exchange-interface v0.1.0
github.com/ipfs/go-ipfs-exchange-offline v0.1.1
github.com/ipfs/go-ipfs-files v0.0.9
Expand Down Expand Up @@ -65,7 +65,7 @@ require (
github.com/jbenet/go-random v0.0.0-20190219211222-123a90aedc0c
github.com/jbenet/go-temp-err-catcher v0.1.0
github.com/jbenet/goprocess v0.1.4
github.com/libp2p/go-doh-resolver v0.3.1
github.com/libp2p/go-doh-resolver v0.4.0
github.com/libp2p/go-libp2p v0.16.0
github.com/libp2p/go-libp2p-connmgr v0.2.4
github.com/libp2p/go-libp2p-core v0.11.0
Expand Down
8 changes: 4 additions & 4 deletions go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -475,8 +475,8 @@ github.com/ipfs/go-ipfs-chunker v0.0.5 h1:ojCf7HV/m+uS2vhUGWcogIIxiO5ubl5O57Q7Na
github.com/ipfs/go-ipfs-chunker v0.0.5/go.mod h1:jhgdF8vxRHycr00k13FM8Y0E+6BoalYeobXmUyTreP8=
github.com/ipfs/go-ipfs-cmds v0.6.0 h1:yAxdowQZzoFKjcLI08sXVNnqVj3jnABbf9smrPQmBsw=
github.com/ipfs/go-ipfs-cmds v0.6.0/go.mod h1:ZgYiWVnCk43ChwoH8hAmI1IRbuVtq3GSTHwtRB/Kqhk=
github.com/ipfs/go-ipfs-config v0.18.0 h1:Ta1aNGNEq6RIvzbw7dqzCVZJKb7j+Dd35JFnAOCpT8g=
github.com/ipfs/go-ipfs-config v0.18.0/go.mod h1:wz2lKzOjgJeYJa6zx8W9VT7mz+iSd0laBMqS/9wmX6A=
github.com/ipfs/go-ipfs-config v0.19.0 h1:OuKIL+BkOZgJ+hb4Wg/9ynCtE/BaZBWcGy8hgdMepAo=
github.com/ipfs/go-ipfs-config v0.19.0/go.mod h1:wz2lKzOjgJeYJa6zx8W9VT7mz+iSd0laBMqS/9wmX6A=
github.com/ipfs/go-ipfs-delay v0.0.0-20181109222059-70721b86a9a8/go.mod h1:8SP1YXK1M1kXuc4KJZINY3TQQ03J2rwBG9QfXmbRPrw=
github.com/ipfs/go-ipfs-delay v0.0.1 h1:r/UXYyRcddO6thwOnhiznIAiSvxMECGgtv35Xs1IeRQ=
github.com/ipfs/go-ipfs-delay v0.0.1/go.mod h1:8SP1YXK1M1kXuc4KJZINY3TQQ03J2rwBG9QfXmbRPrw=
Expand Down Expand Up @@ -673,8 +673,8 @@ github.com/libp2p/go-conn-security-multistream v0.2.0/go.mod h1:hZN4MjlNetKD3Rq5
github.com/libp2p/go-conn-security-multistream v0.2.1/go.mod h1:cR1d8gA0Hr59Fj6NhaTpFhJZrjSYuNmhpT2r25zYR70=
github.com/libp2p/go-conn-security-multistream v0.3.0 h1:9UCIKlBL1hC9u7nkMXpD1nkc/T53PKMAn3/k9ivBAVc=
github.com/libp2p/go-conn-security-multistream v0.3.0/go.mod h1:EEP47t4fw/bTelVmEzIDqSe69hO/ip52xBEhZMLWAHM=
github.com/libp2p/go-doh-resolver v0.3.1 h1:1wbVGkB4Tdj4WEvjAuYknOPyt4vSSDn9thnj13pKPaY=
github.com/libp2p/go-doh-resolver v0.3.1/go.mod h1:y5go1ZppAq9N2eppbX0xON01CyPBeUg2yS6BTssssog=
github.com/libp2p/go-doh-resolver v0.4.0 h1:gUBa1f1XsPwtpE1du0O+nnZCUqtG7oYi7Bb+0S7FQqw=
github.com/libp2p/go-doh-resolver v0.4.0/go.mod h1:v1/jwsFusgsWIGX/c6vCRrnJ60x7bhTiq/fs2qt0cAg=
github.com/libp2p/go-eventbus v0.1.0/go.mod h1:vROgu5cs5T7cv7POWlWxBaVLxfSegC5UGQf8A2eEmx4=
github.com/libp2p/go-eventbus v0.2.1 h1:VanAdErQnpTioN2TowqNcOijf6YwhuODe4pPKSDpxGc=
github.com/libp2p/go-eventbus v0.2.1/go.mod h1:jc2S4SoEVPP48H9Wpzm5aiGwUCBMfGhVhhBjyhhCJs8=
Expand Down