upstream

Documentation

Overview

Package upstream implements DNS clients for all known DNS encryption protocols.

Index

• Constants
• Variables
• func LookupParallel(ctx context.Context, resolvers []Resolver, host string) (addrs []netip.Addr, err error)
• type ConsequentResolver
  • func (resolvers ConsequentResolver) LookupNetIP(ctx context.Context, network string, host string) (addrs []netip.Addr, err error)
• type DialerInitializer
• type ExchangeAllResult
  • func ExchangeAll(ups []Upstream, req *dns.Msg) (res []ExchangeAllResult, err error)
• type HTTPVersion
• type NotBootstrapError
  • func (e NotBootstrapError) Error() (msg string)
  • func (e NotBootstrapError) Unwrap() (reason error)
• type Options
  • func (o *Options) Clone() (clone *Options)
• type ParallelResolver
• type QUICTraceFunc
• type Resolver
• type StaticResolver
  • func (r StaticResolver) LookupNetIP(ctx context.Context, network string, host string) (addrs []netip.Addr, err error)
• type Upstream
  • func AddressToUpstream(addr string, opts *Options) (u Upstream, err error)
  • func ExchangeParallel(ups []Upstream, req *dns.Msg) (reply *dns.Msg, resolved Upstream, err error)
• type UpstreamResolver
  • func NewUpstreamResolver(resolverAddress string, opts *Options) (r *UpstreamResolver, err error)
  • func (r *UpstreamResolver) LookupNetIP(_ context.Context, network string, host string) (ips []netip.Addr, err error)

Constants

const (
	// ErrNoUpstreams is returned from the methods that expect at least a single
	// upstream to work with when no upstreams specified.
	ErrNoUpstreams errors.Error = "no upstream specified"

	// ErrNoReply is returned from [ExchangeAll] when no upstreams replied.
	ErrNoReply errors.Error = "no reply"
)

const (
	// QUICCodeNoError is used when the connection or stream needs to be closed,
	// but there is no error to signal.
	QUICCodeNoError = quic.ApplicationErrorCode(0)

	// QUICCodeInternalError signals that the DoQ implementation encountered
	// an internal error and is incapable of pursuing the transaction or the
	// connection.
	QUICCodeInternalError = quic.ApplicationErrorCode(1)

	// QUICKeepAlivePeriod is the value that we pass to *quic.Config and that
	// controls the period with with keep-alive frames are being sent to the
	// connection. We set it to 20s as it would be in the quic-go@v0.27.1 with
	// KeepAlive field set to true This value is specified in
	// https://pkg.go.dev/github.com/quic-go/quic-go/internal/protocol#MaxKeepAliveInterval.
	//
	// TODO(ameshkov):  Consider making it configurable.
	QUICKeepAlivePeriod = time.Second * 2

	// NextProtoDQ is the ALPN token for DoQ. During the connection establishment,
	// DNS/QUIC support is indicated by selecting the ALPN token "doq" in the
	// crypto handshake.
	//
	// See https://datatracker.ietf.org/doc/rfc9250.
	NextProtoDQ = "doq"
)

Variables

var DefaultHTTPVersions = []HTTPVersion{HTTPVersion11, HTTPVersion2}

DefaultHTTPVersions is the list of HTTPVersion that we use by default in the DNS-over-HTTPS client.

Functions

func LookupParallel

func LookupParallel(
	ctx context.Context,
	resolvers []Resolver,
	host string,
) (addrs []netip.Addr, err error)

LookupParallel tries to lookup for ip of host with all resolvers concurrently.

Deprecated: Use ParallelResolver instead.

Types

type ConsequentResolver

type ConsequentResolver []Resolver

ConsequentResolver is a slice of resolvers that are queried in order until the first successful non-empty response, as opposed to just successful response requirement in ParallelResolver.

func (ConsequentResolver) LookupNetIP

func (resolvers ConsequentResolver) LookupNetIP(
	ctx context.Context,
	network string,
	host string,
) (addrs []netip.Addr, err error)

LookupNetIP implements the Resolver interface for ConsequentResolver.

type DialerInitializer

type DialerInitializer func() (handler bootstrap.DialHandler, err error)

DialerInitializer returns the handler that it creates. All the subsequent calls to it, except the first one, will return the same handler so that resolving will be performed only once.

type ExchangeAllResult

type ExchangeAllResult struct {
	// Resp is the response DNS request resolved into.
	Resp *dns.Msg

	// Upstream is the upstream that successfully resolved the request.
	Upstream Upstream
}

ExchangeAllResult is the successful result of ExchangeAll for a single upstream.

func ExchangeAll

func ExchangeAll(ups []Upstream, req *dns.Msg) (res []ExchangeAllResult, err error)

ExchangeAll returns the responses from all of u. It returns an error only if all upstreams failed to exchange the request.

type HTTPVersion

type HTTPVersion string

HTTPVersion is an enumeration of the HTTP versions that we support. Values that we use in this enumeration are also used as ALPN values.

const (
	// HTTPVersion11 is HTTP/1.1.
	HTTPVersion11 HTTPVersion = "http/1.1"
	// HTTPVersion2 is HTTP/2.
	HTTPVersion2 HTTPVersion = "h2"
	// HTTPVersion3 is HTTP/3.
	HTTPVersion3 HTTPVersion = "h3"
)

type NotBootstrapError

type NotBootstrapError struct {
	// contains filtered or unexported fields
}

NotBootstrapError is returned by AddressToUpstream when the parsed upstream can't be used as a bootstrap and wraps the actual reason.

func (NotBootstrapError) Error

func (e NotBootstrapError) Error() (msg string)

Error implements the [error] interface for NotBootstrapError.

func (NotBootstrapError) Unwrap

func (e NotBootstrapError) Unwrap() (reason error)

Unwrap implements the errors.Wrapper interface.

type Options

type Options struct {
	// VerifyServerCertificate is used to set the VerifyPeerCertificate property
	// of the *tls.Config for DNS-over-HTTPS, DNS-over-QUIC, and DNS-over-TLS.
	VerifyServerCertificate func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error

	// VerifyConnection is used to set the VerifyConnection property
	// of the *tls.Config for DNS-over-HTTPS, DNS-over-QUIC, and DNS-over-TLS.
	VerifyConnection func(state tls.ConnectionState) error

	// VerifyDNSCryptCertificate is the callback the DNSCrypt server certificate
	// will be passed to.  It's called in dnsCrypt.exchangeDNSCrypt.
	// Upstream.Exchange method returns any error caused by it.
	VerifyDNSCryptCertificate func(cert *dnscrypt.Cert) error

	// QUICTracer is an optional callback that allows tracing every QUIC
	// connection and logging every packet that goes through.
	QUICTracer QUICTraceFunc

	// RootCAs is the CertPool that must be used by all upstreams.  Redefining
	// RootCAs makes sense on iOS to overcome the 15MB memory limit of the
	// NEPacketTunnelProvider.
	RootCAs *x509.CertPool

	// CipherSuites is a custom list of TLSv1.2 ciphers.
	CipherSuites []uint16

	// Bootstrap is used to resolve upstreams' hostnames.  If nil, the
	// [net.DefaultResolver] will be used.
	Bootstrap Resolver

	// HTTPVersions is a list of HTTP versions that should be supported by the
	// DNS-over-HTTPS client.  If not set, HTTP/1.1 and HTTP/2 will be used.
	HTTPVersions []HTTPVersion

	// Timeout is the default upstream timeout.  It's also used as a timeout for
	// bootstrap DNS requests.  Zero value disables the timeout.
	Timeout time.Duration

	// InsecureSkipVerify disables verifying the server's certificate.
	InsecureSkipVerify bool

	// PreferIPv6 tells the bootstrapper to prefer IPv6 addresses for an
	// upstream.
	PreferIPv6 bool
}

Options for AddressToUpstream func. With these options we can configure the upstream properties.

func (*Options) Clone

func (o *Options) Clone() (clone *Options)

Clone copies o to a new struct. Note, that this is not a deep clone.

type ParallelResolver

type ParallelResolver = bootstrap.ParallelResolver

ParallelResolver is an alias for the internal bootstrap.ParallelResolver to allow it's usage outside of the module.

type QUICTraceFunc

type QUICTraceFunc func(
	ctx context.Context,
	role logging.Perspective,
	connID quic.ConnectionID,
) (tracer *logging.ConnectionTracer)

QUICTraceFunc is a function that returns a logging.ConnectionTracer specific for a given role and connection ID.

type Resolver

type Resolver = bootstrap.Resolver

Resolver is an alias for the internal bootstrap.Resolver to allow custom implementations. Note, that the net.Resolver from standard library also implements this interface.

type StaticResolver

type StaticResolver []netip.Addr

StaticResolver is a resolver which always responds with an underlying slice of IP addresses.

func (StaticResolver) LookupNetIP

func (r StaticResolver) LookupNetIP(
	ctx context.Context,
	network string,
	host string,
) (addrs []netip.Addr, err error)

LookupNetIP implements the Resolver interface for StaticResolver.

type Upstream

type Upstream interface {
	// Exchange sends the DNS query req to this upstream and returns the
	// response that has been received or an error if something went wrong.
	Exchange(req *dns.Msg) (resp *dns.Msg, err error)

	// Address returns the address of the upstream DNS resolver.
	Address() (addr string)

	// Closer used to close the upstreams properly.  Exchange shouldn't be
	// called after calling Close.
	io.Closer
}

Upstream is an interface for a DNS resolver.

func AddressToUpstream

func AddressToUpstream(addr string, opts *Options) (u Upstream, err error)

AddressToUpstream converts addr to an Upstream using the specified options. addr can be either a URL, or a plain address, either a domain name or an IP.

• udp://5.3.5.3:53 or 5.3.5.3:53 for plain DNS using IP address;
• udp://name.server:53 or name.server:53 for plain DNS using domain name;
• tcp://5.3.5.3:53 for plain DNS-over-TCP using IP address;
• tcp://name.server:53 for plain DNS-over-TCP using domain name;
• tls://5.3.5.3:853 for DNS-over-TLS using IP address;
• tls://name.server:853 for DNS-over-TLS using domain name;
• https://5.3.5.3:443/dns-query for DNS-over-HTTPS using IP address;
• https://name.server:443/dns-query for DNS-over-HTTPS using domain name;
• quic://5.3.5.3:853 for DNS-over-QUIC using IP address;
• quic://name.server:853 for DNS-over-QUIC using domain name;
• h3://dns.google for DNS-over-HTTPS that only works with HTTP/3;
• sdns://... for DNS stamp, see https://dnscrypt.info/stamps-specifications.

If addr doesn't have port specified, the default port of the appropriate protocol will be used.

opts are applied to the u and shouldn't be modified afterwards, nil value is valid.

TODO(e.burkov): Clone opts?

func ExchangeParallel

func ExchangeParallel(ups []Upstream, req *dns.Msg) (reply *dns.Msg, resolved Upstream, err error)

ExchangeParallel returns the dirst successful response from one of u. It returns an error if all upstreams failed to exchange the request.

type UpstreamResolver

type UpstreamResolver struct {
	// Upstream is used for lookups.  It must not be nil.
	Upstream
}

UpstreamResolver is a wrapper around Upstream that implements the bootstrap.Resolver interface.

func NewUpstreamResolver

func NewUpstreamResolver(resolverAddress string, opts *Options) (r *UpstreamResolver, err error)

NewUpstreamResolver creates an upstream that can be used as bootstrap Resolver. resolverAddress format is the same as in the AddressToUpstream. If the upstream can't be used as a bootstrap, the returned error will have the underlying type of NotBootstrapError, and r itself will be fully usable. Closing r.Upstream is caller's responsibility.

func (*UpstreamResolver) LookupNetIP

func (r *UpstreamResolver) LookupNetIP(
	_ context.Context,
	network string,
	host string,
) (ips []netip.Addr, err error)

LookupNetIP implements the Resolver interface for upstreamResolver.

TODO(e.burkov): Use context.