feat: add plugin

doh/doh.go

@@ -0,0 +1,132 @@
+package doh
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"golang.org/x/net/http2"
+
+	"github.com/fumiama/terasu/ip"
+	"github.com/fumiama/terasu/tls"
+)
+
+// RecordType ...
+type RecordType uint16
+
+const (
+	RecordTypeNone RecordType = 0  // RecordTypeNone ...
+	RecordTypeA    RecordType = 1  // RecordTypeA IPv4
+	RecordTypeAAAA RecordType = 28 // RecordTypeAAAA IPv6
+)
+
+// Response represents the JSON response structure for DNS over HTTPS (DoH) queries.
+// It contains DNS query results and metadata about the response.
+type Response struct {
+	// Status indicates the DNS query status code (0 = NOERROR, etc.)
+	Status uint32
+	// TC indicates whether the response was truncated (true if truncated)
+	TC bool
+	// RD indicates whether recursion was requested in the query
+	RD bool
+	// RA indicates whether the server supports recursion
+	RA bool
+	// AD indicates whether the response was authenticated (DNSSEC)
+	AD bool
+	// CD indicates whether the client requested that DNSSEC validation be disabled
+	CD bool
+	// Question contains the DNS query question section with name and type
+	Question []struct {
+		// Name is the domain name being queried
+		Name string `json:"name"`
+		// Type is the DNS record type being requested (A, AAAA, etc.)
+		Type RecordType `json:"type"`
+	}
+	// Answer contains the DNS response answer section with resource records
+	Answer []struct {
+		// Name is the domain name for this resource record
+		Name string `json:"name"`
+		// Type is the DNS record type (A, AAAA, etc.)
+		Type RecordType `json:"type"`
+		// TTL is the time-to-live value for this resource record in seconds
+		TTL uint16
+		// Data is the textual representation of the resource record data
+		Data string `json:"data"`
+	}
+	// EdnsClientSubnet is the EDNS client subnet information for geolocation
+	EdnsClientSubnet string `json:"edns_client_subnet"`
+	// Comment is an optional comment field for additional information
+	Comment string
+}
+
+func (jr *Response) Hosts() []string {
+	if len(jr.Answer) == 0 {
+		return nil
+	}
+	hosts := make([]string, 0, len(jr.Answer))
+	for _, ans := range jr.Answer {
+		if ans.Type == RecordTypeA || ans.Type == RecordTypeAAAA {
+			hosts = append(hosts, ans.Data)
+		}
+	}
+	return hosts
+}
+
+var trsHTTP2ClientWithSystemDNS = http.Client{
+	Transport: &http2.Transport{
+		DialTLSContext: tls.DialTLSContextWithConfigAndSystemResolver,
+	},
+}
+
+// LookupDoH lookup uname's ip from server
+func LookupDoH(ctx context.Context, server, name string) (jr Response, err error) {
+	jr, err = LookupDoHWithType(ctx, server, name, prefertyp())
+	if err == nil {
+		return
+	}
+	if ip.IsIPv6Available {
+		jr, err = LookupDoHWithType(ctx, server, name, RecordTypeA)
+	}
+	return
+}
+
+// LookupDoHWithType ...
+func LookupDoHWithType(ctx context.Context, server, name string, typ RecordType) (jr Response, err error) {
+	sb := strings.Builder{}
+	sb.WriteString(server)
+	sb.WriteString("?name=")
+	sb.WriteString(url.QueryEscape(name))
+	if typ != RecordTypeNone {
+		sb.WriteString("&type=")
+		sb.WriteString(strconv.Itoa(int(typ)))
+	}
+	req, err := http.NewRequestWithContext(ctx, "GET", sb.String(), nil)
+	if err != nil {
+		return
+	}
+	req.Header.Add("accept", "application/dns-json")
+	resp, err := trsHTTP2ClientWithSystemDNS.Do(req)
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+	err = json.NewDecoder(resp.Body).Decode(&jr)
+	if err != nil {
+		return
+	}
+	if jr.Status != 0 {
+		err = errors.New("comment: " + jr.Comment)
+	}
+	return
+}
+
+func prefertyp() RecordType {
+	if ip.IsIPv6Available {
+		return RecordTypeAAAA
+	}
+	return RecordTypeA
+}