--- /dev/null
+//+build ignore
+
+// types_generate.go is meant to run with go generate. It will use
+// go/{importer,types} to track down all the RR struct types. Then for each type
+// it will generate conversion tables (TypeToRR and TypeToString) and banal
+// methods (len, Header, copy) based on the struct tags. The generated source is
+// written to ztypes.go, and is meant to be checked into git.
+package main
+
+import (
+ "bytes"
+ "fmt"
+ "go/format"
+ "go/importer"
+ "go/types"
+ "log"
+ "os"
+)
+
+var packageHdr = `
+// Code generated by "go run duplicate_generate.go"; DO NOT EDIT.
+
+package dns
+
+`
+
+func getTypeStruct(t types.Type, scope *types.Scope) (*types.Struct, bool) {
+ st, ok := t.Underlying().(*types.Struct)
+ if !ok {
+ return nil, false
+ }
+ if st.Field(0).Type() == scope.Lookup("RR_Header").Type() {
+ return st, false
+ }
+ if st.Field(0).Anonymous() {
+ st, _ := getTypeStruct(st.Field(0).Type(), scope)
+ return st, true
+ }
+ return nil, false
+}
+
+func main() {
+ // Import and type-check the package
+ pkg, err := importer.Default().Import("github.com/miekg/dns")
+ fatalIfErr(err)
+ scope := pkg.Scope()
+
+ // Collect actual types (*X)
+ var namedTypes []string
+ for _, name := range scope.Names() {
+ o := scope.Lookup(name)
+ if o == nil || !o.Exported() {
+ continue
+ }
+
+ if st, _ := getTypeStruct(o.Type(), scope); st == nil {
+ continue
+ }
+
+ if name == "PrivateRR" || name == "OPT" {
+ continue
+ }
+
+ namedTypes = append(namedTypes, o.Name())
+ }
+
+ b := &bytes.Buffer{}
+ b.WriteString(packageHdr)
+
+ // Generate the duplicate check for each type.
+ fmt.Fprint(b, "// isDuplicate() functions\n\n")
+ for _, name := range namedTypes {
+
+ o := scope.Lookup(name)
+ st, isEmbedded := getTypeStruct(o.Type(), scope)
+ if isEmbedded {
+ continue
+ }
+ fmt.Fprintf(b, "func (r1 *%s) isDuplicate(_r2 RR) bool {\n", name)
+ fmt.Fprintf(b, "r2, ok := _r2.(*%s)\n", name)
+ fmt.Fprint(b, "if !ok { return false }\n")
+ fmt.Fprint(b, "_ = r2\n")
+ for i := 1; i < st.NumFields(); i++ {
+ field := st.Field(i).Name()
+ o2 := func(s string) { fmt.Fprintf(b, s+"\n", field, field) }
+ o3 := func(s string) { fmt.Fprintf(b, s+"\n", field, field, field) }
+
+ // For some reason, a and aaaa don't pop up as *types.Slice here (mostly like because the are
+ // *indirectly* defined as a slice in the net package).
+ if _, ok := st.Field(i).Type().(*types.Slice); ok {
+ o2("if len(r1.%s) != len(r2.%s) {\nreturn false\n}")
+
+ if st.Tag(i) == `dns:"cdomain-name"` || st.Tag(i) == `dns:"domain-name"` {
+ o3(`for i := 0; i < len(r1.%s); i++ {
+ if !isDuplicateName(r1.%s[i], r2.%s[i]) {
+ return false
+ }
+ }`)
+
+ continue
+ }
+
+ o3(`for i := 0; i < len(r1.%s); i++ {
+ if r1.%s[i] != r2.%s[i] {
+ return false
+ }
+ }`)
+
+ continue
+ }
+
+ switch st.Tag(i) {
+ case `dns:"-"`:
+ // ignored
+ case `dns:"a"`, `dns:"aaaa"`:
+ o2("if !r1.%s.Equal(r2.%s) {\nreturn false\n}")
+ case `dns:"cdomain-name"`, `dns:"domain-name"`:
+ o2("if !isDuplicateName(r1.%s, r2.%s) {\nreturn false\n}")
+ default:
+ o2("if r1.%s != r2.%s {\nreturn false\n}")
+ }
+ }
+ fmt.Fprintf(b, "return true\n}\n\n")
+ }
+
+ // gofmt
+ res, err := format.Source(b.Bytes())
+ if err != nil {
+ b.WriteTo(os.Stderr)
+ log.Fatal(err)
+ }
+
+ // write result
+ f, err := os.Create("zduplicate.go")
+ fatalIfErr(err)
+ defer f.Close()
+ f.Write(res)
+}
+
+func fatalIfErr(err error) {
+ if err != nil {
+ log.Fatal(err)
+ }
+}
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