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//+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 == "RFC3597" {
continue
}
if name == "OPT" || name == "ANY" || name == "IXFR" || name == "AXFR" {
continue
}
namedTypes = append(namedTypes, o.Name())
}
b := &bytes.Buffer{}
b.WriteString(packageHdr)
// Generate the giant switch that calls the correct function for each type.
fmt.Fprint(b, "// isDuplicateRdata calls the rdata specific functions\n")
fmt.Fprint(b, "func isDuplicateRdata(r1, r2 RR) bool {\n")
fmt.Fprint(b, "switch r1.Header().Rrtype {\n")
for _, name := range namedTypes {
o := scope.Lookup(name)
_, isEmbedded := getTypeStruct(o.Type(), scope)
if isEmbedded {
continue
}
fmt.Fprintf(b, "case Type%s:\nreturn isDuplicate%s(r1.(*%s), r2.(*%s))\n", name, name, name, name)
}
fmt.Fprintf(b, "}\nreturn false\n}\n")
// 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 isDuplicate%s(r1, r2 *%s) bool {\n", name, name)
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 || st.Tag(i) == `dns:"a"` || st.Tag(i) == `dns:"aaaa"` {
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 !isDulicateName(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:"cdomain-name"`, `dns:"domain-name"`:
o2("if !isDulicateName(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)
}
}
|
