Generate the compressionHelper functions (#454)
* Generate the compressionHelper functions and fix compression. This was a long standing TODO: generate the compression helper functions. This now automatically picks up new names that can be used for compression. When packing add names to compression map: When packing a message we should only compress when compress is true. But whenever the compression map is not nil we should still add names to it that can be *used* for future compression. The packing inadvertently only added those names when compress would be true. * Removed unused functions
This commit is contained in:
Miek Gieben
GitHub
parent
5a15a35f5f
commit
74ec3b2433
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@ -0,0 +1,184 @@
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//+build ignore
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// compression_generate.go is meant to run with go generate. It will use
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// go/{importer,types} to track down all the RR struct types. Then for each type
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// it will look to see if there are (compressible) names, if so it will add that
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// type to compressionLenHelperType and comressionLenSearchType which "fake" the
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// compression so that Len() is fast.
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package main
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import (
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"bytes"
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"fmt"
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"go/format"
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"go/importer"
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"go/types"
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"log"
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"os"
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)
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var packageHdr = `
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// *** DO NOT MODIFY ***
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// AUTOGENERATED BY go generate from compress_generate.go
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package dns
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`
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// getTypeStruct will take a type and the package scope, and return the
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// (innermost) struct if the type is considered a RR type (currently defined as
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// those structs beginning with a RR_Header, could be redefined as implementing
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// the RR interface). The bool return value indicates if embedded structs were
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// resolved.
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func getTypeStruct(t types.Type, scope *types.Scope) (*types.Struct, bool) {
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st, ok := t.Underlying().(*types.Struct)
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if !ok {
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return nil, false
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}
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if st.Field(0).Type() == scope.Lookup("RR_Header").Type() {
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return st, false
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}
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if st.Field(0).Anonymous() {
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st, _ := getTypeStruct(st.Field(0).Type(), scope)
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return st, true
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}
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return nil, false
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}
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func main() {
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// Import and type-check the package
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pkg, err := importer.Default().Import("github.com/miekg/dns")
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fatalIfErr(err)
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scope := pkg.Scope()
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domainTypes := map[string]bool{} // Types that have a domain name in them (either comressible or not).
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cdomainTypes := map[string]bool{} // Types that have a compressible domain name in them (subset of domainType)
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for _, name := range scope.Names() {
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o := scope.Lookup(name)
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if o == nil || !o.Exported() {
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continue
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}
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st, _ := getTypeStruct(o.Type(), scope)
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if st == nil {
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continue
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}
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if name == "PrivateRR" {
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continue
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}
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if scope.Lookup("Type"+o.Name()) == nil && o.Name() != "RFC3597" {
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log.Fatalf("Constant Type%s does not exist.", o.Name())
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}
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for i := 1; i < st.NumFields(); i++ {
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if _, ok := st.Field(i).Type().(*types.Slice); ok {
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if st.Tag(i) == `dns:"domain-name"` {
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domainTypes[o.Name()] = true
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}
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if st.Tag(i) == `dns:"cdomain-name"` {
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cdomainTypes[o.Name()] = true
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domainTypes[o.Name()] = true
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}
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continue
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}
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switch {
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case st.Tag(i) == `dns:"domain-name"`:
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domainTypes[o.Name()] = true
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case st.Tag(i) == `dns:"cdomain-name"`:
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cdomainTypes[o.Name()] = true
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domainTypes[o.Name()] = true
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}
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}
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}
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b := &bytes.Buffer{}
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b.WriteString(packageHdr)
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// compressionLenHelperType - all types that have domain-name/cdomain-name can be used for compressing names
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fmt.Fprint(b, "func compressionLenHelperType(c map[string]int, r RR) {\n")
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fmt.Fprint(b, "switch x := r.(type) {\n")
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for name, _ := range domainTypes {
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o := scope.Lookup(name)
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st, _ := getTypeStruct(o.Type(), scope)
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fmt.Fprintf(b, "case *%s:\n", name)
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for i := 1; i < st.NumFields(); i++ {
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out := func(s string) { fmt.Fprintf(b, "compressionLenHelper(c, x.%s)\n", st.Field(i).Name()) }
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if _, ok := st.Field(i).Type().(*types.Slice); ok {
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switch st.Tag(i) {
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case `dns:"domain-name"`:
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fallthrough
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case `dns:"cdomain-name"`:
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// For HIP we need to slice over the elements in this slice.
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fmt.Fprintf(b, `for i := range x.%s {
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compressionLenHelper(c, x.%s[i])
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}
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`, st.Field(i).Name(), st.Field(i).Name())
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}
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continue
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}
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switch {
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case st.Tag(i) == `dns:"cdomain-name"`:
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fallthrough
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case st.Tag(i) == `dns:"domain-name"`:
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out(st.Field(i).Name())
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}
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}
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}
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fmt.Fprintln(b, "}\n}\n\n")
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// compressionLenSearchType - search cdomain-tags types for compressible names.
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fmt.Fprint(b, "func compressionLenSearchType(c map[string]int, r RR) (int, bool) {\n")
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fmt.Fprint(b, "switch x := r.(type) {\n")
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for name, _ := range cdomainTypes {
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o := scope.Lookup(name)
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st, _ := getTypeStruct(o.Type(), scope)
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fmt.Fprintf(b, "case *%s:\n", name)
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j := 1
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for i := 1; i < st.NumFields(); i++ {
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out := func(s string, j int) {
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fmt.Fprintf(b, "k%d, ok%d := compressionLenSearch(c, x.%s)\n", j, j, st.Field(i).Name())
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}
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// There are no slice types with names that can be compressed.
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switch {
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case st.Tag(i) == `dns:"cdomain-name"`:
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out(st.Field(i).Name(), j)
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j++
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}
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}
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k := "k1"
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ok := "ok1"
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for i := 2; i < j; i++ {
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k += fmt.Sprintf(" + k%d", i)
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ok += fmt.Sprintf(" && ok%d", i)
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}
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fmt.Fprintf(b, "return %s, %s\n", k, ok)
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}
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fmt.Fprintln(b, "}\nreturn 0, false\n}\n\n")
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// gofmt
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res, err := format.Source(b.Bytes())
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if err != nil {
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b.WriteTo(os.Stderr)
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log.Fatal(err)
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}
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f, err := os.Create("zcompress.go")
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fatalIfErr(err)
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defer f.Close()
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f.Write(res)
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}
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func fatalIfErr(err error) {
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if err != nil {
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log.Fatal(err)
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}
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}
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17
dns_test.go
17
dns_test.go
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@ -310,6 +310,23 @@ func TestMsgLengthCompressionMalformed(t *testing.T) {
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m.Len() // Should not crash.
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}
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func TestMsgCompressLength2(t *testing.T) {
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msg := new(Msg)
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msg.Compress = true
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msg.SetQuestion(Fqdn("bliep."), TypeANY)
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msg.Answer = append(msg.Answer, &SRV{Hdr: RR_Header{Name: "blaat.", Rrtype: 0x21, Class: 0x1, Ttl: 0x3c}, Port: 0x4c57, Target: "foo.bar."})
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msg.Extra = append(msg.Extra, &A{Hdr: RR_Header{Name: "foo.bar.", Rrtype: 0x1, Class: 0x1, Ttl: 0x3c}, A: net.IP{0xac, 0x11, 0x0, 0x3}})
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predicted := msg.Len()
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buf, err := msg.Pack()
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if err != nil {
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t.Error(err)
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}
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if predicted != len(buf) {
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t.Errorf("predicted compressed length is wrong: predicted %s (len=%d) %d, actual %d",
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msg.Question[0].Name, len(msg.Answer), predicted, len(buf))
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}
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}
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func TestToRFC3597(t *testing.T) {
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a, _ := NewRR("miek.nl. IN A 10.0.1.1")
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x := new(RFC3597)
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102
msg.go
102
msg.go
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@ -9,6 +9,7 @@
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package dns
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//go:generate go run msg_generate.go
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//go:generate go run compress_generate.go
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import (
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crand "crypto/rand"
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@ -262,7 +263,9 @@ func packDomainName(s string, msg []byte, off int, compression map[string]int, c
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bsFresh = true
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}
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// Don't try to compress '.'
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if compress && roBs[begin:] != "." {
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// We should only compress when compress it true, but we should also still pick
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// up names that can be used for *future* compression(s).
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if compression != nil && roBs[begin:] != "." {
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if p, ok := compression[roBs[begin:]]; !ok {
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// Only offsets smaller than this can be used.
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if offset < maxCompressionOffset {
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@ -892,10 +895,8 @@ func (dns *Msg) String() string {
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func (dns *Msg) Len() int {
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// We always return one more than needed.
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l := 12 // Message header is always 12 bytes
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var compression map[string]int
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if dns.Compress {
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compression = make(map[string]int)
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}
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compression := map[string]int{}
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for i := 0; i < len(dns.Question); i++ {
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l += dns.Question[i].len()
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if dns.Compress {
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@ -991,97 +992,6 @@ func compressionLenSearch(c map[string]int, s string) (int, bool) {
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return 0, false
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}
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// TODO(miek): should add all types, because the all can be *used* for compression. Autogenerate from msg_generate and put in zmsg.go
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func compressionLenHelperType(c map[string]int, r RR) {
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switch x := r.(type) {
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case *NS:
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compressionLenHelper(c, x.Ns)
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case *MX:
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compressionLenHelper(c, x.Mx)
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case *CNAME:
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compressionLenHelper(c, x.Target)
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case *PTR:
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compressionLenHelper(c, x.Ptr)
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case *SOA:
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compressionLenHelper(c, x.Ns)
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compressionLenHelper(c, x.Mbox)
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case *MB:
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compressionLenHelper(c, x.Mb)
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case *MG:
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compressionLenHelper(c, x.Mg)
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case *MR:
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compressionLenHelper(c, x.Mr)
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case *MF:
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compressionLenHelper(c, x.Mf)
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case *MD:
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compressionLenHelper(c, x.Md)
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case *RT:
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compressionLenHelper(c, x.Host)
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case *RP:
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compressionLenHelper(c, x.Mbox)
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compressionLenHelper(c, x.Txt)
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case *MINFO:
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compressionLenHelper(c, x.Rmail)
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compressionLenHelper(c, x.Email)
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case *AFSDB:
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compressionLenHelper(c, x.Hostname)
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case *SRV:
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compressionLenHelper(c, x.Target)
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case *NAPTR:
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compressionLenHelper(c, x.Replacement)
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case *RRSIG:
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compressionLenHelper(c, x.SignerName)
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case *NSEC:
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compressionLenHelper(c, x.NextDomain)
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// HIP?
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}
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}
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// Only search on compressing these types.
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func compressionLenSearchType(c map[string]int, r RR) (int, bool) {
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switch x := r.(type) {
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case *NS:
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return compressionLenSearch(c, x.Ns)
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case *MX:
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return compressionLenSearch(c, x.Mx)
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case *CNAME:
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return compressionLenSearch(c, x.Target)
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case *DNAME:
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return compressionLenSearch(c, x.Target)
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case *PTR:
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return compressionLenSearch(c, x.Ptr)
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case *SOA:
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k, ok := compressionLenSearch(c, x.Ns)
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k1, ok1 := compressionLenSearch(c, x.Mbox)
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if !ok && !ok1 {
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return 0, false
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}
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return k + k1, true
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case *MB:
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return compressionLenSearch(c, x.Mb)
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case *MG:
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return compressionLenSearch(c, x.Mg)
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case *MR:
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return compressionLenSearch(c, x.Mr)
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case *MF:
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return compressionLenSearch(c, x.Mf)
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case *MD:
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return compressionLenSearch(c, x.Md)
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case *RT:
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return compressionLenSearch(c, x.Host)
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case *MINFO:
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k, ok := compressionLenSearch(c, x.Rmail)
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k1, ok1 := compressionLenSearch(c, x.Email)
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if !ok && !ok1 {
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return 0, false
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}
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return k + k1, true
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case *AFSDB:
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return compressionLenSearch(c, x.Hostname)
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}
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return 0, false
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}
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// Copy returns a new RR which is a deep-copy of r.
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func Copy(r RR) RR { r1 := r.copy(); return r1 }
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@ -0,0 +1,119 @@
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// *** DO NOT MODIFY ***
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// AUTOGENERATED BY go generate from compress_generate.go
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package dns
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func compressionLenHelperType(c map[string]int, r RR) {
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switch x := r.(type) {
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case *AFSDB:
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compressionLenHelper(c, x.Hostname)
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case *RRSIG:
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compressionLenHelper(c, x.SignerName)
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case *MD:
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compressionLenHelper(c, x.Md)
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case *MX:
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compressionLenHelper(c, x.Mx)
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case *TALINK:
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compressionLenHelper(c, x.PreviousName)
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compressionLenHelper(c, x.NextName)
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case *MF:
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compressionLenHelper(c, x.Mf)
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case *RP:
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compressionLenHelper(c, x.Mbox)
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compressionLenHelper(c, x.Txt)
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case *RT:
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compressionLenHelper(c, x.Host)
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case *SOA:
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compressionLenHelper(c, x.Ns)
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compressionLenHelper(c, x.Mbox)
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case *NSAPPTR:
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compressionLenHelper(c, x.Ptr)
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case *CNAME:
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compressionLenHelper(c, x.Target)
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case *LP:
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compressionLenHelper(c, x.Fqdn)
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case *NSEC:
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compressionLenHelper(c, x.NextDomain)
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case *PTR:
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compressionLenHelper(c, x.Ptr)
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case *TSIG:
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compressionLenHelper(c, x.Algorithm)
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case *MG:
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compressionLenHelper(c, x.Mg)
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case *PX:
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compressionLenHelper(c, x.Map822)
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compressionLenHelper(c, x.Mapx400)
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case *SRV:
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compressionLenHelper(c, x.Target)
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case *TKEY:
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compressionLenHelper(c, x.Algorithm)
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case *MINFO:
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compressionLenHelper(c, x.Rmail)
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compressionLenHelper(c, x.Email)
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case *NAPTR:
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compressionLenHelper(c, x.Replacement)
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case *SIG:
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compressionLenHelper(c, x.SignerName)
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case *DNAME:
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compressionLenHelper(c, x.Target)
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case *HIP:
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for i := range x.RendezvousServers {
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compressionLenHelper(c, x.RendezvousServers[i])
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}
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case *KX:
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compressionLenHelper(c, x.Exchanger)
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case *MB:
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compressionLenHelper(c, x.Mb)
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case *MR:
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compressionLenHelper(c, x.Mr)
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case *NS:
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compressionLenHelper(c, x.Ns)
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}
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}
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func compressionLenSearchType(c map[string]int, r RR) (int, bool) {
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switch x := r.(type) {
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case *PTR:
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k1, ok1 := compressionLenSearch(c, x.Ptr)
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return k1, ok1
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case *RT:
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k1, ok1 := compressionLenSearch(c, x.Host)
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return k1, ok1
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case *SOA:
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k1, ok1 := compressionLenSearch(c, x.Ns)
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k2, ok2 := compressionLenSearch(c, x.Mbox)
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return k1 + k2, ok1 && ok2
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case *MB:
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k1, ok1 := compressionLenSearch(c, x.Mb)
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return k1, ok1
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case *MG:
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k1, ok1 := compressionLenSearch(c, x.Mg)
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return k1, ok1
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case *MR:
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k1, ok1 := compressionLenSearch(c, x.Mr)
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return k1, ok1
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case *NS:
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k1, ok1 := compressionLenSearch(c, x.Ns)
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return k1, ok1
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case *MINFO:
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k1, ok1 := compressionLenSearch(c, x.Rmail)
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k2, ok2 := compressionLenSearch(c, x.Email)
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return k1 + k2, ok1 && ok2
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case *MX:
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k1, ok1 := compressionLenSearch(c, x.Mx)
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return k1, ok1
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case *AFSDB:
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k1, ok1 := compressionLenSearch(c, x.Hostname)
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return k1, ok1
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case *CNAME:
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k1, ok1 := compressionLenSearch(c, x.Target)
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return k1, ok1
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case *MD:
|
||||
k1, ok1 := compressionLenSearch(c, x.Md)
|
||||
return k1, ok1
|
||||
case *MF:
|
||||
k1, ok1 := compressionLenSearch(c, x.Mf)
|
||||
return k1, ok1
|
||||
}
|
||||
return 0, false
|
||||
}
|
||||
Loading…
Reference in New Issue