moving a bunch of packages under pkg (#124)

* moving a bunch of packages under pkg

* fix gen

* fix tst

* oops

* fix test fo real

* parse mx/a

pkg/spflib/parse.go

@@ -0,0 +1,107 @@
+package spflib
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/StackExchange/dnscontrol/pkg/dnsresolver"
+)
+
+type SPFRecord struct {
+	Lookups int
+	Parts   []*SPFPart
+}
+
+type SPFPart struct {
+	Text          string
+	Lookups       int
+	IncludeRecord *SPFRecord
+}
+
+func Lookup(target string, dnsres dnsresolver.DnsResolver) (string, error) {
+	txts, err := dnsres.GetTxt(target)
+	if err != nil {
+		return "", err
+	}
+	var result []string
+	for _, txt := range txts {
+		if strings.HasPrefix(txt, "v=spf1 ") {
+			result = append(result, txt)
+		}
+	}
+	if len(result) == 0 {
+		return "", fmt.Errorf("%s has no spf TXT records", target)
+	}
+	if len(result) != 1 {
+		return "", fmt.Errorf("%s has multiple spf TXT records", target)
+	}
+	return result[0], nil
+}
+
+var qualifiers = map[byte]bool{
+	'?': true,
+	'~': true,
+	'-': true,
+	'+': true,
+}
+
+func Parse(text string, dnsres dnsresolver.DnsResolver) (*SPFRecord, error) {
+	if !strings.HasPrefix(text, "v=spf1 ") {
+		return nil, fmt.Errorf("Not an spf record")
+	}
+	parts := strings.Split(text, " ")
+	rec := &SPFRecord{}
+	for _, part := range parts[1:] {
+		p := &SPFPart{Text: part}
+		if qualifiers[part[0]] {
+			part = part[1:]
+		}
+		rec.Parts = append(rec.Parts, p)
+		if part == "all" {
+			//all. nothing else matters.
+			break
+		} else if strings.HasPrefix(part, "a") || strings.HasPrefix(part, "mx") {
+			rec.Lookups++
+			p.Lookups = 1
+		} else if strings.HasPrefix(part, "ip4:") || strings.HasPrefix(part, "ip6:") {
+			//ip address, 0 lookups
+			continue
+		} else if strings.HasPrefix(part, "include:") {
+			rec.Lookups++
+			includeTarget := strings.TrimPrefix(part, "include:")
+			subRecord, err := Lookup(includeTarget, dnsres)
+			if err != nil {
+				return nil, err
+			}
+			p.IncludeRecord, err = Parse(subRecord, dnsres)
+			if err != nil {
+				return nil, fmt.Errorf("In included spf: %s", err)
+			}
+			rec.Lookups += p.IncludeRecord.Lookups
+			p.Lookups = p.IncludeRecord.Lookups + 1
+		} else {
+			return nil, fmt.Errorf("Unsupported spf part %s", part)
+		}
+
+	}
+	return rec, nil
+}
+
+// DumpSPF outputs an SPFRecord and related data for debugging purposes.
+func DumpSPF(rec *SPFRecord, indent string) {
+	fmt.Printf("%sTotal Lookups: %d\n", indent, rec.Lookups)
+	fmt.Print(indent + "v=spf1")
+	for _, p := range rec.Parts {
+		fmt.Print(" " + p.Text)
+	}
+	fmt.Println()
+	indent += "\t"
+	for _, p := range rec.Parts {
+		if p.Lookups > 0 {
+			fmt.Println(indent + p.Text)
+		}
+		if p.IncludeRecord != nil {
+			DumpSPF(p.IncludeRecord, indent+"\t")
+		}
+	}
+}