Add Discover

Author: emersion

README.md

@@ -1,2 +1,7 @@
 # go-openpgp-wks
-A Go library for OpenPGP Web Key Service
+
+A Go library for [OpenPGP Web Key Service](https://tools.ietf.org/html/draft-koch-openpgp-webkey-service-04).
+
+## License
+
+MIT

discovery.go

@@ -0,0 +1,54 @@
+package wks
+
+import (
+"crypto/sha1"
+"errors"
+"io"
+"net/http"
+"strings"
+
+"github.com/tv42/zbase32"
+"golang.org/x/crypto/openpgp"
+"golang.org/x/crypto/openpgp/packet"
+)
+
+func splitAddress(addr string) (local, domain string, err error) {
+parts := strings.Split(addr, "@")
+if len(parts) != 2 {
+return "", "", errors.New("wks: invalid email address")
+}
+return parts[0], parts[1], nil
+}
+
+// Discover retrieves keys associated to an email address.
+func Discover(addr string) ([]*openpgp.Entity, error) {
+local, domain, err := splitAddress(strings.ToLower(addr))
+if err != nil {
+return nil, err
+}
+
+// TODO: SRV record
+
+hashedLocal := sha1.Sum([]byte(local))
+url := "https://"+domain+"/.well-known/openpgpkey/hu/" + zbase32.EncodeToString(hashedLocal[:])
+resp, err := http.Get(url)
+if err != nil {
+return nil, err
+}
+defer resp.Body.Close()
+
+r := packet.NewReader(resp.Body)
+var entities []*openpgp.Entity
+for {
+e, err := openpgp.ReadEntity(r)
+if err == io.EOF {
+break
+} else if err != nil {
+return entities, err
+}
+
+entities = append(entities, e)
+}
+
+return entities, nil
+}

wks.go

@@ -0,0 +1,3 @@
+// wks implements OpenPGP Web Key Service, defined in
+// https://tools.ietf.org/html/draft-koch-openpgp-webkey-service-04
+package wks