Add snapshot and dump methods

Signed-off-by: p4u <p4u@dabax.net>

service/README.md

@@ -19,6 +19,7 @@ processHttp.Listen(1500, "http", pubK)
 
 ```
 curl -d '{"censusID":"GoT_Favorite","claimData":"Jon Snow"}' http://localhost:1500/addClaim
+
 {"error":false,"response":""}
 ```
 
@@ -27,6 +28,7 @@ curl -d '{"censusID":"GoT_Favorite",
 "claimData":"Jon Snow", 
 "timeStamp":"1547814675", 
 "signature":"a117c4ce12b29090884112ffe57e664f007e7ef142a1679996e2d34fd2b852fe76966e47932f1e9d3a54610d0f361383afe2d9aab096e15d136c236abb0a0d0e"}' http://localhost:1500/addClaim
+
 {"error":false,"response":""}
 ```
 
@@ -34,6 +36,7 @@ The signature message is a concatenation of the following strings: `censusID, cl
 
 ```
 curl -d '{"censusID":"GoT_Favorite","claimData":"Tyrion"}' http://localhost:1500/addClaim
+
 {"error":false,"response":""}
 ```
 
@@ -41,6 +44,7 @@ curl -d '{"censusID":"GoT_Favorite","claimData":"Tyrion"}' http://localhost:1500
 
 ```
 curl -d '{"censusID":"GoT_Favorite","claimData":"Jon Snow"}' http://localhost:1500/genProof
+
 {"error":false,"response":"0x000000000000000000000000000000000000000000000000000000000000000352f3ca2aaf635ec2ae4452f6a65be7bca72678287a8bb08ad4babfcccd76c2fef1aac7675261bf6d12c746fb7907beea6d1f1635af93ba931eec0c6a747ecc37"}
 ```
 
@@ -48,10 +52,35 @@ curl -d '{"censusID":"GoT_Favorite","claimData":"Jon Snow"}' http://localhost:15
 
 ```
 curl -d '{"censusID":"GoT_Favorite","claimData":"Jon Snow", "proofData": "0x0000000000000000000000000000000000000000000000000000000000000000000123"}' http://localhost:1500/checkProof
+
 {"error":false,"response":"invalid"}
 ```
 
 ```
 curl -d '{"censusID":"GoT_Favorite","claimData":"Jon Snow", "proofData": "0x000000000000000000000000000000000000000000000000000000000000000352f3ca2aaf635ec2ae4452f6a65be7bca72678287a8bb08ad4babfcccd76c2fef1aac7675261bf6d12c746fb7907beea6d1f1635af93ba931eec0c6a747ecc37"}' http://localhost:1500/checkProof
+
 {"error":false,"response":"valid"}
 ```
+
+#### make snapshot
+
+Snapshots are static and unmutable copies of a specific census
+
+```
+curl -d '{"censusID":"GoT_Favorite"}' http://localhost:1500/snapshot
+
+{"error":false,"response":"snaphost.GoT_Favorite.1548169813"}
+```
+
+The name for the snapshot is "snaphost.GoT_Favorite.1548169813"
+
+Now you can use it as censusID for checkProof, genProof and dump. But addClaim is not longer allowed.
+
+#### dump
+
+Dump contents of a specific censusID (values)
+
+```
+curl -d '{"censusID":"GoT_Favorite"}' http://localhost:1500/dump
+{"error":false,"response":"[\"Tyrion\",\"Jon Snow\"]"}
+```

service/processHttp.go

@@ -107,7 +107,6 @@ func claimHandler(w http.ResponseWriter, req *http.Request, op string) {
 
 	if op == "add" {
 		msg := fmt.Sprintf("%s%s%s", c.CensusID, c.ClaimData, c.TimeStamp)
-		log.Printf("Msg to check: %s", msg)
 		if auth := checkAuth(c.TimeStamp, c.Signature, msg); auth {
 			err = T.AddClaim([]byte(c.ClaimData))
 		} else {
@@ -124,6 +123,38 @@ func claimHandler(w http.ResponseWriter, req *http.Request, op string) {
 		resp.Response = T.GetRoot()
 	}
 
+	if op == "dump" {
+		values, err := T.Dump()
+		if err != nil {
+			resp.Error = true
+			resp.Response = fmt.Sprint(err)
+		} else {
+			jValues, err := json.Marshal(values)
+			if err != nil {
+				resp.Error = true
+				resp.Response = fmt.Sprint(err)
+			} else {
+				resp.Response = string(jValues)
+			}
+		}
+	}
+
+	if op == "snapshot" {
+		msg := fmt.Sprintf("%s%s%s", c.CensusID, c.ClaimData, c.TimeStamp)
+		if auth := checkAuth(c.TimeStamp, c.Signature, msg); auth {
+			snapshotNamespace, err := T.Snapshot()
+			if err != nil {
+				resp.Error = true
+				resp.Response = fmt.Sprint(err)
+			} else {
+				resp.Response = snapshotNamespace
+			}
+		} else {
+			resp.Error = true
+			resp.Response = "invalid authentication"
+		}
+	}
+
 	if op == "check" {
 		if len(c.ProofData) < 1 {
 			resp.Error = true
@@ -172,6 +203,12 @@ func Listen(port int, proto string, pubKey string) {
 	http.HandleFunc("/getRoot", func(w http.ResponseWriter, r *http.Request) {
 		claimHandler(w, r, "root")
 	})
+	http.HandleFunc("/snapshot", func(w http.ResponseWriter, r *http.Request) {
+		claimHandler(w, r, "snapshot")
+	})
+	http.HandleFunc("/dump", func(w http.ResponseWriter, r *http.Request) {
+		claimHandler(w, r, "dump")
+	})
 
 	if len(pubKey) > 1 {
 		log.Printf("Enabling signature authentication with %s\n", pubKey)

tree/README.md

@@ -19,4 +19,4 @@ Example of usage:
 
 #### To-Do
 
-+ Add export/import methods
+Avoid duplicates on dump/snapshot

tree/tree.go

@@ -1,17 +1,23 @@
 package tree
 
 import (
+	"errors"
+	"fmt"
+	"os/user"
+	"strings"
+	"time"
+
+	common3 "github.com/vocdoni/go-iden3/common"
+	mkcore "github.com/vocdoni/go-iden3/core"
 	"github.com/vocdoni/go-iden3/db"
 	"github.com/vocdoni/go-iden3/merkletree"
-  mkcore "github.com/vocdoni/go-iden3/core"
-  common3 "github.com/vocdoni/go-iden3/common"
-  "os/user"
 )
 
 type Tree struct {
 	Namespace string
 	Storage   string
 	Tree      *merkletree.MerkleTree
+	DbStorage *db.LevelDbStorage
 }
 
 func (t *Tree) Init() error {
@@ -19,7 +25,9 @@ func (t *Tree) Init() error {
 		usr, err := user.Current()
 		if err == nil {
 			t.Storage = usr.HomeDir + "/.dvote/Tree"
-    } else { t.Storage = "./dvoteTree" }
+		} else {
+			t.Storage = "./dvoteTree"
+		}
 	}
 	mtdb, err := db.NewLevelDbStorage(t.Storage, false)
 	if err != nil {
@@ -29,6 +37,7 @@ func (t *Tree) Init() error {
 	if err != nil {
 		return err
 	}
+	t.DbStorage = mtdb
 	t.Tree = mt
 	return nil
 }
@@ -38,6 +47,10 @@ func (t *Tree) Close() {
 }
 
 func (t *Tree) AddClaim(data []byte) error {
+	isSnapshot := strings.Contains(t.Namespace, "snapshot.")
+	if isSnapshot {
+		return errors.New("No new claims can be added to a Snapshot")
+	}
 	claim := mkcore.NewGenericClaim(t.Namespace, "default", data, nil)
 	return t.Tree.Add(claim)
 }
@@ -61,6 +74,45 @@ func (t *Tree) CheckProof(data []byte, mpHex string) (bool, error) {
 	return merkletree.CheckProof(t.Tree.Root(), mp, claim.Hi(), claim.Ht(), t.Tree.NumLevels()), nil
 }
 
-func (t *Tree) GetRoot() (string) {
+func (t *Tree) GetRoot() string {
 	return t.Tree.Root().Hex()
 }
+
+/* Dump, Export and Snapshot functions are a bit tricky.
+   Since go-iden3 does not provide the necessary tools. Low level operations must be performed.
+   Once go-iden3 API is mature enough, these functions must be adapted.
+
+   To explore: Values are stored twice in the BD?
+*/
+func (t *Tree) Dump() ([]string, error) {
+	var response []string
+	substorage := t.DbStorage.WithPrefix([]byte(t.Namespace))
+	nsHash := merkletree.HashBytes([]byte(t.Namespace))
+	substorage.Iterate(func(key, value []byte) {
+		nsValue := value[5:37]
+		if fmt.Sprint(nsHash) == fmt.Sprint(nsValue) {
+			response = append(response, string(value[69:]))
+		}
+	})
+	return response, nil
+}
+
+func (t *Tree) Snapshot() (string, error) {
+	substorage := t.DbStorage.WithPrefix([]byte(t.Namespace))
+	nsHash := merkletree.HashBytes([]byte(t.Namespace))
+	currentTime := int64(time.Now().Unix())
+	snapshotNamespace := fmt.Sprintf("snapshot.%s.%d", t.Namespace, currentTime)
+	substorage.Iterate(func(key, value []byte) {
+		nsValue := value[5:37]
+		if fmt.Sprint(nsHash) == fmt.Sprint(nsValue) {
+			data := value[69:]
+			//fmt.Printf(" Adding value: %s\n", data)
+			claim := mkcore.NewGenericClaim(snapshotNamespace, "default", data, nil)
+			err := t.Tree.Add(claim)
+			if err != nil {
+				fmt.Println(err)
+			}
+		}
+	})
+	return snapshotNamespace, nil
+}