initial commit

Author: jasondeutsch

go.mod

@@ -0,0 +1,5 @@
+module github.com/PragmaEngineering/pjwt
+
+go 1.14
+
+require github.com/dgrijalva/jwt-go v3.2.0+incompatible

go.sum

@@ -0,0 +1,3 @@
+github.com/dgrijalva/jwt-go v1.0.2 h1:KPldsxuKGsS2FPWsNeg9ZO18aCrGKujPoWXn2yo+KQM=
+github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
+github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=

middleware.go

@@ -0,0 +1,84 @@
+// a simple middleware for handling JWT Tokens in Pragma Go backends
+package pjwt
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/dgrijalva/jwt-go"
+)
+
+var SECRET_KEY string
+
+func init() {
+	SECRET_KEY = os.Getenv("PRAGMA_JWT_SECRET_KEY")
+	if SECRET_KEY == "" {
+		panic("JWT Secret not found in environment")
+	}
+}
+
+type Adapter func(http.Handler) http.Handler
+
+func SetAuthContext() Adapter {
+	return func(h http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			v := r.Header.Get("Authorization")
+			if !strings.Contains(v, "bearer") {
+				h.ServeHTTP(w, r)
+				return
+			}
+
+			tokenString := strings.SplitAfter(v, " ")[1]
+			token, err := jwt.Parse(tokenString, func(t *jwt.Token) (interface{}, error) {
+				if _, ok := t.Method.(*jwt.SigningMethodHMAC); !ok {
+					return nil, fmt.Errorf("Unexpected signing method: %v", t.Header["alg"])
+				}
+
+				return []byte(SECRET_KEY), nil
+			})
+			if err != nil {
+				panic(err)
+			}
+
+			if !token.Valid {
+				panic(err)
+			}
+
+			claims, ok := token.Claims.(jwt.MapClaims)
+			if !ok {
+				// TODO
+				panic("something not ok")
+			}
+
+			ctx := context.WithValue(r.Context(), "user_id", claims["user_id"])
+
+			h.ServeHTTP(w, r.WithContext(ctx))
+		})
+	}
+}
+
+// create a claims token
+func NewClaims(uid string) *jwt.Token {
+	return jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+		"user_id": uid,
+		"exp":     time.Now().Add(time.Hour * time.Duration(12)).Unix(),
+		"iat":     time.Now().Unix(),
+	})
+}
+
+// create a signed claims string
+func NewSignedString(uid string) (string, error) {
+	return NewClaims(uid).SignedString(SECRET_KEY)
+}
+
+func UserIDFromContext(ctx context.Context) (string, bool) {
+	uid, ok := ctx.Value("user_id").(string)
+	if uid == "" {
+		ok = false
+	}
+	return uid, ok
+}