Add SSO auth token implementation

Author: bluepal-prasanthi-moparthi

v2/connection/auth_jwt_impl.go

@@ -24,11 +24,19 @@ package connection
 
 import (
 	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
 	"net/http"
+	"strings"
+	"time"
 )
 
 func NewJWTAuthWrapper(username, password string) Wrapper {
-	return WrapAuthentication(func(ctx context.Context, conn Connection) (authentication Authentication, err error) {
+	var token string
+	var expiry time.Time
+
+	refresh := func(ctx context.Context, conn Connection) error {
 		url := NewUrl("_open", "auth")
 
 		var data jwtOpenResponse
@@ -40,15 +48,26 @@ func NewJWTAuthWrapper(username, password string) Wrapper {
 
 		resp, err := CallPost(ctx, conn, url, &data, j)
 		if err != nil {
-			return nil, err
+			return err
+		}
+		if resp.Code() != http.StatusOK {
+			return NewError(resp.Code(), "unexpected code")
 		}
 
-		switch resp.Code() {
-		case http.StatusOK:
-			return NewHeaderAuth("Authorization", "bearer %s", data.Token), nil
-		default:
-			return nil, NewError(resp.Code(), "unexpected code")
+		token = data.Token
+		expiry, _ = parseJWTExpiry(token) // ignore error, just fallback to immediate refresh next time
+		return nil
+	}
+
+	return WrapAuthentication(func(ctx context.Context, conn Connection) (Authentication, error) {
+		// First time fetch
+		if token == "" || time.Now().After(expiry) {
+			if err := refresh(ctx, conn); err != nil {
+				return nil, err
+			}
 		}
+
+		return NewHeaderAuth("Authorization", "bearer %s", token), nil
 	})
 }
 
@@ -59,5 +78,68 @@ type jwtOpenRequest struct {
 
 type jwtOpenResponse struct {
 	Token              string `json:"jwt"`
+	ExpiresIn          int    `json:"expires_in,omitempty"`
 	MustChangePassword bool   `json:"must_change_password,omitempty"`
 }
+
+func parseJWTExpiry(token string) (time.Time, error) {
+	parts := strings.Split(token, ".")
+	if len(parts) < 2 {
+		return time.Time{}, fmt.Errorf("invalid JWT format")
+	}
+
+	payload, err := base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	var claims struct {
+		Exp int64 `json:"exp"`
+	}
+	if err := json.Unmarshal(payload, &claims); err != nil {
+		return time.Time{}, err
+	}
+
+	return time.Unix(claims.Exp, 0), nil
+}
+
+func NewSSOAuthWrapper(initialToken string) Wrapper {
+	var token = initialToken
+	var expiry time.Time
+
+	setToken := func(newToken string) {
+		token = newToken
+		expiry, _ = parseJWTExpiry(newToken)
+	}
+
+	// If we already have a token (from an SSO login), parse expiry now
+	if token != "" {
+		setToken(token)
+	}
+
+	return WrapAuthentication(func(ctx context.Context, conn Connection) (Authentication, error) {
+		// No token yet or expired — let caller know they must login via SSO
+		if token == "" || time.Now().After(expiry) {
+			// Try a call to _open/auth just to see if server sends 307
+			url := NewUrl("_open", "auth")
+			var data jwtOpenResponse
+
+			resp, err := CallPost(ctx, conn, url, &data, nil)
+			if err != nil {
+				return nil, err
+			}
+
+			switch resp.Code() {
+			case http.StatusOK:
+				setToken(data.Token)
+			case http.StatusTemporaryRedirect:
+				loc := resp.Header("Location")
+				return nil, fmt.Errorf("SSO redirect: please authenticate via browser at %s", loc)
+			default:
+				return nil, NewError(resp.Code(), "unexpected code")
+			}
+		}
+
+		return NewHeaderAuth("Authorization", "bearer %s", token), nil
+	})
+}