Enable constructs to work with Auth Info context header

auth/const.go

@@ -0,0 +1,17 @@
+// Copyright © 2025 Prabhjot Singh Sethi, All Rights reserved
+// Author: Prabhjot Singh Sethi <prabhjot.sethi@gmail.com>
+
+package auth
+
+const (
+	// Internal Auth Context Header, carries information of the
+	// client that has been authenticated.
+	// Where content itself will be of usual string format, which
+	// is obtained by json marshaling of struct AuthInfo followed
+	// by base64 encoding of the json marshaled content.
+	//
+	// This is usually Added by Auth Gateway, if present it
+	// indicates that authentication is successfully performed
+	// by Auth Gateway.
+	httpClientAuthContext = "Auth-Info"
+)

auth/user.go

@@ -3,6 +3,14 @@
 
 package auth
 
+import (
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+
+	"github.com/Prabhjot-Sethi/core/errors"
+)
+
 // Auth construct obtained as part of the auth action being performed
 // while processing a request, this is json tagged to allow passing
 // the inforamtion internally in the system between the microservices
@@ -14,3 +22,40 @@ type AuthInfo struct {
 	FullName  string `json:"name,omitempty"`
 	SessionID string `json:"sid"`
 }
+
+// Sets Auth Info Header in the provided Http Request typically will
+// be used only by the entity that has performed that authentication
+// on the given http request already and has the relevant Auth Info
+// Context.
+func SetAuthInfoHeader(r http.Request, info *AuthInfo) error {
+	b, err := json.Marshal(info)
+	if err != nil {
+		return errors.Wrapf(errors.InvalidArgument, "failed to generate user info: %s", err)
+	}
+	val := base64.RawURLEncoding.EncodeToString(b)
+	r.Header.Set(httpClientAuthContext, val)
+	return nil
+}
+
+// gets Auth Info Header available in the Http Request
+func GetAuthInfoHeader(r http.Request) (*AuthInfo, error) {
+	val := r.Header.Get(httpClientAuthContext)
+	if val == "" {
+		return nil, errors.Wrapf(errors.NotFound, "Auth info not available in the http request")
+	}
+	b, err := base64.RawURLEncoding.DecodeString(val)
+	if err != nil {
+		return nil, errors.Wrapf(errors.InvalidArgument, "invalid user info received: %s", err)
+	}
+	info := &AuthInfo{}
+	err = json.Unmarshal(b, info)
+	if err != nil {
+		return nil, errors.Wrapf(errors.InvalidArgument, "failed to get user info from header: %s", err)
+	}
+	return info, nil
+}
+
+// delete the Auth info header from the given HTTP request
+func DeleteAuthInfoHeader(r http.Request) {
+	r.Header.Del(httpClientAuthContext)
+}