github.com/adnan-c/fabric_e2e_couchdb@v0.6.1-preview.0.20170228180935-21ce6b23cf91/examples/chaincode/go/asset_management02/cert_handler.go (about)

     1  /*
     2  Copyright IBM Corp. 2016 All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  		 http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package main
    18  
    19  import (
    20  	"errors"
    21  
    22  	"github.com/hyperledger/fabric/accesscontrol/crypto/attr"
    23  	"github.com/hyperledger/fabric/accesscontrol/impl"
    24  	"github.com/hyperledger/fabric/core/chaincode/shim"
    25  )
    26  
    27  // consts associated with TCert
    28  const (
    29  	role        = "role"
    30  	contactInfo = "contactInfo"
    31  )
    32  
    33  //CertHandler provides APIs used to perform operations on incoming TCerts
    34  type certHandler struct {
    35  }
    36  
    37  // NewCertHandler creates a new reference to CertHandler
    38  func NewCertHandler() *certHandler {
    39  	return &certHandler{}
    40  }
    41  
    42  // isAuthorized checks if the transaction invoker has the appropriate role
    43  // stub: chaincodestub
    44  // requiredRole: required role; this function will return true if invoker has this role
    45  func (t *certHandler) isAuthorized(stub shim.ChaincodeStubInterface, requiredRole string) (bool, error) {
    46  	//read transaction invoker's role, and verify that is the same as the required role passed in
    47  	return impl.NewAccessControlShim(stub).VerifyAttribute(role, []byte(requiredRole))
    48  }
    49  
    50  // getContactInfo retrieves the contact info stored as an attribute in a Tcert
    51  // cert: TCert
    52  func (t *certHandler) getContactInfo(cert []byte) (string, error) {
    53  	if len(cert) == 0 {
    54  		return "", errors.New("cert is empty")
    55  	}
    56  
    57  	contactInfo, err := attr.GetValueFrom(contactInfo, cert)
    58  	if err != nil {
    59  		myLogger.Errorf("system error %v", err)
    60  		return "", errors.New("unable to find user contact information")
    61  	}
    62  
    63  	return string(contactInfo), err
    64  }
    65  
    66  // getAccountIDsFromAttribute retrieves account IDs stored in  TCert attributes
    67  // cert: TCert to read account IDs from
    68  // attributeNames: attribute names inside TCert that stores the entity's account IDs
    69  func (t *certHandler) getAccountIDsFromAttribute(cert []byte, attributeNames []string) ([]string, error) {
    70  	if cert == nil || attributeNames == nil {
    71  		return nil, errors.New("cert or accountIDs list is empty")
    72  	}
    73  
    74  	//decleare return object (slice of account IDs)
    75  	var acctIds []string
    76  
    77  	// for each attribute name, look for that attribute name inside TCert,
    78  	// the correspounding value of that attribute is the account ID
    79  	for _, attributeName := range attributeNames {
    80  		myLogger.Debugf("get value from attribute = v%", attributeName)
    81  		//get the attribute value from the corresbonding attribute name
    82  		accountID, err := attr.GetValueFrom(attributeName, cert)
    83  		if err != nil {
    84  			myLogger.Errorf("system error %v", err)
    85  			return nil, errors.New("unable to find user contact information")
    86  		}
    87  
    88  		acctIds = append(acctIds, string(accountID))
    89  	}
    90  
    91  	myLogger.Debugf("ids = %v", acctIds)
    92  	return acctIds, nil
    93  }