72 lines
3.0 KiB
Go
72 lines
3.0 KiB
Go
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// Copyright 2018 by David A. Golden. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package scram
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import (
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"crypto/sha1"
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"crypto/sha256"
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"crypto/sha512"
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"fmt"
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"hash"
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"github.com/xdg-go/stringprep"
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)
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// HashGeneratorFcn abstracts a factory function that returns a hash.Hash
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// value to be used for SCRAM operations. Generally, one would use the
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// provided package variables, `scram.SHA1` and `scram.SHA256`, for the most
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// common forms of SCRAM.
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type HashGeneratorFcn func() hash.Hash
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// SHA1 is a function that returns a crypto/sha1 hasher and should be used to
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// create Client objects configured for SHA-1 hashing.
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var SHA1 HashGeneratorFcn = func() hash.Hash { return sha1.New() }
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// SHA256 is a function that returns a crypto/sha256 hasher and should be used
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// to create Client objects configured for SHA-256 hashing.
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var SHA256 HashGeneratorFcn = func() hash.Hash { return sha256.New() }
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// SHA512 is a function that returns a crypto/sha512 hasher and should be used
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// to create Client objects configured for SHA-512 hashing.
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var SHA512 HashGeneratorFcn = func() hash.Hash { return sha512.New() }
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// NewClient constructs a SCRAM client component based on a given hash.Hash
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// factory receiver. This constructor will normalize the username, password
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// and authzID via the SASLprep algorithm, as recommended by RFC-5802. If
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// SASLprep fails, the method returns an error.
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func (f HashGeneratorFcn) NewClient(username, password, authzID string) (*Client, error) {
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var userprep, passprep, authprep string
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var err error
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if userprep, err = stringprep.SASLprep.Prepare(username); err != nil {
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return nil, fmt.Errorf("Error SASLprepping username '%s': %v", username, err)
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}
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if passprep, err = stringprep.SASLprep.Prepare(password); err != nil {
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return nil, fmt.Errorf("Error SASLprepping password '%s': %v", password, err)
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}
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if authprep, err = stringprep.SASLprep.Prepare(authzID); err != nil {
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return nil, fmt.Errorf("Error SASLprepping authzID '%s': %v", authzID, err)
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}
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return newClient(userprep, passprep, authprep, f), nil
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}
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// NewClientUnprepped acts like NewClient, except none of the arguments will
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// be normalized via SASLprep. This is not generally recommended, but is
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// provided for users that may have custom normalization needs.
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func (f HashGeneratorFcn) NewClientUnprepped(username, password, authzID string) (*Client, error) {
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return newClient(username, password, authzID, f), nil
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}
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// NewServer constructs a SCRAM server component based on a given hash.Hash
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// factory receiver. To be maximally generic, it uses dependency injection to
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// handle credential lookup, which is the process of turning a username string
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// into a struct with stored credentials for authentication.
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func (f HashGeneratorFcn) NewServer(cl CredentialLookup) (*Server, error) {
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return newServer(cl, f)
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}
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