storage.go 4.73 KB
Newer Older
1
2
3
4
5
6
7
8
9
package irmago

import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"os"
	"strconv"

Sietse Ringers's avatar
Sietse Ringers committed
10
11
12
13
	"crypto/rand"
	"encoding/hex"
	"math/big"
	"path"
14
15

	"github.com/mhe/gabi"
16
17
18
19
20
21
22
)

// Filenames in which we store stuff
const (
	skFile         = "sk"
	attributesFile = "attrs"
	signaturesDir  = "sigs"
Sietse Ringers's avatar
Sietse Ringers committed
23
	cardemuXML     = "../cardemu.xml"
24
25
)

26
func PathExists(path string) (bool, error) {
27
28
29
30
31
32
33
34
35
36
37
38
39
40
	_, err := os.Stat(path)
	if err == nil {
		return true, nil
	}
	if os.IsNotExist(err) {
		return false, nil
	}
	return true, err
}

func (cm *CredentialManager) path(file string) string {
	return cm.storagePath + "/" + file
}

Sietse Ringers's avatar
Sietse Ringers committed
41
42
43
44
45
46
47
48
49
func (cm *CredentialManager) signatureFilename(id string, counter int) string {
	return cm.path(signaturesDir) + "/" + id + "-" + strconv.Itoa(counter)
}

// ensureStorageExists initializes the credential storage folder,
// ensuring that it is in a usable state.
// NOTE: we do not create the folder if it does not exist!
// Setting it up in a properly protected location (e.g., with automatic
// backups to iCloud/Google disabled) is the responsibility of the user.
50
func (cm *CredentialManager) ensureStorageExists() (err error) {
51
	exist, err := PathExists(cm.storagePath)
52
53
54
55
56
57
58
	if err != nil {
		return
	}
	if !exist {
		return errors.New("credential storage path does not exist")
	}

59
	exist, err = PathExists(cm.path(signaturesDir))
60
61
62
63
64
65
66
67
68
69
	if err != nil {
		return err
	}
	if !exist {
		err = os.Mkdir(cm.path(signaturesDir), 0700)
	}

	return
}

Sietse Ringers's avatar
Sietse Ringers committed
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
func (cm *CredentialManager) storeSecretKey(sk *big.Int) error {
	return ioutil.WriteFile(cm.path(skFile), sk.Bytes(), 0600)
}

// Save the filecontents at the specified path atomically:
// - first save the content in a temp file with a random filename in the same dir
// - then rename the temp file to the specified filepath, overwriting the old file
func (cm *CredentialManager) saveFile(filepath string, content []byte) (err error) {
	dir := path.Dir(filepath)

	// Read random data for filename and convert to hex
	randBytes := make([]byte, 16)
	_, err = rand.Read(randBytes)
	if err != nil {
		return
	}
	tempfilename := hex.EncodeToString(randBytes)

	// Create temp file
	err = ioutil.WriteFile(dir+"/"+tempfilename, content, 0600)
	if err != nil {
		return
	}

	// Rename, overwriting old file
	return os.Rename(dir+"/"+tempfilename, filepath)
96
97
}

98
func (cm *CredentialManager) storeSignature(cred *Credential, counter int) (err error) {
99
100
101
102
103
104
105
106
107
108
	if cred.CredentialType() == nil {
		return errors.New("cannot add unknown credential type")
	}

	credbytes, err := json.Marshal(cred.Signature)
	if err != nil {
		return err
	}

	// TODO existence check
109
	filename := cm.signatureFilename(cred.CredentialType().Identifier().String(), counter)
110
111
112
113
114
	err = ioutil.WriteFile(filename, credbytes, 0600)
	return
}

func (cm *CredentialManager) storeAttributes() (err error) {
115
	// Unfortunately, the type of cm.attributes (map[CredentialTypeIdentifier][]*AttributeList)
116
117
118
119
120
121
	// cannot be passed directly to json.Marshal(), so we copy it into a temp list.
	temp := make(map[string][]*AttributeList)
	for credid, list := range cm.attributes {
		temp[credid.String()] = list
	}
	attrbytes, err := json.Marshal(temp)
122
	if err != nil {
123
		return err
124
125
126
127
128
129
	}

	// TODO existence check
	err = ioutil.WriteFile(cm.path(attributesFile), attrbytes, 0600)
	return
}
Sietse Ringers's avatar
Sietse Ringers committed
130

131
func (cm *CredentialManager) loadSignature(id CredentialTypeIdentifier, counter int) (signature *gabi.CLSignature, err error) {
132
	path := cm.signatureFilename(id.String(), counter)
133
	exists, err := PathExists(path)
Sietse Ringers's avatar
Sietse Ringers committed
134
135
136
137
138
139
140
141
142
143
144
145
	if err != nil || !exists {
		return
	}
	bytes, err := ioutil.ReadFile(path)
	signature = new(gabi.CLSignature)
	err = json.Unmarshal(bytes, signature)
	return
}

// loadSecretKey retrieves and returns the secret key from storage, or if no secret key
// was found in storage, it generates, saves, and returns a new secret key.
func (cm *CredentialManager) loadSecretKey() (*big.Int, error) {
146
	exists, err := PathExists(cm.path(skFile))
Sietse Ringers's avatar
Sietse Ringers committed
147
148
149
150
151
152
153
154
155
156
	if err != nil {
		return nil, err
	}
	if exists {
		bytes, err := ioutil.ReadFile(cm.path(skFile))
		if err != nil {
			return nil, err
		}
		return new(big.Int).SetBytes(bytes), nil
	}
157
158
159
160
161
162
163
164
165
166

	sk, err := cm.generateSecretKey()
	if err != nil {
		return nil, err
	}
	err = cm.storeSecretKey(sk)
	if err != nil {
		return nil, err
	}
	return sk, nil
Sietse Ringers's avatar
Sietse Ringers committed
167
168
}

169
170
func (cm *CredentialManager) loadAttributes() (list map[CredentialTypeIdentifier][]*AttributeList, err error) {
	list = make(map[CredentialTypeIdentifier][]*AttributeList)
171
	temp := make(map[string][]*AttributeList)
Sietse Ringers's avatar
Sietse Ringers committed
172

173
	exists, err := PathExists(cm.path(attributesFile))
Sietse Ringers's avatar
Sietse Ringers committed
174
175
176
177
178
179
180
181
	if err != nil || !exists {
		return
	}

	bytes, err := ioutil.ReadFile(cm.path(attributesFile))
	if err != nil {
		return nil, err
	}
182
183
184
185
	err = json.Unmarshal(bytes, &temp)
	if err != nil {
		return nil, err
	}
Sietse Ringers's avatar
Sietse Ringers committed
186

187
	for credid, attrs := range temp {
188
		list[NewCredentialTypeIdentifier(credid)] = attrs
189
190
	}
	return list, nil
Sietse Ringers's avatar
Sietse Ringers committed
191
}