1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
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
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
package main
import (
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"database/sql"
"encoding/base64"
"fmt"
"net/http"
"strings"
"time"
)
const (
BasicAuthPrompt = `Basic realm="auth for monfront"`
SessionCookie = `session`
UserAnonymous = `anonymous`
)
type (
// Authenticator is a middleware taking a context and authenticating
// the user.
Authenticator struct {
db *sql.DB
Mode string
Token []byte
AllowAnonymous bool
Header string
List [][]string
ClientCA string
sessions map[string]*session // maps a session key to a user
}
session struct {
user string
t time.Time
}
)
// Handler returns the handler for the authentication configuration.
func (a *Authenticator) Handler() (func(*Context) error, error) {
switch a.Mode {
case "none":
return func(_ *Context) error { return nil }, nil
case "header":
if a.Header == "" {
return nil, fmt.Errorf("authentication mode is 'header' but no header was provided")
}
return func(c *Context) error {
if user := c.r.Header.Get(a.Header); user == "" {
if a.AllowAnonymous {
c.User = UserAnonymous
return nil
}
return a.Unauthorized(c)
} else {
c.User = user
}
return nil
}, nil
case "list":
return func(c *Context) error {
user, pass, ok := c.r.BasicAuth()
if !ok || user == "" || pass == "" {
if a.AllowAnonymous {
c.User = UserAnonymous
return nil
}
c.w.Header().Set("WWW-Authenticate", BasicAuthPrompt)
return a.Unauthorized(c)
}
var found string
for _, entry := range a.List {
if entry[0] == user {
found = entry[1]
}
}
if found == "" {
c.w.Header().Set("WWW-Authenticate", BasicAuthPrompt)
return a.Unauthorized(c)
}
p := pwHash{}
if err := p.Parse(found); err != nil {
c.log.Warn("could not parse hash for user", "user", user, "error", err)
return a.Unauthorized(c)
}
if ok, err := p.compare(pass); err != nil {
c.w.Header().Set("WWW-Authenticate", BasicAuthPrompt)
return a.Unauthorized(c)
} else if !ok {
c.w.Header().Set("WWW-Authenticate", BasicAuthPrompt)
return a.Unauthorized(c)
}
c.User = user
return nil
}, nil
case "db":
return func(c *Context) error {
sessCookie := c.GetCookieVal(SessionCookie)
if sessCookie != "" {
ses := a.getSession(sessCookie)
if ses != "" {
// TODO fix time limit to make it variable
c.SetCookie(SessionCookie, sessCookie, time.Now().Add(2*time.Hour))
c.User = ses
return nil
}
}
return fmt.Errorf("NOT YET IMPLEMENTED")
}, fmt.Errorf("NOT YET IMPLEMENTED")
case "cert":
return func(c *Context) error {
return fmt.Errorf("NOT YET IMPLEMENTED")
}, fmt.Errorf("NOT YET IMPLEMENTED")
default:
return nil, fmt.Errorf("unknown mode '%s' for authentication", a.Mode)
}
return nil, fmt.Errorf("could not create authenticator")
}
func (a *Authenticator) Unauthorized(c *Context) error {
c.w.WriteHeader(http.StatusUnauthorized)
fmt.Fprintf(c.w, "unauthorized\n")
return fmt.Errorf("no authentication")
}
// creates a session for a user
func (a *Authenticator) createSession(user string) (string, error) {
raw := make([]byte, 32)
if _, err := rand.Read(raw); err != nil {
return "", fmt.Errorf("could not generate new session key")
}
res := a.mac(raw)
ses := fmt.Sprintf(
"%s-%s",
base64.StdEncoding.EncodeToString(raw),
base64.StdEncoding.EncodeToString(res),
)
a.sessions[ses] = &session{user: user, t: time.Now()}
return ses, nil
}
func (a *Authenticator) mac(input []byte) []byte {
mac := hmac.New(sha256.New, a.Token)
mac.Write(input)
return mac.Sum(nil)
}
// getSession returns the username of the current session.
func (a *Authenticator) getSession(session string) string {
if session == "" {
return ""
}
parts := strings.Split(session, "-")
if len(parts) != 2 {
return ""
}
msg, err := base64.StdEncoding.DecodeString(parts[0])
if err != nil {
return ""
}
mac, err := base64.StdEncoding.DecodeString(parts[1])
if err != nil {
return ""
}
verify := a.mac(msg)
if !hmac.Equal(mac, verify) {
return ""
}
if ses, found := a.sessions[session]; found {
// TODO make timeout a config option
if time.Now().Sub(ses.t) < 8*time.Hour {
delete(a.sessions, session)
return ""
}
ses.t = time.Now()
return ses.user
}
return ""
}
|
