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1 | ;;; GNU Guix --- Functional package management for GNU |
2 | ;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org> | |
3 | ;;; | |
4 | ;;; This file is part of GNU Guix. | |
5 | ;;; | |
6 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
7 | ;;; under the terms of the GNU General Public License as published by | |
8 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
9 | ;;; your option) any later version. | |
10 | ;;; | |
11 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
12 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ;;; GNU General Public License for more details. | |
15 | ;;; | |
16 | ;;; You should have received a copy of the GNU General Public License | |
17 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
18 | ||
19 | (define-module (gnu system nss) | |
20 | #:use-module (rnrs enums) | |
21 | #:use-module (guix records) | |
22 | #:use-module (srfi srfi-9) | |
23 | #:use-module (ice-9 match) | |
24 | #:export (name-service-switch? | |
25 | name-service-switch | |
26 | name-service? | |
27 | name-service | |
28 | ||
29 | lookup-specification | |
30 | ||
31 | %default-nss | |
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32 | %mdns-host-lookup-nss |
33 | ||
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34 | %files |
35 | %compat | |
36 | %dns | |
37 | ||
38 | name-service-switch->string)) | |
39 | ||
40 | ;;; Commentary: | |
41 | ;;; | |
42 | ;;; Bindings for libc's name service switch (NSS) configuration. | |
43 | ;;; | |
44 | ;;; Code: | |
45 | ||
46 | (define-record-type* <name-service> name-service | |
47 | make-name-service | |
48 | name-service? | |
49 | (name name-service-name) | |
50 | (reaction name-service-reaction | |
51 | (default (lookup-specification)))) | |
52 | ||
53 | ;; Lookup specification (info "(libc) Actions in the NSS Configuration"). | |
54 | ||
55 | (define-enumeration lookup-action | |
56 | (return continue) | |
57 | make-lookup-action) | |
58 | ||
59 | (define-enumeration lookup-status | |
60 | (success | |
61 | not-found | |
62 | unavailable | |
63 | try-again) | |
64 | make-lookup-status) | |
65 | ||
66 | (define-record-type <lookup-status-negation> | |
67 | (lookup-status-negation status) | |
68 | lookup-status-negation? | |
69 | (status lookup-status-negation-status)) | |
70 | ||
71 | (define-record-type <lookup-reaction> | |
72 | (make-lookup-reaction status action) | |
73 | lookup-reaction? | |
74 | (status lookup-reaction-status) | |
75 | (action lookup-reaction-action)) | |
76 | ||
77 | (define-syntax lookup-reaction | |
78 | (syntax-rules (not =>) | |
79 | ((_ ((not status) => action)) | |
80 | (make-lookup-reaction (lookup-status-negation (lookup-status status)) | |
81 | (lookup-action action))) | |
82 | ((_ (status => action)) | |
83 | (make-lookup-reaction (lookup-status status) | |
84 | (lookup-action action))))) | |
85 | ||
86 | (define-syntax-rule (lookup-specification reaction ...) | |
87 | "Return an NSS lookup specification." | |
88 | (list (lookup-reaction reaction) ...)) | |
89 | ||
90 | \f | |
91 | ;;; | |
92 | ;;; Common name services and default NSS configuration. | |
93 | ;;; | |
94 | ||
95 | (define %compat | |
96 | (name-service | |
97 | (name "compat") | |
98 | (reaction (lookup-specification (not-found => return))))) | |
99 | ||
100 | (define %files | |
101 | (name-service (name "files"))) | |
102 | ||
103 | (define %dns | |
104 | ;; DNS is supposed to be authoritative, so unless it's unavailable, return | |
105 | ;; what it finds. | |
106 | (name-service | |
107 | (name "dns") | |
108 | (reaction (lookup-specification ((not unavailable) => return))))) | |
109 | ||
110 | ;; The NSS. We list all the databases here because that allows us to | |
111 | ;; statically ensure that the user's configuration refers to existing | |
112 | ;; databases. See libc/nss/databases.def for the list of databases. Default | |
113 | ;; values obtained by looking for "DEFAULT_CONFIG" in libc/nss/*.c. | |
114 | ;; | |
115 | ;; Although libc places 'dns' before 'files' in the default configurations of | |
116 | ;; the 'hosts' and 'networks' databases, we choose to put 'files' before 'dns' | |
117 | ;; by default, so that users can override host/address mappings in /etc/hosts | |
118 | ;; and bypass DNS to improve their privacy and escape NSA's MORECOWBELL. | |
119 | (define-record-type* <name-service-switch> name-service-switch | |
120 | make-name-service-switch | |
121 | name-service-switch? | |
122 | (aliases name-service-switch-aliases | |
123 | (default '())) | |
124 | (ethers name-service-switch-ethers | |
125 | (default '())) | |
126 | (group name-service-switch-group | |
127 | (default (list %compat %files))) | |
128 | (gshadow name-service-switch-gshadow | |
129 | (default '())) | |
130 | (hosts name-service-switch-hosts | |
131 | (default (list %files %dns))) | |
132 | (initgroups name-service-switch-initgroups | |
133 | (default '())) | |
134 | (netgroup name-service-switch-netgroup | |
135 | (default '())) | |
136 | (networks name-service-switch-networks | |
137 | (default (list %files %dns))) | |
138 | (password name-service-switch-password | |
139 | (default (list %compat %files))) | |
140 | (public-key name-service-switch-public-key | |
141 | (default '())) | |
142 | (rpc name-service-switch-rpc | |
143 | (default '())) | |
144 | (services name-service-switch-services | |
145 | (default '())) | |
146 | (shadow name-service-switch-shadow | |
147 | (default (list %compat %files)))) | |
148 | ||
149 | (define %default-nss | |
150 | ;; Default NSS configuration. | |
151 | (name-service-switch)) | |
152 | ||
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153 | (define %mdns-host-lookup-nss |
154 | (name-service-switch | |
155 | (hosts (list %files ;first, check /etc/hosts | |
156 | ||
157 | ;; If the above did not succeed, try with 'mdns_minimal'. | |
158 | (name-service | |
159 | (name "mdns_minimal") | |
160 | ||
161 | ;; 'mdns_minimal' is authoritative for '.local'. When it | |
162 | ;; returns "not found", no need to try the next methods. | |
163 | (reaction (lookup-specification | |
164 | (not-found => return)))) | |
165 | ||
166 | ;; Then fall back to DNS. | |
167 | (name-service | |
168 | (name "dns")) | |
169 | ||
170 | ;; Finally, try with the "full" 'mdns'. | |
171 | (name-service | |
172 | (name "mdns")))))) | |
173 | ||
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174 | \f |
175 | ;;; | |
176 | ;;; Serialization. | |
177 | ;;; | |
178 | ||
179 | (define (lookup-status->string status) | |
180 | (match status | |
181 | ('success "SUCCESS") | |
182 | ('not-found "NOTFOUND") | |
183 | ('unavailable "UNAVAIL") | |
184 | ('try-again "TRYAGAIN") | |
185 | (($ <lookup-status-negation> status) | |
186 | (string-append "!" (lookup-status->string status))))) | |
187 | ||
188 | (define lookup-reaction->string | |
189 | (match-lambda | |
190 | (($ <lookup-reaction> status action) | |
191 | (string-append (lookup-status->string status) "=" | |
192 | (symbol->string action))))) | |
193 | ||
194 | (define name-service->string | |
195 | (match-lambda | |
196 | (($ <name-service> name ()) | |
197 | name) | |
198 | (($ <name-service> name reactions) | |
199 | (string-append name " [" | |
200 | (string-join (map lookup-reaction->string reactions)) | |
201 | "]")))) | |
202 | ||
203 | (define (name-service-switch->string nss) | |
204 | "Return the 'nsswitch.conf' contents for NSS as a string. See \"NSS | |
205 | Configuration File\" in the libc manual." | |
206 | (let-syntax ((->string | |
207 | (syntax-rules () | |
208 | ((_ name field) | |
209 | (match (field nss) | |
210 | (() ;keep the default config | |
211 | "") | |
212 | ((services (... ...)) | |
213 | (string-append name ":\t" | |
214 | (string-join | |
215 | (map name-service->string services)) | |
216 | "\n"))))))) | |
217 | (string-append (->string "aliases" name-service-switch-aliases) | |
218 | (->string "ethers" name-service-switch-ethers) | |
219 | (->string "group" name-service-switch-group) | |
220 | (->string "gshadow" name-service-switch-gshadow) | |
221 | (->string "hosts" name-service-switch-hosts) | |
222 | (->string "initgroups" name-service-switch-initgroups) | |
223 | (->string "netgroup" name-service-switch-netgroup) | |
224 | (->string "networks" name-service-switch-networks) | |
225 | (->string "passwd" name-service-switch-password) | |
226 | (->string "publickey" name-service-switch-public-key) | |
227 | (->string "rpc" name-service-switch-rpc) | |
228 | (->string "services" name-service-switch-services) | |
229 | (->string "shadow" name-service-switch-shadow)))) | |
230 | ||
231 | ;;; Local Variables: | |
232 | ;;; eval: (put 'name-service 'scheme-indent-function 0) | |
233 | ;;; eval: (put 'name-service-switch 'scheme-indent-function 0) | |
234 | ;;; End: | |
235 | ||
236 | ;;; nss.scm ends here |