aboutsummaryrefslogtreecommitdiff
path: root/guix/scripts/publish.scm
blob: efaa549676c0c5745b868bd6cd348a7a3ff6f7d2 (plain)
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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (guix scripts publish)
  #:use-module ((system repl server) #:prefix repl:)
  #:use-module (ice-9 binary-ports)
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 rdelim)
  #:use-module (ice-9 threads)
  #:use-module (rnrs bytevectors)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-2)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-9 gnu)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-37)
  #:use-module (web http)
  #:use-module (web request)
  #:use-module (web response)
  #:use-module (web server)
  #:use-module (web uri)
  #:autoload   (sxml simple) (sxml->xml)
  #:use-module (guix base32)
  #:use-module (guix base64)
  #:use-module (guix config)
  #:use-module (guix derivations)
  #:use-module (guix hash)
  #:use-module (guix pki)
  #:use-module (guix pk-crypto)
  #:use-module (guix workers)
  #:use-module (guix store)
  #:use-module ((guix serialization) #:select (write-file))
  #:use-module (guix zlib)
  #:use-module (guix cache)
  #:use-module (guix ui)
  #:use-module (guix scripts)
  #:use-module ((guix utils)
                #:select (with-atomic-file-output compressed-file?))
  #:use-module ((guix build utils)
                #:select (dump-port mkdir-p find-files))
  #:export (%public-key
            %private-key

            guix-publish))

(define (show-help)
  (format #t (G_ "Usage: guix publish [OPTION]...
Publish ~a over HTTP.\n") %store-directory)
  (display (G_ "
  -p, --port=PORT        listen on PORT"))
  (display (G_ "
      --listen=HOST      listen on the network interface for HOST"))
  (display (G_ "
  -u, --user=USER        change privileges to USER as soon as possible"))
  (display (G_ "
  -C, --compression[=LEVEL]
                         compress archives at LEVEL"))
  (display (G_ "
  -c, --cache=DIRECTORY  cache published items to DIRECTORY"))
  (display (G_ "
      --workers=N        use N workers to bake items"))
  (display (G_ "
      --ttl=TTL          announce narinfos can be cached for TTL seconds"))
  (display (G_ "
      --nar-path=PATH    use PATH as the prefix for nar URLs"))
  (display (G_ "
      --public-key=FILE  use FILE as the public key for signatures"))
  (display (G_ "
      --private-key=FILE use FILE as the private key for signatures"))
  (display (G_ "
  -r, --repl[=PORT]      spawn REPL server on PORT"))
  (newline)
  (display (G_ "
  -h, --help             display this help and exit"))
  (display (G_ "
  -V, --version          display version information and exit"))
  (newline)
  (show-bug-report-information))

(define (getaddrinfo* host)
  "Like 'getaddrinfo', but properly report errors."
  (catch 'getaddrinfo-error
    (lambda ()
      (getaddrinfo host))
    (lambda (key error)
      (leave (G_ "lookup of host '~a' failed: ~a~%")
             host (gai-strerror error)))))

;; Nar compression parameters.
(define-record-type <compression>
  (compression type level)
  compression?
  (type   compression-type)
  (level  compression-level))

(define %no-compression
  (compression 'none 0))

(define %default-gzip-compression
  ;; Since we compress on the fly, default to fast compression.
  (compression 'gzip 3))

(define (actual-compression item requested)
  "Return the actual compression used for ITEM, which may be %NO-COMPRESSION
if ITEM is already compressed."
  (if (compressed-file? item)
      %no-compression
      requested))

(define %options
  (list (option '(#\h "help") #f #f
                (lambda _
                  (show-help)
                  (exit 0)))
        (option '(#\V "version") #f #f
                (lambda _
                  (show-version-and-exit "guix publish")))
        (option '(#\u "user") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'user arg result)))
        (option '(#\p "port") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'port (string->number* arg) result)))
        (option '("listen") #t #f
                (lambda (opt name arg result)
                  (match (getaddrinfo* arg)
                    ((info _ ...)
                     (alist-cons 'address (addrinfo:addr info)
                                 result))
                    (()
                     (leave (G_ "lookup of host '~a' returned nothing")
                            name)))))
        (option '(#\C "compression") #f #t
                (lambda (opt name arg result)
                  (match (if arg (string->number* arg) 3)
                    (0
                     (alist-cons 'compression %no-compression result))
                    (level
                     (if (zlib-available?)
                         (alist-cons 'compression
                                     (compression 'gzip level)
                                     result)
                         (begin
                           (warning (G_ "zlib support is missing; \
compression disabled~%"))
                           result))))))
        (option '(#\c "cache") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'cache arg result)))
        (option '("workers") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'workers (string->number* arg)
                              result)))
        (option '("ttl") #t #f
                (lambda (opt name arg result)
                  (let ((duration (string->duration arg)))
                    (unless duration
                      (leave (G_ "~a: invalid duration~%") arg))
                    (alist-cons 'narinfo-ttl (time-second duration)
                                result))))
        (option '("nar-path") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'nar-path arg result)))
        (option '("public-key") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'public-key-file arg result)))
        (option '("private-key" "secret-key") #t #f
                (lambda (opt name arg result)
                  (alist-cons 'private-key-file arg result)))
        (option '(#\r "repl") #f #t
                (lambda (opt name arg result)
                  ;; If port unspecified, use default Guile REPL port.
                  (let ((port (and arg (string->number* arg))))
                    (alist-cons 'repl (or port 37146) result))))))

(define %default-options
  `((port . 8080)

    ;; By default, serve nars under "/nar".
    (nar-path . "nar")

    (public-key-file . ,%public-key-file)
    (private-key-file . ,%private-key-file)

    ;; Default to fast & low compression.
    (compression . ,(if (zlib-available?)
                        %default-gzip-compression
                        %no-compression))

    ;; Default number of workers when caching is enabled.
    (workers . ,(current-processor-count))

    (address . ,(make-socket-address AF_INET INADDR_ANY 0))
    (repl . #f)))

;; The key pair used to sign narinfos.
(define %private-key
  (make-parameter #f))
(define %public-key
  (make-parameter #f))

(define %nix-cache-info
  `(("StoreDir" . ,%store-directory)
    ("WantMassQuery" . 0)
    ("Priority" . 100)))

(define (load-derivation file)
  "Read the derivation from FILE."
  (call-with-input-file file read-derivation))

(define (signed-string s)
  "Sign the hash of the string S with the daemon's key."
  (let* ((public-key (%public-key))
         (hash (bytevector->hash-data (sha256 (string->utf8 s))
                                      #:key-type (key-type public-key))))
    (signature-sexp hash (%private-key) public-key)))

(define base64-encode-string
  (compose base64-encode string->utf8))

(define* (narinfo-string store store-path key
                         #:key (compression %no-compression)
                         (nar-path "nar") file-size)
  "Generate a narinfo key/value string for STORE-PATH; an exception is raised
if STORE-PATH is invalid.  Produce a URL that corresponds to COMPRESSION.  The
narinfo is signed with KEY.  NAR-PATH specifies the prefix for nar URLs.
Optionally, FILE-SIZE can specify the size in bytes of the compressed NAR; it
informs the client of how much needs to be downloaded."
  (let* ((path-info  (query-path-info store store-path))
         (compression (actual-compression store-path compression))
         (url        (encode-and-join-uri-path
                      `(,@(split-and-decode-uri-path nar-path)
                        ,@(match compression
                            (($ <compression> 'none)
                             '())
                            (($ <compression> type)
                             (list (symbol->string type))))
                        ,(basename store-path))))
         (hash       (bytevector->nix-base32-string
                      (path-info-hash path-info)))
         (size       (path-info-nar-size path-info))
         (file-size  (or file-size
                         (and (eq? compression %no-compression) size)))
         (references (string-join
                      (map basename (path-info-references path-info))
                      " "))
         (deriver    (path-info-deriver path-info))
         (base-info  (format #f
                             "\
StorePath: ~a
URL: ~a
Compression: ~a
NarHash: sha256:~a
NarSize: ~d
References: ~a~%~a"
                             store-path url
                             (compression-type compression)
                             hash size references
                             (if file-size
                                 (format #f "FileSize: ~a~%" file-size)
                                 "")))
         ;; Do not render a "Deriver" or "System" line if we are rendering
         ;; info for a derivation.
         (info       (if (not deriver)
                         base-info
                         (catch 'system-error
                           (lambda ()
                             (let ((drv (load-derivation deriver)))
                               (format #f "~aSystem: ~a~%Deriver: ~a~%"
                                       base-info (derivation-system drv)
                                       (basename deriver))))
                           (lambda args
                             ;; DERIVER might be missing, but that's fine:
                             ;; it's only used for <substitutable> where it's
                             ;; optional.  'System' is currently unused.
                             (if (= ENOENT (system-error-errno args))
                                 base-info
                                 (apply throw args))))))
         (signature  (base64-encode-string
                      (canonical-sexp->string (signed-string info)))))
    (format #f "~aSignature: 1;~a;~a~%" info (gethostname) signature)))

(define (not-found request)
  "Render 404 response for REQUEST."
  (values (build-response #:code 404)
          (string-append "Resource not found: "
                         (uri-path (request-uri request)))))

(define (render-nix-cache-info)
  "Render server information."
  (values '((content-type . (text/plain)))
          (lambda (port)
            (for-each (match-lambda
                       ((key . value)
                        (format port "~a: ~a~%" key value)))
                      %nix-cache-info))))

(define* (render-narinfo store request hash
                         #:key ttl (compression %no-compression)
                         (nar-path "nar"))
  "Render metadata for the store path corresponding to HASH.  If TTL is true,
advertise it as the maximum validity period (in seconds) via the
'Cache-Control' header.  This allows 'guix substitute' to cache it for an
appropriate duration.  NAR-PATH specifies the prefix for nar URLs."
  (let ((store-path (hash-part->path store hash)))
    (if (string-null? store-path)
        (not-found request)
        (values `((content-type . (application/x-nix-narinfo))
                  ,@(if ttl
                        `((cache-control (max-age . ,ttl)))
                        '()))
                (cut display
                  (narinfo-string store store-path (%private-key)
                                  #:nar-path nar-path
                                  #:compression compression)
                  <>)))))

(define* (nar-cache-file directory item
                             #:key (compression %no-compression))
  (string-append directory "/"
                 (symbol->string (compression-type compression))
                 "/" (basename item) ".nar"))

(define* (narinfo-cache-file directory item
                             #:key (compression %no-compression))
  (string-append directory "/"
                 (symbol->string (compression-type compression))
                 "/" (basename item)
                 ".narinfo"))

(define run-single-baker
  (let ((baking (make-weak-value-hash-table))
        (mutex  (make-mutex)))
    (lambda (item thunk)
      "Run THUNK, which is supposed to bake ITEM, but make sure only one
thread is baking ITEM at a given time."
      (define selected?
        (with-mutex mutex
          (and (not (hash-ref baking item))
               (begin
                 (hash-set! baking item (current-thread))
                 #t))))

      (when selected?
        (dynamic-wind
          (const #t)
          thunk
          (lambda ()
            (with-mutex mutex
              (hash-remove! baking item))))))))

(define-syntax-rule (single-baker item exp ...)
  "Bake ITEM by evaluating EXP, but make sure there's only one baker for ITEM
at a time."
  (run-single-baker item (lambda () exp ...)))


(define (narinfo-files cache)
  "Return the list of .narinfo files under CACHE."
  (if (file-is-directory? cache)
      (find-files cache
                  (lambda (file stat)
                    (string-suffix? ".narinfo" file)))
      '()))

(define* (render-narinfo/cached store request hash
                                #:key ttl (compression %no-compression)
                                (nar-path "nar")
                                cache pool)
  "Respond to the narinfo request for REQUEST.  If the narinfo is available in
CACHE, then send it; otherwise, return 404 and \"bake\" that nar and narinfo
requested using POOL."
  (define (delete-entry narinfo)
    ;; Delete NARINFO and the corresponding nar from CACHE.
    (let ((nar (string-append (string-drop-right narinfo
                                                 (string-length ".narinfo"))
                              ".nar")))
      (delete-file* narinfo)
      (delete-file* nar)))

  (let* ((item        (hash-part->path store hash))
         (compression (actual-compression item compression))
         (cached      (and (not (string-null? item))
                           (narinfo-cache-file cache item
                                               #:compression compression))))
    (cond ((string-null? item)
           (not-found request))
          ((file-exists? cached)
           ;; Narinfo is in cache, send it.
           (values `((content-type . (application/x-nix-narinfo))
                     ,@(if ttl
                           `((cache-control (max-age . ,ttl)))
                           '()))
                   (lambda (port)
                     (display (call-with-input-file cached
                                read-string)
                              port))))
          ((valid-path? store item)
           ;; Nothing in cache: bake the narinfo and nar in the background and
           ;; return 404.
           (eventually pool
             (single-baker item
               ;; (format #t "baking ~s~%" item)
               (bake-narinfo+nar cache item
                                 #:ttl ttl
                                 #:compression compression
                                 #:nar-path nar-path))

             (when ttl
               (single-baker 'cache-cleanup
                 (maybe-remove-expired-cache-entries cache
                                                     narinfo-files
                                                     #:entry-expiration
                                                     (file-expiration-time ttl)
                                                     #:delete-entry delete-entry
                                                     #:cleanup-period ttl))))
           (not-found request))
          (else
           (not-found request)))))

(define* (bake-narinfo+nar cache item
                           #:key ttl (compression %no-compression)
                           (nar-path "/nar"))
  "Write the narinfo and nar for ITEM to CACHE."
  (let* ((compression (actual-compression item compression))
         (nar         (nar-cache-file cache item
                                      #:compression compression))
         (narinfo     (narinfo-cache-file cache item
                                          #:compression compression)))

    (mkdir-p (dirname nar))
    (match (compression-type compression)
      ('gzip
       ;; Note: the file port gets closed along with the gzip port.
       (call-with-gzip-output-port (open-output-file (string-append nar ".tmp"))
         (lambda (port)
           (write-file item port))
         #:level (compression-level compression)
         #:buffer-size (* 128 1024))
       (rename-file (string-append nar ".tmp") nar))
      ('none
       ;; When compression is disabled, we retrieve files directly from the
       ;; store; no need to cache them.
       #t))

    (mkdir-p (dirname narinfo))
    (with-atomic-file-output narinfo
      (lambda (port)
        ;; Open a new connection to the store.  We cannot reuse the main
        ;; thread's connection to the store since we would end up sending
        ;; stuff concurrently on the same channel.
        (with-store store
          (display (narinfo-string store item
                                   (%private-key)
                                   #:nar-path nar-path
                                   #:compression compression
                                   #:file-size (stat:size (stat nar)))
                   port))))))

;; XXX: Declare the 'Guix-Compression' HTTP header, which is in fact for
;; internal consumption: it allows us to pass the compression info to
;; 'http-write', as part of the workaround to <http://bugs.gnu.org/21093>.
(declare-header! "Guix-Nar-Compression"
                 (lambda (str)
                   (match (call-with-input-string str read)
                     (('compression type level)
                      (compression type level))))
                 compression?
                 (lambda (compression port)
                   (match compression
                     (($ <compression> type level)
                      (write `(compression ,type ,level) port)))))

(define* (render-nar store request store-item
                     #:key (compression %no-compression))
  "Render archive of the store path corresponding to STORE-ITEM."
  (let ((store-path (string-append %store-directory "/" store-item)))
    ;; The ISO-8859-1 charset *must* be used otherwise HTTP clients will
    ;; interpret the byte stream as UTF-8 and arbitrarily change invalid byte
    ;; sequences.
    (if (valid-path? store store-path)
        (values `((content-type . (application/x-nix-archive
                                   (charset . "ISO-8859-1")))
                  (guix-nar-compression . ,compression))
                ;; XXX: We're not returning the actual contents, deferring
                ;; instead to 'http-write'.  This is a hack to work around
                ;; <http://bugs.gnu.org/21093>.
                store-path)
        (not-found request))))

(define* (render-nar/cached store cache request store-item
                            #:key (compression %no-compression))
  "Respond to REQUEST with a nar for STORE-ITEM.  If the nar is in CACHE,
return it; otherwise, return 404."
  (let ((cached (nar-cache-file cache store-item
                                #:compression compression)))
    (if (file-exists? cached)
        (values `((content-type . (application/octet-stream
                                   (charset . "ISO-8859-1"))))
                ;; XXX: We're not returning the actual contents, deferring
                ;; instead to 'http-write'.  This is a hack to work around
                ;; <http://bugs.gnu.org/21093>.
                cached)
        (not-found request))))

(define (render-content-addressed-file store request
                                       name algo hash)
  "Return the content of the result of the fixed-output derivation NAME that
has the given HASH of type ALGO."
  ;; TODO: Support other hash algorithms.
  (if (and (eq? algo 'sha256) (= 32 (bytevector-length hash)))
      (let ((item (fixed-output-path name hash
                                     #:hash-algo algo
                                     #:recursive? #f)))
        (if (valid-path? store item)
            (values `((content-type . (application/octet-stream
                                       (charset . "ISO-8859-1"))))
                    ;; XXX: We're not returning the actual contents, deferring
                    ;; instead to 'http-write'.  This is a hack to work around
                    ;; <http://bugs.gnu.org/21093>.
                    item)
            (not-found request)))
      (not-found request)))

(define (render-home-page request)
  "Render the home page."
  (values `((content-type . (text/html (charset . "UTF-8"))))
          (call-with-output-string
            (lambda (port)
              (sxml->xml '(html
                           (head (title "GNU Guix Substitute Server"))
                           (body
                            (h1 "GNU Guix Substitute Server")
                            (p "Hi, "
                               (a (@ (href
                                      "https://gnu.org/s/guix/manual/html_node/Invoking-guix-publish.html"))
                                  (tt "guix publish"))
                               " speaking.  Welcome!")))
                         port)))))

(define extract-narinfo-hash
  (let ((regexp (make-regexp "^([a-df-np-sv-z0-9]{32}).narinfo$")))
    (lambda (str)
      "Return the hash within the narinfo resource string STR, or false if STR
is invalid."
      (and=> (regexp-exec regexp str)
             (cut match:substring <> 1)))))

(define (get-request? request)
  "Return #t if REQUEST uses the GET method."
  (eq? (request-method request) 'GET))

(define (request-path-components request)
  "Split the URI path of REQUEST into a list of component strings.  For
example: \"/foo/bar\" yields '(\"foo\" \"bar\")."
  (split-and-decode-uri-path (uri-path (request-uri request))))


;;;
;;; Server.
;;;

(define %http-write
  (@@ (web server http) http-write))

(define (sans-content-length response)
  "Return RESPONSE without its 'content-length' header."
  (set-field response (response-headers)
             (alist-delete 'content-length
                           (response-headers response)
                           eq?)))

(define (with-content-length response length)
  "Return RESPONSE with a 'content-length' header set to LENGTH."
  (set-field response (response-headers)
             (alist-cons 'content-length length
                         (alist-delete 'content-length
                                       (response-headers response)
                                       eq?))))

(define-syntax-rule (swallow-EPIPE exp ...)
  "Swallow EPIPE errors raised by EXP..."
  (catch 'system-error
    (lambda ()
      exp ...)
    (lambda args
      (if (= EPIPE (system-error-errno args))
          (values)
          (apply throw args)))))

(define-syntax-rule (swallow-zlib-error exp ...)
  "Swallow 'zlib-error' exceptions raised by EXP..."
  (catch 'zlib-error
    (lambda ()
      exp ...)
    (const #f)))

(define (nar-response-port response)
  "Return a port on which to write the body of RESPONSE, the response of a
/nar request, according to COMPRESSION."
  (match (assoc-ref (response-headers response) 'guix-nar-compression)
    (($ <compression> 'gzip level)
     ;; Note: We cannot used chunked encoding here because
     ;; 'make-gzip-output-port' wants a file port.
     (make-gzip-output-port (response-port response)
                            #:level level
                            #:buffer-size (* 64 1024)))
    (($ <compression> 'none)
     (response-port response))
    (#f
     (response-port response))))

(define (http-write server client response body)
  "Write RESPONSE and BODY to CLIENT, possibly in a separate thread to avoid
blocking."
  (match (response-content-type response)
    (('application/x-nix-archive . _)
     ;; Sending the the whole archive can take time so do it in a separate
     ;; thread so that the main thread can keep working in the meantime.
     (call-with-new-thread
      (lambda ()
        (let* ((response (write-response (sans-content-length response)
                                         client))
               (port     (begin
                           (force-output client)
                           (nar-response-port response))))
          ;; XXX: Given our ugly workaround for <http://bugs.gnu.org/21093> in
          ;; 'render-nar', BODY here is just the file name of the store item.
          ;; We call 'write-file' from here because we know that's the only
          ;; way to avoid building the whole nar in memory, which could
          ;; quickly become a real problem.  As a bonus, we even do
          ;; sendfile(2) directly from the store files to the socket.
          (swallow-zlib-error
           (swallow-EPIPE
            (write-file (utf8->string body) port)))
          (swallow-zlib-error
           (close-port port))
          (values)))))
    (('application/octet-stream . _)
     ;; Send a raw file in a separate thread.
     (call-with-new-thread
      (lambda ()
        (catch 'system-error
          (lambda ()
            (call-with-input-file (utf8->string body)
              (lambda (input)
                (let* ((size     (stat:size (stat input)))
                       (response (write-response (with-content-length response
                                                                      size)
                                                 client))
                       (output   (response-port response)))
                  (if (file-port? output)
                      (sendfile output input size)
                      (dump-port input output))
                  (close-port output)
                  (values)))))
          (lambda args
            ;; If the file was GC'd behind our back, that's fine.  Likewise if
            ;; the client closes the connection.
            (unless (memv (system-error-errno args)
                          (list ENOENT EPIPE ECONNRESET))
              (apply throw args))
            (values))))))
    (_
     ;; Handle other responses sequentially.
     (%http-write server client response body))))

(define-server-impl concurrent-http-server
  ;; A variant of Guile's built-in HTTP server that offloads possibly long
  ;; responses to a different thread.
  (@@ (web server http) http-open)
  (@@ (web server http) http-read)
  http-write
  (@@ (web server http) http-close))

(define* (make-request-handler store
                               #:key
                               cache pool
                               narinfo-ttl
                               (nar-path "nar")
                               (compression %no-compression))
  (define nar-path?
    (let ((expected (split-and-decode-uri-path nar-path)))
      (cut equal? expected <>)))

  (lambda (request body)
    (format #t "~a ~a~%"
            (request-method request)
            (uri-path (request-uri request)))
    (if (get-request? request)                    ;reject POST, PUT, etc.
        (match (request-path-components request)
          ;; /nix-cache-info
          (("nix-cache-info")
           (render-nix-cache-info))
          ;; /
          ((or () ("index.html"))
           (render-home-page request))
          ;; /<hash>.narinfo
          (((= extract-narinfo-hash (? string? hash)))
           ;; TODO: Register roots for HASH that will somehow remain for
           ;; NARINFO-TTL.
           (if cache
               (render-narinfo/cached store request hash
                                      #:cache cache
                                      #:pool pool
                                      #:ttl narinfo-ttl
                                      #:nar-path nar-path
                                      #:compression compression)
               (render-narinfo store request hash
                               #:ttl narinfo-ttl
                               #:nar-path nar-path
                               #:compression compression)))
          ;; /nar/file/NAME/sha256/HASH
          (("file" name "sha256" hash)
           (guard (c ((invalid-base32-character? c)
                      (not-found request)))
             (let ((hash (nix-base32-string->bytevector hash)))
               (render-content-addressed-file store request
                                              name 'sha256 hash))))

          ;; Use different URLs depending on the compression type.  This
          ;; guarantees that /nar URLs remain valid even when 'guix publish'
          ;; is restarted with different compression parameters.

          ;; /nar/gzip/<store-item>
          ((components ... "gzip" store-item)
           (if (and (nar-path? components) (zlib-available?))
               (let ((compression (match compression
                                    (($ <compression> 'gzip)
                                     compression)
                                    (_
                                     %default-gzip-compression))))
                 (if cache
                     (render-nar/cached store cache request store-item
                                        #:compression compression)
                     (render-nar store request store-item
                                 #:compression compression)))
               (not-found request)))

          ;; /nar/<store-item>
          ((components ... store-item)
           (if (nar-path? components)
               (render-nar store request store-item
                           #:compression %no-compression)
               (not-found request)))

          (x (not-found request)))
        (not-found request))))

(define* (run-publish-server socket store
                             #:key (compression %no-compression)
                             (nar-path "nar") narinfo-ttl
                             cache pool)
  (run-server (make-request-handler store
                                    #:cache cache
                                    #:pool pool
                                    #:nar-path nar-path
                                    #:narinfo-ttl narinfo-ttl
                                    #:compression compression)
              concurrent-http-server
              `(#:socket ,socket)))

(define (open-server-socket address)
  "Return a TCP socket bound to ADDRESS, a socket address."
  (let ((sock (socket (sockaddr:fam address) SOCK_STREAM 0)))
    (setsockopt sock SOL_SOCKET SO_REUSEADDR 1)
    (bind sock address)
    sock))

(define (gather-user-privileges user)
  "Switch to the identity of USER, a user name."
  (catch 'misc-error
    (lambda ()
      (let ((user (getpw user)))
        (setgroups #())
        (setgid (passwd:gid user))
        (setuid (passwd:uid user))))
    (lambda (key proc message args . rest)
      (leave (G_ "user '~a' not found: ~a~%")
             user (apply format #f message args)))))


;;;
;;; Entry point.
;;;

(define (guix-publish . args)
  (with-error-handling
    (let* ((opts    (args-fold* args %options
                                (lambda (opt name arg result)
                                  (leave (G_ "~A: unrecognized option~%") name))
                                (lambda (arg result)
                                  (leave (G_ "~A: extraneous argument~%") arg))
                                %default-options))
           (user    (assoc-ref opts 'user))
           (port    (assoc-ref opts 'port))
           (ttl     (assoc-ref opts 'narinfo-ttl))
           (compression (assoc-ref opts 'compression))
           (address (let ((addr (assoc-ref opts 'address)))
                      (make-socket-address (sockaddr:fam addr)
                                           (sockaddr:addr addr)
                                           port)))
           (socket  (open-server-socket address))
           (nar-path  (assoc-ref opts 'nar-path))
           (repl-port (assoc-ref opts 'repl))
           (cache     (assoc-ref opts 'cache))
           (workers   (assoc-ref opts 'workers))

           ;; Read the key right away so that (1) we fail early on if we can't
           ;; access them, and (2) we can then drop privileges.
           (public-key  (read-file-sexp (assoc-ref opts 'public-key-file)))
           (private-key (read-file-sexp (assoc-ref opts 'private-key-file))))

      (when user
        ;; Now that we've read the key material and opened the socket, we can
        ;; drop privileges.
        (gather-user-privileges user))

      (when (zero? (getuid))
        (warning (G_ "server running as root; \
consider using the '--user' option!~%")))

      (parameterize ((%public-key public-key)
                     (%private-key private-key))
        (format #t (G_ "publishing ~a on ~a, port ~d~%")
                %store-directory
                (inet-ntop (sockaddr:fam address) (sockaddr:addr address))
                (sockaddr:port address))
        (when repl-port
          (repl:spawn-server (repl:make-tcp-server-socket #:port repl-port)))
        (with-store store
          (run-publish-server socket store
                              #:cache cache
                              #:pool (and cache (make-pool workers))
                              #:nar-path nar-path
                              #:compression compression
                              #:narinfo-ttl ttl))))))

;;; Local Variables:
;;; eval: (put 'single-baker 'scheme-indent-function 1)
;;; End: