about summary refs log tree commit diff
path: root/src/libstore/download.cc
blob: 22a3f969c7c1526ea628800c9b8c967c54532121 (plain) (blame)
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
#include "download.hh"
#include "util.hh"
#include "globals.hh"
#include "hash.hh"
#include "store-api.hh"
#include "archive.hh"

#include <unistd.h>
#include <fcntl.h>

#include <curl/curl.h>

#include <iostream>
#include <thread>
#include <cmath>
#include <random>


namespace nix {

double getTime()
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    return tv.tv_sec + (tv.tv_usec / 1000000.0);
}

std::string resolveUri(const std::string & uri)
{
    if (uri.compare(0, 8, "channel:") == 0)
        return "https://nixos.org/channels/" + std::string(uri, 8) + "/nixexprs.tar.xz";
    else
        return uri;
}

struct CurlDownloader : public Downloader
{
    CURLM * curlm = 0;

    std::random_device rd;
    std::mt19937 mt19937;

    bool enableHttp2;

    struct DownloadItem : public std::enable_shared_from_this<DownloadItem>
    {
        CurlDownloader & downloader;
        DownloadRequest request;
        DownloadResult result;
        bool done = false; // whether either the success or failure function has been called
        std::function<void(const DownloadResult &)> success;
        std::function<void(std::exception_ptr exc)> failure;
        CURL * req = 0;
        bool active = false; // whether the handle has been added to the multi object
        std::string status;

        bool showProgress = false;
        double prevProgressTime{0}, startTime{0};
        unsigned int moveBack{1};

        unsigned int attempt = 0;

        /* Don't start this download until the specified time point
           has been reached. */
        std::chrono::steady_clock::time_point embargo;

        struct curl_slist * requestHeaders = 0;

        DownloadItem(CurlDownloader & downloader, const DownloadRequest & request)
            : downloader(downloader), request(request)
        {
            showProgress =
                request.showProgress == DownloadRequest::yes ||
                (request.showProgress == DownloadRequest::automatic && isatty(STDERR_FILENO));

            if (!request.expectedETag.empty())
                requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + request.expectedETag).c_str());
        }

        ~DownloadItem()
        {
            if (req) {
                if (active)
                    curl_multi_remove_handle(downloader.curlm, req);
                curl_easy_cleanup(req);
            }
            if (requestHeaders) curl_slist_free_all(requestHeaders);
            try {
                if (!done)
                    fail(DownloadError(Interrupted, format("download of ‘%s’ was interrupted") % request.uri));
            } catch (...) {
                ignoreException();
            }
        }

        template<class T>
        void fail(const T & e)
        {
            assert(!done);
            done = true;
            callFailure(failure, std::make_exception_ptr(e));
        }

        size_t writeCallback(void * contents, size_t size, size_t nmemb)
        {
            size_t realSize = size * nmemb;
            result.data->append((char *) contents, realSize);
            return realSize;
        }

        static size_t writeCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
        {
            return ((DownloadItem *) userp)->writeCallback(contents, size, nmemb);
        }

        size_t headerCallback(void * contents, size_t size, size_t nmemb)
        {
            size_t realSize = size * nmemb;
            std::string line((char *) contents, realSize);
            printMsg(lvlVomit, format("got header for ‘%s’: %s") % request.uri % trim(line));
            if (line.compare(0, 5, "HTTP/") == 0) { // new response starts
                result.etag = "";
                auto ss = tokenizeString<vector<string>>(line, " ");
                status = ss.size() >= 2 ? ss[1] : "";
                result.data = std::make_shared<std::string>();
            } else {
                auto i = line.find(':');
                if (i != string::npos) {
                    string name = toLower(trim(string(line, 0, i)));
                    if (name == "etag") {
                        result.etag = trim(string(line, i + 1));
                        /* Hack to work around a GitHub bug: it sends
                           ETags, but ignores If-None-Match. So if we get
                           the expected ETag on a 200 response, then shut
                           down the connection because we already have the
                           data. */
                        if (result.etag == request.expectedETag && status == "200") {
                            debug(format("shutting down on 200 HTTP response with expected ETag"));
                            return 0;
                        }
                    }
                }
            }
            return realSize;
        }

        static size_t headerCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
        {
            return ((DownloadItem *) userp)->headerCallback(contents, size, nmemb);
        }

        int progressCallback(double dltotal, double dlnow)
        {
            if (showProgress) {
                double now = getTime();
                if (prevProgressTime <= now - 1) {
                    string s = (format(" [%1$.0f/%2$.0f KiB, %3$.1f KiB/s]")
                        % (dlnow / 1024.0)
                        % (dltotal / 1024.0)
                        % (now == startTime ? 0 : dlnow / 1024.0 / (now - startTime))).str();
                    std::cerr << "\e[" << moveBack << "D" << s;
                    moveBack = s.size();
                    std::cerr.flush();
                    prevProgressTime = now;
                }
            }
            return _isInterrupted;
        }

        static int progressCallbackWrapper(void * userp, double dltotal, double dlnow, double ultotal, double ulnow)
        {
            return ((DownloadItem *) userp)->progressCallback(dltotal, dlnow);
        }

        void init()
        {
            // FIXME: handle parallel downloads.
            if (showProgress) {
                std::cerr << (format("downloading ‘%1%’... ") % request.uri);
                std::cerr.flush();
                startTime = getTime();
            }

            if (!req) req = curl_easy_init();

            curl_easy_reset(req);
            curl_easy_setopt(req, CURLOPT_URL, request.uri.c_str());
            curl_easy_setopt(req, CURLOPT_FOLLOWLOCATION, 1L);
            curl_easy_setopt(req, CURLOPT_NOSIGNAL, 1);
            curl_easy_setopt(req, CURLOPT_USERAGENT, ("Nix/" + nixVersion).c_str());
            curl_easy_setopt(req, CURLOPT_PIPEWAIT, 1);
            if (downloader.enableHttp2)
                curl_easy_setopt(req, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
            curl_easy_setopt(req, CURLOPT_WRITEFUNCTION, DownloadItem::writeCallbackWrapper);
            curl_easy_setopt(req, CURLOPT_WRITEDATA, this);
            curl_easy_setopt(req, CURLOPT_HEADERFUNCTION, DownloadItem::headerCallbackWrapper);
            curl_easy_setopt(req, CURLOPT_HEADERDATA, this);

            curl_easy_setopt(req, CURLOPT_PROGRESSFUNCTION, progressCallbackWrapper);
            curl_easy_setopt(req, CURLOPT_PROGRESSDATA, this);
            curl_easy_setopt(req, CURLOPT_NOPROGRESS, 0);

            curl_easy_setopt(req, CURLOPT_HTTPHEADER, requestHeaders);

            if (request.head)
                curl_easy_setopt(req, CURLOPT_NOBODY, 1);

            if (request.verifyTLS)
                curl_easy_setopt(req, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
            else {
                curl_easy_setopt(req, CURLOPT_SSL_VERIFYPEER, 0);
                curl_easy_setopt(req, CURLOPT_SSL_VERIFYHOST, 0);
            }

            result.data = std::make_shared<std::string>();
        }

        void finish(CURLcode code)
        {
            if (showProgress)
                //std::cerr << "\e[" << moveBack << "D\e[K\n";
                std::cerr << "\n";

            long httpStatus = 0;
            curl_easy_getinfo(req, CURLINFO_RESPONSE_CODE, &httpStatus);

            char * effectiveUrlCStr;
            curl_easy_getinfo(req, CURLINFO_EFFECTIVE_URL, &effectiveUrlCStr);
            if (effectiveUrlCStr)
                result.effectiveUrl = effectiveUrlCStr;

            debug(format("finished download of ‘%s’; curl status = %d, HTTP status = %d, body = %d bytes")
                % request.uri % code % httpStatus % (result.data ? result.data->size() : 0));

            if (code == CURLE_WRITE_ERROR && result.etag == request.expectedETag) {
                code = CURLE_OK;
                httpStatus = 304;
            }

            if (code == CURLE_OK &&
                (httpStatus == 200 || httpStatus == 304 || httpStatus == 226 /* FTP */ || httpStatus == 0 /* other protocol */))
            {
                result.cached = httpStatus == 304;
                done = true;
                callSuccess(success, failure, const_cast<const DownloadResult &>(result));
            } else {
                Error err =
                    (httpStatus == 404 || code == CURLE_FILE_COULDNT_READ_FILE) ? NotFound :
                    httpStatus == 403 ? Forbidden :
                    (httpStatus == 408 || httpStatus == 500 || httpStatus == 503
                        || httpStatus == 504  || httpStatus == 522 || httpStatus == 524
                        || code == CURLE_COULDNT_RESOLVE_HOST) ? Transient :
                    Misc;

                attempt++;

                auto exc =
                    code == CURLE_ABORTED_BY_CALLBACK && _isInterrupted
                    ? DownloadError(Interrupted, format("download of ‘%s’ was interrupted") % request.uri)
                    : httpStatus != 0
                      ? DownloadError(err, format("unable to download ‘%s’: HTTP error %d") % request.uri % httpStatus)
                      : DownloadError(err, format("unable to download ‘%s’: %s (%d)") % request.uri % curl_easy_strerror(code) % code);

                /* If this is a transient error, then maybe retry the
                   download after a while. */
                if (err == Transient && attempt < request.tries) {
                    int ms = request.baseRetryTimeMs * std::pow(2.0f, attempt - 1 + std::uniform_real_distribution<>(0.0, 0.5)(downloader.mt19937));
                    printError(format("warning: %s; retrying in %d ms") % exc.what() % ms);
                    embargo = std::chrono::steady_clock::now() + std::chrono::milliseconds(ms);
                    downloader.enqueueItem(shared_from_this());
                }
                else
                    fail(exc);
            }
        }
    };

    struct State
    {
        bool quit = false;
        std::vector<std::shared_ptr<DownloadItem>> incoming;
    };

    Sync<State> state_;

    /* We can't use a std::condition_variable to wake up the curl
       thread, because it only monitors file descriptors. So use a
       pipe instead. */
    Pipe wakeupPipe;

    std::thread workerThread;

    CurlDownloader()
    {
        static std::once_flag globalInit;
        std::call_once(globalInit, curl_global_init, CURL_GLOBAL_ALL);

        curlm = curl_multi_init();

        curl_multi_setopt(curlm, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
        curl_multi_setopt(curlm, CURLMOPT_MAX_TOTAL_CONNECTIONS,
            settings.get("binary-caches-parallel-connections", 25));

        enableHttp2 = settings.get("enable-http2", true);

        wakeupPipe.create();
        fcntl(wakeupPipe.readSide.get(), F_SETFL, O_NONBLOCK);

        workerThread = std::thread([&]() { workerThreadEntry(); });
    }

    ~CurlDownloader()
    {
        /* Signal the worker thread to exit. */
        {
            auto state(state_.lock());
            state->quit = true;
        }
        writeFull(wakeupPipe.writeSide.get(), " ");

        workerThread.join();

        if (curlm) curl_multi_cleanup(curlm);
    }

    void workerThreadMain()
    {
        std::map<CURL *, std::shared_ptr<DownloadItem>> items;

        bool quit;

        std::chrono::steady_clock::time_point nextWakeup;

        while (!quit) {
            checkInterrupt();

            /* Let curl do its thing. */
            int running;
            CURLMcode mc = curl_multi_perform(curlm, &running);
            if (mc != CURLM_OK)
                throw nix::Error(format("unexpected error from curl_multi_perform(): %s") % curl_multi_strerror(mc));

            /* Set the promises of any finished requests. */
            CURLMsg * msg;
            int left;
            while ((msg = curl_multi_info_read(curlm, &left))) {
                if (msg->msg == CURLMSG_DONE) {
                    auto i = items.find(msg->easy_handle);
                    assert(i != items.end());
                    i->second->finish(msg->data.result);
                    curl_multi_remove_handle(curlm, i->second->req);
                    i->second->active = false;
                    items.erase(i);
                }
            }

            /* Wait for activity, including wakeup events. */
            int numfds = 0;
            struct curl_waitfd extraFDs[1];
            extraFDs[0].fd = wakeupPipe.readSide.get();
            extraFDs[0].events = CURL_WAIT_POLLIN;
            extraFDs[0].revents = 0;
            auto sleepTimeMs =
                nextWakeup != std::chrono::steady_clock::time_point()
                ? std::max(0, (int) std::chrono::duration_cast<std::chrono::milliseconds>(nextWakeup - std::chrono::steady_clock::now()).count())
                : 1000000000;
            //printMsg(lvlVomit, format("download thread waiting for %d ms") % sleepTimeMs);
            mc = curl_multi_wait(curlm, extraFDs, 1, sleepTimeMs, &numfds);
            if (mc != CURLM_OK)
                throw nix::Error(format("unexpected error from curl_multi_wait(): %s") % curl_multi_strerror(mc));

            nextWakeup = std::chrono::steady_clock::time_point();

            /* Add new curl requests from the incoming requests queue,
               except for requests that are embargoed (waiting for a
               retry timeout to expire). FIXME: should use a priority
               queue for the embargoed items to prevent repeated O(n)
               checks. */
            if (extraFDs[0].revents & CURL_WAIT_POLLIN) {
                char buf[1024];
                auto res = read(extraFDs[0].fd, buf, sizeof(buf));
                if (res == -1 && errno != EINTR)
                    throw SysError("reading curl wakeup socket");
            }

            std::vector<std::shared_ptr<DownloadItem>> incoming, embargoed;
            auto now = std::chrono::steady_clock::now();

            {
                auto state(state_.lock());
                for (auto & item: state->incoming) {
                    if (item->embargo <= now)
                        incoming.push_back(item);
                    else {
                        embargoed.push_back(item);
                        if (nextWakeup == std::chrono::steady_clock::time_point()
                            || item->embargo < nextWakeup)
                            nextWakeup = item->embargo;
                    }
                }
                state->incoming = embargoed;
                quit = state->quit;
            }

            for (auto & item : incoming) {
                debug(format("starting download of %s") % item->request.uri);
                item->init();
                curl_multi_add_handle(curlm, item->req);
                item->active = true;
                items[item->req] = item;
            }
        }

        debug("download thread shutting down");
    }

    void workerThreadEntry()
    {
        try {
            workerThreadMain();
        } catch (nix::Interrupted & e) {
        } catch (std::exception & e) {
            printError(format("unexpected error in download thread: %s") % e.what());
        }

        {
            auto state(state_.lock());
            state->incoming.clear();
            state->quit = true;
        }
    }

    void enqueueItem(std::shared_ptr<DownloadItem> item)
    {
        {
            auto state(state_.lock());
            if (state->quit)
                throw nix::Error("cannot enqueue download request because the download thread is shutting down");
            state->incoming.push_back(item);
        }
        writeFull(wakeupPipe.writeSide.get(), " ");
    }

    void enqueueDownload(const DownloadRequest & request,
        std::function<void(const DownloadResult &)> success,
        std::function<void(std::exception_ptr exc)> failure) override
    {
        auto item = std::make_shared<DownloadItem>(*this, request);
        item->success = success;
        item->failure = failure;
        enqueueItem(item);
    }
};

ref<Downloader> getDownloader()
{
    static std::shared_ptr<Downloader> downloader;
    static std::once_flag downloaderCreated;
    std::call_once(downloaderCreated, [&]() { downloader = makeDownloader(); });
    return ref<Downloader>(downloader);
}

ref<Downloader> makeDownloader()
{
    return make_ref<CurlDownloader>();
}

std::future<DownloadResult> Downloader::enqueueDownload(const DownloadRequest & request)
{
    auto promise = std::make_shared<std::promise<DownloadResult>>();
    enqueueDownload(request,
        [promise](const DownloadResult & result) { promise->set_value(result); },
        [promise](std::exception_ptr exc) { promise->set_exception(exc); });
    return promise->get_future();
}

DownloadResult Downloader::download(const DownloadRequest & request)
{
    return enqueueDownload(request).get();
}

Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, string name, const Hash & expectedHash, string * effectiveUrl)
{
    auto url = resolveUri(url_);

    if (name == "") {
        auto p = url.rfind('/');
        if (p != string::npos) name = string(url, p + 1);
    }

    Path expectedStorePath;
    if (expectedHash) {
        expectedStorePath = store->makeFixedOutputPath(unpack, expectedHash, name);
        if (store->isValidPath(expectedStorePath))
            return expectedStorePath;
    }

    Path cacheDir = getCacheDir() + "/nix/tarballs";
    createDirs(cacheDir);

    string urlHash = printHash32(hashString(htSHA256, url));

    Path dataFile = cacheDir + "/" + urlHash + ".info";
    Path fileLink = cacheDir + "/" + urlHash + "-file";

    Path storePath;

    string expectedETag;

    int ttl = settings.get("tarball-ttl", 60 * 60);
    bool skip = false;

    if (pathExists(fileLink) && pathExists(dataFile)) {
        storePath = readLink(fileLink);
        store->addTempRoot(storePath);
        if (store->isValidPath(storePath)) {
            auto ss = tokenizeString<vector<string>>(readFile(dataFile), "\n");
            if (ss.size() >= 3 && ss[0] == url) {
                time_t lastChecked;
                if (string2Int(ss[2], lastChecked) && lastChecked + ttl >= time(0)) {
                    skip = true;
                    if (effectiveUrl)
                        *effectiveUrl = url_;
                } else if (!ss[1].empty()) {
                    debug(format("verifying previous ETag ‘%1%’") % ss[1]);
                    expectedETag = ss[1];
                }
            }
        } else
            storePath = "";
    }

    if (!skip) {

        try {
            DownloadRequest request(url);
            request.expectedETag = expectedETag;
            auto res = download(request);
            if (effectiveUrl)
                *effectiveUrl = res.effectiveUrl;

            if (!res.cached) {
                ValidPathInfo info;
                StringSink sink;
                dumpString(*res.data, sink);
                Hash hash = hashString(expectedHash ? expectedHash.type : htSHA256, *res.data);
                info.path = store->makeFixedOutputPath(false, hash, name);
                info.narHash = hashString(htSHA256, *sink.s);
                store->addToStore(info, *sink.s, false, true);
                storePath = info.path;
            }

            assert(!storePath.empty());
            replaceSymlink(storePath, fileLink);

            writeFile(dataFile, url + "\n" + res.etag + "\n" + std::to_string(time(0)) + "\n");
        } catch (DownloadError & e) {
            if (storePath.empty()) throw;
            printError(format("warning: %1%; using cached result") % e.msg());
        }
    }

    if (unpack) {
        Path unpackedLink = cacheDir + "/" + baseNameOf(storePath) + "-unpacked";
        Path unpackedStorePath;
        if (pathExists(unpackedLink)) {
            unpackedStorePath = readLink(unpackedLink);
            store->addTempRoot(unpackedStorePath);
            if (!store->isValidPath(unpackedStorePath))
                unpackedStorePath = "";
        }
        if (unpackedStorePath.empty()) {
            printInfo(format("unpacking ‘%1%’...") % url);
            Path tmpDir = createTempDir();
            AutoDelete autoDelete(tmpDir, true);
            // FIXME: this requires GNU tar for decompression.
            runProgram("tar", true, {"xf", storePath, "-C", tmpDir, "--strip-components", "1"}, "");
            unpackedStorePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, false);
        }
        replaceSymlink(unpackedStorePath, unpackedLink);
        storePath = unpackedStorePath;
    }

    if (expectedStorePath != "" && storePath != expectedStorePath)
        throw nix::Error(format("hash mismatch in file downloaded from ‘%s’") % url);

    return storePath;
}


bool isUri(const string & s)
{
    if (s.compare(0, 8, "channel:") == 0) return true;
    size_t pos = s.find("://");
    if (pos == string::npos) return false;
    string scheme(s, 0, pos);
    return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git";
}


}