forked from lix-project/lix
66adbdfd97
This makes us more robust against 500 errors from CloudFront or S3 (assuming the 500 error isn't cached by CloudFront...).
361 lines
12 KiB
C++
361 lines
12 KiB
C++
#include "download.hh"
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#include "util.hh"
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#include "globals.hh"
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#include "hash.hh"
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#include "store-api.hh"
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#include "archive.hh"
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#include <curl/curl.h>
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#include <iostream>
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#include <thread>
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namespace nix {
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double getTime()
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{
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struct timeval tv;
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gettimeofday(&tv, 0);
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return tv.tv_sec + (tv.tv_usec / 1000000.0);
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}
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std::string resolveUri(const std::string & uri)
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{
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if (uri.compare(0, 8, "channel:") == 0)
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return "https://nixos.org/channels/" + std::string(uri, 8) + "/nixexprs.tar.xz";
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else
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return uri;
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}
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struct CurlDownloader : public Downloader
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{
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CURL * curl;
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ref<std::string> data;
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string etag, status, expectedETag;
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struct curl_slist * requestHeaders;
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bool showProgress;
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double prevProgressTime{0}, startTime{0};
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unsigned int moveBack{1};
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size_t writeCallback(void * contents, size_t size, size_t nmemb)
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{
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size_t realSize = size * nmemb;
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data->append((char *) contents, realSize);
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return realSize;
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}
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static size_t writeCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
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{
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return ((CurlDownloader *) userp)->writeCallback(contents, size, nmemb);
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}
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size_t headerCallback(void * contents, size_t size, size_t nmemb)
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{
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size_t realSize = size * nmemb;
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string line = string((char *) contents, realSize);
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printMsg(lvlVomit, format("got header: %1%") % trim(line));
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if (line.compare(0, 5, "HTTP/") == 0) { // new response starts
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etag = "";
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auto ss = tokenizeString<vector<string>>(line, " ");
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status = ss.size() >= 2 ? ss[1] : "";
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} else {
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auto i = line.find(':');
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if (i != string::npos) {
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string name = trim(string(line, 0, i));
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if (name == "ETag") { // FIXME: case
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etag = trim(string(line, i + 1));
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/* Hack to work around a GitHub bug: it sends
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ETags, but ignores If-None-Match. So if we get
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the expected ETag on a 200 response, then shut
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down the connection because we already have the
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data. */
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printMsg(lvlDebug, format("got ETag: %1%") % etag);
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if (etag == expectedETag && status == "200") {
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printMsg(lvlDebug, format("shutting down on 200 HTTP response with expected ETag"));
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return 0;
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}
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}
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}
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}
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return realSize;
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}
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static size_t headerCallbackWrapper(void * contents, size_t size, size_t nmemb, void * userp)
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{
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return ((CurlDownloader *) userp)->headerCallback(contents, size, nmemb);
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}
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int progressCallback(double dltotal, double dlnow)
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{
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if (showProgress) {
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double now = getTime();
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if (prevProgressTime <= now - 1) {
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string s = (format(" [%1$.0f/%2$.0f KiB, %3$.1f KiB/s]")
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% (dlnow / 1024.0)
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% (dltotal / 1024.0)
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% (now == startTime ? 0 : dlnow / 1024.0 / (now - startTime))).str();
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std::cerr << "\e[" << moveBack << "D" << s;
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moveBack = s.size();
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std::cerr.flush();
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prevProgressTime = now;
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}
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}
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return _isInterrupted;
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}
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static int progressCallbackWrapper(void * userp, double dltotal, double dlnow, double ultotal, double ulnow)
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{
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return ((CurlDownloader *) userp)->progressCallback(dltotal, dlnow);
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}
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CurlDownloader()
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: data(make_ref<std::string>())
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{
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requestHeaders = 0;
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curl = curl_easy_init();
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if (!curl) throw nix::Error("unable to initialize curl");
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}
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~CurlDownloader()
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{
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if (curl) curl_easy_cleanup(curl);
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if (requestHeaders) curl_slist_free_all(requestHeaders);
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}
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bool fetch(const string & url, const DownloadOptions & options)
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{
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showProgress =
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options.showProgress == DownloadOptions::yes ||
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(options.showProgress == DownloadOptions::automatic && isatty(STDERR_FILENO));
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curl_easy_reset(curl);
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curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
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curl_easy_setopt(curl, CURLOPT_USERAGENT, ("Nix/" + nixVersion).c_str());
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curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
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curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallbackWrapper);
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curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *) this);
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curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, headerCallbackWrapper);
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curl_easy_setopt(curl, CURLOPT_HEADERDATA, (void *) this);
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curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progressCallbackWrapper);
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curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, (void *) this);
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curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);
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curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
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curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
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if (options.verifyTLS)
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curl_easy_setopt(curl, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
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else {
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curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
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curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
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}
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data = make_ref<std::string>();
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if (requestHeaders) {
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curl_slist_free_all(requestHeaders);
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requestHeaders = 0;
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}
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if (!options.expectedETag.empty()) {
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this->expectedETag = options.expectedETag;
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requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + options.expectedETag).c_str());
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}
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curl_easy_setopt(curl, CURLOPT_HTTPHEADER, requestHeaders);
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if (options.head)
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curl_easy_setopt(curl, CURLOPT_NOBODY, 1);
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if (showProgress) {
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std::cerr << (format("downloading ‘%1%’... ") % url);
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std::cerr.flush();
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startTime = getTime();
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}
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CURLcode res = curl_easy_perform(curl);
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if (showProgress)
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//std::cerr << "\e[" << moveBack << "D\e[K\n";
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std::cerr << "\n";
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checkInterrupt();
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if (res == CURLE_WRITE_ERROR && etag == options.expectedETag) return false;
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long httpStatus = -1;
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curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &httpStatus);
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if (res != CURLE_OK) {
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Error err =
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httpStatus == 404 ? NotFound :
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httpStatus == 403 ? Forbidden :
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(httpStatus == 408 || httpStatus == 500 || httpStatus == 503
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|| httpStatus == 504 || httpStatus == 522 || httpStatus == 524
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|| res == CURLE_COULDNT_RESOLVE_HOST) ? Transient :
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Misc;
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if (res == CURLE_HTTP_RETURNED_ERROR && httpStatus != -1)
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throw DownloadError(err, format("unable to download ‘%s’: HTTP error %d")
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% url % httpStatus);
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else
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throw DownloadError(err, format("unable to download ‘%s’: %s (%d)")
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% url % curl_easy_strerror(res) % res);
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}
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if (httpStatus == 304) return false;
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return true;
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}
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DownloadResult download(string url, const DownloadOptions & options) override
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{
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size_t attempt = 0;
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while (true) {
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try {
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DownloadResult res;
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if (fetch(resolveUri(url), options)) {
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res.cached = false;
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res.data = data;
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} else
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res.cached = true;
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res.etag = etag;
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return res;
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} catch (DownloadError & e) {
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attempt++;
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if (e.error != Transient || attempt >= options.tries) throw;
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auto ms = 25 * (1 << (attempt - 1));
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printMsg(lvlError, format("warning: %s; retrying in %d ms") % e.what() % ms);
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std::this_thread::sleep_for(std::chrono::milliseconds(ms));
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}
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}
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}
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};
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ref<Downloader> makeDownloader()
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{
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return make_ref<CurlDownloader>();
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}
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Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, const Hash & expectedHash)
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{
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auto url = resolveUri(url_);
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string name;
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auto p = url.rfind('/');
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if (p != string::npos) name = string(url, p + 1);
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Path expectedStorePath;
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if (expectedHash) {
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expectedStorePath = store->makeFixedOutputPath(unpack, expectedHash, name);
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if (store->isValidPath(expectedStorePath))
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return expectedStorePath;
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}
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Path cacheDir = getCacheDir() + "/nix/tarballs";
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createDirs(cacheDir);
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string urlHash = printHash32(hashString(htSHA256, url));
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Path dataFile = cacheDir + "/" + urlHash + ".info";
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Path fileLink = cacheDir + "/" + urlHash + "-file";
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Path storePath;
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string expectedETag;
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int ttl = settings.get("tarball-ttl", 60 * 60);
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bool skip = false;
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if (pathExists(fileLink) && pathExists(dataFile)) {
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storePath = readLink(fileLink);
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store->addTempRoot(storePath);
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if (store->isValidPath(storePath)) {
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auto ss = tokenizeString<vector<string>>(readFile(dataFile), "\n");
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if (ss.size() >= 3 && ss[0] == url) {
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time_t lastChecked;
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if (string2Int(ss[2], lastChecked) && lastChecked + ttl >= time(0))
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skip = true;
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else if (!ss[1].empty()) {
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printMsg(lvlDebug, format("verifying previous ETag ‘%1%’") % ss[1]);
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expectedETag = ss[1];
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}
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}
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} else
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storePath = "";
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}
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if (!skip) {
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try {
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DownloadOptions options;
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options.expectedETag = expectedETag;
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auto res = download(url, options);
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if (!res.cached) {
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ValidPathInfo info;
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StringSink sink;
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dumpString(*res.data, sink);
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Hash hash = hashString(expectedHash ? expectedHash.type : htSHA256, *res.data);
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info.path = store->makeFixedOutputPath(false, hash, name);
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info.narHash = hashString(htSHA256, *sink.s);
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store->addToStore(info, *sink.s, false, true);
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storePath = info.path;
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}
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assert(!storePath.empty());
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replaceSymlink(storePath, fileLink);
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writeFile(dataFile, url + "\n" + res.etag + "\n" + std::to_string(time(0)) + "\n");
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} catch (DownloadError & e) {
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if (storePath.empty()) throw;
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printMsg(lvlError, format("warning: %1%; using cached result") % e.msg());
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}
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}
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if (unpack) {
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Path unpackedLink = cacheDir + "/" + baseNameOf(storePath) + "-unpacked";
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Path unpackedStorePath;
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if (pathExists(unpackedLink)) {
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unpackedStorePath = readLink(unpackedLink);
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store->addTempRoot(unpackedStorePath);
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if (!store->isValidPath(unpackedStorePath))
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unpackedStorePath = "";
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}
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if (unpackedStorePath.empty()) {
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printMsg(lvlInfo, format("unpacking ‘%1%’...") % url);
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Path tmpDir = createTempDir();
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AutoDelete autoDelete(tmpDir, true);
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// FIXME: this requires GNU tar for decompression.
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runProgram("tar", true, {"xf", storePath, "-C", tmpDir, "--strip-components", "1"}, "");
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unpackedStorePath = store->addToStore(name, tmpDir, true, htSHA256, defaultPathFilter, false);
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}
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replaceSymlink(unpackedStorePath, unpackedLink);
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storePath = unpackedStorePath;
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}
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if (expectedStorePath != "" && storePath != expectedStorePath)
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throw nix::Error(format("hash mismatch in file downloaded from ‘%s’") % url);
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return storePath;
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}
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bool isUri(const string & s)
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{
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if (s.compare(0, 8, "channel:") == 0) return true;
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size_t pos = s.find("://");
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if (pos == string::npos) return false;
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string scheme(s, 0, pos);
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return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git";
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}
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}
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