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#include "download.hh"
#include "util.hh"
#include "globals.hh"
#include <curl/curl.h>
namespace nix {
struct Curl
{
CURL * curl;
string data;
string etag, status, expectedETag;
struct curl_slist * requestHeaders;
static size_t writeCallback(void * contents, size_t size, size_t nmemb, void * userp)
{
Curl & c(* (Curl *) userp);
size_t realSize = size * nmemb;
c.data.append((char *) contents, realSize);
return realSize;
}
static size_t headerCallback(void * contents, size_t size, size_t nmemb, void * userp)
{
Curl & c(* (Curl *) userp);
size_t realSize = size * nmemb;
string line = string((char *) contents, realSize);
printMsg(lvlVomit, format("got header: %1%") % trim(line));
if (line.compare(0, 5, "HTTP/") == 0) { // new response starts
c.etag = "";
auto ss = tokenizeString<vector<string>>(line, " ");
c.status = ss.size() >= 2 ? ss[1] : "";
} else {
auto i = line.find(':');
if (i != string::npos) {
string name = trim(string(line, 0, i));
if (name == "ETag") { // FIXME: case
c.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. */
printMsg(lvlDebug, format("got ETag: %1%") % c.etag);
if (c.etag == c.expectedETag && c.status == "200") {
printMsg(lvlDebug, format("shutting down on 200 HTTP response with expected ETag"));
return 0;
}
}
}
}
return realSize;
}
Curl()
{
requestHeaders = 0;
curl = curl_easy_init();
if (!curl) throw Error("unable to initialize curl");
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
curl_easy_setopt(curl, CURLOPT_USERAGENT, ("Nix/" + nixVersion).c_str());
curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *) &curl);
curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, headerCallback);
curl_easy_setopt(curl, CURLOPT_HEADERDATA, (void *) &curl);
}
~Curl()
{
if (curl) curl_easy_cleanup(curl);
if (requestHeaders) curl_slist_free_all(requestHeaders);
}
bool fetch(const string & url, const string & expectedETag = "")
{
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
data.clear();
if (requestHeaders) {
curl_slist_free_all(requestHeaders);
requestHeaders = 0;
}
if (!expectedETag.empty()) {
this->expectedETag = expectedETag;
requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + expectedETag).c_str());
}
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, requestHeaders);
CURLcode res = curl_easy_perform(curl);
if (res == CURLE_WRITE_ERROR && etag == expectedETag) return false;
if (res != CURLE_OK)
throw DownloadError(format("unable to download ‘%1%’: %2% (%3%)")
% url % curl_easy_strerror(res) % res);
long httpStatus = 0;
curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &httpStatus);
if (httpStatus == 304) return false;
return true;
}
};
DownloadResult downloadFile(string url, string expectedETag)
{
DownloadResult res;
Curl curl;
if (curl.fetch(url, expectedETag)) {
res.cached = false;
res.data = curl.data;
} else
res.cached = true;
res.etag = curl.etag;
return res;
}
}
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