Disable TLS verification for builtin fetchurl

This makes it consistent with the Nixpkgs fetchurl and makes it work
in chroots. We don't need verification because the hash of the result
is checked anyway.

src/libstore/builtins.cc

@@ -8,7 +8,13 @@ void builtinFetchurl(const BasicDerivation & drv)
     auto url = drv.env.find("url");
     if (url == drv.env.end()) throw Error("attribute ‘url’ missing");
     printMsg(lvlInfo, format("downloading ‘%1%’...") % url->second);
-    auto data = downloadFile(url->second); // FIXME: show progress
+
+    /* No need to do TLS verification, because we check the hash of
+       the result anyway. */
+    DownloadOptions options;
+    options.verifyTLS = false;
+
+    auto data = downloadFile(url->second, options); // FIXME: show progress
 
     auto out = drv.env.find("out");
     if (out == drv.env.end()) throw Error("attribute ‘url’ missing");

src/libstore/download.cc

@@ -102,7 +102,6 @@ struct Curl
         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);
 
@@ -125,10 +124,17 @@ struct Curl
         if (requestHeaders) curl_slist_free_all(requestHeaders);
     }
 
-    bool fetch(const string & url, const string & expectedETag = "")
+    bool fetch(const string & url, const DownloadOptions & options)
     {
         curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
 
+        if (options.verifyTLS)
+            curl_easy_setopt(curl, CURLOPT_CAINFO, getEnv("SSL_CERT_FILE", "/etc/ssl/certs/ca-certificates.crt").c_str());
+        else {
+            curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
+            curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
+        }
+
         data.clear();
 
         if (requestHeaders) {
@@ -136,9 +142,9 @@ struct Curl
             requestHeaders = 0;
         }
 
-        if (!expectedETag.empty()) {
-            this->expectedETag = expectedETag;
-            requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + expectedETag).c_str());
+        if (!options.expectedETag.empty()) {
+            this->expectedETag = options.expectedETag;
+            requestHeaders = curl_slist_append(requestHeaders, ("If-None-Match: " + options.expectedETag).c_str());
         }
 
         curl_easy_setopt(curl, CURLOPT_HTTPHEADER, requestHeaders);
@@ -154,7 +160,7 @@ struct Curl
             //std::cerr << "\e[" << moveBack << "D\e[K\n";
             std::cerr << "\n";
         checkInterrupt();
-        if (res == CURLE_WRITE_ERROR && etag == expectedETag) return false;
+        if (res == CURLE_WRITE_ERROR && etag == options.expectedETag) return false;
         if (res != CURLE_OK)
             throw DownloadError(format("unable to download ‘%1%’: %2% (%3%)")
                 % url % curl_easy_strerror(res) % res);
@@ -168,11 +174,11 @@ struct Curl
 };
 
 
-DownloadResult downloadFile(string url, string expectedETag)
+DownloadResult downloadFile(string url, const DownloadOptions & options)
 {
     DownloadResult res;
     Curl curl;
-    if (curl.fetch(url, expectedETag)) {
+    if (curl.fetch(url, options)) {
         res.cached = false;
         res.data = curl.data;
     } else
@@ -224,7 +230,9 @@ Path downloadFileCached(const string & url, bool unpack)
     if (!skip) {
 
         try {
-            auto res = downloadFile(url, expectedETag);
+            DownloadOptions options;
+            options.expectedETag = expectedETag;
+            auto res = downloadFile(url, options);
 
             if (!res.cached)
                 storePath = store->addTextToStore(name, res.data, PathSet(), false);

src/libstore/download.hh

@@ -5,13 +5,19 @@
 
 namespace nix {
 
+struct DownloadOptions
+{
+    string expectedETag;
+    bool verifyTLS{true};
+};
+
 struct DownloadResult
 {
     bool cached;
     string data, etag;
 };
 
-DownloadResult downloadFile(string url, string expectedETag = "");
+DownloadResult downloadFile(string url, const DownloadOptions & options);
 
 Path downloadFileCached(const string & url, bool unpack);
 

src/nix-prefetch-url/nix-prefetch-url.cc

@@ -158,7 +158,7 @@ int main(int argc, char * * argv)
             auto actualUri = resolveMirrorUri(state, uri);
 
             /* Download the file. */
-            auto result = downloadFile(actualUri);
+            auto result = downloadFile(actualUri, DownloadOptions());
 
             AutoDelete tmpDir(createTempDir(), true);
             Path tmpFile = (Path) tmpDir + "/tmp";