Using proxy for zarr data and metadata

include/zarr.h

@@ -94,6 +94,7 @@ class ZarrFunctions: public ZarrTypes
  std::unique_ptr<GenericCache> cache;
  CURLRAII                      chandle;
  MString                       url;
+ MString                       proxyurl;
 
  std::vector<std::vector<size_t>> chunks;
 
@@ -107,6 +108,8 @@ class ZarrFunctions: public ZarrTypes
  {
   auto oldprefix = michlib::GPL.UsePrefix("ZARR");
   cache.reset(CreateCache(michlib::GPL.ParameterSValue("Cache", "")));
+  proxyurl = michlib::GPL.ParameterSValue("Proxy", "");
+  if(proxyurl.Exist()) curl_easy_setopt(chandle, CURLOPT_PROXY, proxyurl.Buf());
   michlib::GPL.UsePrefix(oldprefix);
   if(!cache)
   {

src/zarr.cpp

@@ -171,6 +171,7 @@ Error ZarrFunctions::GetChunk(const MString& var, const std::vector<size_t>& chu
  {
   michlib::message(str + " not found in cache, downloading");
   CURLRAII myhandle; // TODO: remove this workaround of unknown bug
+  if(proxyurl.Exist()) curl_easy_setopt(myhandle, CURLOPT_PROXY, proxyurl.Buf());
   //auto [out, res] = GetUrl(chandle, str);
   auto [out, res] = GetUrl(myhandle, str);
   if(res != CURLE_OK) return Error(pref, MString("can't download chunk: ") + chandle.Err());