Proof not showing up (#1028)

* fix proof header

* fix set directive

* var mismatch

* var mismatch

* add comments

docker/nginx/conf.d/client.conf

@@ -426,6 +426,10 @@ server {
 		set $skylink_v1 $skylink;
 		set $skylink_v2 $skylink;
 
+		# variable for Skynet-Proof header that we need to inject 
+		# into a response if the request was for skylink v2
+		set $skynet_proof '';
+
 		access_by_lua_block {
 			-- detect whether requested skylink is v2
 			local isBase32v2 = string.len(ngx.var.skylink) == 55 and string.sub(ngx.var.skylink, 0, 2) == "04"
@@ -437,6 +441,7 @@ server {
 					local json = require('cjson')
 					local resolve = json.decode(res.body)
 					ngx.var.skylink_v1 = resolve.skylink
+					ngx.var.skynet_proof = res.header["Skynet-Proof"]
 				end
 			end
 
@@ -451,10 +456,20 @@ server {
 			end
 		}
 
+		header_filter_by_lua_block {
+			-- not empty skynet_proof means this is a skylink v2 request
+			-- so we should replace the Skynet-Proof header with the one
+			-- we got from /skynet/resolve/ endpoint, otherwise we would
+			-- be serving cached empty v1 skylink Skynet-Proof header
+			if ngx.var.skynet_proof then
+				ngx.header["Skynet-Proof"] = ngx.var.skynet_proof
+			end
+		}
+
 		proxy_read_timeout 600;
 		proxy_set_header User-Agent: Sia-Agent;
 		
-		proxy_pass http://siad/skynet/skylink/$skylink$path$is_args$args;
+		proxy_pass http://siad/skynet/skylink/$skylink_v1$path$is_args$args;
 	}
 
 	location @dnslink_lookup {