From ef7d46723d8a1d00e6dd6dafa5d55e70032c9182 Mon Sep 17 00:00:00 2001
From: Igor Chubin <igor@chub.in>
Date: Mon, 8 Jun 2020 07:26:38 +0200
Subject: [PATCH] dont cache cyclic requests (#460)

---
 cmd/processRequest.go | 19 ++++++++++++++++++-
 lib/cache.py          | 13 +++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/cmd/processRequest.go b/cmd/processRequest.go
index 25209b6..7c44a9f 100644
--- a/cmd/processRequest.go
+++ b/cmd/processRequest.go
@@ -7,15 +7,21 @@ import (
 	"math/rand"
 	"net"
 	"net/http"
+	"strings"
 	"time"
 )
 
 func processRequest(r *http.Request) responseWithHeader {
 	var response responseWithHeader
 
-	foundInCache := false
+	if dontCache(r) {
+		return get(r)
+	}
+
 	cacheDigest := getCacheDigest(r)
 
+	foundInCache := false
+
 	savePeakRequest(cacheDigest, r)
 
 	cacheBody, ok := lruCache.Get(cacheDigest)
@@ -109,6 +115,17 @@ func getCacheDigest(req *http.Request) string {
 	return fmt.Sprintf("%s:%s%s:%s:%s", userAgent, queryHost, queryString, clientIPAddress, lang)
 }
 
+// return true if request should not be cached
+func dontCache(req *http.Request) bool {
+
+	// dont cache cyclic requests
+	loc := strings.Split(req.RequestURI, "?")[0]
+	if strings.Contains(loc, ":") {
+		return true
+	}
+	return false
+}
+
 func readUserIP(r *http.Request) string {
 	IPAddress := r.Header.Get("X-Real-Ip")
 	if IPAddress == "" {
diff --git a/lib/cache.py b/lib/cache.py
index 2dd1151..3317cb7 100644
--- a/lib/cache.py
+++ b/lib/cache.py
@@ -34,8 +34,16 @@ def get_signature(user_agent, query_string, client_ip_address, lang):
     """
     Get cache signature based on `user_agent`, `url_string`,
     `lang`, and `client_ip_address`
+    Return `None` if query should not be cached.
     """
 
+    if "?" in query_string:
+        location = query_string.split("?", 1)[0]
+    else:
+        location = query_string
+    if ":" in location:
+        return None
+
     signature = "%s:%s:%s:%s" % \
         (user_agent, query_string, client_ip_address, lang)
     print(signature)
@@ -48,6 +56,9 @@ def get(signature):
     the `_update_answer` function.
     """
 
+    if not signature:
+        return None
+
     value_record = CACHE.get(signature)
     if not value_record:
         return None
@@ -69,6 +80,8 @@ def store(signature, value):
     """
     Store in cache `value` for `signature`
     """
+    if not signature:
+        return value
 
     if len(value) >= MIN_SIZE_FOR_FILECACHE:
         value_to_store = _store_in_file(signature, value)