only dowload CRL once

hooks/timestamping

@@ -535,7 +535,7 @@ download_crls_for_chain() {
   assert "[ -f $CERT_FILE ]" "Precondition: Certificate file $CERT_FILE must exist."
 
   echo -n > "$OUTPUT_FILE"
-  local CRL_TMP="$TMP_DIR"/crl_tmp.crl
+
   #remove files from possible previous runs
   rm -f "$TMP_DIR"/*.extracted.pem.cer
   #extract all contained certificates into separate files
@@ -553,7 +553,13 @@ download_crls_for_chain() {
       local URL=$(openssl x509 -inform PEM -in $EXTRACTED_CERT -text -noout \
                   | awk '/CRL Distribution Points:/{f=1} f && /URI:/ {print; exit}' \
                   | sed 's/^.*URI://1')
-      if curl -L "$URL" --output "$CRL_TMP" &> "$OUT_STREAM"; then
+      local CRL_TMP="$TMP_DIR"/crl_tmp.$(echo "$URL" | sha256sum -z | awk '{printf "%s",$1}').crl
+      local CURL_EXIT_CODE=0
+      if [ ! -f $CRL_TMP ]; then
+        curl -L "$URL" --output "$CRL_TMP" &> "$OUT_STREAM"
+        CURL_EXIT_CODE=$?
+      fi
+      if [ $CURL_EXIT_CODE -eq 0 ]; then
         if openssl crl -in "$CRL_TMP" -inform DER -noout &> "$OUT_STREAM"; then
           openssl crl -in "$CRL_TMP" -inform DER >> "$OUTPUT_FILE"
         elif openssl crl -in "$CRL_TMP" -inform PEM -noout &> "$OUT_STREAM"; then