log_ref_setup(): improve robustness against races

diff --git a/http-walker.c b/http-walker.c
index c2f81cd6af9d9da0f10fa2e657e6fe62bdbdc4bc..b34b6ace7cd80a482eae16e2063aa9d8960e8729 100644 (file)
--- a/http-walker.c
+++ b/http-walker.c
@@ -3,6 +3,7 @@
 #include "walker.h"
 #include "http.h"
 #include "list.h"
+#include "transport.h"
 
 struct alt_base {
        char *base;
@@ -160,6 +161,32 @@ static void prefetch(struct walker *walker, unsigned char *sha1)
 #endif
 }
 
+static int is_alternate_allowed(const char *url)
+{
+       const char *protocols[] = {
+               "http", "https", "ftp", "ftps"
+       };
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(protocols); i++) {
+               const char *end;
+               if (skip_prefix(url, protocols[i], &end) &&
+                   starts_with(end, "://"))
+                       break;
+       }
+
+       if (i >= ARRAY_SIZE(protocols)) {
+               warning("ignoring alternate with unknown protocol: %s", url);
+               return 0;
+       }
+       if (!is_transport_allowed(protocols[i], 0)) {
+               warning("ignoring alternate with restricted protocol: %s", url);
+               return 0;
+       }
+
+       return 1;
+}
+
 static void process_alternates_response(void *callback_data)
 {
        struct alternates_request *alt_req =
@@ -274,17 +301,20 @@ static void process_alternates_response(void *callback_data)
                                struct strbuf target = STRBUF_INIT;
                                strbuf_add(&target, base, serverlen);
                                strbuf_add(&target, data + i, posn - i - 7);
-                               warning("adding alternate object store: %s",
-                                       target.buf);
-                               newalt = xmalloc(sizeof(*newalt));
-                               newalt->next = NULL;
-                               newalt->base = strbuf_detach(&target, NULL);
-                               newalt->got_indices = 0;
-                               newalt->packs = NULL;
-
-                               while (tail->next != NULL)
-                                       tail = tail->next;
-                               tail->next = newalt;
+
+                               if (is_alternate_allowed(target.buf)) {
+                                       warning("adding alternate object store: %s",
+                                               target.buf);
+                                       newalt = xmalloc(sizeof(*newalt));
+                                       newalt->next = NULL;
+                                       newalt->base = strbuf_detach(&target, NULL);
+                                       newalt->got_indices = 0;
+                                       newalt->packs = NULL;
+
+                                       while (tail->next != NULL)
+                                               tail = tail->next;
+                                       tail->next = newalt;
+                               }
                        }
                }
                i = posn + 1;