http: always update the base URL for redirects

diff --git a/http.c b/http.c
index df6dd01594a0c7bacbb9beacec683072de38a5b1..718d2109bcd1d6f2a887b180aea094e8b4d8e4d1 100644 (file)
--- a/http.c
+++ b/http.c
@@ -1105,7 +1105,7 @@ void append_remote_object_url(struct strbuf *buf, const char *url,
 
        strbuf_addf(buf, "objects/%.*s/", 2, hex);
        if (!only_two_digit_prefix)
-               strbuf_addf(buf, "%s", hex+2);
+               strbuf_addstr(buf, hex + 2);
 }
 
 char *get_remote_object_url(const char *url, const char *hex,
@@ -1491,16 +1491,16 @@ static int http_request(const char *url,
  *
  * Note that this assumes a sane redirect scheme. It's entirely possible
  * in the example above to end up at a URL that does not even end in
- * "info/refs".  In such a case we simply punt, as there is not much we can
- * do (and such a scheme is unlikely to represent a real git repository,
- * which means we are likely about to abort anyway).
+ * "info/refs".  In such a case we die. There's not much we can do, such a
+ * scheme is unlikely to represent a real git repository, and failing to
+ * rewrite the base opens options for malicious redirects to do funny things.
  */
 static int update_url_from_redirect(struct strbuf *base,
                                    const char *asked,
                                    const struct strbuf *got)
 {
        const char *tail;
-       size_t tail_len;
+       size_t new_len;
 
        if (!strcmp(asked, got->buf))
                return 0;
@@ -1509,14 +1509,16 @@ static int update_url_from_redirect(struct strbuf *base,
                die("BUG: update_url_from_redirect: %s is not a superset of %s",
                    asked, base->buf);
 
-       tail_len = strlen(tail);
-
-       if (got->len < tail_len ||
-           strcmp(tail, got->buf + got->len - tail_len))
-               return 0; /* insane redirect scheme */
+       new_len = got->len;
+       if (!strip_suffix_mem(got->buf, &new_len, tail))
+               die(_("unable to update url base from redirection:\n"
+                     "  asked for: %s\n"
+                     "   redirect: %s"),
+                   asked, got->buf);
 
        strbuf_reset(base);
-       strbuf_add(base, got->buf, got->len - tail_len);
+       strbuf_add(base, got->buf, new_len);
+
        return 1;
 }