Backported and commited

jimjag · jimjag · commit 1c1cd8611bd5 · 2009-03-10T15:00:54.000Z
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@752129 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/STATUS b/STATUS
@@ -86,16 +86,6 @@ RELEASE SHOWSTOPPERS:
 PATCHES ACCEPTED TO BACKPORT FROM TRUNK:
   [ start all new proposals below, under PATCHES PROPOSED. ]
 
- * mod_deflate: Fix creation of invalid Etags with mod_deflate
-   (PR 39727, comment #22)
-   (updated to use Roy's patch)
-   Trunk version of patch:
-      (http://svn.apache.org/viewvc?view=rev&revision=740149)
-      http://svn.apache.org/viewvc?view=rev&revision=743595
-   Backport version for 2.2.x of patch:
-      http://people.apache.org/~lars/mod_deflate_etagfix.patch 
-   +1: lars, fielding, minfrin
-
 
 PATCHES PROPOSED TO BACKPORT FROM TRUNK:
   [ New proposals should be added at the end of the list ]
diff --git a/modules/filters/mod_deflate.c b/modules/filters/mod_deflate.c
@@ -372,22 +372,40 @@ static apr_status_t deflate_ctx_cleanup(void *data)
         ctx->libz_end_func(&ctx->stream);
     return APR_SUCCESS;
 }
-/* PR 39727: we're screwing up our clients if we leave a strong ETag
- * header while transforming content.  Henrik Nordstrom suggests
- * appending ";gzip".
- *
- * Pending a more thorough review of our Etag handling, let's just
- * implement his suggestion.  It fixes the bug, or at least turns it
- * from a showstopper to an inefficiency.  And it breaks nothing that
- * wasn't already broken.
+/* ETag must be unique among the possible representations, so a change
+ * to content-encoding requires a corresponding change to the ETag.
+ * This routine appends -transform (e.g., -gzip) to the entity-tag
+ * value inside the double-quotes if an ETag has already been set
+ * and its value already contains double-quotes. PR 39727
  */
 static void deflate_check_etag(request_rec *r, const char *transform)
 {
     const char *etag = apr_table_get(r->headers_out, "ETag");
-    if (etag && (((etag[0] != 'W') && (etag[0] !='w')) || (etag[1] != '/'))) {
-        apr_table_set(r->headers_out, "ETag",
-                      apr_pstrcat(r->pool, etag, "-", transform, NULL));
-    }
+    apr_size_t etaglen;
+
+    if ((etag && ((etaglen = strlen(etag)) > 2))) {
+        if (etag[etaglen - 1] == '"') {
+            apr_size_t transformlen = strlen(transform);
+            char *newtag = apr_palloc(r->pool, etaglen + transformlen + 2);
+            char *d = newtag;
+            char *e = d + etaglen - 1;
+            const char *s = etag;
+
+            for (; d < e; ++d, ++s) {
+                *d = *s;          /* copy etag to newtag up to last quote */
+            }
+            *d++ = '-';           /* append dash to newtag */
+            s = transform;
+            e = d + transformlen;
+            for (; d < e; ++d, ++s) {
+                *d = *s;          /* copy transform to newtag */
+            }
+            *d++ = '"';           /* append quote to newtag */
+            *d   = '\0';          /* null terminate newtag */
+
+            apr_table_setn(r->headers_out, "ETag", newtag);
+        }
+    }   
 }
 static apr_status_t deflate_out_filter(ap_filter_t *f,
                                        apr_bucket_brigade *bb)
