Re: [PATCH ASF bugzilla #56288] mod_proxy_html could rewrite URLs in HTML style attributes too

[Micha Lenk]

Hi,

the patch was missing in my previous mail. See attachment.

Regards,
Micha


On 19.03.2014 22:26, Micha Lenk wrote:

Hi Apache developers,

In HTML you can have <div> tags that have a background image by
providing a style attribute. E.g. this can be done by something fancy
like this:

<div style="background:url(http://www.example.com/fancy-background.png)
right 0px no-repeat; height:325px;">

Currently mod_proxy_html doesn't rewrite the URL in such style
attributes (Thomas, Ewald, this is issue #22583 in our Mantis).

The attached patch tries to fix that by applying the configured string
replacements also on style attributes.

Additionally it tries to make the code a bit more readable by renaming
the function dump_content() to apply_urlmap(). This is what it actually
does, especially after the call to AP_fwrite() has been moved outside of
this function.

Please note that this patch requires the patch from issue #56284 to be
applied first. Otherwise the last chunk will not apply. The attached
patch is based on httpd trunk, rev. 1579365 plus the patch for issue
#56284 applied.

Regards,
Micha

diff --git a/modules/filters/mod_proxy_html.c b/modules/filters/mod_proxy_html.c
index 04e4ab7..12fb008 100644
--- a/modules/filters/mod_proxy_html.c
+++ b/modules/filters/mod_proxy_html.c
@@ -201,7 +201,7 @@ static void pappend(saxctxt *ctx, const char *buf, const size_t len)
     ctx->offset += len;
 }
 
-static void dump_content(saxctxt *ctx)
+static void apply_urlmap(saxctxt *ctx)
 {
     urlmap *m;
     char *found;
@@ -281,7 +281,6 @@ static void dump_content(saxctxt *ctx)
             }
         }
     }
-    AP_fwrite(ctx, ctx->buf, strlen(ctx->buf), 1);
 }
 static void pcdata(void *ctxt, const xmlChar *uchars, int length)
 {
@@ -338,8 +337,9 @@ static void pendElement(void *ctxt, const xmlChar *uname)
     /* nah.  Keeping the stack is too much overhead */
 
     if (ctx->offset > 0) {
-        dump_content(ctx);
-        ctx->offset = 0;        /* having dumped it, we can re-use the memory */
+        apply_urlmap(ctx);
+        AP_fwrite(ctx, ctx->buf, strlen(ctx->buf), 1);
+        ctx->offset = 0;        /* having written the buffer, we can re-use it */
     }
     if (!desc || !desc->empty) {
         ap_fprintf(ctx->f->next, ctx->bb, "</%s>", name);
@@ -628,6 +628,12 @@ static void pstartElement(void *ctxt, const xmlChar *uname,
                    anything that needs it in the value.
                 */
                 ap_fputstrs(ctx->f->next, ctx->bb, " ", a[0], "=\"", NULL);
+                if (!strcasecmp(a[0], "style")) {
+                    /* apply URL map on attribute value */
+                    ap_log_rerror(APLOG_MARK, APLOG_TRACE3, 0, ctx->f->r,
+                                  "applying URLMap on style attribute value: '%s'", ctx->buf);
+                    apply_urlmap(ctx);
+                }
                 pcharacters(ctx, (const xmlChar*)ctx->buf, strlen(ctx->buf));
                 ap_fputc(ctx->f->next, ctx->bb, '"');
             }
@@ -1075,7 +1081,9 @@ static int proxy_css_filter(ap_filter_t *f, apr_bucket_brigade *bb)
             ap_log_rerror(APLOG_MARK, APLOG_TRACE3, 0, f->r, "Processing chunk: [%s]", buf_log);
 
             // Replace matching regexps
-            dump_content(fctx);
+            apply_urlmap(fctx);
+            AP_fwrite(fctx, fctx->buf, strlen(fctx->buf), 1);
+            fctx->offset = 0;        /* having written the buffer, we can re-use it */
         }
         if (APR_BUCKET_IS_EOS(current_bucket)) {
             APR_BUCKET_REMOVE(current_bucket);