[epiphany] uri-helpers: Use ICU to decode punycode for display

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 6b7c6dec3bc1dc91bbda12cccf5c3cfd36397578
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Fri Dec 16 11:55:59 2016 -0600

    uri-helpers: Use ICU to decode punycode for display
    
    This adds support for properly displaying IDNA URIs, instead of showing
    punycode-encoded URIs.
    
    ICU is already a dependency of WebKit.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=747376

 configure.ac           |    1 +
 lib/Makefile.am        |    2 +
 lib/ephy-uri-helpers.c |   56 ++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 55 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 3f8eb26..5d1523e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,6 +107,7 @@ PKG_CHECK_MODULES([GLIB], [glib-2.0 >= $GLIB_REQUIRED])
 PKG_CHECK_MODULES([GNOME_DESKTOP], [gnome-desktop-3.0 >= 2.91.2])
 PKG_CHECK_MODULES([GTK], [gtk+-3.0 >= $GTK_REQUIRED])
 PKG_CHECK_MODULES([GTK_UNIX_PRINT], [gtk+-unix-print-3.0 >= $GTK_REQUIRED])
+PKG_CHECK_MODULES([ICU_UC], [icu-uc >= 4.6])
 PKG_CHECK_MODULES([JSON_GLIB], [json-glib-1.0 >= 1.2.0])
 PKG_CHECK_MODULES([LIBNOTIFY], [libnotify >= 0.5.1])
 PKG_CHECK_MODULES([LIBSECRET], [libsecret-1 >= 0.14])
diff --git a/lib/Makefile.am b/lib/Makefile.am
index f8f21d0..43a25f2 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -74,6 +74,7 @@ libephymisc_la_CPPFLAGS = \
        $(GLIB_CFLAGS)                                  \
        $(GNOME_DESKTOP_CFLAGS)                         \
        $(GTK_CFLAGS)                                   \
+       $(ICU_UC_CFLAGS)                                \
        $(LIBSECRET_CFLAGS)                             \
        $(LIBSOUP_CFLAGS)                               \
        $(LIBXML_CFLAGS)                                \
@@ -95,6 +96,7 @@ libephymisc_la_LIBADD = \
        $(GLIB_LIBS)            \
        $(GNOME_DESKTOP_LIBS)   \
        $(GTK_LIBS)             \
+       $(ICU_UC_LIBS)          \
        $(LIBSECRET_LIBS)       \
        $(LIBSOUP_LIBS)         \
        $(LIBXML_LIBS)          \
diff --git a/lib/ephy-uri-helpers.c b/lib/ephy-uri-helpers.c
index e0a1450..53e5dd1 100644
--- a/lib/ephy-uri-helpers.c
+++ b/lib/ephy-uri-helpers.c
@@ -24,6 +24,7 @@
 #include <glib.h>
 #include <libsoup/soup.h>
 #include <string.h>
+#include <unicode/uidna.h>
 
 /**
  * SECTION:ephy-uri-helpers
@@ -249,18 +250,65 @@ ephy_remove_tracking_from_uri (const char *uri_string)
   return ret;
 }
 
+/* Use this function to format a URI for display. The URIs used
+ * internally by WebKit may contain percent-encoded characters or
+ * punycode, which we do not want the user to see.
+ *
+ * Note this should probably be handled by WebKit instead.
+ */
 char *
 ephy_uri_decode (const char *uri_string)
 {
-  char *decoded_uri;
+  static const guint MAX_DOMAIN_LENGTH = 255;
+  SoupURI *uri;
+  char *percent_encoded_uri;
+  char *idna_decoded_name;
+  char *fully_decoded_uri;
+  UIDNA *idna;
+  UIDNAInfo info = UIDNA_INFO_INITIALIZER;
+  UErrorCode error = U_ZERO_ERROR;
 
   /* This function is not null-safe since it is mostly used in scenarios where
    * passing or returning null would typically lead to a security issue. */
   g_assert (uri_string);
 
-  /* Protect against escaped null characters and escaped slashes. */
-  decoded_uri = g_uri_unescape_string (uri_string, "/");
-  return decoded_uri ? decoded_uri : g_strdup (uri_string);
+  /* Process any punycode in the host portion of the URI. */
+  uri = soup_uri_new (uri_string);
+  if (uri->host != NULL) {
+    /* Ideally this context object would be cached and reused across function
+     * calls. The object is itself threadsafe, but a mutex would still be needed
+     * to create it and assign it to a local variable, unless we use thread-
+     * local storage, which seems overkill for a threadsafe object. So just
+     * create a new one on each call for now. */
+    idna = uidna_openUTS46 (UIDNA_DEFAULT, &error);
+    if (U_FAILURE (error))
+      g_error ("ICU error opening UTS #46 context: %d", error);
+
+    idna_decoded_name = g_malloc (MAX_DOMAIN_LENGTH);
+    uidna_nameToUnicodeUTF8 (idna, uri->host, -1, idna_decoded_name, MAX_DOMAIN_LENGTH, &info, &error);
+    uidna_close (idna);
+
+    if (U_FAILURE (error)) {
+      g_warning ("ICU error converting domain %s for display: %d", uri->host, error);
+      return g_strdup (uri_string);
+    }
+
+    g_free (uri->host);
+    uri->host = idna_decoded_name;
+  }
+
+  /* Note: this also strips passwords from the display URI. */
+  percent_encoded_uri = soup_uri_to_string (uri, FALSE);
+  soup_uri_free (uri);
+
+  /* Now, decode any percent-encoded characters in the URI. If there are null
+   * characters or escaped slashes, this returns NULL, so just display the
+   * encoded URI in that case. */
+  fully_decoded_uri = g_uri_unescape_string (percent_encoded_uri, "/");
+  if (fully_decoded_uri == NULL)
+    return percent_encoded_uri;
+  g_free (percent_encoded_uri);
+  return fully_decoded_uri;
 }
 
 char *