/pidgin/main: 7ca529729634: Remove purple_util_get_image_checksu...

[Mark Doliner]

Changeset: 7ca52972963453b64c3fef3549442e3bd5e64175
Author:	 Mark Doliner <mark at kingant.net>
Date:	 2013-02-18 22:13 -0800
Branch:	 default
URL: http://hg.pidgin.im/pidgin/main/rev/7ca529729634

Description:

Remove purple_util_get_image_checksum and use
 g_compute_checksum_for_data(G_CHECKSUM_SHA1, ...), instead

diffstat:

 ChangeLog.API      |   2 ++
 libpurple/smiley.c |   3 ++-
 libpurple/util.c   |  38 +++++---------------------------------
 libpurple/util.h   |   5 -----
 4 files changed, 9 insertions(+), 39 deletions(-)

diffs (91 lines):

diff --git a/ChangeLog.API b/ChangeLog.API
--- a/ChangeLog.API
+++ b/ChangeLog.API
@@ -231,6 +231,8 @@ version 3.0.0 (??/??/????):
 		* purple_util_fetch_url_request, instead.
 		* purple_util_fetch_url_request_len_with_account.  Use
 		  purple_util_fetch_url_request, instead.
+		* purple_util_get_image_checksum.  Use
+		  g_compute_checksum_for_data(G_CHECKSUM_SHA1, ...), instead.
 		* PurpleCertificateVerificationStatus.PURPLE_CERTIFICATE_INVALID
 		* PurpleConnectionUiOps.report_disconnect_reason
 		* PurplePluginProtocolInfo.add_buddy_with_invite
diff --git a/libpurple/smiley.c b/libpurple/smiley.c
--- a/libpurple/smiley.c
+++ b/libpurple/smiley.c
@@ -348,7 +348,8 @@ purple_smiley_set_property(GObject *obje
 
 				smiley->img = img;
 				if (img) {
-					smiley->checksum = purple_util_get_image_checksum(
+					smiley->checksum = g_compute_checksum_for_data(
+							G_CHECKSUM_SHA1,
 							purple_imgstore_get_data(img),
 							purple_imgstore_get_size(img));
 					purple_smiley_data_store(img);
diff --git a/libpurple/util.c b/libpurple/util.c
--- a/libpurple/util.c
+++ b/libpurple/util.c
@@ -3180,42 +3180,14 @@ purple_util_get_image_extension(gconstpo
 	return "icon";
 }
 
-/*
- * We thought about using non-cryptographic hashes like CRC32 here.
- * They would be faster, but we think using something more secure is
- * important, so that it is more difficult for someone to maliciously
- * replace one buddy's icon with something else.
- */
-char *
-purple_util_get_image_checksum(gconstpointer image_data, size_t image_len)
-{
-	PurpleCipherContext *context;
-	gchar digest[41];
-
-	context = purple_cipher_context_new_by_name("sha1", NULL);
-	if (context == NULL)
-	{
-		purple_debug_error("util", "Could not find sha1 cipher\n");
-		g_return_val_if_reached(NULL);
-	}
-
-	/* Hash the image data */
-	purple_cipher_context_append(context, image_data, image_len);
-	if (!purple_cipher_context_digest_to_str(context, sizeof(digest), digest, NULL))
-	{
-		purple_debug_error("util", "Failed to get SHA-1 digest.\n");
-		g_return_val_if_reached(NULL);
-	}
-	purple_cipher_context_destroy(context);
-
-	return g_strdup(digest);
-}
-
 char *
 purple_util_get_image_filename(gconstpointer image_data, size_t image_len)
 {
-	/* Return the filename */
-	char *checksum = purple_util_get_image_checksum(image_data, image_len);
+	/* Use a cryptographic hash to avoid the possibility of user A
+	   intentionally causing a collision with user B.  It's not a
+	   horrible problem, but it's something we should try to avoid. */
+	char *checksum = g_compute_checksum_for_data(G_CHECKSUM_SHA1,
+			image_data, image_len);
 	char *filename = g_strdup_printf("%s.%s", checksum,
 	                       purple_util_get_image_extension(image_data, image_len));
 	g_free(checksum);
diff --git a/libpurple/util.h b/libpurple/util.h
--- a/libpurple/util.h
+++ b/libpurple/util.h
@@ -823,11 +823,6 @@ const char *
 purple_util_get_image_extension(gconstpointer data, size_t len);
 
 /**
- * Returns a SHA-1 hash string of the data passed in.
- */
-char *purple_util_get_image_checksum(gconstpointer image_data, size_t image_len);
-
-/**
  * @return A hex encoded version of the SHA-1 hash of the data passed
  *         in with the correct file extention appended.  The file
  *         extension is determined by calling