arbitrary masks. This is much like the equivalent OpenFlow
1.1 feature.
- - However, unlike OpenFlow 1.1, OFPC_MODIFY and
- OFPFC_MODIFY_STRICT, regardless of whether there was a match
- based on a cookie or not, always add a new flow if there is
- no match, and they always update the cookies of flows that
- they do match.
+ - Like OpenFlow 1.1, OFPC_MODIFY and OFPFC_MODIFY_STRICT add a
+ new flow if there is no match and the mask is zero (or not
+ given).
+
+ - The "cookie" field in OFPT_FLOW_MOD and NXT_FLOW_MOD messages
+ is used as the cookie value for OFPFC_ADD commands, as
+ described in OpenFlow 1.0. For OFPFC_MODIFY and
+ OFPFC_MODIFY_STRICT commands, the "cookie" field is used as a
+ new cookie for flows that match unless it is UINT64_MAX, in
+ which case the flow's cookie is not updated.
- NXT_PACKET_IN (the Nicira extended version of
OFPT_PACKET_IN) reports the cookie of the rule that
packet. (Older versions of OVS used all-0-bits instead of
all-1-bits.)
+The following table shows the handling of different protocols when
+receiving OFPFC_MODIFY and OFPFC_MODIFY_STRICT messages. A mask of 0
+indicates either an explicit mask of zero or an implicit one by not
+specifying the NXM_NX_COOKIE(_W) field.
+
+ Match Update Add on miss Add on miss
+ cookie cookie mask!=0 mask==0
+ ====== ====== =========== ===========
+OpenFlow 1.0 no yes <always add on miss>
+OpenFlow 1.1 yes no no yes
+OpenFlow 1.2 yes no no no
+NXM yes yes* no yes
+
+* Updates the flow's cookie unless the "cookie" field is UINT64_MAX.
+
Multiple Table Support
======================
/* NXT_FLOW_MOD (analogous to OFPT_FLOW_MOD).
*
* It is possible to limit flow deletions and modifications to certain
- * cookies by using the NXM_NX_COOKIE and NXM_NX_COOKIE_W matches. For
- * these commands, the "cookie" field is always ignored. Flow additions
- * make use of the "cookie" field and ignore any NXM_NX_COOKIE*
- * definitions.
+ * cookies by using the NXM_NX_COOKIE(_W) matches. The "cookie" field
+ * is used only to add or modify flow cookies.
*/
struct nx_flow_mod {
struct nicira_header nxh;
struct ofpbuf actions;
cls_rule_init_catchall(&fm->cr, ntohs(learn->priority));
- fm->cookie = learn->cookie;
- fm->cookie_mask = htonll(UINT64_MAX);
+ fm->cookie = htonll(0);
+ fm->cookie_mask = htonll(0);
+ fm->new_cookie = learn->cookie;
fm->table_id = learn->table_id;
fm->command = OFPFC_MODIFY_STRICT;
fm->idle_timeout = ntohs(learn->idle_timeout);
cls_rule_init_catchall(&fm->cr, OFP_DEFAULT_PRIORITY);
fm->cookie = htonll(0);
fm->cookie_mask = htonll(0);
+ if (command == OFPFC_MODIFY || command == OFPFC_MODIFY_STRICT) {
+ /* For modify, by default, don't update the cookie. */
+ fm->new_cookie = htonll(UINT64_MAX);
+ } else{
+ fm->new_cookie = htonll(0);
+ }
fm->table_id = 0xff;
fm->command = command;
fm->idle_timeout = OFP_FLOW_PERMANENT;
fm->hard_timeout = str_to_u16(value, name);
} else if (!strcmp(name, "cookie")) {
char *mask = strchr(value, '/');
+
if (mask) {
+ /* A mask means we're searching for a cookie. */
if (command == OFPFC_ADD) {
ofp_fatal(str_, verbose, "flow additions cannot use "
"a cookie mask");
}
*mask = '\0';
+ fm->cookie = htonll(str_to_u64(value));
fm->cookie_mask = htonll(str_to_u64(mask+1));
} else {
- fm->cookie_mask = htonll(UINT64_MAX);
+ /* No mask means that the cookie is being set. */
+ if (command != OFPFC_ADD && command != OFPFC_MODIFY
+ && command != OFPFC_MODIFY_STRICT) {
+ ofp_fatal(str_, verbose, "cannot set cookie");
+ }
+ fm->new_cookie = htonll(str_to_u64(value));
}
- fm->cookie = htonll(str_to_u64(value));
} else if (mf_from_name(name)) {
parse_field(mf_from_name(name), value, &fm->cr);
} else if (!strcmp(name, "duration")
}
}
}
+ if (!fm->cookie_mask && fm->new_cookie == htonll(UINT64_MAX)
+ && (command == OFPFC_MODIFY || command == OFPFC_MODIFY_STRICT)) {
+ /* On modifies without a mask, we are supposed to add a flow if
+ * one does not exist. If a cookie wasn't been specified, use a
+ * default of zero. */
+ fm->new_cookie = htonll(0);
+ }
if (fields & F_ACTIONS) {
struct ofpbuf actions;
if (ds_last(s) != ' ') {
ds_put_char(s, ' ');
}
- if (fm.cookie != htonll(0)) {
- ds_put_format(s, "cookie:0x%"PRIx64" ", ntohll(fm.cookie));
+ if (fm.new_cookie != htonll(0)) {
+ ds_put_format(s, "cookie:0x%"PRIx64" ", ntohll(fm.new_cookie));
+ }
+ if (fm.cookie_mask != htonll(0)) {
+ ds_put_format(s, "cookie:0x%"PRIx64"/0x%"PRIx64" ",
+ ntohll(fm.cookie), ntohll(fm.cookie_mask));
}
if (fm.idle_timeout != OFP_FLOW_PERMANENT) {
ds_put_format(s, "idle:%"PRIu16" ", fm.idle_timeout);
ofputil_normalize_rule(&fm->cr);
/* Translate the message. */
- fm->cookie = ofm->cookie;
- fm->cookie_mask = htonll(UINT64_MAX);
command = ntohs(ofm->command);
+ fm->cookie = htonll(0);
+ fm->cookie_mask = htonll(0);
+ fm->new_cookie = ofm->cookie;
fm->idle_timeout = ntohs(ofm->idle_timeout);
fm->hard_timeout = ntohs(ofm->hard_timeout);
fm->buffer_id = ntohl(ofm->buffer_id);
/* Translate the message. */
command = ntohs(nfm->command);
- if (command == OFPFC_ADD) {
- if (fm->cookie_mask) {
- /* The "NXM_NX_COOKIE*" matches are not valid for flow
- * additions. Additions must use the "cookie" field of
- * the "nx_flow_mod" structure. */
- return OFPERR_NXBRC_NXM_INVALID;
- } else {
- fm->cookie = nfm->cookie;
- fm->cookie_mask = htonll(UINT64_MAX);
- }
+ if ((command & 0xff) == OFPFC_ADD && fm->cookie_mask) {
+ /* Flow additions may only set a new cookie, not match an
+ * existing cookie. */
+ return OFPERR_NXBRC_NXM_INVALID;
}
+ fm->new_cookie = nfm->cookie;
fm->idle_timeout = ntohs(nfm->idle_timeout);
fm->hard_timeout = ntohs(nfm->hard_timeout);
fm->buffer_id = ntohl(nfm->buffer_id);
msg = ofpbuf_new(sizeof *ofm + actions_len);
ofm = put_openflow(sizeof *ofm, OFPT10_FLOW_MOD, msg);
ofputil_cls_rule_to_match(&fm->cr, &ofm->match);
- ofm->cookie = fm->cookie;
+ ofm->cookie = fm->new_cookie;
ofm->command = htons(command);
ofm->idle_timeout = htons(fm->idle_timeout);
ofm->hard_timeout = htons(fm->hard_timeout);
put_nxmsg(sizeof *nfm, NXT_FLOW_MOD, msg);
nfm = msg->data;
nfm->command = htons(command);
- if (command == OFPFC_ADD) {
- nfm->cookie = fm->cookie;
- match_len = nx_put_match(msg, &fm->cr, 0, 0);
- } else {
- nfm->cookie = 0;
- match_len = nx_put_match(msg, &fm->cr,
- fm->cookie, fm->cookie_mask);
- }
+ nfm->cookie = fm->new_cookie;
+ match_len = nx_put_match(msg, &fm->cr, fm->cookie, fm->cookie_mask);
nfm->idle_timeout = htons(fm->idle_timeout);
nfm->hard_timeout = htons(fm->hard_timeout);
nfm->priority = htons(fm->cr.priority);
if (fm->table_id != 0xff) {
usable_protocols &= OFPUTIL_P_TID;
}
- if (fm->command != OFPFC_ADD && fm->cookie_mask != htonll(0)) {
+
+ /* Matching of the cookie is only supported through NXM. */
+ if (fm->cookie_mask != htonll(0)) {
usable_protocols &= OFPUTIL_P_NXM_ANY;
}
}
/* NXT_FLOW_MOD_TABLE_ID extension. */
struct ofpbuf *ofputil_make_flow_mod_table_id(bool flow_mod_table_id);
-/* Protocol-independent flow_mod. */
+/* Protocol-independent flow_mod.
+ *
+ * The handling of cookies across multiple versions of OpenFlow is a bit
+ * confusing. A full description of Open vSwitch's cookie handling is
+ * in the DESIGN file. The following table shows the expected values of
+ * the cookie-related fields for the different flow_mod commands in
+ * OpenFlow 1.0 ("OF10") and NXM. "<used>" and "-" indicate a value
+ * that may be populated and an ignored field, respectively.
+ *
+ * cookie cookie_mask new_cookie
+ * ====== =========== ==========
+ * OF10 Add - 0 <used>
+ * OF10 Modify - 0 <used>
+ * OF10 Delete - 0 -
+ * NXM Add - 0 <used>
+ * NXM Modify <used> <used> <used>
+ * NXM Delete <used> <used> -
+ */
struct ofputil_flow_mod {
struct cls_rule cr;
- ovs_be64 cookie;
- ovs_be64 cookie_mask;
+ ovs_be64 cookie; /* Cookie bits to match. */
+ ovs_be64 cookie_mask; /* 1-bit in each 'cookie' bit to match. */
+ ovs_be64 new_cookie; /* New cookie to install or -1. */
uint8_t table_id;
uint16_t command;
uint16_t idle_timeout;
cls_rule_init_catchall(&fm.cr, 0);
cls_rule_set_reg(&fm.cr, 0, id);
+ fm.new_cookie = htonll(0);
fm.cookie = htonll(0);
fm.cookie_mask = htonll(0);
fm.table_id = TBL_INTERNAL;
rule->ofproto = ofproto;
rule->cr = fm->cr;
rule->pending = NULL;
- rule->flow_cookie = fm->cookie;
+ rule->flow_cookie = fm->new_cookie;
rule->created = rule->modified = rule->used = time_msec();
rule->idle_timeout = fm->idle_timeout;
rule->hard_timeout = fm->hard_timeout;
} else {
rule->modified = time_msec();
}
- rule->flow_cookie = fm->cookie;
+ if (fm->new_cookie != htonll(UINT64_MAX)) {
+ rule->flow_cookie = fm->new_cookie;
+ }
}
ofopgroup_submit(group);
error = collect_rules_loose(ofproto, fm->table_id, &fm->cr,
fm->cookie, fm->cookie_mask,
OFPP_NONE, &rules);
- return (error ? error
- : list_is_empty(&rules) ? add_flow(ofproto, ofconn, fm, request)
- : modify_flows__(ofproto, ofconn, fm, request, &rules));
+ if (error) {
+ return error;
+ } else if (list_is_empty(&rules)) {
+ return fm->cookie_mask ? 0 : add_flow(ofproto, ofconn, fm, request);
+ } else {
+ return modify_flows__(ofproto, ofconn, fm, request, &rules);
+ }
}
/* Implements OFPFC_MODIFY_STRICT. Returns 0 on success or an OpenFlow error
error = collect_rules_strict(ofproto, fm->table_id, &fm->cr,
fm->cookie, fm->cookie_mask,
OFPP_NONE, &rules);
- return (error ? error
- : list_is_empty(&rules) ? add_flow(ofproto, ofconn, fm, request)
- : list_is_singleton(&rules) ? modify_flows__(ofproto, ofconn,
- fm, request, &rules)
- : 0);
+
+ if (error) {
+ return error;
+ } else if (list_is_empty(&rules)) {
+ return fm->cookie_mask ? 0 : add_flow(ofproto, ofconn, fm, request);
+ } else {
+ return list_is_singleton(&rules) ? modify_flows__(ofproto, ofconn,
+ fm, request, &rules)
+ : 0;
+ }
}
\f
/* OFPFC_DELETE implementation. */
AT_CHECK([ovs-ofctl dump-aggregate br0 table=0 | STRIP_XIDS], [0], [dnl
NXST_AGGREGATE reply: packet_count=0 byte_count=0 flow_count=3
])
-AT_CHECK([ovs-ofctl dump-flows br0 cookie=0x3 | ofctl_strip | sort], [0], [dnl
+AT_CHECK([ovs-ofctl dump-flows br0 cookie=0x3/-1 | ofctl_strip | sort], [0], [dnl
cookie=0x3, in_port=3 actions=output:0
NXST_FLOW reply:
])
-AT_CHECK([ovs-ofctl dump-aggregate br0 cookie=0x3 | STRIP_XIDS], [0], [dnl
+AT_CHECK([ovs-ofctl dump-aggregate br0 cookie=0x3/-1 | STRIP_XIDS], [0], [dnl
NXST_AGGREGATE reply: packet_count=0 byte_count=0 flow_count=1
])
OVS_VSWITCHD_STOP
OVS_VSWITCHD_STOP
AT_CLEANUP
-AT_SETUP([ofproto - del flows with cookie])
+AT_SETUP([ofproto - mod flow with cookie change (OpenFlow 1.0)])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl -F openflow10 add-flow br0 cookie=0x1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F openflow10 dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:0
+OFPST_FLOW reply:
+])
+
+AT_CHECK([ovs-ofctl -F openflow10 mod-flows br0 cookie=0x2,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F openflow10 dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x2, in_port=1 actions=output:0
+OFPST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - mod flow with cookie change (NXM)])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl -F nxm add-flow br0 cookie=0x1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:0
+NXST_FLOW reply:
+])
+
+AT_CHECK([ovs-ofctl -F nxm mod-flows br0 cookie=0x2,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x2, in_port=1 actions=output:0
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - mod flows based on cookie mask])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=2,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x2,in_port=3,actions=0])
+AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:0
+ cookie=0x1, in_port=2 actions=output:0
+ cookie=0x2, in_port=3 actions=output:0
+NXST_FLOW reply:
+])
+
+AT_CHECK([ovs-ofctl -F nxm mod-flows br0 cookie=0x1/0xff,actions=4])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:4
+ cookie=0x1, in_port=2 actions=output:4
+ cookie=0x2, in_port=3 actions=output:0
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - mod flows based on cookie mask with cookie change])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=2,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x2,in_port=3,actions=0])
+AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:0
+ cookie=0x1, in_port=2 actions=output:0
+ cookie=0x2, in_port=3 actions=output:0
+NXST_FLOW reply:
+])
+
+AT_CHECK([ovs-ofctl -F nxm mod-flows br0 cookie=1/-1,cookie=4,actions=4])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x2, in_port=3 actions=output:0
+ cookie=0x4, in_port=1 actions=output:4
+ cookie=0x4, in_port=2 actions=output:4
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - mod flow with cookie miss (mask==0)])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl -F nxm mod-flows br0 in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ in_port=1 actions=output:0
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - mod flow with cookie miss (mask!=0)])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl -F nxm mod-flows br0 cookie=1/1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl -F nxm dump-flows br0 | ofctl_strip | sort], [0], [dnl
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - del flows with cookies])
+OVS_VSWITCHD_START
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=1,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x2,in_port=2,actions=0])
+AT_CHECK([ovs-ofctl add-flow br0 cookie=0x3,in_port=3,actions=0])
+AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
+ cookie=0x1, in_port=1 actions=output:0
+ cookie=0x2, in_port=2 actions=output:0
+ cookie=0x3, in_port=3 actions=output:0
+NXST_FLOW reply:
+])
+
+AT_CHECK([ovs-ofctl del-flows br0])
+AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
+NXST_FLOW reply:
+])
+OVS_VSWITCHD_STOP
+AT_CLEANUP
+
+AT_SETUP([ofproto - del flows based on cookie])
OVS_VSWITCHD_START
AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=1,actions=0])
AT_CHECK([ovs-ofctl add-flow br0 cookie=0x2,in_port=2,actions=0])
NXST_FLOW reply:
])
-AT_CHECK([ovs-ofctl del-flows br0 cookie=0x3])
+AT_CHECK([ovs-ofctl del-flows br0 cookie=0x3/-1])
AT_CHECK([ovs-ofctl dump-flows br0 | ofctl_strip | sort], [0], [dnl
cookie=0x1, in_port=1 actions=output:0
cookie=0x2, in_port=2 actions=output:0
OVS_VSWITCHD_STOP
AT_CLEANUP
-AT_SETUP([ofproto - del flows with cookie mask])
+AT_SETUP([ofproto - del flows based on cookie mask])
OVS_VSWITCHD_START
AT_CHECK([ovs-ofctl add-flow br0 cookie=0x1,in_port=1,actions=0])
AT_CHECK([ovs-ofctl add-flow br0 cookie=0x2,in_port=2,actions=0])
An opaque identifier called a cookie can be used as a handle to identify
a set of flows:
.
-.IP \fBcookie=\fIvalue\fR[\fB/\fImask\fR]
+.IP \fBcookie=\fIvalue\fR
+.
+A cookie can be associated with a flow using the \fBadd\-flow\fR,
+\fBadd\-flows\fR, and \fBmod\-flows\fR commands. \fIvalue\fR can be any
+64-bit number and need not be unique among flows. If this field is
+omitted, a default cookie value of 0 is used.
+.
+.IP \fBcookie=\fIvalue\fR\fB/\fImask\fR
.
-A cookie can be associated with a flow using the \fBadd-flow\fR and
-\fBadd-flows\fR commands. \fIvalue\fR can be any 64-bit number and need
-not be unique among flows. If this field is omitted, a default cookie
-value of 0 is used.
-.IP
When using NXM, the cookie can be used as a handle for querying,
-modifying, and deleting flows. In addition to \fIvalue\fR, an optional
-\fImask\fR may be supplied for the \fBdel-flows\fR, \fBmod-flows\fR,
-\fBdump-flows\fR, and \fBdump-aggregate\fR commands to limit matching
-cookies. A 1-bit in \fImask\fR indicates that the corresponding bit in
-\fIcookie\fR must match exactly, and a 0-bit wildcards that bit.
+modifying, and deleting flows. \fIvalue\fR and \fImask\fR may be
+supplied for the \fBdel\-flows\fR, \fBmod\-flows\fR, \fBdump\-flows\fR, and
+\fBdump\-aggregate\fR commands to limit matching cookies. A 1-bit in
+\fImask\fR indicates that the corresponding bit in \fIcookie\fR must
+match exactly, and a 0-bit wildcards that bit. A mask of \-1 may be used
+to exactly match a cookie.
+.IP
+The \fBmod\-flows\fR command can update the cookies of flows that
+match a cookie by specifying the \fIcookie\fR field twice (once with a
+mask for matching and once without to indicate the new value):
+.RS
+.IP "\fBovs\-ofctl mod\-flows br0 cookie=1,actions=normal\fR"
+Change all flows' cookies to 1 and change their actions to \fBnormal\fR.
+.IP "\fBovs\-ofctl mod\-flows br0 cookie=1/\-1,cookie=2,actions=normal\fR"
+Update cookies with a value of 1 to 2 and change their actions to
+\fBnormal\fR.
+.RE
+.IP
+The ability to match on cookies was added in Open vSwitch 1.5.0.
.
.PP
The following additional field sets the priority for flows added by
the \fBadd\-flow\fR and \fBadd\-flows\fR commands. For
\fBmod\-flows\fR and \fBdel\-flows\fR when \fB\-\-strict\fR is
specified, priority must match along with the rest of the flow
-specification. For \fBmod\-flows\fR without \fB\-\-strict\fR,
+specification. For \fBmod-flows\fR without \fB\-\-strict\fR,
priority is only significant if the command creates a new flow, that
is, non-strict \fBmod\-flows\fR does not match on priority and will
not change the priority of existing flows. Other commands do not
parse_ofp_str(&fm, OFPFC_ADD, ds_cstr(&s), true);
version = xmalloc(sizeof *version);
- version->cookie = fm.cookie;
+ version->cookie = fm.new_cookie;
version->idle_timeout = fm.idle_timeout;
version->hard_timeout = fm.hard_timeout;
version->flags = fm.flags & (OFPFF_SEND_FLOW_REM | OFPFF_EMERG);
struct ofpbuf *ofm;
fm.cr = fte->rule;
- fm.cookie = version->cookie;
+ fm.cookie = htonll(0);
+ fm.cookie_mask = htonll(0);
+ fm.new_cookie = version->cookie;
fm.table_id = 0xff;
fm.command = command;
fm.idle_timeout = version->idle_timeout;
projects / openvswitch / commitdiff