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Improve MTU handling

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- setting MTU on an interface updates the L3 max bytes too
- value cached in the adjacency is also updated
- MTU exceeded generates ICMP to sender

Change-Id: I343ec71d8e903b529594c4bd0543f04bc7f370b3
Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
This commit is contained in:
Neale Ranns
2018-02-09 06:05:16 -08:00
committed by Damjan Marion
parent 2d6f66e174
commit ffd78d1ef8
11 changed files with 142 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
src/vnet/adj/adj.c
View File

@ -338,6 +338,43 @@ adj_feature_update (u32 sw_if_index,
adj_walk (sw_if_index, adj_feature_update_walk_cb, &ctx);
}
static adj_walk_rc_t
adj_mtu_update_walk_cb (adj_index_t ai,
void *arg)
{
ip_adjacency_t *adj;
adj = adj_get(ai);
vnet_rewrite_update_mtu (vnet_get_main(),
&adj->rewrite_header);
return (ADJ_WALK_RC_CONTINUE);
}
static void
adj_sw_mtu_update (vnet_main_t * vnm,
u32 sw_if_index,
void *ctx)
{
/*
* Walk all the adjacencies on the interface to update the cached MTU
*/
adj_walk (sw_if_index, adj_mtu_update_walk_cb, NULL);
}
void
adj_mtu_update (u32 hw_if_index)
{
/*
* Walk all the SW interfaces on the HW interface to update the cached MTU
*/
vnet_hw_interface_walk_sw(vnet_get_main(),
hw_if_index,
adj_sw_mtu_update,
NULL);
}
/**
* @brief Walk the Adjacencies on a given interface
*/

6
src/vnet/adj/adj.h
View File

@ -344,6 +344,12 @@ extern const u8* adj_get_rewrite (adj_index_t ai);
*/
extern void adj_feature_update (u32 sw_if_index, u8 arc_index, u8 is_enable);
/**
* @brief Notify the adjacency subsystem that the MTU settings for
* an HW interface have changed
*/
extern void adj_mtu_update (u32 hw_if_index);
/**
* @brief
* The global adjacnecy pool. Exposed for fast/inline data-plane access

12
src/vnet/adj/rewrite.c
View File

@ -77,15 +77,14 @@ format_vnet_rewrite (u8 * s, va_list * args)
vnet_sw_interface_t *si;
si = vnet_get_sw_interface_safe (vnm, rw->sw_if_index);
if (NULL != si)
s = format (s, "%U: ", format_vnet_sw_interface_name, vnm, si);
s = format (s, "%U:", format_vnet_sw_interface_name, vnm, si);
else
s = format (s, "DELETED:%d", rw->sw_if_index);
}
/* Format rewrite string. */
if (rw->data_bytes > 0)
s = format (s, "%U",
s = format (s, " %U",
format_hex_bytes,
rw->data + max_data_bytes - rw->data_bytes, rw->data_bytes);
@ -110,6 +109,13 @@ vnet_rewrite_init (vnet_main_t * vnm,
vnet_sw_interface_get_mtu (vnm, sw_if_index, VLIB_TX);
}
void
vnet_rewrite_update_mtu (vnet_main_t * vnm, vnet_rewrite_header_t * rw)
{
rw->max_l3_packet_bytes =
vnet_sw_interface_get_mtu (vnm, rw->sw_if_index, VLIB_TX);
}
void
vnet_rewrite_for_sw_interface (vnet_main_t * vnm,
vnet_link_t link_type,

3
src/vnet/adj/rewrite.h
View File

@ -328,6 +328,9 @@ void vnet_rewrite_init (struct vnet_main_t *vnm,
u32 this_node,
u32 next_node, vnet_rewrite_header_t * rw);
void vnet_rewrite_update_mtu (struct vnet_main_t *vnm,
vnet_rewrite_header_t * rw);
u8 *vnet_build_rewrite_for_sw_interface (struct vnet_main_t *vnm,
u32 sw_if_index,
vnet_link_t packet_type,

16
src/vnet/interface.c
View File

@ -122,6 +122,22 @@ unserialize_vnet_sw_interface_set_flags (serialize_main_t * m, va_list * va)
/* helper_flags no redistribution */ 0);
}
void
vnet_hw_interface_set_mtu (vnet_main_t * vnm, u32 hw_if_index, u32 mtu)
{
vnet_hw_interface_t *hi = vnet_get_hw_interface (vnm, hw_if_index);
if (hi->max_packet_bytes != mtu)
{
u16 l3_pad = hi->max_packet_bytes - hi->max_l3_packet_bytes[VLIB_TX];
hi->max_packet_bytes = mtu;
hi->max_l3_packet_bytes[VLIB_TX] =
hi->max_l3_packet_bytes[VLIB_RX] = mtu - l3_pad;
ethernet_set_flags (vnm, hw_if_index, ETHERNET_INTERFACE_FLAG_MTU);
adj_mtu_update (hw_if_index);
}
}
static void
unserialize_vnet_hw_interface_set_flags (serialize_main_t * m, va_list * va)
{

7
src/vnet/interface_api.c
View File

@ -98,7 +98,6 @@ vl_api_sw_interface_set_mtu_t_handler (vl_api_sw_interface_set_mtu_t * mp)
{
vl_api_sw_interface_set_mtu_reply_t *rmp;
vnet_main_t *vnm = vnet_get_main ();
u32 flags = ETHERNET_INTERFACE_FLAG_MTU;
u32 sw_if_index = ntohl (mp->sw_if_index);
u16 mtu = ntohs (mp->mtu);
ethernet_main_t *em = &ethernet_main;
@ -134,11 +133,7 @@ vl_api_sw_interface_set_mtu_t_handler (vl_api_sw_interface_set_mtu_t * mp)
goto bad_sw_if_index;
}
if (hi->max_packet_bytes != mtu)
{
hi->max_packet_bytes = mtu;
ethernet_set_flags (vnm, si->hw_if_index, flags);
}
vnet_hw_interface_set_mtu (vnm, si->hw_if_index, mtu);
BAD_SW_IF_INDEX_LABEL;
REPLY_MACRO (VL_API_SW_INTERFACE_SET_MTU_REPLY);

7
src/vnet/interface_cli.c
View File

@ -1132,7 +1132,6 @@ mtu_cmd (vlib_main_t * vm, unformat_input_t * input, vlib_cli_command_t * cmd)
{
vnet_main_t *vnm = vnet_get_main ();
u32 hw_if_index, mtu;
u32 flags = ETHERNET_INTERFACE_FLAG_MTU;
ethernet_main_t *em = &ethernet_main;
if (unformat (input, "%d %U", &mtu,
@ -1153,11 +1152,7 @@ mtu_cmd (vlib_main_t * vm, unformat_input_t * input, vlib_cli_command_t * cmd)
return clib_error_return (0, "Invalid mtu (%d): must be <= (%d)", mtu,
hi->max_supported_packet_bytes);
if (hi->max_packet_bytes != mtu)
{
hi->max_packet_bytes = mtu;
ethernet_set_flags (vnm, hw_if_index, flags);
}
vnet_hw_interface_set_mtu (vnm, hw_if_index, mtu);
}
else
return clib_error_return (0, "unknown input `%U'",

3
src/vnet/interface_funcs.h
View File

@ -292,6 +292,9 @@ clib_error_t *set_hw_interface_change_rx_mode (vnet_main_t * vnm,
vnet_hw_interface_rx_mode
mode);
/* Set the MTU on the HW interface */
void vnet_hw_interface_set_mtu (vnet_main_t * vnm, u32 hw_if_index, u32 mtu);
/* Formats sw/hw interface. */
format_function_t format_vnet_hw_interface;
format_function_t format_vnet_hw_interface_rx_mode;

43
src/vnet/ip/ip4_forward.c
View File

@ -2109,16 +2109,26 @@ ip4_rewrite_inline (vlib_main_t * vm,
vnet_buffer (p1)->ip.save_rewrite_length = rw_len1;
/* Check MTU of outgoing interface. */
error0 =
(vlib_buffer_length_in_chain (vm, p0) >
adj0[0].
rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
error0);
error1 =
(vlib_buffer_length_in_chain (vm, p1) >
adj1[0].
rewrite_header.max_l3_packet_bytes ? IP4_ERROR_MTU_EXCEEDED :
error1);
if (vlib_buffer_length_in_chain (vm, p0) >
adj0[0].rewrite_header.max_l3_packet_bytes)
{
error0 = IP4_ERROR_MTU_EXCEEDED;
next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
icmp4_error_set_vnet_buffer
(p0, ICMP4_destination_unreachable,
ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
0);
}
if (vlib_buffer_length_in_chain (vm, p1) >
adj1[0].rewrite_header.max_l3_packet_bytes)
{
error1 = IP4_ERROR_MTU_EXCEEDED;
next1 = IP4_REWRITE_NEXT_ICMP_ERROR;
icmp4_error_set_vnet_buffer
(p1, ICMP4_destination_unreachable,
ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
0);
}
if (is_mcast)
{
@ -2290,9 +2300,16 @@ ip4_rewrite_inline (vlib_main_t * vm,
vlib_buffer_length_in_chain (vm, p0) + rw_len0);
/* Check MTU of outgoing interface. */
error0 = (vlib_buffer_length_in_chain (vm, p0)
> adj0[0].rewrite_header.max_l3_packet_bytes
? IP4_ERROR_MTU_EXCEEDED : error0);
if (vlib_buffer_length_in_chain (vm, p0) >
adj0[0].rewrite_header.max_l3_packet_bytes)
{
error0 = IP4_ERROR_MTU_EXCEEDED;
next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
icmp4_error_set_vnet_buffer
(p0, ICMP4_destination_unreachable,
ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
0);
}
if (is_mcast)
{
error0 = ((adj0[0].rewrite_header.sw_if_index ==

26
test/test_ip4.py
View File

@ -1287,6 +1287,32 @@ class TestIPInput(VppTestCase):
self.assertEqual(icmp.src, self.pg0.remote_ip4)
self.assertEqual(icmp.dst, self.pg1.remote_ip4)
#
# MTU exceeded
#
p_mtu = (Ether(src=self.pg0.remote_mac,
dst=self.pg0.local_mac) /
IP(src=self.pg0.remote_ip4,
dst=self.pg1.remote_ip4,
ttl=10) /
UDP(sport=1234, dport=1234) /
Raw('\xa5' * 2000))
self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, 1500)
rx = self.send_and_expect(self.pg0, p_mtu * 65, self.pg0)
rx = rx[0]
icmp = rx[ICMP]
self.assertEqual(icmptypes[icmp.type], "dest-unreach")
self.assertEqual(icmpcodes[icmp.type][icmp.code],
"fragmentation-needed")
self.assertEqual(icmp.src, self.pg0.remote_ip4)
self.assertEqual(icmp.dst, self.pg1.remote_ip4)
self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, 2500)
rx = self.send_and_expect(self.pg0, p_mtu * 65, self.pg1)
if __name__ == '__main__':
unittest.main(testRunner=VppTestRunner)

10
test/vpp_papi_provider.py
View File

@ -629,6 +629,16 @@ class VppPapiProvider(object):
{'sw_if_index': sw_if_index,
'admin_up_down': admin_up_down})
def sw_interface_set_mtu(self, sw_if_index, mtu):
"""
:param sw_if_index:
:param mtu:
"""
return self.api(self.papi.sw_interface_set_mtu,
{'sw_if_index': sw_if_index,
'mtu': mtu})
def create_subif(self, sw_if_index, sub_id, outer_vlan, inner_vlan,
no_tags=0, one_tag=0, two_tags=0, dot1ad=0, exact_match=0,
default_sub=0, outer_vlan_id_any=0, inner_vlan_id_any=0):