/*
* Copyright (c) 2015 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under th/*
* mss_clamp_node.c - Node implementing TCP MSS clamping
*
* Copyright (c) 2018 Cisco and/or its affiliates
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vppinfra/error.h>
#include <mss_clamp/mss_clamp.h>
#include <mss_clamp/mss_clamp.api_enum.h>
#include <vnet/fib/fib_types.h>
#include <vnet/feature/feature.h>
#include <vnet/ip/ip4.h>
#include <vnet/ip/ip6.h>
#include <vnet/tcp/tcp_packet.h>
extern vlib_node_registration_t mssc_ip4_in_node, mssc_ip4_out_node;
extern vlib_node_registration_t mssc_ip6_in_node, mssc_ip6_out_node;
typedef struct mssc_trace_t_
{
u32 max_mss;
u32 clamped;
} mssc_trace_t;
/* packet trace format function */
static u8 *
format_mssc_trace (u8 *s, va_list *args)
{
CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
mssc_trace_t *t = va_arg (*args, mssc_trace_t *);
s = format (s, "max mss: %d clamped: %d", t->max_mss, t->clamped);
return s;
}
typedef enum
{
MSSC_NEXT_DROP,
MSSC_N_NEXT,
} mssc_next_t;
/*
* fixup the maximum segment size if it's a syn packet
* return 1 if the mss was changed otherwise 0
*/
always_inline u32
mssc_mss_fixup (vlib_buffer_t *b0, tcp_header_t *tcp0, u16 max_mss0)
{
ip_csum_t sum0;
if (PREDICT_FALSE (tcp_syn (tcp0)))
{
u8 opt_len, opts_len, kind;
const u8 *data;
u16 mss0, new_mss0;
opts_len = (tcp_doff (tcp0) << 2) - sizeof (tcp_header_t);
data = (const u8 *) (tcp0 + 1);
for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
{
kind = data[0];
/* Get options length */
if (kind == TCP_OPTION_EOL)
break;
else if (kind == TCP_OPTION_NOOP)
{
opt_len = 1;
continue;
}
else
{
/* broken options */
if (opts_len < 2)
return 0;
opt_len = data[1];
/* weird option length */
if (opt_len < 2 || opt_len > opts_len)
return 0;
}
if (kind == TCP_OPTION_MSS)
{
mss0 = *(u16 *) (data + 2);
if (clib_net_to_host_u16 (mss0) > max_mss0)
{
new_mss0 = clib_host_to_net_u16 (max_mss0);
*((u16 *) (data + 2)) = new_mss0;
sum0 = tcp0->checksum;
sum0 = ip_csum_update (sum0, mss0, new_mss0, tcp_header_t,
checksum);
tcp0->checksum = ip_csum_fold (sum0);
return 1;
}
}
}
}
return 0;
}
always_inline uword
mssc_inline (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame,
vlib_dir_t dir, fib_protocol_t fproto)
{
mssc_main_t *cm = &mssc_main;
vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
u16 nexts[VLIB_FRAME_SIZE], *next;
u32 n_left, *from;
u32 pkts_clamped = 0;
from = vlib_frame_vector_args (frame);
n_left = frame->n_vectors;
b = bufs;
next = nexts;
vlib_get_buffers (vm, from, bufs, n_left);
while (n_left >= 4)
{
u32 sw_if_index0, sw_if_index1;
const u8 *h0, *h1;
u32 clamped0, clamped1;
/* Prefetch next iteration. */
{
vlib_prefetch_buffer_header (b[2], LOAD);
vlib_prefetch_buffer_header (b[3], LOAD);
vlib_prefetch_buffer_data (b[2], LOAD);
vlib_prefetch_buffer_data (b[3], LOAD);
}
sw_if_index0 = vnet_buffer (b[0])->sw_if_index[dir];
sw_if_index1 = vnet_buffer (b[1])->sw_if_index[dir];
clamped0 = clamped1 = 0;
/* speculatively enqueue b0 to the current next frame */
vnet_feature_next_u16 (&next[0], b[0]);
vnet_feature_next_u16 (&next[1], b[1]);
h0 = (u8 *) vlib_buffer_get_current (b[0]);
h1 = (u8 *) vlib_buffer_get_current (b[1]);
if (VLIB_TX == dir)
{
h0 += vnet_buffer (b[0])->ip.save_rewrite_length;
h1 += vnet_buffer (b[1])->ip.save_rewrite_length;
}
if (FIB_PROTOCOL_IP4 == fproto)
{
ip4_header_t *ip0 = (ip4_header_t *) h0;
ip4_header_t *ip1 = (ip4_header_t *) h1;
if (IP_PROTOCOL_TCP == ip0->protocol)
{
clamped0 = mssc_mss_fixup (b[0], ip4_next_header (ip0),
cm->max_mss4[sw_if_index0]);
}
if (IP_PROTOCOL_TCP == ip1->protocol)
{
clamped1 = mssc_mss_fixup (b[1], ip4_next_header (ip1),
cm->max_mss4[sw_if_index1]);
}
}
else if (FIB_PROTOCOL_IP6 == fproto)
{
ip6_header_t *ip0 = (ip6_header_t *) h0;
ip6_header_t *ip1 = (ip6_header_t *) h1;
if (IP_PROTOCOL_TCP == ip0->protocol)
{
clamped0 = mssc_mss_fixup (b[0], ip6_next_header (ip0),
cm->max_mss6[sw_if_index0]);
}
if (IP_PROTOCOL_TCP == ip1->protocol)
{
clamped1 = mssc_mss_fixup (b[1], ip6_next_header (ip1),
cm->max_mss6[sw_if_index1]);
}
}
pkts_clamped += clamped0 + clamped1;
if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
{
if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
{
mssc_trace_t *t;
t = vlib_add_trace (vm, node, b[0], sizeof (*t));
t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
cm->max_mss4[sw_if_index0] :
cm->max_mss6[sw_if_index0];
t->clamped = clamped0;
}
if (b[1]->flags & VLIB_BUFFER_IS_TRACED)
{
mssc_trace_t *t;
t = vlib_add_trace (vm, node, b[1], sizeof (*t));
t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
cm->max_mss4[sw_if_index1] :
cm->max_mss6[sw_if_index1];
t->clamped = clamped1;
}
}
b += 2;
next += 2;
n_left -= 2;
}
while (n_left > 0)
{
u32 sw_if_index0;
const u8 *h0;
u32 clamped0;
sw_if_index0 = vnet_buffer (b[0])->sw_if_index[dir];
clamped0 = 0;
/* speculatively enqueue b0 to the current next frame */
vnet_feature_next_u16 (&next[0], b[0]);
h0 = (u8 *) vlib_buffer_get_current (b[0]);
if (VLIB_TX == dir)
h0 += vnet_buffer (b[0])->ip.save_rewrite_length;
if (FIB_PROTOCOL_IP4 == fproto)
{
ip4_header_t *ip0 = (ip4_header_t *) h0;
if (IP_PROTOCOL_TCP == ip0->protocol)
{
clamped0 = mssc_mss_fixup (b[0], ip4_next_header (ip0),
cm->max_mss4[sw_if_index0]);
}
}
else if (FIB_PROTOCOL_IP6 == fproto)
{
ip6_header_t *ip0 = (ip6_header_t *) h0;
if (IP_PROTOCOL_TCP == ip0->protocol)
{
clamped0 = mssc_mss_fixup (b[0], ip6_next_header (ip0),
cm->max_mss6[sw_if_index0]);
}
}
pkts_clamped += clamped0;
if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
(b[0]->flags & VLIB_BUFFER_IS_TRACED)))
{
mssc_trace_t *t;
t = vlib_add_trace (vm, node, b[0], sizeof (*t));
t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
cm->max_mss4[sw_if_index0] :
cm->max_mss6[sw_if_index0];
t->clamped = clamped0;
}
b++;
next++;
n_left--;
}
vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
vlib_node_increment_counter (vm, node->node_index, MSS_CLAMP_ERROR_CLAMPED,
pkts_clamped);
return frame->n_vectors;
}
static uword
mssc_ip4_in (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
return (mssc_inline (vm, node, frame, VLIB_RX, FIB_PROTOCOL_IP4));
}
static uword
mssc_ip4_out (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
return (mssc_inline (vm, node, frame, VLIB_TX, FIB_PROTOCOL_IP4));
}
static uword
mssc_ip6_in (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
return (mssc_inline (vm, node, frame, VLIB_RX, FIB_PROTOCOL_IP6));
}
static uword
mssc_ip6_out (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
return (mssc_inline (vm, node, frame, VLIB_TX, FIB_PROTOCOL_IP6));
}
VLIB_REGISTER_NODE (mssc_ip4_in_node) =
{
.function = mssc_ip4_in,
.name = "tcp-mss-clamping-ip4-in",
.vector_size = sizeof (u32),
.format_trace = format_mssc_trace,
.type = VLIB_NODE_TYPE_INTERNAL,
.n_errors = MSS_CLAMP_N_ERROR,
.error_counters = mss_clamp_error_counters,
.n_next_nodes = MSSC_N_NEXT,
.next_nodes = {
[MSSC_NEXT_DROP] = "error-drop",
},
};
VLIB_REGISTER_NODE (mssc_ip4_out_node) =
{
.function = mssc_ip4_out,
.name = "tcp-mss-clamping-ip4-out",
.vector_size = sizeof (u32),
.format_trace = format_mssc_trace,
.type = VLIB_NODE_TYPE_INTERNAL,
.n_errors = MSS_CLAMP_N_ERROR,
.error_counters = mss_clamp_error_counters,
.n_next_nodes = MSSC_N_NEXT,
.next_nodes = {
[MSSC_NEXT_DROP] = "error-drop",
},
};
VLIB_REGISTER_NODE (mssc_ip6_in_node) =
{
.function = mssc_ip6_in,
.name = "tcp-mss-clamping-ip6-in",
.vector_size = sizeof (u32),
.format_trace = format_mssc_trace,
.type = VLIB_NODE_TYPE_INTERNAL,
.n_errors = MSS_CLAMP_N_ERROR,
.error_counters = mss_clamp_error_counters,
.n_next_nodes = MSSC_N_NEXT,
.next_nodes = {
[MSSC_NEXT_DROP] = "error-drop",
},
};
VLIB_REGISTER_NODE (mssc_ip6_out_node) =
{
.function = mssc_ip6_out,
.name = "tcp-mss-clamping-ip6-out",
.vector_size = sizeof (u32),
.format_trace = format_mssc_trace,
.type = VLIB_NODE_TYPE_INTERNAL,
.n_errors = MSS_CLAMP_N_ERROR,
.error_counters = mss_clamp_error_counters,
.n_next_nodes = MSSC_N_NEXT,
.next_nodes = {
[MSSC_NEXT_DROP] = "error-drop",
},
};
VNET_FEATURE_INIT (mssc_ip4_in_feat, static) = {
.arc_name = "ip4-unicast",
.node_name = "tcp-mss-clamping-ip4-in",
.runs_after = VNET_FEATURES ("ip4-policer-classify"),
};
VNET_FEATURE_INIT (mssc_ip4_out_feat, static) = {
.arc_name = "ip4-output",
.node_name = "tcp-mss-clamping-ip4-out",
};
VNET_FEATURE_INIT (mssc_ip6_in_feat, static) = {
.arc_name = "ip6-unicast",
.node_name = "tcp-mss-clamping-ip6-in",
.runs_after = VNET_FEATURES ("ip6-policer-classify"),
};
VNET_FEATURE_INIT (mssc_ip6_out_feat, static) = {
.arc_name = "ip6-output",
.node_name = "tcp-mss-clamping-ip6-out",
};
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/