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/*
* Copyright (c) 2021 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.
*/
#ifndef included_pnat_node_h
#define included_pnat_node_h
#include "pnat.h"
#include <pnat/pnat.api_enum.h>
#include <vnet/feature/feature.h>
#include <vnet/udp/udp_packet.h>
#include <vnet/tcp/tcp_packet.h>
#include <vnet/ip/format.h>
/* PNAT next-nodes */
typedef enum { PNAT_NEXT_DROP, PNAT_N_NEXT } pnat_next_t;
u8 *format_pnat_match_tuple(u8 *s, va_list *args);
u8 *format_pnat_rewrite_tuple(u8 *s, va_list *args);
static inline u8 *format_pnat_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 *);
pnat_trace_t *t = va_arg(*args, pnat_trace_t *);
s = format(s, "pnat: index %d\n", t->pool_index);
if (t->pool_index != ~0) {
s = format(s, " match: %U\n", format_pnat_match_tuple,
&t->match);
s = format(s, " rewrite: %U", format_pnat_rewrite_tuple,
&t->rewrite);
}
return s;
}
/*
* Given a packet and rewrite instructions from a translation modify packet.
*/
// TODO: Generalize to write with mask
static u32 pnat_rewrite_ip4(u32 pool_index, ip4_header_t *ip) {
pnat_main_t *pm = &pnat_main;
if (pool_is_free_index(pm->translations, pool_index))
return PNAT_ERROR_REWRITE;
pnat_translation_t *t = pool_elt_at_index(pm->translations, pool_index);
ip_csum_t csumd = 0;
if (t->instructions & PNAT_INSTR_DESTINATION_ADDRESS) {
csumd = ip_csum_sub_even(csumd, ip->dst_address.as_u32);
csumd = ip_csum_add_even(csumd, t->post_da.as_u32);
ip->dst_address = t->post_da;
}
if (t->instructions & PNAT_INSTR_SOURCE_ADDRESS) {
csumd = ip_csum_sub_even(csumd, ip->src_address.as_u32);
csumd = ip_csum_add_even(csumd, t->post_sa.as_u32);
ip->src_address = t->post_sa;
}
ip_csum_t csum = ip->checksum;
csum = ip_csum_sub_even(csum, csumd);
ip->checksum = ip_csum_fold(csum);
if (ip->checksum == 0xffff)
ip->checksum = 0;
ASSERT(ip->checksum == ip4_header_checksum(ip));
u16 plen = clib_net_to_host_u16(ip->length);
/* Nothing more to do if this is a fragment. */
if (ip4_is_fragment(ip))
return PNAT_ERROR_NONE;
/* L4 ports */
if (ip->protocol == IP_PROTOCOL_TCP) {
/* Assume IP4 header is 20 bytes */
if (plen < sizeof(ip4_header_t) + sizeof(tcp_header_t))
return PNAT_ERROR_TOOSHORT;
tcp_header_t *tcp = ip4_next_header(ip);
ip_csum_t l4csum = tcp->checksum;
if (t->instructions & PNAT_INSTR_DESTINATION_PORT) {
l4csum = ip_csum_sub_even(l4csum, tcp->dst_port);
l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_dp));
tcp->dst_port = clib_net_to_host_u16(t->post_dp);
}
if (t->instructions & PNAT_INSTR_SOURCE_PORT) {
l4csum = ip_csum_sub_even(l4csum, tcp->src_port);
l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_sp));
tcp->src_port = clib_net_to_host_u16(t->post_sp);
}
l4csum = ip_csum_sub_even(l4csum, csumd);
tcp->checksum = ip_csum_fold(l4csum);
} else if (ip->protocol == IP_PROTOCOL_UDP) {
if (plen < sizeof(ip4_header_t) + sizeof(udp_header_t))
return PNAT_ERROR_TOOSHORT;
udp_header_t *udp = ip4_next_header(ip);
ip_csum_t l4csum = udp->checksum;
if (t->instructions & PNAT_INSTR_DESTINATION_PORT) {
l4csum = ip_csum_sub_even(l4csum, udp->dst_port);
l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_dp));
udp->dst_port = clib_net_to_host_u16(t->post_dp);
}
if (t->instructions & PNAT_INSTR_SOURCE_PORT) {
l4csum = ip_csum_sub_even(l4csum, udp->src_port);
l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_sp));
udp->src_port = clib_net_to_host_u16(t->post_sp);
}
if (udp->checksum) {
l4csum = ip_csum_sub_even(l4csum, csumd);
udp->checksum = ip_csum_fold(l4csum);
}
}
if (t->instructions & PNAT_INSTR_COPY_BYTE) {
/* Copy byte from somewhere in packet to elsewhere */
if (t->to_offset >= plen || t->from_offset > plen) {
return PNAT_ERROR_TOOSHORT;
}
u8 *p = (u8 *)ip;
p[t->to_offset] = p[t->from_offset];
ip->checksum = ip4_header_checksum(ip);
// TODO: L4 checksum
}
if (t->instructions & PNAT_INSTR_CLEAR_BYTE) {
/* Clear byte at offset */
u8 *p = (u8 *)ip;
p[t->clear_offset] = 0;
ip->checksum = ip4_header_checksum(ip);
// TODO: L4 checksum
}
return PNAT_ERROR_NONE;
}
/*
* Lookup the packet tuple in the flow cache, given the lookup mask.
* If a binding is found, rewrite the packet according to instructions,
* otherwise follow configured default action (forward, punt or drop)
*/
// TODO: Make use of SVR configurable
static_always_inline uword pnat_node_inline(vlib_main_t *vm,
vlib_node_runtime_t *node,
vlib_frame_t *frame,
pnat_attachment_point_t attachment,
int dir) {
pnat_main_t *pm = &pnat_main;
u32 n_left_from, *from;
u16 nexts[VLIB_FRAME_SIZE] = {0}, *next = nexts;
u32 pool_indicies[VLIB_FRAME_SIZE], *pi = pool_indicies;
vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
clib_bihash_kv_16_8_t kv, value;
ip4_header_t *ip0;
from = vlib_frame_vector_args(frame);
n_left_from = frame->n_vectors;
vlib_get_buffers(vm, from, b, n_left_from);
pnat_interface_t *interface;
/* Stage 1: build vector of flow hash (based on lookup mask) */
while (n_left_from > 0) {
u32 sw_if_index0 = vnet_buffer(b[0])->sw_if_index[dir];
u16 sport0 = vnet_buffer(b[0])->ip.reass.l4_src_port;
u16 dport0 = vnet_buffer(b[0])->ip.reass.l4_dst_port;
u32 iph_offset =
dir == VLIB_TX ? vnet_buffer(b[0])->ip.save_rewrite_length : 0;
ip0 = (ip4_header_t *)(vlib_buffer_get_current(b[0]) + iph_offset);
interface = pnat_interface_by_sw_if_index(sw_if_index0);
ASSERT(interface);
pnat_mask_fast_t mask = interface->lookup_mask_fast[attachment];
pnat_calc_key(sw_if_index0, attachment, ip0->src_address,
ip0->dst_address, ip0->protocol, sport0, dport0, mask,
&kv);
/* By default pass packet to next node in the feature chain */
vnet_feature_next_u16(next, b[0]);
if (clib_bihash_search_16_8(&pm->flowhash, &kv, &value) == 0) {
/* Cache hit */
*pi = value.value;
u32 errno0 = pnat_rewrite_ip4(value.value, ip0);
if (PREDICT_FALSE(errno0)) {
next[0] = PNAT_NEXT_DROP;
b[0]->error = node->errors[errno0];
}
} else {
/* Cache miss */
*pi = ~0;
}
/*next: */
next += 1;
n_left_from -= 1;
b += 1;
pi += 1;
}
/* Packet trace */
if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE))) {
u32 i;
b = bufs;
pi = pool_indicies;
for (i = 0; i < frame->n_vectors; i++) {
if (b[0]->flags & VLIB_BUFFER_IS_TRACED) {
pnat_trace_t *t = vlib_add_trace(vm, node, b[0], sizeof(*t));
if (*pi != ~0) {
if (!pool_is_free_index(pm->translations, *pi)) {
pnat_translation_t *tr =
pool_elt_at_index(pm->translations, *pi);
t->match = tr->match;
t->rewrite = tr->rewrite;
}
}
t->pool_index = *pi;
b += 1;
pi += 1;
} else
break;
}
}
vlib_buffer_enqueue_to_next(vm, node, from, nexts, frame->n_vectors);
return frame->n_vectors;
}
#endif
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