src/plugins/nat/pnat/pnat_node.h

   1 /*
   2  * Copyright (c) 2021 Cisco and/or its affiliates.
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #ifndef included_pnat_node_h
  17 #define included_pnat_node_h
  18
  19 #include "pnat.h"
  20 #include <pnat/pnat.api_enum.h>
  21 #include <vnet/feature/feature.h>
  22 #include <vnet/udp/udp_packet.h>
  23 #include <vnet/ip/format.h>
  24
  25 /* PNAT next-nodes */
  26 typedef enum { PNAT_NEXT_DROP, PNAT_N_NEXT } pnat_next_t;
  27
  28 // u8 *format_pnat_key(u8 *s, va_list *args);
  29 u8 *format_pnat_5tuple(u8 *s, va_list *args);
  30 static inline u8 *format_pnat_trace(u8 *s, va_list *args) {
  31     CLIB_UNUSED(vlib_main_t * vm) = va_arg(*args, vlib_main_t *);
  32     CLIB_UNUSED(vlib_node_t * node) = va_arg(*args, vlib_node_t *);
  33     pnat_trace_t *t = va_arg(*args, pnat_trace_t *);
  34
  35     s = format(s, "pnat: index %d\n", t->pool_index);
  36     if (t->pool_index != ~0) {
  37         s = format(s, "        match: %U\n", format_pnat_5tuple, &t->match);
  38         s = format(s, "        rewrite: %U", format_pnat_5tuple, &t->rewrite);
  39     }
  40     return s;
  41 }
  42
  43 /*
  44  * Given a packet and rewrite instructions from a translation modify packet.
  45  */
  46 static u32 pnat_rewrite_ip4(u32 pool_index, ip4_header_t *ip) {
  47     pnat_main_t *pm = &pnat_main;
  48     if (pool_is_free_index(pm->translations, pool_index))
  49         return PNAT_ERROR_REWRITE;
  50     pnat_translation_t *t = pool_elt_at_index(pm->translations, pool_index);
  51
  52     ip_csum_t csumd = 0;
  53
  54     if (t->instructions & PNAT_INSTR_DESTINATION_ADDRESS) {
  55         csumd = ip_csum_sub_even(csumd, ip->dst_address.as_u32);
  56         csumd = ip_csum_add_even(csumd, t->post_da.as_u32);
  57         ip->dst_address = t->post_da;
  58     }
  59     if (t->instructions & PNAT_INSTR_SOURCE_ADDRESS) {
  60         csumd = ip_csum_sub_even(csumd, ip->src_address.as_u32);
  61         csumd = ip_csum_add_even(csumd, t->post_sa.as_u32);
  62         ip->src_address = t->post_sa;
  63     }
  64
  65     ip_csum_t csum = ip->checksum;
  66     csum = ip_csum_sub_even(csum, csumd);
  67     ip->checksum = ip_csum_fold(csum);
  68     ASSERT(ip->checksum == ip4_header_checksum(ip));
  69
  70     /* L4 ports */
  71     if (ip->protocol == IP_PROTOCOL_TCP) {
  72         tcp_header_t *tcp = ip4_next_header(ip);
  73         ip_csum_t l4csum = tcp->checksum;
  74         if (t->instructions & PNAT_INSTR_DESTINATION_PORT) {
  75             l4csum = ip_csum_sub_even(l4csum, tcp->dst_port);
  76             l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_dp));
  77             tcp->dst_port = clib_net_to_host_u16(t->post_dp);
  78         }
  79         if (t->instructions & PNAT_INSTR_SOURCE_PORT) {
  80             l4csum = ip_csum_sub_even(l4csum, tcp->src_port);
  81             l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_sp));
  82             tcp->src_port = clib_net_to_host_u16(t->post_sp);
  83         }
  84         l4csum = ip_csum_sub_even(l4csum, csumd);
  85         tcp->checksum = ip_csum_fold(l4csum);
  86     } else if (ip->protocol == IP_PROTOCOL_UDP) {
  87         udp_header_t *udp = ip4_next_header(ip);
  88         ip_csum_t l4csum = udp->checksum;
  89         if (t->instructions & PNAT_INSTR_DESTINATION_PORT) {
  90             l4csum = ip_csum_sub_even(l4csum, udp->dst_port);
  91             l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_dp));
  92             udp->dst_port = clib_net_to_host_u16(t->post_dp);
  93         }
  94         if (t->instructions & PNAT_INSTR_SOURCE_PORT) {
  95             l4csum = ip_csum_sub_even(l4csum, udp->src_port);
  96             l4csum = ip_csum_add_even(l4csum, clib_net_to_host_u16(t->post_sp));
  97             udp->src_port = clib_net_to_host_u16(t->post_sp);
  98         }
  99         if (udp->checksum) {
 100             l4csum = ip_csum_sub_even(l4csum, csumd);
 101             udp->checksum = ip_csum_fold(l4csum);
 102         }
 103     }
 104     return PNAT_ERROR_NONE;
 105 }
 106
 107 /*
 108  * Lookup the packet tuple in the flow cache, given the lookup mask.
 109  * If a binding is found, rewrite the packet according to instructions,
 110  * otherwise follow configured default action (forward, punt or drop)
 111  */
 112 static_always_inline uword pnat_node_inline(vlib_main_t *vm,
 113                                             vlib_node_runtime_t *node,
 114                                             vlib_frame_t *frame,
 115                                             pnat_attachment_point_t attachment,
 116                                             int dir) {
 117     pnat_main_t *pm = &pnat_main;
 118     u32 n_left_from, *from;
 119     u16 nexts[VLIB_FRAME_SIZE] = {0}, *next = nexts;
 120     u32 pool_indicies[VLIB_FRAME_SIZE], *pi = pool_indicies;
 121     vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
 122     clib_bihash_kv_16_8_t kv, value;
 123     ip4_header_t *ip0;
 124
 125     from = vlib_frame_vector_args(frame);
 126     n_left_from = frame->n_vectors;
 127     vlib_get_buffers(vm, from, b, n_left_from);
 128     pnat_interface_t *interface;
 129
 130     /* Stage 1: build vector of flow hash (based on lookup mask) */
 131     while (n_left_from > 0) {
 132         u32 sw_if_index0 = vnet_buffer(b[0])->sw_if_index[dir];
 133         u16 sport0 = vnet_buffer(b[0])->ip.reass.l4_src_port;
 134         u16 dport0 = vnet_buffer(b[0])->ip.reass.l4_dst_port;
 135         u32 iph_offset = vnet_buffer(b[0])->ip.reass.save_rewrite_length;
 136         ip0 = (ip4_header_t *)(vlib_buffer_get_current(b[0]) + iph_offset);
 137         interface = pnat_interface_by_sw_if_index(sw_if_index0);
 138         ASSERT(interface);
 139         pnat_mask_fast_t mask = interface->lookup_mask_fast[attachment];
 140         pnat_calc_key(sw_if_index0, attachment, ip0->src_address,
 141                       ip0->dst_address, ip0->protocol, sport0, dport0, mask,
 142                       &kv);
 143         /* By default pass packet to next node in the feature chain */
 144         vnet_feature_next_u16(next, b[0]);
 145
 146         if (clib_bihash_search_16_8(&pm->flowhash, &kv, &value) == 0) {
 147             /* Cache hit */
 148             *pi = value.value;
 149             u32 iph_offset = vnet_buffer(b[0])->ip.reass.save_rewrite_length;
 150             ip0 = (ip4_header_t *)(vlib_buffer_get_current(b[0]) + iph_offset);
 151             u32 errno0 = pnat_rewrite_ip4(value.value, ip0);
 152             if (PREDICT_FALSE(errno0)) {
 153                 next[0] = PNAT_NEXT_DROP;
 154                 b[0]->error = node->errors[errno0];
 155             }
 156         } else {
 157             /* Cache miss */
 158             *pi = ~0;
 159         }
 160         next += 1;
 161
 162         /*next: */
 163         n_left_from -= 1;
 164         b += 1;
 165         pi += 1;
 166     }
 167
 168     /* Packet trace */
 169     if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE))) {
 170         u32 i;
 171         b = bufs;
 172         pi = pool_indicies;
 173         for (i = 0; i < frame->n_vectors; i++) {
 174             if (b[0]->flags & VLIB_BUFFER_IS_TRACED) {
 175                 pnat_trace_t *t = vlib_add_trace(vm, node, b[0], sizeof(*t));
 176                 if (*pi != ~0) {
 177                     if (!pool_is_free_index(pm->translations, *pi)) {
 178                         pnat_translation_t *tr =
 179                             pool_elt_at_index(pm->translations, *pi);
 180                         t->match = tr->match;
 181                         t->rewrite = tr->rewrite;
 182                     }
 183                 }
 184                 t->pool_index = *pi;
 185                 b += 1;
 186                 pi += 1;
 187             } else
 188                 break;
 189         }
 190     }
 191
 192     vlib_buffer_enqueue_to_next(vm, node, from, nexts, frame->n_vectors);
 193
 194     return frame->n_vectors;
 195 }
 196 #endif