packets.c revision ea93e48c
1/*
2 * Copyright (c) 2016 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#include <vnet/lisp-cp/packets.h>
17#include <vnet/lisp-cp/lisp_cp_messages.h>
18#include <vnet/udp/udp_packet.h>
19
20/* Returns IP ID for the packet */
21/* static u16 ip_id = 0;
22static inline u16
23get_IP_ID()
24{
25    ip_id++;
26    return (ip_id);
27} */
28
29u16
30udp_ip4_checksum (const void *b, u32 len, u8 * src, u8 * dst)
31{
32  const u16 *buf = b;
33  u16 *ip_src = (u16 *) src;
34  u16 *ip_dst = (u16 *) dst;
35  u32 length = len;
36  u32 sum = 0;
37
38  while (len > 1)
39    {
40      sum += *buf++;
41      if (sum & 0x80000000)
42	sum = (sum & 0xFFFF) + (sum >> 16);
43      len -= 2;
44    }
45
46  /* Add the padding if the packet length is odd */
47  if (len & 1)
48    sum += *((u8 *) buf);
49
50  /* Add the pseudo-header */
51  sum += *(ip_src++);
52  sum += *ip_src;
53
54  sum += *(ip_dst++);
55  sum += *ip_dst;
56
57  sum += clib_host_to_net_u16 (IP_PROTOCOL_UDP);
58  sum += clib_host_to_net_u16 (length);
59
60  /* Add the carries */
61  while (sum >> 16)
62    sum = (sum & 0xFFFF) + (sum >> 16);
63
64  /* Return the one's complement of sum */
65  return ((u16) (~sum));
66}
67
68u16
69udp_ip6_checksum (ip6_header_t * ip6, udp_header_t * up, u32 len)
70{
71  size_t i;
72  register const u16 *sp;
73  u32 sum;
74  union
75  {
76    struct
77    {
78      ip6_address_t ph_src;
79      ip6_address_t ph_dst;
80      u32 ph_len;
81      u8 ph_zero[3];
82      u8 ph_nxt;
83    } ph;
84    u16 pa[20];
85  } phu;
86
87  /* pseudo-header */
88  clib_memset (&phu, 0, sizeof (phu));
89  phu.ph.ph_src = ip6->src_address;
90  phu.ph.ph_dst = ip6->dst_address;
91  phu.ph.ph_len = clib_host_to_net_u32 (len);
92  phu.ph.ph_nxt = IP_PROTOCOL_UDP;
93
94  sum = 0;
95  for (i = 0; i < sizeof (phu.pa) / sizeof (phu.pa[0]); i++)
96    sum += phu.pa[i];
97
98  sp = (const u16 *) up;
99
100  for (i = 0; i < (len & ~1); i += 2)
101    sum += *sp++;
102
103  if (len & 1)
104    sum += clib_host_to_net_u16 ((*(const u8 *) sp) << 8);
105
106  while (sum > 0xffff)
107    sum = (sum & 0xffff) + (sum >> 16);
108  sum = ~sum & 0xffff;
109
110  return (sum);
111}
112
113u16
114udp_checksum (udp_header_t * uh, u32 udp_len, void *ih, u8 version)
115{
116  switch (version)
117    {
118    case AF_IP4:
119      return (udp_ip4_checksum (uh, udp_len,
120				((ip4_header_t *) ih)->src_address.as_u8,
121				((ip4_header_t *) ih)->dst_address.as_u8));
122    case AF_IP6:
123      return (udp_ip6_checksum (ih, uh, udp_len));
124    default:
125      return ~0;
126    }
127}
128
129void *
130pkt_push_udp (vlib_main_t * vm, vlib_buffer_t * b, u16 sp, u16 dp)
131{
132  udp_header_t *uh;
133  u16 udp_len = sizeof (udp_header_t) + vlib_buffer_length_in_chain (vm, b);
134
135  uh = vlib_buffer_push_uninit (b, sizeof (*uh));
136
137  uh->src_port = clib_host_to_net_u16 (sp);
138  uh->dst_port = clib_host_to_net_u16 (dp);
139  uh->length = clib_host_to_net_u16 (udp_len);
140  uh->checksum = 0;
141  return uh;
142}
143
144void *
145pkt_push_ip (vlib_main_t * vm, vlib_buffer_t * b, ip_address_t * src,
146	     ip_address_t * dst, u32 proto, u8 csum_offload)
147{
148  if (ip_addr_version (src) != ip_addr_version (dst))
149    {
150      clib_warning ("src %U and dst %U IP have different AFI! Discarding!",
151		    format_ip_address, src, format_ip_address, dst);
152      return 0;
153    }
154
155  switch (ip_addr_version (src))
156    {
157    case AF_IP4:
158      return vlib_buffer_push_ip4 (vm, b, &ip_addr_v4 (src),
159				   &ip_addr_v4 (dst), proto, csum_offload);
160      break;
161    case AF_IP6:
162      return vlib_buffer_push_ip6 (vm, b, &ip_addr_v6 (src),
163				   &ip_addr_v6 (dst), proto);
164      break;
165    }
166
167  return 0;
168}
169
170void *
171pkt_push_udp_and_ip (vlib_main_t * vm, vlib_buffer_t * b, u16 sp, u16 dp,
172		     ip_address_t * sip, ip_address_t * dip, u8 csum_offload)
173{
174  u16 udpsum;
175  udp_header_t *uh;
176  void *ih;
177
178  uh = pkt_push_udp (vm, b, sp, dp);
179
180  if (csum_offload)
181    {
182      ih = pkt_push_ip (vm, b, sip, dip, IP_PROTOCOL_UDP, 1);
183      b->flags |= VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
184      vnet_buffer (b)->l3_hdr_offset = (u8 *) ih - b->data;
185      vnet_buffer (b)->l4_hdr_offset = (u8 *) uh - b->data;
186      uh->checksum = 0;
187    }
188  else
189    {
190      ih = pkt_push_ip (vm, b, sip, dip, IP_PROTOCOL_UDP, 0);
191      udpsum = udp_checksum (uh, clib_net_to_host_u16 (uh->length), ih,
192			     ip_addr_version (sip));
193      if (udpsum == (u16) ~ 0)
194	{
195	  clib_warning ("Failed UDP checksum! Discarding");
196	  return 0;
197	}
198      /* clear flags used for csum since we're not offloading */
199      b->flags &= ~(VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_IS_IP6);
200      uh->checksum = udpsum;
201    }
202  return ih;
203}
204
205void *
206pkt_push_ecm_hdr (vlib_buffer_t * b)
207{
208  ecm_hdr_t *h;
209  h = vlib_buffer_push_uninit (b, sizeof (h[0]));
210
211  clib_memset (h, 0, sizeof (h[0]));
212  h->type = LISP_ENCAP_CONTROL_TYPE;
213  clib_memset (h->reserved2, 0, sizeof (h->reserved2));
214
215  return h;
216}
217
218/* *INDENT-ON* */
219
220/*
221 * fd.io coding-style-patch-verification: ON
222 *
223 * Local Variables:
224 * eval: (c-set-style "gnu")
225 * End:
226 */
227