lib/ip_frag/rte_ipv4_fragmentation.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2010-2014 Intel Corporation
   3  */
   4
   5 #include <stddef.h>
   6 #include <errno.h>
   7
   8 #include <rte_memcpy.h>
   9 #include <rte_ether.h>
  10
  11 #include "ip_frag_common.h"
  12
  13 /* Fragment Offset */
  14 #define RTE_IPV4_HDR_DF_SHIFT                   14
  15 #define RTE_IPV4_HDR_MF_SHIFT                   13
  16 #define RTE_IPV4_HDR_FO_SHIFT                   3
  17
  18 #define IPV4_HDR_DF_MASK                        (1 << RTE_IPV4_HDR_DF_SHIFT)
  19 #define IPV4_HDR_MF_MASK                        (1 << RTE_IPV4_HDR_MF_SHIFT)
  20
  21 #define IPV4_HDR_FO_ALIGN                       (1 << RTE_IPV4_HDR_FO_SHIFT)
  22
  23 static inline void __fill_ipv4hdr_frag(struct rte_ipv4_hdr *dst,
  24                 const struct rte_ipv4_hdr *src, uint16_t header_len,
  25                 uint16_t len, uint16_t fofs, uint16_t dofs, uint32_t mf)
  26 {
  27         rte_memcpy(dst, src, header_len);
  28         fofs = (uint16_t)(fofs + (dofs >> RTE_IPV4_HDR_FO_SHIFT));
  29         fofs = (uint16_t)(fofs | mf << RTE_IPV4_HDR_MF_SHIFT);
  30         dst->fragment_offset = rte_cpu_to_be_16(fofs);
  31         dst->total_length = rte_cpu_to_be_16(len);
  32         dst->hdr_checksum = 0;
  33 }
  34
  35 static inline void __free_fragments(struct rte_mbuf *mb[], uint32_t num)
  36 {
  37         uint32_t i;
  38         for (i = 0; i != num; i++)
  39                 rte_pktmbuf_free(mb[i]);
  40 }
  41
  42 /**
  43  * IPv4 fragmentation.
  44  *
  45  * This function implements the fragmentation of IPv4 packets.
  46  *
  47  * @param pkt_in
  48  *   The input packet.
  49  * @param pkts_out
  50  *   Array storing the output fragments.
  51  * @param mtu_size
  52  *   Size in bytes of the Maximum Transfer Unit (MTU) for the outgoing IPv4
  53  *   datagrams. This value includes the size of the IPv4 header.
  54  * @param pool_direct
  55  *   MBUF pool used for allocating direct buffers for the output fragments.
  56  * @param pool_indirect
  57  *   MBUF pool used for allocating indirect buffers for the output fragments.
  58  * @return
  59  *   Upon successful completion - number of output fragments placed
  60  *   in the pkts_out array.
  61  *   Otherwise - (-1) * <errno>.
  62  */
  63 int32_t
  64 rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
  65         struct rte_mbuf **pkts_out,
  66         uint16_t nb_pkts_out,
  67         uint16_t mtu_size,
  68         struct rte_mempool *pool_direct,
  69         struct rte_mempool *pool_indirect)
  70 {
  71         struct rte_mbuf *in_seg = NULL;
  72         struct rte_ipv4_hdr *in_hdr;
  73         uint32_t out_pkt_pos, in_seg_data_pos;
  74         uint32_t more_in_segs;
  75         uint16_t fragment_offset, flag_offset, frag_size, header_len;
  76         uint16_t frag_bytes_remaining;
  77
  78         /*
  79          * Formal parameter checking.
  80          */
  81         if (unlikely(pkt_in == NULL) || unlikely(pkts_out == NULL) ||
  82             unlikely(nb_pkts_out == 0) ||
  83             unlikely(pool_direct == NULL) || unlikely(pool_indirect == NULL) ||
  84             unlikely(mtu_size < RTE_ETHER_MIN_MTU))
  85                 return -EINVAL;
  86
  87         in_hdr = rte_pktmbuf_mtod(pkt_in, struct rte_ipv4_hdr *);
  88         header_len = (in_hdr->version_ihl & RTE_IPV4_HDR_IHL_MASK) *
  89             RTE_IPV4_IHL_MULTIPLIER;
  90
  91         /* Check IP header length */
  92         if (unlikely(pkt_in->data_len < header_len) ||
  93             unlikely(mtu_size < header_len))
  94                 return -EINVAL;
  95
  96         /*
  97          * Ensure the IP payload length of all fragments is aligned to a
  98          * multiple of 8 bytes as per RFC791 section 2.3.
  99          */
 100         frag_size = RTE_ALIGN_FLOOR((mtu_size - header_len),
 101                                     IPV4_HDR_FO_ALIGN);
 102
 103         flag_offset = rte_cpu_to_be_16(in_hdr->fragment_offset);
 104
 105         /* If Don't Fragment flag is set */
 106         if (unlikely ((flag_offset & IPV4_HDR_DF_MASK) != 0))
 107                 return -ENOTSUP;
 108
 109         /* Check that pkts_out is big enough to hold all fragments */
 110         if (unlikely(frag_size * nb_pkts_out <
 111             (uint16_t)(pkt_in->pkt_len - header_len)))
 112                 return -EINVAL;
 113
 114         in_seg = pkt_in;
 115         in_seg_data_pos = header_len;
 116         out_pkt_pos = 0;
 117         fragment_offset = 0;
 118
 119         more_in_segs = 1;
 120         while (likely(more_in_segs)) {
 121                 struct rte_mbuf *out_pkt = NULL, *out_seg_prev = NULL;
 122                 uint32_t more_out_segs;
 123                 struct rte_ipv4_hdr *out_hdr;
 124
 125                 /* Allocate direct buffer */
 126                 out_pkt = rte_pktmbuf_alloc(pool_direct);
 127                 if (unlikely(out_pkt == NULL)) {
 128                         __free_fragments(pkts_out, out_pkt_pos);
 129                         return -ENOMEM;
 130                 }
 131
 132                 /* Reserve space for the IP header that will be built later */
 133                 out_pkt->data_len = header_len;
 134                 out_pkt->pkt_len = header_len;
 135                 frag_bytes_remaining = frag_size;
 136
 137                 out_seg_prev = out_pkt;
 138                 more_out_segs = 1;
 139                 while (likely(more_out_segs && more_in_segs)) {
 140                         struct rte_mbuf *out_seg = NULL;
 141                         uint32_t len;
 142
 143                         /* Allocate indirect buffer */
 144                         out_seg = rte_pktmbuf_alloc(pool_indirect);
 145                         if (unlikely(out_seg == NULL)) {
 146                                 rte_pktmbuf_free(out_pkt);
 147                                 __free_fragments(pkts_out, out_pkt_pos);
 148                                 return -ENOMEM;
 149                         }
 150                         out_seg_prev->next = out_seg;
 151                         out_seg_prev = out_seg;
 152
 153                         /* Prepare indirect buffer */
 154                         rte_pktmbuf_attach(out_seg, in_seg);
 155                         len = frag_bytes_remaining;
 156                         if (len > (in_seg->data_len - in_seg_data_pos)) {
 157                                 len = in_seg->data_len - in_seg_data_pos;
 158                         }
 159                         out_seg->data_off = in_seg->data_off + in_seg_data_pos;
 160                         out_seg->data_len = (uint16_t)len;
 161                         out_pkt->pkt_len = (uint16_t)(len +
 162                             out_pkt->pkt_len);
 163                         out_pkt->nb_segs += 1;
 164                         in_seg_data_pos += len;
 165                         frag_bytes_remaining -= len;
 166
 167                         /* Current output packet (i.e. fragment) done ? */
 168                         if (unlikely(frag_bytes_remaining == 0))
 169                                 more_out_segs = 0;
 170
 171                         /* Current input segment done ? */
 172                         if (unlikely(in_seg_data_pos == in_seg->data_len)) {
 173                                 in_seg = in_seg->next;
 174                                 in_seg_data_pos = 0;
 175
 176                                 if (unlikely(in_seg == NULL))
 177                                         more_in_segs = 0;
 178                         }
 179                 }
 180
 181                 /* Build the IP header */
 182
 183                 out_hdr = rte_pktmbuf_mtod(out_pkt, struct rte_ipv4_hdr *);
 184
 185                 __fill_ipv4hdr_frag(out_hdr, in_hdr, header_len,
 186                     (uint16_t)out_pkt->pkt_len,
 187                     flag_offset, fragment_offset, more_in_segs);
 188
 189                 fragment_offset = (uint16_t)(fragment_offset +
 190                     out_pkt->pkt_len - header_len);
 191
 192                 out_pkt->l3_len = header_len;
 193
 194                 /* Write the fragment to the output list */
 195                 pkts_out[out_pkt_pos] = out_pkt;
 196                 out_pkt_pos ++;
 197         }
 198
 199         return out_pkt_pos;
 200 }