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