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