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authorAllain Legacy <allain.legacy@windriver.com>2017-03-14 11:14:47 -0400
committerThomas Monjalon <thomas@monjalon.net>2017-06-22 17:59:05 +0200
commit8d4d3a4f7337888871be8c52c26a9d6ade96955f (patch)
tree844ce28159af8a4cfa1d86e69937d7654658749e /lib/librte_ip_frag
parent95908f52393da36c47905a777f64c0650585c12b (diff)
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ip_frag: handle MTU sizes not aligned to 8 bytes
The rte_ipv4_fragment_packet API expects that the link/interface MTU value passed in be divisible by 8 bytes. Given the name of the parameter is "mtu" rather than "frag_size" it is not necessarily the case that it will be divisible by 8. An MTU of 1500 happens to produce a max fragment size of 1480 (1500 - sizeof(ipv4_hdr)) which is divisible by 8 but other MTU values such as 1600 or 9000 do not produce values that are divisible by 8. Unfortunately, the API checks that the frag_size value produced is divisible by 8 with a call to RTE_ASSERT which is only enabled when the RTE_LOG_LEVEL >= RTE_LOG_DEBUG. In cases where the log level is set normally the code silently continues and produces IP fragments that have invalid fragment offset values. An application may not have control over what MTU a user selects and rather than have each application adjust the MTU to pass a suitable value to the fragmentation API this change modifies the fragmentation API to handle cases where the "mtu" argument is not divisible by 8 and automatically adjust the internal "frag_size". Signed-off-by: Allain Legacy <allain.legacy@windriver.com> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Diffstat (limited to 'lib/librte_ip_frag')
-rw-r--r--lib/librte_ip_frag/rte_ipv4_fragmentation.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/lib/librte_ip_frag/rte_ipv4_fragmentation.c b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
index a2259e8..8c5f5ec 100644
--- a/lib/librte_ip_frag/rte_ipv4_fragmentation.c
+++ b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
@@ -48,7 +48,7 @@
#define IPV4_HDR_DF_MASK (1 << IPV4_HDR_DF_SHIFT)
#define IPV4_HDR_MF_MASK (1 << IPV4_HDR_MF_SHIFT)
-#define IPV4_HDR_FO_MASK ((1 << IPV4_HDR_FO_SHIFT) - 1)
+#define IPV4_HDR_FO_ALIGN (1 << IPV4_HDR_FO_SHIFT)
static inline void __fill_ipv4hdr_frag(struct ipv4_hdr *dst,
const struct ipv4_hdr *src, uint16_t len, uint16_t fofs,
@@ -103,11 +103,14 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
uint32_t out_pkt_pos, in_seg_data_pos;
uint32_t more_in_segs;
uint16_t fragment_offset, flag_offset, frag_size;
+ uint16_t frag_bytes_remaining;
- frag_size = (uint16_t)(mtu_size - sizeof(struct ipv4_hdr));
-
- /* Fragment size should be a multiply of 8. */
- RTE_ASSERT((frag_size & IPV4_HDR_FO_MASK) == 0);
+ /*
+ * Ensure the IP payload length of all fragments is aligned to a
+ * multiple of 8 bytes as per RFC791 section 2.3.
+ */
+ frag_size = RTE_ALIGN_FLOOR((mtu_size - sizeof(struct ipv4_hdr)),
+ IPV4_HDR_FO_ALIGN);
in_hdr = rte_pktmbuf_mtod(pkt_in, struct ipv4_hdr *);
flag_offset = rte_cpu_to_be_16(in_hdr->fragment_offset);
@@ -142,6 +145,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
/* Reserve space for the IP header that will be built later */
out_pkt->data_len = sizeof(struct ipv4_hdr);
out_pkt->pkt_len = sizeof(struct ipv4_hdr);
+ frag_bytes_remaining = frag_size;
out_seg_prev = out_pkt;
more_out_segs = 1;
@@ -161,7 +165,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
/* Prepare indirect buffer */
rte_pktmbuf_attach(out_seg, in_seg);
- len = mtu_size - out_pkt->pkt_len;
+ len = frag_bytes_remaining;
if (len > (in_seg->data_len - in_seg_data_pos)) {
len = in_seg->data_len - in_seg_data_pos;
}
@@ -171,9 +175,10 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
out_pkt->pkt_len);
out_pkt->nb_segs += 1;
in_seg_data_pos += len;
+ frag_bytes_remaining -= len;
/* Current output packet (i.e. fragment) done ? */
- if (unlikely(out_pkt->pkt_len >= mtu_size))
+ if (unlikely(frag_bytes_remaining == 0))
more_out_segs = 0;
/* Current input segment done ? */