From: Grigore Ion <ion.grig...@freescale.com>

This patch fixes the following problems:
- checksum computation for LE platforms
- checksum computation for packets having the UDP length not a
multiple of 2
- checksum computation in the test and the example applications

Signed-off-by: Grigore Ion <ion.grig...@freescale.com>
---
v9:
- Fix comments (Ilya Maximets)
v8:
- Checksum in BE endianness (Ilya Maximets)
v7:
- Make code simpler and more understandable as it was
sugessted by Ilya Maximets
v6:
- Make code more understandable. Not done as it was
sugessted by Ilya Maximets.
v5:
- Checksum in CPU endianness fix added (Ilya Maximets)
v4:
- Verify checksum in CPU endianness in the associated test
(Ilya Maximets)
v3:
- fix the UDP checksum computation in the associated test
(Maxim Uvarov)
v2:
- patch updated to the last master (Maxim Uvarov)
v1:
- Move variables declaration on top of block. (Maxim Uvarov)
- Check patch with checkpatch script.  (Maxim Uvarov)
- L3 header presence is tested twice. (Alexandru Badicioiu)
- Remove unnecessary check for L3 header presence. (Bill Fischofer)

 example/generator/odp_generator.c |  2 +-
 helper/include/odp/helper/udp.h   | 66 ++++++++++++++++++++-------------------
 helper/test/odp_chksum.c          |  4 +--
 test/validation/pktio/pktio.c     |  2 +-
 4 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/example/generator/odp_generator.c 
b/example/generator/odp_generator.c
index cdbc761..757dc54 100644
--- a/example/generator/odp_generator.c
+++ b/example/generator/odp_generator.c
@@ -242,7 +242,7 @@ static odp_packet_t pack_udp_pkt(odp_pool_t pool)
        udp->dst_port = 0;
        udp->length = odp_cpu_to_be_16(args->appl.payload + ODPH_UDPHDR_LEN);
        udp->chksum = 0;
-       udp->chksum = odp_cpu_to_be_16(odph_ipv4_udp_chksum(pkt));
+       udp->chksum = odph_ipv4_udp_chksum(pkt);
 
        return pkt;
 }
diff --git a/helper/include/odp/helper/udp.h b/helper/include/odp/helper/udp.h
index 06c439b..93b342d 100644
--- a/helper/include/odp/helper/udp.h
+++ b/helper/include/odp/helper/udp.h
@@ -4,7 +4,6 @@
  * SPDX-License-Identifier:     BSD-3-Clause
  */
 
-
 /**
  * @file
  *
@@ -22,7 +21,6 @@ extern "C" {
 #include <odp/debug.h>
 #include <odp/byteorder.h>
 
-
 /** @addtogroup odph_header ODPH HEADER
  *  @{
  */
@@ -44,46 +42,50 @@ typedef struct ODP_PACKED {
  * This function uses odp packet to calc checksum
  *
  * @param pkt  calculate chksum for pkt
- * @return  checksum value
+ * @return  checksum value in BE endianness
  */
 static inline uint16_t odph_ipv4_udp_chksum(odp_packet_t pkt)
 {
-       uint32_t sum = 0;
-       odph_udphdr_t *udph;
-       odph_ipv4hdr_t *iph;
-       uint16_t udplen;
-       uint8_t *buf;
-
-       if (!odp_packet_l3_offset(pkt))
+       odph_ipv4hdr_t  *iph;
+       odph_udphdr_t   *udph;
+       uint32_t        sum;
+       uint16_t        udplen, *buf;
+       union {
+               uint8_t v8[2];
+               uint16_t v16;
+       } val;
+
+       if (odp_packet_l4_offset(pkt) == ODP_PACKET_OFFSET_INVALID)
                return 0;
-
-       if (!odp_packet_l4_offset(pkt))
-               return 0;
-
        iph = (odph_ipv4hdr_t *)odp_packet_l3_ptr(pkt, NULL);
        udph = (odph_udphdr_t *)odp_packet_l4_ptr(pkt, NULL);
-       udplen = odp_be_to_cpu_16(udph->length);
-
-       /* 32-bit sum of all 16-bit words covered by UDP chksum */
+       /* 32-bit sum of UDP pseudo-header, seen as a series of 16-bit words */
        sum = (iph->src_addr & 0xFFFF) + (iph->src_addr >> 16) +
-             (iph->dst_addr & 0xFFFF) + (iph->dst_addr >> 16) +
-             (uint16_t)iph->proto + udplen;
-       for (buf = (uint8_t *)udph; udplen > 1; udplen -= 2) {
-               sum += ((*buf << 8) + *(buf + 1));
-               buf += 2;
+                       (iph->dst_addr & 0xFFFF) + (iph->dst_addr >> 16) +
+                       udph->length;
+       val.v8[0] = 0;
+       val.v8[1] = iph->proto;
+       sum += val.v16;
+       /* 32-bit sum of UDP header (checksum field cleared) and UDP data, seen
+        * as a series of 16-bit words */
+       udplen = odp_be_to_cpu_16(udph->length);
+       buf = (uint16_t *)((void *)udph);
+       for ( ; udplen > 1; udplen -= 2)
+               sum += *buf++;
+       /* Length is not a multiple of 2 bytes */
+       if (udplen) {
+               val.v8[0] = *buf;
+               val.v8[1] = 0;
+               sum += val.v16;
        }
-
-       /* Fold sum to 16 bits: add carrier to result */
-       while (sum >> 16)
-               sum = (sum & 0xFFFF) + (sum >> 16);
-
+       /* Fold sum to 16 bits */
+       sum = (sum & 0xFFFF) + (sum >> 16);
+       /* Add carrier (0/1) to result */
+       sum += (sum >> 16);
        /* 1's complement */
        sum = ~sum;
-
-       /* set computation result */
-       sum = (sum == 0x0) ? 0xFFFF : sum;
-
-       return sum;
+       /* Return checksum in BE endianness */
+       return (sum == 0x0) ? 0xFFFF : sum;
 }
 
 /** @internal Compile time assert */
diff --git a/helper/test/odp_chksum.c b/helper/test/odp_chksum.c
index 1d417a8..b71fabc 100644
--- a/helper/test/odp_chksum.c
+++ b/helper/test/odp_chksum.c
@@ -194,9 +194,9 @@ int main(int argc TEST_UNUSED, char *argv[] TEST_UNUSED)
        if (udp->chksum == 0)
                return -1;
 
-       printf("chksum = 0x%x\n", udp->chksum);
+       printf("chksum = 0x%x\n", odp_be_to_cpu_16(udp->chksum));
 
-       if (udp->chksum != 0xab2d)
+       if (odp_be_to_cpu_16(udp->chksum) != 0x7e5a)
                status = -1;
 
        odp_packet_free(test_packet);
diff --git a/test/validation/pktio/pktio.c b/test/validation/pktio/pktio.c
index e473a1d..8121f1e 100644
--- a/test/validation/pktio/pktio.c
+++ b/test/validation/pktio/pktio.c
@@ -232,7 +232,7 @@ static int pktio_fixup_checksums(odp_packet_t pkt)
        ip->chksum = 0;
        odph_ipv4_csum_update(pkt);
        udp->chksum = 0;
-       udp->chksum = odp_cpu_to_be_16(odph_ipv4_udp_chksum(pkt));
+       udp->chksum = odph_ipv4_udp_chksum(pkt);
 
        return 0;
 }
-- 
1.9.3

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