Hello Alexandru,

Your patch fixes check summ now that function is better:


20:49:45.613467 IP (tos 0x0, id 35630, offset 0, flags [none], proto UDP (17), length 84) 192.168.0.1.0 > 192.168.0.2.0: [bad udp cksum 0x1a7e -> 0x7e1a!] UDP, length 56 20:49:45.613470 IP (tos 0x0, id 35662, offset 0, flags [none], proto UDP (17), length 84) 192.168.0.1.0 > 192.168.0.2.0: [bad udp cksum 0x1a7e -> 0x7e1a!] UDP, length 56

I used packets generated with our odp_generator.

After that fix check summ is valid:

--- a/example/generator/odp_generator.c
+++ b/example/generator/odp_generator.c
@@ -238,7 +238,6 @@ 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;

That will work on both BE/LE right?

Thanks,
Maxim.



On 05/05/2015 15:07, alexandru.badici...@linaro.org wrote:
From: Alexandru Badicioiu <alexandru.badici...@linaro.org>

v1 - fixed compile error due to -Wcast-align

Signed-off-by: Alexandru Badicioiu <alexandru.badici...@linaro.org>
---
  helper/include/odp/helper/udp.h |   37 +++++++++++++------------------------
  1 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/helper/include/odp/helper/udp.h b/helper/include/odp/helper/udp.h
index 99a96f2..d14cbef 100644
--- a/helper/include/odp/helper/udp.h
+++ b/helper/include/odp/helper/udp.h
@@ -33,15 +33,6 @@ typedef struct ODP_PACKED {
        uint16be_t chksum;   /**< UDP header and data checksum (0 if not used)*/
  } odph_udphdr_t;
-/** UDP pseudo header */
-typedef struct ODPH_PACKET {
-       uint32be_t src_addr; /**< Source addr */
-       uint32be_t dst_addr; /**< Destination addr */
-       uint8_t pad;         /**< pad byte */
-       uint8_t proto;       /**< UDP protocol */
-       uint16be_t length;   /**< data length */
-} odph_udpphdr_t;
-
  /**
   * UDP checksum
   *
@@ -53,10 +44,10 @@ typedef struct ODPH_PACKET {
  static inline uint16_t odph_ipv4_udp_chksum(odp_packet_t pkt)
  {
        uint32_t sum = 0;
-       odph_udpphdr_t phdr;
        odph_udphdr_t *udph;
        odph_ipv4hdr_t *iph;
        uint16_t udplen;
+       uint8_t *buf;
if (!odp_packet_l3_offset(pkt))
                return 0;
@@ -68,24 +59,22 @@ static inline uint16_t odph_ipv4_udp_chksum(odp_packet_t 
pkt)
        udph = (odph_udphdr_t *)odp_packet_l4_ptr(pkt, NULL);
        udplen = odp_be_to_cpu_16(udph->length);
- /* the source ip */
-       phdr.src_addr = iph->src_addr;
-       /* the dest ip */
-       phdr.dst_addr = iph->dst_addr;
-       /* proto */
-       phdr.pad = 0;
-       phdr.proto = ODPH_IPPROTO_UDP;
-       /* the length */
-       phdr.length = udph->length;
-
-       /* calc UDP pseudo header chksum */
-       sum = (__odp_force uint32_t) odp_chksum(&phdr, sizeof(odph_udpphdr_t));
-       /* calc udp header and data chksum */
-       sum += (__odp_force uint32_t) odp_chksum(udph, udplen);
+       /* 32-bit sum of all 16-bit words covered by UDP chksum */
+       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;
+       }
/* Fold sum to 16 bits: add carrier to result */
        while (sum >> 16)
                sum = (sum & 0xFFFF) + (sum >> 16);
+
+       /* 1's complement */
+       sum = ~sum;
+
        /* set computation result */
        sum = (sum == 0x0) ? 0xFFFF : sum;

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