Thank you. I make a error with "tot_len".
2014-09-16 23:05 GMT+08:00 ankur dwivedi <ankurengg2003@xxxxxxxxx>:
What is getting shown in tcpdump?I guess its a checksum problem.On Sun, Sep 7, 2014 at 2:42 PM, lx <lxlenovostar@xxxxxxxxx> wrote:_______________________________________________hi all:I want to send a udp packet in kernel module. the codes is:####################################################/** send UDP packet*/char *dest_addr = "192.168.109.176";int eth_len, udph_len, iph_len, len;eth_len = sizeof(struct ethhdr);iph_len = sizeof(struct iphdr);udph_len = sizeof(struct udphdr);len = eth_len + iph_len + udph_len;struct sk_buff *send_skb = alloc_skb(len, GFP_ATOMIC);if (!send_skb)return NF_DROP;//skb_put(send_skb, len);skb_reserve(send_skb, len);skb_push(send_skb, sizeof(struct udphdr));skb_reset_transport_header(send_skb);udph = udp_hdr(send_skb);udph->source = dport;udph->dest = dport;udph->len = htons(udph_len);udph->check = 0;udph->check = csum_tcpudp_magic(daddr, in_aton(dest_addr), udph_len, IPPROTO_UDP, csum_partial(udph, udph_len, 0));//if (udph->check == 0)// udph->check = CSUM_MANGLED_0;skb_push(send_skb, sizeof(struct iphdr));skb_reset_network_header(send_skb);send_iph = ip_hdr(send_skb);// iph->version = 4; iph->ihl = 5;put_unaligned(0x45, (unsigned char *)send_iph);send_iph->tos = 0;put_unaligned(htons(iph_len), &(send_iph->tot_len));//send_iph->id = htons(atomic_inc_return(&ip_ident));send_iph->id = 0;send_iph->frag_off = 0;send_iph->ttl = 64;send_iph->protocol = IPPROTO_UDP;send_iph->check = 0;put_unaligned(daddr, &(send_iph->saddr));put_unaligned(in_aton(dest_addr), &(send_iph->daddr));send_iph->check = ip_fast_csum((unsigned char *)send_iph, send_iph->ihl);eth = (struct ethhdr *) skb_push(send_skb, ETH_HLEN);skb_reset_mac_header(send_skb);send_skb->protocol = eth->h_proto = htons(ETH_P_IP);memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);memcpy(eth->h_dest, "00:0C:29:DC:2D:F5", ETH_ALEN);send_skb->dev = dev;dev_queue_xmit(send_skb);####################################################I think the udp packe is sent,but the wirshark detect this packet is error.The Error message is:####################################################
####################################################Tell me how to debug it? I'm a new one,Thank you.
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ankur dwivedi
http://about.me/ankur_dwivedi
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