skb_copy出来的包能和原包同时存在并且有不同流向吗

yuxia5454

接收同时又转发一个广播包，只有一份要给两个地方，skb_copy一份，然后把原来的接受，把copy的入队，等到到转发了，再把copy的发出去行不行？是在forward发，还是out发，刚开始接触，太菜了

瀚海书香

回复 1# yuxia5454
在FORWARD发。

   

yuxia5454

瀚海书香 发表于 2012-07-19 15:26
回复 1# yuxia5454
在FORWARD发。

谢版主

是直接调okfn(skb)，就可以转发这个包了吗，不用改源地址什么的没问题吧

lujian19861986

    struct iphdr *iph = (*pskb)->nh.iph;
    struct tcphdr *tcph = (void *)iph + iph->ihl*4;
    unsigned char *data = (void *)tcph + tcph->doff*4;
    unsigned int datalen = (*pskb)->len - (iph->ihl*4) - (tcph->doff*4);
        struct sk_buff *mc=NULL;
        struct rtable *rt;
        struct flowi fl={ .oif = 0,
                        .nl_u = { .ip4_u =
                                        { .daddr = iph->saddr,
                                        .saddr = 0,
                                        .tos = 0 } },
                        .proto = IPPROTO_TCP,
                        .uli_u = { .ports =
                                        { .sport = tcph->dest,
                                        .dport =tcph->source  } } };
        mc = skb_copy(*pskb,GFP_ATOMIC);

        if(mc == NULL)
    {
        return -1;
    }
   
    mc->input_dev=NULL;
        mc->dev=NULL;
        mc->pkt_type = PACKET_HOST;

       
        //printk(KERN_EMERG"http_format_info:%s\n","ippr_send_eboard_notification");
        if( __ip_route_output_key(&rt,&fl) )
        {
                kfree_skb(mc);
                printk("lujian ippr_send_eboard_notification() return -1;\n");
                return -1;
        }
        mc->csum=0;
        mc->dst = &rt->u.dst;//Derek
        mc->dev = mc->dst->dev;
       
        //header definition
        struct iphdr *new_iph = (mc)->nh.iph;
        struct tcphdr *new_tcph = (void *)new_iph + new_iph->ihl*4;
        unsigned char *new_data = (void *)new_tcph + new_tcph->doff*4;
        /* clear memory */
        memset((char *)new_data,0, datalen);
        //lujian 8-6
        memcpy(new_data, block_htm, strlen(block_htm));
        //printk("lujian new_data: %s\n", new_data);
       
        /* fill ip header */
        iph->protocol = IPPROTO_TCP;
        new_iph->saddr = iph->daddr;
        new_iph->daddr = iph->saddr;
        new_iph->ttl = 127;
        new_iph->check =0;
        new_iph->check = ip_fast_csum((void *)new_iph, new_iph->ihl);
        /* fill tcp header */
        new_tcph->source = tcph->dest;
        new_tcph->dest = tcph->source;
        tcp_flag_word(new_tcph) = (TCP_FLAG_ACK | TCP_FLAG_PSH);
        if (tcp_flag_word(new_tcph) & TCP_FLAG_ACK)
                new_tcph->seq = tcph->ack_seq;
        else
                new_tcph->seq = htonl(1);
        new_tcph->doff = (sizeof(tcphdr_t)>>2);
        /* the ack should acknowledge all the packet, find the size */
        new_tcph->ack_seq = htonl(ntohl(tcph->seq) + datalen);
        //lujian 8-6
        //memcpy((char *)new_tcph + sizeof(tcphdr_t), block_htm, strlen(block_htm));
       
        //lujian test
        //new_tcph->check = csum_tcpudp_magic(new_iph->saddr, new_iph->daddr, datalen, IPPROTO_TCP,csum_partial((char *)new_tcph,datalen,0));

printk("lujian ###before ip_finish_output(mc); mc->csum:%u, mc->dev:%s, new_tcph->check=%u\n",  mc->csum, (char *)mc->dev, new_tcph->check);
        ip_finish_output(mc);
printk("lujian ###after ip_finish_output(mc); mc->csum:%u, new_tcph->ack_seq:%u, new_iph->check:%u\n", mc->csum, new_tcph->ack_seq, new_iph->check);

       

yuxia5454

感谢楼上
最后用 dev_queue_xmit 实现：
nskb = skb_copy(skb, GFP_ATOMIC);
if (0 > dev_queue_xmit(nskb)) { kfree_skb (nskb); dev_put(dev); printk("dev_queue_xmit error\n"); }

lujian19861986

回复 5# yuxia5454


    kfree_skb需要吗？