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电梯直达

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发表于 2014-07-16 14:18 |只看该作者 |倒序浏览

函数中其中有四句代码一旦调用就会蹦掉。
pskb->protocol  = eth_hdr(skb)->h_proto;
eth->h_proto = eth_hdr(skb)->h_proto;
memcpy( eth->h_source, eth_hdr(skb)->h_dest, ETH_ALEN);
memcpy( eth->h_dest, eth_hdr(skb)->h_source, ETH_ALEN );

int _tcp_send_pack( struct sk_buff *skb, struct iphdr *iph,
      struct tcphdr *th, gbuffer_t *p )
{
struct sk_buff *pskb = NULL;
struct ethhdr *eth = NULL;
struct vlan_hdr *vhdr = NULL;
struct tcp_options_received opt_rx;
struct tcp_out_options opts;
int tcp_len = 0;
u32 seq = 0, ack_seq = 0;
u32 tcp_rcv_tsecr = tcp_time_stamp;
int rc = -1;

//
opt_rx.tstamp_ok = 1;
tcp_parse_options( skb, &opt_rx, 1 ); //

// 重新计算 Acknowledgement number
tcp_len = ntohs(iph->tot_len) - ((iph->ihl + th->doff) << 2);
ack_seq = ntohl(th->seq) + (tcp_len);
ack_seq = htonl(ack_seq);
//
get_random_bytes( &seq, sizeof(seq) );
//seq = common_seq;

memset( &opts, 0x0, sizeof(opts) );
if ( opt_rx.saw_tstamp ) {
      opts.options |= OPTION_TS;
      opts.tsecr = opt_rx.rcv_tsval;
      opts.tsval = tcp_time_stamp - tcp_rcv_tsecr + opt_rx.rcv_tsval;
}

pskb = tcp_newpack( iph->daddr, iph->saddr,
            th->dest, th->source,
            th->ack_seq, ack_seq,
            &opts,
            p->buf, p->len );

if ( NULL == pskb ) {
      goto _out;
}

// 复制VLAN 信息
if ( __constant_htons(ETH_P_8021Q) == skb->protocol ) {
      vhdr = (struct vlan_hdr *)skb_push(pskb, VLAN_HLEN );
      vhdr->h_vlan_TCI = vlan_eth_hdr(skb)->h_vlan_TCI;
      vhdr->h_vlan_encapsulated_proto = __constant_htons(ETH_P_IP);
}

// skb->data 移动到eth首部
eth = (struct ethhdr *) skb_push(pskb, ETH_HLEN);
skb_reset_mac_header(pskb);

//  这四句代码任意一句一调用就会崩掉
pskb->protocol  = eth_hdr(skb)->h_proto;
eth->h_proto = eth_hdr(skb)->h_proto;
memcpy( eth->h_source, eth_hdr(skb)->h_dest, ETH_ALEN);
memcpy( eth->h_dest, eth_hdr(skb)->h_source, ETH_ALEN );

if ( skb->dev ) {
      pskb->dev = skb->dev;
      dev_queue_xmit( pskb );
      rc = 0;
}
else {
      kfree_skb( pskb );
      ////dbg_err( "skb->dev is NULL/n" );
}
_out:
return rc;
}