//We need this in addition to hook_receive_skb() because not dropping a packet
//while stopped in gdb may invoke some processing functions from the network stack that
//would like to take resources owned by other cores (that are now stopped).
//We don't want to guess and pre-acquire those resources, so we just drop all packets while stopped in kgdb.
static rx_handler_result_t netpoll_wrapper_rx_handler(struct sk_buff **pskb)
{
struct netpoll_wrapper *pWrapper = (struct netpoll_wrapper *)(*pskb)->dev->rx_handler_data;
bool drop = false;
BUG_ON(!pWrapper);
if (pWrapper->drop_other_packets)
drop = true;
else
{
int ulen;
struct iphdr *iph;
struct udphdr *uh;
if (parse_udp_packet(*pskb, &iph, &uh, &ulen))
{
if (pWrapper->netpoll_obj.local_port && pWrapper->netpoll_obj.local_port == ntohs(uh->dest) && (ip_addr_as_int(pWrapper->netpoll_obj.local_ip) && ip_addr_as_int(pWrapper->netpoll_obj.local_ip) == iph->daddr))
{
//Otherwise Linux itself may handle it, reply with ICMP 'port not available' and force GDB to disconnect.
drop = true;
}
}
}
if (drop)
{
kfree_skb(*pskb);
return RX_HANDLER_CONSUMED;
}
else
return RX_HANDLER_PASS;
}
static int pares_ipv4_packet(struct sk_buff *skb, struct iphdr *iphdr, dba_result_t *res)
{
int ret = 0;
if (unlikely(!iphdr)) {
return -1;
}
switch (iphdr->protocol) {
case IPPROTO_ICMP:
ret = parse_icmp_packet(skb, (struct icmphdr *)(IPv4_NXT_HDR(iphdr)), res);
break;
case IPPROTO_IGMP:
ret = parse_igmp_packet(skb, (struct igmphdr *)(IPv4_NXT_HDR(iphdr)), res);
break;
case IPPROTO_TCP:
ret = parse_tcp_packet(skb, (struct tcphdr *)(IPv4_NXT_HDR(iphdr)), res);
break;
case IPPROTO_UDP:
ret = parse_udp_packet(skb, (struct udphdr *)(IPv4_NXT_HDR(iphdr)), res);
break;
case IPPROTO_IPV6:
break;
default:
break;
}
return ret;
}
//We need this function in addition to netpoll_wrapper_rx_handler() because pre-3.15 kernel versions
//will not call the rx handler for the packets matching the IP/port of our netpoll objects (expecting them
//to be handled in rx_hook that we don't use because it provides no way of reading the MAC address).
static void hook_receive_skb(void *pContext, struct sk_buff *skb)
{
int ulen;
struct iphdr *iph;
struct udphdr *uh;
struct netpoll_wrapper *pWrapper = (struct netpoll_wrapper *)pContext;
BUG_ON(!pWrapper);
if (skb->dev != pWrapper->pDeviceWithHandler)
return;
if (pWrapper->handle_arp && skb->protocol == htons(ETH_P_ARP))
{
netpoll_wrapper_handle_arp(pWrapper, skb);
return;
}
if (!parse_udp_packet(skb, &iph, &uh, &ulen))
return;
if (pWrapper->netpoll_obj.local_port && pWrapper->netpoll_obj.local_port == ntohs(uh->dest))
{
if ((ip_addr_as_int(pWrapper->netpoll_obj.local_ip) && ip_addr_as_int(pWrapper->netpoll_obj.local_ip) == iph->daddr) ||
(support_broadcast_packets && iph->daddr == 0xffffffff))
{
pWrapper->netpoll_obj.remote_port = ntohs(uh->source);
ip_addr_as_int(pWrapper->netpoll_obj.remote_ip) = iph->saddr;
memcpy(pWrapper->netpoll_obj.remote_mac, eth_hdr(skb)->h_source, sizeof(pWrapper->netpoll_obj.remote_mac));
if (pWrapper->pReceiveHandler)
pWrapper->pReceiveHandler(pWrapper, ntohs(uh->source), (char *)(uh + 1), ulen - sizeof(struct udphdr));
}
}
}
bool CTDMHttpRequest::decode( CUdpCommonBufMsgBody* msgBody )
{
int len = msgBody->Size();
if ( len <= 0 ) return false;
int ret = parse_udp_packet( msgBody->GetBuf(), len );
if ( ret == -1 ) {
WriteRunInfo::WriteLog( "parse http request packet error" );
return false;
}
return true;
}
boolean parse_packet(struct sk_buff *skb, struct sniffed_packet_descr_t *descr)
{
struct iphdr *ip_header;
/* we only handle packets, which are big enough
* to contain an IP-header.
*/
if(skb->len < sizeof(struct iphdr) )
return FALSE;
ip_header = (struct iphdr *) skb->data;
/*
check range of IHL-field
*/
if(ip_header->ihl < 5 || ip_header->ihl > 15)
return FALSE;
/*
check ihl against skb-len
*/
if(skb->len < ip_header->ihl * 4)
return FALSE;
/* It has been verified that skb->data[0] to skb->data[ihl*4-1]
* is readable. Extract information from ip-header
*/
descr->subject = descr->src = ip_header->saddr;
if(ip_header->protocol == IPPROTO_TCP)
return parse_tcp_packet(skb, descr);
else if(ip_header->protocol == IPPROTO_ICMP)
return parse_icmp_packet(skb, descr);
else if(ip_header->protocol == IPPROTO_UDP)
return parse_udp_packet(skb, descr);
return FALSE;
}
