NDIS 修改数据包，拦截URL
想实现：本机输入www.baidu.com 拦截后显示，This page is restricted by xiaoc!
下面这个函数就是在MPSend 和 MPSendOnePacket 调用后修改数据包的。
修改完后就会调用NdisSend发送，运行结果是输入www.baidu.com 后无法找到该页
不知道错在哪里？还有如何知道效验值check的正确性？
void FilterHttpRequest(PUCHAR p){ __u32 u32temp; __u16 u16temp; struct psdhdr ph; /* pseudo header declaration */ //////////////////////////SENDING BLOCK PAGE TO CLIENT////////////////////////// // Use the first 40 bytes of m_pBlockBuffer for future TCP control packet transmission. char* pBlockBuffer; struct iphdr* respIpHdr; struct tcphdr* respTcpHdr; char* pTcpData; unsigned int dsize; //DbgBreakPoint(); respIpHdr = (struct iphdr*)(p + sizeof(struct ethhdr)); respTcpHdr = ((struct tcphdr*)((char*)respIpHdr + sizeof (struct iphdr))); pTcpData = (char*)respIpHdr + sizeof(struct iphdr) + sizeof(struct tcphdr); NdisAllocateMemoryWithTag(&pBlockBuffer, 512, TAG); NdisZeroMemory(pBlockBuffer, 512); sprintf(pBlockBuffer, "%s", "<html>" "<head>" "<title>HTTPFilter block page</title></head><body><TABLE height=\"100%\" width=\"100%\">" "<TR>" "<TD align=\"center\"><h1>This page is restricted by xiaoc!</h1>" "</TD>" "</TR>" "</TABLE>" "</body>" "</html>\n\n\n" ); dsize = Xc_strlen(pBlockBuffer, '\0'); NdisZeroMemory(pBlockBuffer, 512); sprintf(pBlockBuffer, "HTTP/1.1 200 OK\r\n" "Content-Type: Text/HTML\r\n" "Connection: close\r\n" "Content-Lenght: %d" "\r\n\r\n" "%s", dsize, "<html>" "<head>" "<title>HTTPFilter block page</title></head><body><TABLE height=\"100%\" width=\"100%\">" "<TR>" "<TD align=\"center\"><h1>This page is restricted by xiaoc!</h1>" "</TD>" "</TR>" "</TABLE>" "</body>" "</html>\n\n\n" ); dsize = Xc_strlen(pBlockBuffer, '\0'); DbgPrint("[xiaoc httpfiter] block info : %s", pBlockBuffer); NdisZeroMemory(pTcpData, XC_ntohs(respIpHdr->tot_len) - sizeof(struct iphdr) - sizeof(struct tcphdr)); NdisMoveMemory(pTcpData, pBlockBuffer, dsize); DbgPrint("[xiaoc httpfilter] FilterHttpRequest debug 1"); respIpHdr->check = 0; u32temp = respIpHdr->daddr; respIpHdr->daddr = respIpHdr->saddr; respIpHdr->saddr = u32temp; respIpHdr->tot_len = XC_htons(sizeof (struct iphdr) + sizeof (struct tcphdr) + dsize); respIpHdr->id = XC_htons((__u16)2); respIpHdr->frag_off = 0; respIpHdr->protocol = 0x06; respIpHdr->check = CalcIPSum((__u16*) respIpHdr, sizeof(struct iphdr)); u32temp = respTcpHdr->ack_seq; respTcpHdr->ack_seq = XC_htonl (XC_htonl (respTcpHdr->seq) + dsize); respTcpHdr->seq = u32temp; u16temp = respTcpHdr->source; respTcpHdr->source = respTcpHdr->dest; respTcpHdr->dest = u16temp; respTcpHdr->ack = 1; respTcpHdr->fin = 1; //SET_TCP_OFFSET(respTcpHdr, 0x5); //SET_TCP_X2(respTcpHdr, 0x0); respTcpHdr->urg = 0; ph.sourceip = respIpHdr->saddr; ph.destip = respIpHdr->daddr; ph.mbz = 0; ph.ptcl = 0x06; ph.plen = XC_htons((__u16)(sizeof (struct tcphdr) + dsize)); respTcpHdr->check = 0; respTcpHdr->check = CalcTCPSum((__u16 *)&ph, (__u16 *)respTcpHdr, sizeof(struct tcphdr) + dsize); if( pBlockBuffer ) { NdisFreeMemory(pBlockBuffer, 512, 0); }}