void send_udp_transmit(uint8_t *buf,uint16_t datalen)
{
uint16_t tmp16;
tmp16=IP_HEADER_LEN+UDP_HEADER_LEN+datalen;
buf[IP_TOTLEN_L_P]=tmp16& 0xff;
buf[IP_TOTLEN_H_P]=tmp16>>8;
fill_ip_hdr_checksum(buf);
tmp16=UDP_HEADER_LEN+datalen;
buf[UDP_LEN_L_P]=tmp16& 0xff;
buf[UDP_LEN_H_P]=tmp16>>8;
//
tmp16=checksum(&buf[IP_SRC_P], 16 + datalen,1);
buf[UDP_CHECKSUM_L_P]=tmp16& 0xff;
buf[UDP_CHECKSUM_H_P]=tmp16>>8;
enc28j60PacketSend(UDP_HEADER_LEN+IP_HEADER_LEN+ETH_HEADER_LEN+datalen,buf);
}
void client_ntp_request(uint8_t *buf,uint8_t *ntpip,uint8_t srcport,uint8_t *dstmac)
{
uint8_t i=0;
uint16_t ck;
//
while(i<6){
buf[ETH_DST_MAC +i]=dstmac[i]; // gw mac in local lan or host mac
buf[ETH_SRC_MAC +i]=macaddr[i];
i++;
}
buf[ETH_TYPE_H_P] = ETHTYPE_IP_H_V;
buf[ETH_TYPE_L_P] = ETHTYPE_IP_L_V;
fill_buf_p(&buf[IP_P],9,iphdr);
buf[IP_ID_L_P]=ipid; ipid++;
buf[IP_TOTLEN_L_P]=0x4c;
buf[IP_PROTO_P]=IP_PROTO_UDP_V;
i=0;
while(i<4){
buf[IP_DST_P+i]=ntpip[i];
buf[IP_SRC_P+i]=ipaddr[i];
i++;
}
fill_ip_hdr_checksum(buf);
buf[UDP_DST_PORT_H_P]=0;
buf[UDP_DST_PORT_L_P]=0x7b; // ntp=123
buf[UDP_SRC_PORT_H_P]=10;
buf[UDP_SRC_PORT_L_P]=srcport; // lower 8 bit of src port
buf[UDP_LEN_H_P]=0;
buf[UDP_LEN_L_P]=56; // fixed len
// zero the checksum
buf[UDP_CHECKSUM_H_P]=0;
buf[UDP_CHECKSUM_L_P]=0;
// copy the data:
i=0;
// most fields are zero, here we zero everything and fill later
while(i<48){
buf[UDP_DATA_P+i]=0;
i++;
}
fill_buf_p(&buf[UDP_DATA_P],10,ntpreqhdr);
//
ck=checksum(&buf[IP_SRC_P], 16 + 48,1);
buf[UDP_CHECKSUM_H_P]=ck>>8;
buf[UDP_CHECKSUM_L_P]=ck& 0xff;
enc28j60PacketSend(90,buf);
}
void EtherShield::ES_fill_ip_hdr_checksum(uint8_t *buf) {
fill_ip_hdr_checksum(buf);
}