TCP/UDP checksum (MIPS)
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由於在網路找到的sample都難直接拿來用，可能是因為MIPS很少人用，而MIPS因為byte order跟network byte order一樣所以被排擠，所以我把最後集各家之大成試出來可以用的sample放在這邊
struct pseudoHeader {uint32_t ip_src;uint32_t ip_dst;uint8_t zero;//always zerouint8_t protocol;uint16_t len;};static inline uint16_tchecksum (uint16_t *data, int len){uint16_t ret = 0;uint32_t sum = 0;while (len > 1) {sum += *data++;len -= 2;}if (len > 0) {sum += ((*data)&0xFF00);}sum = (sum >> 16) + (sum & 0xffff);sum += (sum >> 16);ret = ~sum;return ret;}uint16_ttcp_udp_checksum(struct ip *iph, uint8_t *header, int header_size, uint8_t protocol, uint8_t *data, int size){struct pseudoHeader psd_header;psd_header.ip_dst = (uint32_t)iph->ip_dst.s_addr;psd_header.ip_src = (uint32_t)iph->ip_src.s_addr;psd_header.zero = 0;psd_header.protocol = protocol;psd_header.len = header_size+size;uint8_t buf[4096];memcpy(buf, &psd_header, sizeof(struct pseudoHeader));memcpy(buf+sizeof(struct pseudoHeader), header, header_size);memcpy(buf+sizeof(struct pseudoHeader)+header_size, data, size);return checksum((uint16_t *)buf, sizeof(struct pseudoHeader)+header_size+size);}voidtest(void){tcph->chksum = 0tcph->chksum = tcp_udp_checksum (iphdr, (uint8_t *)tcph, 20, 6, payload, payload_size);udph->check = 0;udph->check = tcp_udp_checksum (iphdr, (uint8_t *)udph, sizeof(struct udphdr) , 17, payload, payload_size);}
Jy Lin
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