54 lines
1.0 KiB
C
Executable File
54 lines
1.0 KiB
C
Executable File
#define _GNU_SOURCE
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#include <arpa/inet.h>
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#include <linux/ip.h>
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#include "includes.h"
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#include "checksum.h"
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uint16_t checksum_generic(uint16_t *addr, uint32_t count)
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{
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register unsigned long sum = 0;
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for (sum = 0; count > 1; count -= 2)
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sum += *addr++;
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if (count == 1)
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sum += (char)*addr;
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sum = (sum >> 16) + (sum & 0xFFFF);
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sum += (sum >> 16);
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return ~sum;
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}
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uint16_t checksum_tcpudp(struct iphdr *iph, void *buff, uint16_t data_len, int len)
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{
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const uint16_t *buf = buff;
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uint32_t ip_src = iph->saddr;
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uint32_t ip_dst = iph->daddr;
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uint32_t sum = 0;
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int length = len;
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while (len > 1)
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{
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sum += *buf;
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buf++;
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len -= 2;
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}
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if (len == 1)
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sum += *((uint8_t *) buf);
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sum += (ip_src >> 16) & 0xFFFF;
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sum += ip_src & 0xFFFF;
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sum += (ip_dst >> 16) & 0xFFFF;
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sum += ip_dst & 0xFFFF;
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sum += htons(iph->protocol);
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sum += data_len;
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while (sum >> 16)
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sum = (sum & 0xFFFF) + (sum >> 16);
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return ((uint16_t) (~sum));
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}
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