31 lines
873 B
C
31 lines
873 B
C
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#include "hash.h"
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#include "c_string.h"
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/* Caution: When changing this, update COAP_DEFAULT_WKC_HASHKEY
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* accordingly (see int coap_hash_path());
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*/
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void coap_hash(const unsigned char *s, unsigned int len, coap_key_t h) {
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size_t j;
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while (len--) {
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j = sizeof(coap_key_t)-1;
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while (j) {
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h[j] = ((h[j] << 7) | (h[j-1] >> 1)) + h[j];
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--j;
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}
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h[0] = (h[0] << 7) + h[0] + *s++;
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}
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}
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void coap_transaction_id(const uint32_t ip, const uint32_t port, const coap_packet_t *pkt, coap_tid_t *id) {
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coap_key_t h;
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c_memset(h, 0, sizeof(coap_key_t));
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/* Compare the transport address. */
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coap_hash((const unsigned char *)&(port), sizeof(port), h);
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coap_hash((const unsigned char *)&(ip), sizeof(ip), h);
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coap_hash((const unsigned char *)(pkt->hdr.id), sizeof(pkt->hdr.id), h);
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*id = ((h[0] << 8) | h[1]) ^ ((h[2] << 8) | h[3]);
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}
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