mirror of https://git.lain.church/x3/caniadd.git
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
#include <assert.h>
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#include "ed2k.h"
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/* https://wiki.anidb.net/Ed2k-hash */
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/* This is using the red method */
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#define ED2K_CHUNK_SIZE 9728000
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#define MIN(a,b) (((a) < (b)) ? (a) : (b))
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void ed2k_init(struct ed2k_ctx *ctx)
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{
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md4_init(&ctx->chunk_md4_ctx);
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md4_init(&ctx->hash_md4_ctx);
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ctx->byte_count = 0;
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}
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static void ed2k_hash_chunk(struct ed2k_ctx *ctx)
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{
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unsigned char chunk_hash[MD4_DIGEST_SIZE];
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md4_final(&ctx->chunk_md4_ctx, chunk_hash);
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md4_update(&ctx->hash_md4_ctx, chunk_hash, sizeof(chunk_hash));
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md4_init(&ctx->chunk_md4_ctx);
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}
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void ed2k_update(struct ed2k_ctx *ctx, const void *data, size_t data_len)
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{
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const char *bytes = (const char*)data;
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while (data_len) {
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size_t hdata_size = MIN(ED2K_CHUNK_SIZE -
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(ctx->byte_count % ED2K_CHUNK_SIZE), data_len);
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md4_update(&ctx->chunk_md4_ctx, bytes, hdata_size);
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ctx->byte_count += hdata_size;
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if (ctx->byte_count % ED2K_CHUNK_SIZE == 0)
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ed2k_hash_chunk(ctx);
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data_len -= hdata_size;
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bytes += hdata_size;
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}
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}
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void ed2k_final(struct ed2k_ctx *ctx, unsigned char *out_hash)
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{
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struct md4_ctx *md_ctx;
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if (ctx->byte_count < ED2K_CHUNK_SIZE) {
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/* File has only 1 chunk, so return the md4 hash of that chunk */
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md_ctx = &ctx->chunk_md4_ctx;
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} else {
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/* Else hash the md4 hashes, and return that hash */
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ed2k_hash_chunk(ctx); /* Hash the last partial chunk here */
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md_ctx = &ctx->hash_md4_ctx;
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}
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md4_final(md_ctx, out_hash);
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}
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