Import BSDDB 4.7.25 (as of svn r89086)
This commit is contained in:
234
hmac/hmac.c
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234
hmac/hmac.c
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 2001,2008 Oracle. All rights reserved.
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*
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* Some parts of this code originally written by Adam Stubblefield,
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* -- astubble@rice.edu.
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*
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* $Id: hmac.c 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#include "db_config.h"
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#include "db_int.h"
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#include "dbinc/crypto.h"
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#include "dbinc/db_page.h" /* for hash.h only */
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#include "dbinc/hash.h"
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#include "dbinc/hmac.h"
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#include "dbinc/log.h"
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#define HMAC_OUTPUT_SIZE 20
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#define HMAC_BLOCK_SIZE 64
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static void __db_hmac __P((u_int8_t *, u_int8_t *, size_t, u_int8_t *));
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/*
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* !!!
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* All of these functions use a ctx structure on the stack. The __db_SHA1Init
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* call does not initialize the 64-byte buffer portion of it. The
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* underlying SHA1 functions will properly pad the buffer if the data length
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* is less than 64-bytes, so there isn't a chance of reading uninitialized
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* memory. Although it would be cleaner to do a memset(ctx.buffer, 0, 64)
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* we do not want to incur that penalty if we don't have to for performance.
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*/
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/*
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* __db_hmac --
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* Do a hashed MAC.
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*/
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static void
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__db_hmac(k, data, data_len, mac)
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u_int8_t *k, *data, *mac;
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size_t data_len;
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{
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SHA1_CTX ctx;
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u_int8_t key[HMAC_BLOCK_SIZE];
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u_int8_t ipad[HMAC_BLOCK_SIZE];
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u_int8_t opad[HMAC_BLOCK_SIZE];
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u_int8_t tmp[HMAC_OUTPUT_SIZE];
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int i;
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memset(key, 0x00, HMAC_BLOCK_SIZE);
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memset(ipad, 0x36, HMAC_BLOCK_SIZE);
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memset(opad, 0x5C, HMAC_BLOCK_SIZE);
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memcpy(key, k, HMAC_OUTPUT_SIZE);
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for (i = 0; i < HMAC_BLOCK_SIZE; i++) {
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ipad[i] ^= key[i];
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opad[i] ^= key[i];
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}
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__db_SHA1Init(&ctx);
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__db_SHA1Update(&ctx, ipad, HMAC_BLOCK_SIZE);
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__db_SHA1Update(&ctx, data, data_len);
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__db_SHA1Final(tmp, &ctx);
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__db_SHA1Init(&ctx);
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__db_SHA1Update(&ctx, opad, HMAC_BLOCK_SIZE);
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__db_SHA1Update(&ctx, tmp, HMAC_OUTPUT_SIZE);
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__db_SHA1Final(mac, &ctx);
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return;
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}
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/*
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* __db_chksum --
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* Create a MAC/SHA1 checksum.
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*
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* PUBLIC: void __db_chksum __P((void *,
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* PUBLIC: u_int8_t *, size_t, u_int8_t *, u_int8_t *));
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*/
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void
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__db_chksum(hdr, data, data_len, mac_key, store)
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void *hdr;
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u_int8_t *data;
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size_t data_len;
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u_int8_t *mac_key;
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u_int8_t *store;
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{
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int sumlen;
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u_int32_t hash4;
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/*
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* Since the checksum might be on a page of data we are checksumming
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* we might be overwriting after checksumming, we zero-out the
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* checksum value so that we can have a known value there when
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* we verify the checksum.
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* If we are passed a log header XOR in prev and len so we have
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* some redundancy on these fields. Mostly we need to be sure that
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* we detect a race when doing hot backups and reading a live log
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* file.
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*/
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if (mac_key == NULL)
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sumlen = sizeof(u_int32_t);
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else
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sumlen = DB_MAC_KEY;
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if (hdr == NULL)
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memset(store, 0, sumlen);
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else
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store = ((HDR*)hdr)->chksum;
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if (mac_key == NULL) {
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/* Just a hash, no MAC */
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hash4 = __ham_func4(NULL, data, (u_int32_t)data_len);
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if (hdr != NULL)
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hash4 ^= ((HDR *)hdr)->prev ^ ((HDR *)hdr)->len;
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memcpy(store, &hash4, sumlen);
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} else {
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__db_hmac(mac_key, data, data_len, store);
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if (hdr != 0) {
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((int *)store)[0] ^= ((HDR *)hdr)->prev;
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((int *)store)[1] ^= ((HDR *)hdr)->len;
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}
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}
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return;
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}
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/*
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* __db_derive_mac --
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* Create a MAC/SHA1 key.
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*
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* PUBLIC: void __db_derive_mac __P((u_int8_t *, size_t, u_int8_t *));
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*/
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void
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__db_derive_mac(passwd, plen, mac_key)
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u_int8_t *passwd;
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size_t plen;
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u_int8_t *mac_key;
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{
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SHA1_CTX ctx;
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/* Compute the MAC key. mac_key must be 20 bytes. */
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__db_SHA1Init(&ctx);
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__db_SHA1Update(&ctx, passwd, plen);
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__db_SHA1Update(&ctx, (u_int8_t *)DB_MAC_MAGIC, strlen(DB_MAC_MAGIC));
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__db_SHA1Update(&ctx, passwd, plen);
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__db_SHA1Final(mac_key, &ctx);
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return;
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}
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/*
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* __db_check_chksum --
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* Verify a checksum.
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*
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* Return 0 on success, >0 (errno) on error, -1 on checksum mismatch.
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*
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* PUBLIC: int __db_check_chksum __P((ENV *,
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* PUBLIC: void *, DB_CIPHER *, u_int8_t *, void *, size_t, int));
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*/
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int
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__db_check_chksum(env, hdr, db_cipher, chksum, data, data_len, is_hmac)
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ENV *env;
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void *hdr;
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DB_CIPHER *db_cipher;
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u_int8_t *chksum;
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void *data;
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size_t data_len;
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int is_hmac;
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{
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int ret;
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size_t sum_len;
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u_int32_t hash4;
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u_int8_t *mac_key, old[DB_MAC_KEY], new[DB_MAC_KEY];
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/*
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* If we are just doing checksumming and not encryption, then checksum
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* is 4 bytes. Otherwise, it is DB_MAC_KEY size. Check for illegal
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* combinations of crypto/non-crypto checksums.
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*/
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if (is_hmac == 0) {
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if (db_cipher != NULL) {
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__db_errx(env,
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"Unencrypted checksum with a supplied encryption key");
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return (EINVAL);
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}
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sum_len = sizeof(u_int32_t);
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mac_key = NULL;
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} else {
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if (db_cipher == NULL) {
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__db_errx(env,
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"Encrypted checksum: no encryption key specified");
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return (EINVAL);
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}
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sum_len = DB_MAC_KEY;
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mac_key = db_cipher->mac_key;
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}
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/*
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* !!!
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* Since the checksum might be on the page, we need to have known data
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* there so that we can generate the same original checksum. We zero
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* it out, just like we do in __db_chksum above.
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* If there is a log header, XOR the prev and len fields.
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*/
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retry:
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if (hdr == NULL) {
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memcpy(old, chksum, sum_len);
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memset(chksum, 0, sum_len);
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chksum = old;
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}
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if (mac_key == NULL) {
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/* Just a hash, no MAC */
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hash4 = __ham_func4(NULL, data, (u_int32_t)data_len);
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if (hdr != NULL)
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LOG_HDR_SUM(0, hdr, &hash4);
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ret = memcmp((u_int32_t *)chksum, &hash4, sum_len) ? -1 : 0;
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} else {
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__db_hmac(mac_key, data, data_len, new);
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if (hdr != NULL)
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LOG_HDR_SUM(1, hdr, new);
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ret = memcmp(chksum, new, sum_len) ? -1 : 0;
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}
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/*
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* !!!
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* We might be looking at an old log even with the new
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* code. So, if we have a hdr, and the checksum doesn't
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* match, try again without a hdr.
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*/
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if (hdr != NULL && ret != 0) {
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hdr = NULL;
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goto retry;
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}
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return (ret);
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}
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