File: [local] / src / usr.bin / rsync / blocks.c (download)
Revision 1.17, Sun Jun 2 14:30:51 2019 UTC (5 years ago) by deraadt
Branch: MAIN
Changes since 1.16: +1 -2 lines
have_md is initialized at startup, don't need to do it again later
from Hiltjo Posthuma
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/* $Id: blocks.c,v 1.17 2019/06/02 14:30:51 deraadt Exp $ */
/*
* Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/stat.h>
#include <assert.h>
#include <endian.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/md4.h>
#include "extern.h"
/*
* From our current position of "offs" in buffer "buf" of total size
* "size", see if we can find a matching block in our list of blocks.
* The "hint" refers to the block that *might* work.
* Returns the blk or NULL if no matching block was found.
*/
static struct blk *
blk_find(struct sess *sess, const void *buf, off_t size, off_t offs,
const struct blkset *blks, const char *path, size_t hint)
{
unsigned char md[MD4_DIGEST_LENGTH];
uint32_t fhash;
off_t remain, osz;
size_t i;
int have_md = 0;
/*
* First, compute our fast hash.
* FIXME: yes, this can be a rolling computation, but I'm
* deliberately making it simple first.
*/
remain = size - offs;
assert(remain);
osz = remain < (off_t)blks->len ? remain : (off_t)blks->len;
fhash = hash_fast(buf + offs, (size_t)osz);
/*
* Start with our match hint.
* This just runs the fast and slow check with the hint.
*/
if (hint < blks->blksz &&
fhash == blks->blks[hint].chksum_short &&
(size_t)osz == blks->blks[hint].len) {
hash_slow(buf + offs, (size_t)osz, md, sess);
have_md = 1;
if (memcmp(md, blks->blks[hint].chksum_long, blks->csum) == 0) {
LOG4("%s: found matching hinted match: "
"position %jd, block %zu (position %jd, size %zu)",
path,
(intmax_t)offs, blks->blks[hint].idx,
(intmax_t)blks->blks[hint].offs,
blks->blks[hint].len);
return &blks->blks[hint];
}
}
/*
* Now loop and look for the fast hash.
* If it's found, move on to the slow hash.
*/
for (i = 0; i < blks->blksz; i++) {
if (fhash != blks->blks[i].chksum_short)
continue;
if ((size_t)osz != blks->blks[i].len)
continue;
LOG4("%s: found matching fast match: "
"position %jd, block %zu (position %jd, size %zu)",
path,
(intmax_t)offs, blks->blks[i].idx,
(intmax_t)blks->blks[i].offs,
blks->blks[i].len);
/* Compute slow hash on demand. */
if (have_md == 0) {
hash_slow(buf + offs, (size_t)osz, md, sess);
have_md = 1;
}
if (memcmp(md, blks->blks[i].chksum_long, blks->csum))
continue;
LOG4("%s: sender verifies slow match", path);
return &blks->blks[i];
}
return NULL;
}
/*
* Given a local file "path" and the blocks created by a remote machine,
* find out which blocks of our file they don't have and send them.
* This function is reentrant: it must be called while there's still
* data to send.
*/
void
blk_match(struct sess *sess, const struct blkset *blks,
const char *path, struct blkstat *st)
{
off_t last, end, sz;
int32_t tok;
struct blk *blk;
/*
* If the file's empty or we don't have any blocks from the
* sender, then simply send the whole file.
* Otherwise, run the hash matching routine and send raw chunks
* and subsequent matching tokens.
*/
if (st->mapsz && blks->blksz) {
/*
* Stop searching at the length of the file minus the
* size of the last block.
* The reason for this being that we don't need to do an
* incremental hash within the last block---if it
* doesn't match, it doesn't match.
*/
end = st->mapsz + 1 - blks->blks[blks->blksz - 1].len;
last = st->offs;
for ( ; st->offs < end; st->offs++) {
blk = blk_find(sess, st->map, st->mapsz,
st->offs, blks, path, st->hint);
if (blk == NULL)
continue;
sz = st->offs - last;
st->dirty += sz;
st->total += sz;
LOG4("%s: flushing %jd B before %zu B block %zu",
path, (intmax_t)sz,
blk->len, blk->idx);
tok = -(blk->idx + 1);
/*
* Write the data we have, then follow it with
* the tag of the block that matches.
*/
st->curpos = last;
st->curlen = st->curpos + sz;
st->curtok = tok;
assert(st->curtok != 0);
st->curst = sz ? BLKSTAT_DATA : BLKSTAT_TOK;
st->total += blk->len;
st->offs += blk->len;
st->hint = blk->idx + 1;
return;
}
/* Emit remaining data and send terminator token. */
sz = st->mapsz - last;
LOG4("%s: flushing remaining %jd B",
path, (intmax_t)sz);
st->total += sz;
st->dirty += sz;
st->curpos = last;
st->curlen = st->curpos + sz;
st->curtok = 0;
st->curst = sz ? BLKSTAT_DATA : BLKSTAT_TOK;
} else {
st->curpos = 0;
st->curlen = st->mapsz;
st->curtok = 0;
st->curst = st->mapsz ? BLKSTAT_DATA : BLKSTAT_TOK;
st->dirty = st->total = st->mapsz;
LOG4("%s: flushing whole file %zu B",
path, st->mapsz);
}
}
/*
* Buffer the message from sender to the receiver indicating that the
* block set has been received.
* Symmetrises blk_send_ack().
*/
void
blk_recv_ack(char buf[20], const struct blkset *blocks, int32_t idx)
{
size_t pos = 0, sz;
sz = sizeof(int32_t) + /* index */
sizeof(int32_t) + /* block count */
sizeof(int32_t) + /* block length */
sizeof(int32_t) + /* checksum length */
sizeof(int32_t); /* block remainder */
assert(sz == 20);
io_buffer_int(buf, &pos, sz, idx);
io_buffer_int(buf, &pos, sz, blocks->blksz);
io_buffer_int(buf, &pos, sz, blocks->len);
io_buffer_int(buf, &pos, sz, blocks->csum);
io_buffer_int(buf, &pos, sz, blocks->rem);
assert(pos == sz);
}
/*
* Read all of the checksums for a file's blocks.
* Returns the set of blocks or NULL on failure.
*/
struct blkset *
blk_recv(struct sess *sess, int fd, const char *path)
{
struct blkset *s;
int32_t i;
size_t j;
struct blk *b;
off_t offs = 0;
if ((s = calloc(1, sizeof(struct blkset))) == NULL) {
ERR("calloc");
return NULL;
}
/*
* The block prologue consists of a few values that we'll need
* in reading the individual blocks for this file.
* FIXME: read into buffer and unbuffer.
*/
if (!io_read_size(sess, fd, &s->blksz)) {
ERRX1("io_read_size");
goto out;
} else if (!io_read_size(sess, fd, &s->len)) {
ERRX1("io_read_size");
goto out;
} else if (!io_read_size(sess, fd, &s->csum)) {
ERRX1("io_read_int");
goto out;
} else if (!io_read_size(sess, fd, &s->rem)) {
ERRX1("io_read_int");
goto out;
} else if (s->rem && s->rem >= s->len) {
ERRX("block remainder is "
"greater than block size");
goto out;
}
LOG3("%s: read block prologue: %zu blocks of "
"%zu B, %zu B remainder, %zu B checksum", path,
s->blksz, s->len, s->rem, s->csum);
if (s->blksz) {
s->blks = calloc(s->blksz, sizeof(struct blk));
if (s->blks == NULL) {
ERR("calloc");
goto out;
}
}
/*
* Read each block individually.
* FIXME: read buffer and unbuffer.
*/
for (j = 0; j < s->blksz; j++) {
b = &s->blks[j];
if (!io_read_int(sess, fd, &i)) {
ERRX1("io_read_int");
goto out;
}
b->chksum_short = i;
assert(s->csum <= sizeof(b->chksum_long));
if (!io_read_buf(sess,
fd, b->chksum_long, s->csum)) {
ERRX1("io_read_buf");
goto out;
}
/*
* If we're the last block, then we're assigned the
* remainder of the data.
*/
b->offs = offs;
b->idx = j;
b->len = (j == (s->blksz - 1) && s->rem) ?
s->rem : s->len;
offs += b->len;
LOG4("%s: read block %zu, length %zu B",
path, b->idx, b->len);
}
s->size = offs;
LOG3("%s: read blocks: %zu blocks, %jd B total blocked data",
path, s->blksz, (intmax_t)s->size);
return s;
out:
free(s->blks);
free(s);
return NULL;
}
/*
* Symmetrise blk_recv_ack(), except w/o the leading identifier.
* Return zero on failure, non-zero on success.
*/
int
blk_send_ack(struct sess *sess, int fd, struct blkset *p)
{
char buf[16];
size_t pos = 0, sz;
/* Put the entire send routine into a buffer. */
sz = sizeof(int32_t) + /* block count */
sizeof(int32_t) + /* block length */
sizeof(int32_t) + /* checksum length */
sizeof(int32_t); /* block remainder */
assert(sz <= sizeof(buf));
if (!io_read_buf(sess, fd, buf, sz)) {
ERRX1("io_read_buf");
return 0;
}
if (!io_unbuffer_size(buf, &pos, sz, &p->blksz))
ERRX1("io_unbuffer_size");
else if (!io_unbuffer_size(buf, &pos, sz, &p->len))
ERRX1("io_unbuffer_size");
else if (!io_unbuffer_size(buf, &pos, sz, &p->csum))
ERRX1("io_unbuffer_size");
else if (!io_unbuffer_size(buf, &pos, sz, &p->rem))
ERRX1("io_unbuffer_size");
else if (p->len && p->rem >= p->len)
ERRX1("non-zero length is less than remainder");
else if (p->csum == 0 || p->csum > 16)
ERRX1("inappropriate checksum length");
else
return 1;
return 0;
}
/*
* Transmit the metadata for set and blocks.
* Return zero on failure, non-zero on success.
*/
int
blk_send(struct sess *sess, int fd, size_t idx,
const struct blkset *p, const char *path)
{
char *buf;
size_t i, pos = 0, sz;
int rc = 0;
/* Put the entire send routine into a buffer. */
sz = sizeof(int32_t) + /* identifier */
sizeof(int32_t) + /* block count */
sizeof(int32_t) + /* block length */
sizeof(int32_t) + /* checksum length */
sizeof(int32_t) + /* block remainder */
p->blksz *
(sizeof(int32_t) + /* short checksum */
p->csum); /* long checksum */
if ((buf = malloc(sz)) == NULL) {
ERR("malloc");
return 0;
}
io_buffer_int(buf, &pos, sz, idx);
io_buffer_int(buf, &pos, sz, p->blksz);
io_buffer_int(buf, &pos, sz, p->len);
io_buffer_int(buf, &pos, sz, p->csum);
io_buffer_int(buf, &pos, sz, p->rem);
for (i = 0; i < p->blksz; i++) {
io_buffer_int(buf, &pos,
sz, p->blks[i].chksum_short);
io_buffer_buf(buf, &pos, sz, p->blks[i].chksum_long, p->csum);
}
assert(pos == sz);
if (!io_write_buf(sess, fd, buf, sz)) {
ERRX1("io_write_buf");
goto out;
}
LOG3("%s: sent block prologue: %zu blocks of %zu B, "
"%zu B remainder, %zu B checksum",
path, p->blksz, p->len, p->rem, p->csum);
rc = 1;
out:
free(buf);
return rc;
}