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content_encoding: rework zlib_inflate

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- When zlib version is < 1.2.0.4, process gzip trailer before considering
extra data as an error.
- Inflate with Z_BLOCK instead of Z_SYNC_FLUSH to maximize correct data
and minimize corrupt data output.
- Do not try to restart deflate decompression in raw mode if output has
started or if the leading data is not available anymore.
- New test 232 checks inflating raw-deflated content.

Closes #2068
This commit is contained in:
Patrick Monnerat 2017-12-20 16:02:42 +01:00
parent e639d4ca4d
commit 4acc9d3d1a
3 changed files with 305 additions and 54 deletions
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155
lib/content_encoding.c
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@ -73,14 +73,17 @@
typedef enum {
ZLIB_UNINIT, /* uninitialized */
ZLIB_INIT, /* initialized */
ZLIB_INFLATING, /* Inflating started. */
ZLIB_GZIP_HEADER, /* reading gzip header */
ZLIB_GZIP_TRAILER, /* reading gzip trailer */
ZLIB_GZIP_INFLATING, /* inflating gzip stream */
ZLIB_INIT_GZIP /* initialized in transparent gzip mode */
} zlibInitState;
/* Writer parameters. */
typedef struct {
zlibInitState zlib_init; /* zlib init state */
zlibInitState zlib_init; /* zlib init state */
uInt trailerlen; /* Remaining trailer byte count. */
z_stream z; /* State structure for zlib. */
} zlib_params;
@ -130,80 +133,120 @@ exit_zlib(struct connectdata *conn,
return result;
}
static CURLcode
inflate_stream(struct connectdata *conn, contenc_writer *writer)
static CURLcode process_trailer(struct connectdata *conn, zlib_params *zp)
{
z_stream *z = &zp->z;
CURLcode result = CURLE_OK;
uInt len = z->avail_in < zp->trailerlen? z->avail_in: zp->trailerlen;
/* Consume expected trailer bytes. Terminate stream if exhausted.
Issue an error if unexpected bytes follow. */
zp->trailerlen -= len;
z->avail_in -= len;
z->next_in += len;
if(z->avail_in)
result = CURLE_WRITE_ERROR;
if(result || !zp->trailerlen)
result = exit_zlib(conn, z, &zp->zlib_init, result);
else {
/* Only occurs for gzip with zlib < 1.2.0.4. */
zp->zlib_init = ZLIB_GZIP_TRAILER;
}
return result;
}
static CURLcode inflate_stream(struct connectdata *conn,
contenc_writer *writer, zlibInitState started)
{
zlib_params *zp = (zlib_params *) &writer->params;
int allow_restart = 1;
z_stream *z = &zp->z; /* zlib state structure */
uInt nread = z->avail_in;
Bytef *orig_in = z->next_in;
int status; /* zlib status */
bool done = FALSE;
CURLcode result = CURLE_OK; /* Curl_client_write status */
char *decomp; /* Put the decompressed data here. */
/* Check state. */
if(zp->zlib_init != ZLIB_INIT &&
zp->zlib_init != ZLIB_INFLATING &&
zp->zlib_init != ZLIB_INIT_GZIP &&
zp->zlib_init != ZLIB_GZIP_INFLATING)
return exit_zlib(conn, z, &zp->zlib_init, CURLE_WRITE_ERROR);
/* Dynamically allocate a buffer for decompression because it's uncommonly
large to hold on the stack */
decomp = malloc(DSIZ);
if(decomp == NULL) {
if(decomp == NULL)
return exit_zlib(conn, z, &zp->zlib_init, CURLE_OUT_OF_MEMORY);
}
/* because the buffer size is fixed, iteratively decompress and transfer to
the client via client_write. */
for(;;) {
if(z->avail_in == 0) {
free(decomp);
return result;
}
the client via downstream_write function. */
while(!done) {
done = TRUE;
/* (re)set buffer for decompressed output for every iteration */
z->next_out = (Bytef *) decomp;
z->avail_out = DSIZ;
status = inflate(z, Z_SYNC_FLUSH);
if(status == Z_OK || status == Z_STREAM_END) {
allow_restart = 0;
result = Curl_unencode_write(conn, writer->downstream, decomp,
DSIZ - z->avail_out);
/* if !CURLE_OK, clean up, return */
if(result) {
free(decomp);
return exit_zlib(conn, z, &zp->zlib_init, result);
status = inflate(z, Z_BLOCK);
/* Flush output data if some. */
if(z->avail_out != DSIZ) {
if(status == Z_OK || status == Z_STREAM_END) {
zp->zlib_init = started; /* Data started. */
result = Curl_unencode_write(conn, writer->downstream, decomp,
DSIZ - z->avail_out);
if(result) {
exit_zlib(conn, z, &zp->zlib_init, result);
break;
}
}
/* Done? clean up, return */
if(status == Z_STREAM_END) {
free(decomp);
return exit_zlib(conn, z, &zp->zlib_init, result);
}
/* Done with these bytes, exit */
/* status is always Z_OK at this point! */
continue;
}
else if(allow_restart && status == Z_DATA_ERROR) {
/* Dispatch by inflate() status. */
switch(status) {
case Z_OK:
/* Always loop: there may be unflushed latched data in zlib state. */
done = FALSE;
break;
case Z_BUF_ERROR:
/* No more data to flush: just exit loop. */
break;
case Z_STREAM_END:
result = process_trailer(conn, zp);
break;
case Z_DATA_ERROR:
/* some servers seem to not generate zlib headers, so this is an attempt
to fix and continue anyway */
(void) inflateEnd(z); /* don't care about the return code */
if(inflateInit2(z, -MAX_WBITS) != Z_OK) {
free(decomp);
zp->zlib_init = ZLIB_UNINIT; /* inflateEnd() already called. */
return exit_zlib(conn, z, &zp->zlib_init, process_zlib_error(conn, z));
if(zp->zlib_init == ZLIB_INIT) {
/* Do not use inflateReset2(): only available since zlib 1.2.3.4. */
(void) inflateEnd(z); /* don't care about the return code */
if(inflateInit2(z, -MAX_WBITS) == Z_OK) {
z->next_in = orig_in;
z->avail_in = nread;
zp->zlib_init = ZLIB_INFLATING;
done = FALSE;
break;
}
zp->zlib_init = ZLIB_UNINIT; /* inflateEnd() already called. */
}
z->next_in = orig_in;
z->avail_in = nread;
allow_restart = 0;
continue;
}
else { /* Error; exit loop, handle below */
free(decomp);
return exit_zlib(conn, z, &zp->zlib_init, process_zlib_error(conn, z));
/* FALLTHROUGH */
default:
result = exit_zlib(conn, z, &zp->zlib_init, process_zlib_error(conn, z));
break;
}
}
/* UNREACHED */
free(decomp);
/* We're about to leave this call so the `nread' data bytes won't be seen
again. If we are in a state that would wrongly allow restart in raw mode
at the next call, assume output has already started. */
if(nread && zp->zlib_init == ZLIB_INIT)
zp->zlib_init = started; /* Cannot restart anymore. */
return result;
}
@ -239,7 +282,7 @@ static CURLcode deflate_unencode_write(struct connectdata *conn,
z->avail_in = (uInt) nbytes;
/* Now uncompress the data */
return inflate_stream(conn, writer);
return inflate_stream(conn, writer, ZLIB_INFLATING);
}
static void deflate_close_writer(struct connectdata *conn,
@ -283,11 +326,12 @@ static CURLcode gzip_init_writer(struct connectdata *conn,
zp->zlib_init = ZLIB_INIT_GZIP; /* Transparent gzip decompress state */
}
else {
/* we must parse the gzip header ourselves */
/* we must parse the gzip header and trailer ourselves */
if(inflateInit2(z, -MAX_WBITS) != Z_OK) {
return process_zlib_error(conn, z);
}
zp->zlib_init = ZLIB_INIT; /* Initial call state */
zp->trailerlen = 8; /* A CRC-32 and a 32-bit input size (RFC 1952, 2.2) */
zp->zlib_init = ZLIB_INIT; /* Initial call state */
}
return CURLE_OK;
@ -389,7 +433,7 @@ static CURLcode gzip_unencode_write(struct connectdata *conn,
z->next_in = (Bytef *) buf;
z->avail_in = (uInt) nbytes;
/* Now uncompress the data */
return inflate_stream(conn, writer);
return inflate_stream(conn, writer, ZLIB_INIT_GZIP);
}
#ifndef OLD_ZLIB_SUPPORT
@ -482,6 +526,11 @@ static CURLcode gzip_unencode_write(struct connectdata *conn,
}
break;
case ZLIB_GZIP_TRAILER:
z->next_in = (Bytef *) buf;
z->avail_in = (uInt) nbytes;
return process_trailer(conn, zp);
case ZLIB_GZIP_INFLATING:
default:
/* Inflating stream state */
@ -496,7 +545,7 @@ static CURLcode gzip_unencode_write(struct connectdata *conn,
}
/* We've parsed the header, now uncompress the data */
return inflate_stream(conn, writer);
return inflate_stream(conn, writer, ZLIB_GZIP_INFLATING);
#endif
}