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qemu-e2k/block/curl.c
Matthew Booth b7079df410 curl: Fix hang reading from slow connections 
When receiving a new aio read request, we first look for an existing
transaction whose range will cover the read request by the time it
completes. However, we weren't checking that the existing transaction
was still active. If it had timed out, we were adding the request to a
transaction which would never complete and had already been cancelled,
resulting in a hang.

Signed-off-by: Matthew Booth <mbooth@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-04-30 16:34:21 +02:00

750 lines
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/*
* QEMU Block driver for CURL images
*
* Copyright (c) 2009 Alexander Graf <agraf@suse.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "block/block_int.h"
#include <curl/curl.h>
// #define DEBUG
// #define DEBUG_VERBOSE
#ifdef DEBUG_CURL
#define DPRINTF(fmt, ...) do { printf(fmt, ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) do { } while (0)
#endif
#if LIBCURL_VERSION_NUM >= 0x071000
/* The multi interface timer callback was introduced in 7.16.0 */
#define NEED_CURL_TIMER_CALLBACK
#endif
#define PROTOCOLS (CURLPROTO_HTTP | CURLPROTO_HTTPS | \
CURLPROTO_FTP | CURLPROTO_FTPS | \
CURLPROTO_TFTP)
#define CURL_NUM_STATES 8
#define CURL_NUM_ACB 8
#define SECTOR_SIZE 512
#define READ_AHEAD_SIZE (256 * 1024)
#define FIND_RET_NONE 0
#define FIND_RET_OK 1
#define FIND_RET_WAIT 2
struct BDRVCURLState;
typedef struct CURLAIOCB {
BlockDriverAIOCB common;
QEMUBH *bh;
QEMUIOVector *qiov;
int64_t sector_num;
int nb_sectors;
size_t start;
size_t end;
} CURLAIOCB;
typedef struct CURLState
{
struct BDRVCURLState *s;
CURLAIOCB *acb[CURL_NUM_ACB];
CURL *curl;
curl_socket_t sock_fd;
char *orig_buf;
size_t buf_start;
size_t buf_off;
size_t buf_len;
char range[128];
char errmsg[CURL_ERROR_SIZE];
char in_use;
} CURLState;
typedef struct BDRVCURLState {
CURLM *multi;
QEMUTimer timer;
size_t len;
CURLState states[CURL_NUM_STATES];
char *url;
size_t readahead_size;
bool accept_range;
} BDRVCURLState;
static void curl_clean_state(CURLState *s);
static void curl_multi_do(void *arg);
static void curl_multi_read(void *arg);
#ifdef NEED_CURL_TIMER_CALLBACK
static int curl_timer_cb(CURLM *multi, long timeout_ms, void *opaque)
{
BDRVCURLState *s = opaque;
DPRINTF("CURL: timer callback timeout_ms %ld\n", timeout_ms);
if (timeout_ms == -1) {
timer_del(&s->timer);
} else {
int64_t timeout_ns = (int64_t)timeout_ms * 1000 * 1000;
timer_mod(&s->timer,
qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + timeout_ns);
}
return 0;
}
#endif
static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
void *s, void *sp)
{
CURLState *state = NULL;
curl_easy_getinfo(curl, CURLINFO_PRIVATE, (char **)&state);
state->sock_fd = fd;
DPRINTF("CURL (AIO): Sock action %d on fd %d\n", action, fd);
switch (action) {
case CURL_POLL_IN:
qemu_aio_set_fd_handler(fd, curl_multi_read, NULL, state);
break;
case CURL_POLL_OUT:
qemu_aio_set_fd_handler(fd, NULL, curl_multi_do, state);
break;
case CURL_POLL_INOUT:
qemu_aio_set_fd_handler(fd, curl_multi_read, curl_multi_do, state);
break;
case CURL_POLL_REMOVE:
qemu_aio_set_fd_handler(fd, NULL, NULL, NULL);
break;
}
return 0;
}
static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
{
BDRVCURLState *s = opaque;
size_t realsize = size * nmemb;
const char *accept_line = "Accept-Ranges: bytes";
if (realsize >= strlen(accept_line)
&& strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) {
s->accept_range = true;
}
return realsize;
}
static size_t curl_read_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
{
CURLState *s = ((CURLState*)opaque);
size_t realsize = size * nmemb;
int i;
DPRINTF("CURL: Just reading %zd bytes\n", realsize);
if (!s || !s->orig_buf)
return 0;
if (s->buf_off >= s->buf_len) {
/* buffer full, read nothing */
return 0;
}
realsize = MIN(realsize, s->buf_len - s->buf_off);
memcpy(s->orig_buf + s->buf_off, ptr, realsize);
s->buf_off += realsize;
for(i=0; i<CURL_NUM_ACB; i++) {
CURLAIOCB *acb = s->acb[i];
if (!acb)
continue;
if ((s->buf_off >= acb->end)) {
qemu_iovec_from_buf(acb->qiov, 0, s->orig_buf + acb->start,
acb->end - acb->start);
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
s->acb[i] = NULL;
}
}
return realsize;
}
static int curl_find_buf(BDRVCURLState *s, size_t start, size_t len,
CURLAIOCB *acb)
{
int i;
size_t end = start + len;
for (i=0; i<CURL_NUM_STATES; i++) {
CURLState *state = &s->states[i];
size_t buf_end = (state->buf_start + state->buf_off);
size_t buf_fend = (state->buf_start + state->buf_len);
if (!state->orig_buf)
continue;
if (!state->buf_off)
continue;
// Does the existing buffer cover our section?
if ((start >= state->buf_start) &&
(start <= buf_end) &&
(end >= state->buf_start) &&
(end <= buf_end))
{
char *buf = state->orig_buf + (start - state->buf_start);
qemu_iovec_from_buf(acb->qiov, 0, buf, len);
acb->common.cb(acb->common.opaque, 0);
return FIND_RET_OK;
}
// Wait for unfinished chunks
if (state->in_use &&
(start >= state->buf_start) &&
(start <= buf_fend) &&
(end >= state->buf_start) &&
(end <= buf_fend))
{
int j;
acb->start = start - state->buf_start;
acb->end = acb->start + len;
for (j=0; j<CURL_NUM_ACB; j++) {
if (!state->acb[j]) {
state->acb[j] = acb;
return FIND_RET_WAIT;
}
}
}
}
return FIND_RET_NONE;
}
static void curl_multi_check_completion(BDRVCURLState *s)
{
int msgs_in_queue;
/* Try to find done transfers, so we can free the easy
* handle again. */
for (;;) {
CURLMsg *msg;
msg = curl_multi_info_read(s->multi, &msgs_in_queue);
/* Quit when there are no more completions */
if (!msg)
break;
if (msg->msg == CURLMSG_DONE) {
CURLState *state = NULL;
curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE,
(char **)&state);
/* ACBs for successful messages get completed in curl_read_cb */
if (msg->data.result != CURLE_OK) {
int i;
for (i = 0; i < CURL_NUM_ACB; i++) {
CURLAIOCB *acb = state->acb[i];
if (acb == NULL) {
continue;
}
acb->common.cb(acb->common.opaque, -EIO);
qemu_aio_release(acb);
state->acb[i] = NULL;
}
}
curl_clean_state(state);
break;
}
}
}
static void curl_multi_do(void *arg)
{
CURLState *s = (CURLState *)arg;
int running;
int r;
if (!s->s->multi) {
return;
}
do {
r = curl_multi_socket_action(s->s->multi, s->sock_fd, 0, &running);
} while(r == CURLM_CALL_MULTI_PERFORM);
}
static void curl_multi_read(void *arg)
{
CURLState *s = (CURLState *)arg;
curl_multi_do(arg);
curl_multi_check_completion(s->s);
}
static void curl_multi_timeout_do(void *arg)
{
#ifdef NEED_CURL_TIMER_CALLBACK
BDRVCURLState *s = (BDRVCURLState *)arg;
int running;
if (!s->multi) {
return;
}
curl_multi_socket_action(s->multi, CURL_SOCKET_TIMEOUT, 0, &running);
curl_multi_check_completion(s);
#else
abort();
#endif
}
static CURLState *curl_init_state(BDRVCURLState *s)
{
CURLState *state = NULL;
int i, j;
do {
for (i=0; i<CURL_NUM_STATES; i++) {
for (j=0; j<CURL_NUM_ACB; j++)
if (s->states[i].acb[j])
continue;
if (s->states[i].in_use)
continue;
state = &s->states[i];
state->in_use = 1;
break;
}
if (!state) {
qemu_aio_wait();
}
} while(!state);
if (!state->curl) {
state->curl = curl_easy_init();
if (!state->curl) {
return NULL;
}
curl_easy_setopt(state->curl, CURLOPT_URL, s->url);
curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, 5);
curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION,
(void *)curl_read_cb);
curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
curl_easy_setopt(state->curl, CURLOPT_PRIVATE, (void *)state);
curl_easy_setopt(state->curl, CURLOPT_AUTOREFERER, 1);
curl_easy_setopt(state->curl, CURLOPT_FOLLOWLOCATION, 1);
curl_easy_setopt(state->curl, CURLOPT_NOSIGNAL, 1);
curl_easy_setopt(state->curl, CURLOPT_ERRORBUFFER, state->errmsg);
curl_easy_setopt(state->curl, CURLOPT_FAILONERROR, 1);
/* Restrict supported protocols to avoid security issues in the more
* obscure protocols. For example, do not allow POP3/SMTP/IMAP see
* CVE-2013-0249.
*
* Restricting protocols is only supported from 7.19.4 upwards.
*/
#if LIBCURL_VERSION_NUM >= 0x071304
curl_easy_setopt(state->curl, CURLOPT_PROTOCOLS, PROTOCOLS);
curl_easy_setopt(state->curl, CURLOPT_REDIR_PROTOCOLS, PROTOCOLS);
#endif
#ifdef DEBUG_VERBOSE
curl_easy_setopt(state->curl, CURLOPT_VERBOSE, 1);
#endif
}
state->s = s;
return state;
}
static void curl_clean_state(CURLState *s)
{
if (s->s->multi)
curl_multi_remove_handle(s->s->multi, s->curl);
s->in_use = 0;
}
static void curl_parse_filename(const char *filename, QDict *options,
Error **errp)
{
#define RA_OPTSTR ":readahead="
char *file;
char *ra;
const char *ra_val;
int parse_state = 0;
file = g_strdup(filename);
/* Parse a trailing ":readahead=#:" param, if present. */
ra = file + strlen(file) - 1;
while (ra >= file) {
if (parse_state == 0) {
if (*ra == ':') {
parse_state++;
} else {
break;
}
} else if (parse_state == 1) {
if (*ra > '9' || *ra < '0') {
char *opt_start = ra - strlen(RA_OPTSTR) + 1;
if (opt_start > file &&
strncmp(opt_start, RA_OPTSTR, strlen(RA_OPTSTR)) == 0) {
ra_val = ra + 1;
ra -= strlen(RA_OPTSTR) - 1;
*ra = '\0';
qdict_put(options, "readahead", qstring_from_str(ra_val));
}
break;
}
}
ra--;
}
qdict_put(options, "url", qstring_from_str(file));
g_free(file);
}
static QemuOptsList runtime_opts = {
.name = "curl",
.head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
.desc = {
{
.name = "url",
.type = QEMU_OPT_STRING,
.help = "URL to open",
},
{
.name = "readahead",
.type = QEMU_OPT_SIZE,
.help = "Readahead size",
},
{ /* end of list */ }
},
};
static int curl_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVCURLState *s = bs->opaque;
CURLState *state = NULL;
QemuOpts *opts;
Error *local_err = NULL;
const char *file;
double d;
static int inited = 0;
if (flags & BDRV_O_RDWR) {
error_setg(errp, "curl block device does not support writes");
return -EROFS;
}
opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto out_noclean;
}
s->readahead_size = qemu_opt_get_size(opts, "readahead", READ_AHEAD_SIZE);
if ((s->readahead_size & 0x1ff) != 0) {
error_setg(errp, "HTTP_READAHEAD_SIZE %zd is not a multiple of 512",
s->readahead_size);
goto out_noclean;
}
file = qemu_opt_get(opts, "url");
if (file == NULL) {
error_setg(errp, "curl block driver requires an 'url' option");
goto out_noclean;
}
if (!inited) {
curl_global_init(CURL_GLOBAL_ALL);
inited = 1;
}
DPRINTF("CURL: Opening %s\n", file);
s->url = g_strdup(file);
state = curl_init_state(s);
if (!state)
goto out_noclean;
// Get file size
s->accept_range = false;
curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1);
curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION,
curl_header_cb);
curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, s);
if (curl_easy_perform(state->curl))
goto out;
curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d);
if (d)
s->len = (size_t)d;
else if(!s->len)
goto out;
if ((!strncasecmp(s->url, "http://", strlen("http://"))
|| !strncasecmp(s->url, "https://", strlen("https://")))
&& !s->accept_range) {
pstrcpy(state->errmsg, CURL_ERROR_SIZE,
"Server does not support 'range' (byte ranges).");
goto out;
}
DPRINTF("CURL: Size = %zd\n", s->len);
curl_clean_state(state);
curl_easy_cleanup(state->curl);
state->curl = NULL;
aio_timer_init(bdrv_get_aio_context(bs), &s->timer,
QEMU_CLOCK_REALTIME, SCALE_NS,
curl_multi_timeout_do, s);
// Now we know the file exists and its size, so let's
// initialize the multi interface!
s->multi = curl_multi_init();
curl_multi_setopt(s->multi, CURLMOPT_SOCKETFUNCTION, curl_sock_cb);
#ifdef NEED_CURL_TIMER_CALLBACK
curl_multi_setopt(s->multi, CURLMOPT_TIMERDATA, s);
curl_multi_setopt(s->multi, CURLMOPT_TIMERFUNCTION, curl_timer_cb);
#endif
qemu_opts_del(opts);
return 0;
out:
error_setg(errp, "CURL: Error opening file: %s", state->errmsg);
curl_easy_cleanup(state->curl);
state->curl = NULL;
out_noclean:
g_free(s->url);
qemu_opts_del(opts);
return -EINVAL;
}
static void curl_aio_cancel(BlockDriverAIOCB *blockacb)
{
// Do we have to implement canceling? Seems to work without...
}
static const AIOCBInfo curl_aiocb_info = {
.aiocb_size = sizeof(CURLAIOCB),
.cancel = curl_aio_cancel,
};
static void curl_readv_bh_cb(void *p)
{
CURLState *state;
int running;
CURLAIOCB *acb = p;
BDRVCURLState *s = acb->common.bs->opaque;
qemu_bh_delete(acb->bh);
acb->bh = NULL;
size_t start = acb->sector_num * SECTOR_SIZE;
size_t end;
// In case we have the requested data already (e.g. read-ahead),
// we can just call the callback and be done.
switch (curl_find_buf(s, start, acb->nb_sectors * SECTOR_SIZE, acb)) {
case FIND_RET_OK:
qemu_aio_release(acb);
// fall through
case FIND_RET_WAIT:
return;
default:
break;
}
// No cache found, so let's start a new request
state = curl_init_state(s);
if (!state) {
acb->common.cb(acb->common.opaque, -EIO);
qemu_aio_release(acb);
return;
}
acb->start = 0;
acb->end = (acb->nb_sectors * SECTOR_SIZE);
state->buf_off = 0;
if (state->orig_buf)
g_free(state->orig_buf);
state->buf_start = start;
state->buf_len = acb->end + s->readahead_size;
end = MIN(start + state->buf_len, s->len) - 1;
state->orig_buf = g_malloc(state->buf_len);
state->acb[0] = acb;
snprintf(state->range, 127, "%zd-%zd", start, end);
DPRINTF("CURL (AIO): Reading %d at %zd (%s)\n",
(acb->nb_sectors * SECTOR_SIZE), start, state->range);
curl_easy_setopt(state->curl, CURLOPT_RANGE, state->range);
curl_multi_add_handle(s->multi, state->curl);
/* Tell curl it needs to kick things off */
curl_multi_socket_action(s->multi, CURL_SOCKET_TIMEOUT, 0, &running);
}
static BlockDriverAIOCB *curl_aio_readv(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
CURLAIOCB *acb;
acb = qemu_aio_get(&curl_aiocb_info, bs, cb, opaque);
acb->qiov = qiov;
acb->sector_num = sector_num;
acb->nb_sectors = nb_sectors;
acb->bh = qemu_bh_new(curl_readv_bh_cb, acb);
qemu_bh_schedule(acb->bh);
return &acb->common;
}
static void curl_close(BlockDriverState *bs)
{
BDRVCURLState *s = bs->opaque;
int i;
DPRINTF("CURL: Close\n");
for (i=0; i<CURL_NUM_STATES; i++) {
if (s->states[i].in_use)
curl_clean_state(&s->states[i]);
if (s->states[i].curl) {
curl_easy_cleanup(s->states[i].curl);
s->states[i].curl = NULL;
}
if (s->states[i].orig_buf) {
g_free(s->states[i].orig_buf);
s->states[i].orig_buf = NULL;
}
}
if (s->multi)
curl_multi_cleanup(s->multi);
timer_del(&s->timer);
g_free(s->url);
}
static int64_t curl_getlength(BlockDriverState *bs)
{
BDRVCURLState *s = bs->opaque;
return s->len;
}
static BlockDriver bdrv_http = {
.format_name = "http",
.protocol_name = "http",
.instance_size = sizeof(BDRVCURLState),
.bdrv_parse_filename = curl_parse_filename,
.bdrv_file_open = curl_open,
.bdrv_close = curl_close,
.bdrv_getlength = curl_getlength,
.bdrv_aio_readv = curl_aio_readv,
};
static BlockDriver bdrv_https = {
.format_name = "https",
.protocol_name = "https",
.instance_size = sizeof(BDRVCURLState),
.bdrv_parse_filename = curl_parse_filename,
.bdrv_file_open = curl_open,
.bdrv_close = curl_close,
.bdrv_getlength = curl_getlength,
.bdrv_aio_readv = curl_aio_readv,
};
static BlockDriver bdrv_ftp = {
.format_name = "ftp",
.protocol_name = "ftp",
.instance_size = sizeof(BDRVCURLState),
.bdrv_parse_filename = curl_parse_filename,
.bdrv_file_open = curl_open,
.bdrv_close = curl_close,
.bdrv_getlength = curl_getlength,
.bdrv_aio_readv = curl_aio_readv,
};
static BlockDriver bdrv_ftps = {
.format_name = "ftps",
.protocol_name = "ftps",
.instance_size = sizeof(BDRVCURLState),
.bdrv_parse_filename = curl_parse_filename,
.bdrv_file_open = curl_open,
.bdrv_close = curl_close,
.bdrv_getlength = curl_getlength,
.bdrv_aio_readv = curl_aio_readv,
};
static BlockDriver bdrv_tftp = {
.format_name = "tftp",
.protocol_name = "tftp",
.instance_size = sizeof(BDRVCURLState),
.bdrv_parse_filename = curl_parse_filename,
.bdrv_file_open = curl_open,
.bdrv_close = curl_close,
.bdrv_getlength = curl_getlength,
.bdrv_aio_readv = curl_aio_readv,
};
static void curl_block_init(void)
{
bdrv_register(&bdrv_http);
bdrv_register(&bdrv_https);
bdrv_register(&bdrv_ftp);
bdrv_register(&bdrv_ftps);
bdrv_register(&bdrv_tftp);
}
block_init(curl_block_init);
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