Similar to nbdkit-retry-filter, but this only retries single failing requests rather than reopening the whole plugin. This is intended to be used with the curl filter to solve: https://bugzilla.redhat.com/show_bug.cgi?id=2013000 --- docs/nbdkit-captive.pod | 3 +- .../nbdkit-retry-request-filter.pod | 74 +++++ filters/retry/nbdkit-retry-filter.pod | 7 +- plugins/curl/nbdkit-curl-plugin.pod | 1 + configure.ac | 2 + filters/retry-request/Makefile.am | 68 +++++ tests/Makefile.am | 8 + filters/retry-request/retry-request.c | 278 ++++++++++++++++++ tests/test-retry-request.sh | 94 ++++++ 9 files changed, 533 insertions(+), 2 deletions(-) diff --git a/docs/nbdkit-captive.pod b/docs/nbdkit-captive.pod index d340b8ae0..eafe36d8b 100644 --- a/docs/nbdkit-captive.pod +++ b/docs/nbdkit-captive.pod @@ -118,7 +118,8 @@ help performance: --run 'qemu-img convert $nbd disk.img' If the source suffers from temporary network failures -L<nbdkit-retry-filter(1)> may help. +L<nbdkit-retry-filter(1)> or L<nbdkit-retry-request-filter(1)> may +help. To overwrite a file inside an uncompressed tar file (the file being overwritten must be the same size), use L<nbdkit-tar-filter(1)> like diff --git a/filters/retry-request/nbdkit-retry-request-filter.pod b/filters/retry-request/nbdkit-retry-request-filter.pod new file mode 100644 index 000000000..fbb467ca9 --- /dev/null +++ b/filters/retry-request/nbdkit-retry-request-filter.pod @@ -0,0 +1,74 @@ +=head1 NAME + +nbdkit-retry-request-filter - retry single requests on error + +=head1 SYNOPSIS + + nbdkit --filter=retry-request PLUGIN + [retry-request-retries=N] [retry-request-delay=N] + [retry-request-open=false] + +=head1 DESCRIPTION + +C<nbdkit-retry-request-filter> is a filter for nbdkit that +transparently retries single requests if they fail. This is useful +for plugins that are not completely reliable or have random behaviour. +For example L<nbdkit-curl-plugin(1)> might behave this way if pointed +at a load balancer which sometimes redirects to web server that is not +responsive. + +An alternative filter with different trade-offs is +L<nbdkit-retry-filter(1)>. That filter is more heavyweight because it +always reopens the whole plugin connection on failure. + +=head1 PARAMETERS + +=over 4 + +=item B<retry-request-retries=>N + +The number of times any single request will be retried before we give +up and fail the operation. The default is 2. + +=item B<retry-request-delay=>N + +The number of seconds to wait before retrying. The default is 2 +seconds. + +=item B<retry-request-open=false> + +If set to false, do not retry opening the plugin. The default is to +treat plugin open in the same way as other requests. + +=back + +=head1 FILES + +=over 4 + +=item F<$filterdir/nbdkit-retry-request-filter.so> + +The filter. + +Use C<nbdkit --dump-config> to find the location of C<$filterdir>. + +=back + +=head1 VERSION + +C<nbdkit-retry-filter> first appeared in nbdkit 1.30. + +=head1 SEE ALSO + +L<nbdkit(1)>, +L<nbdkit-filter(3)>, +L<nbdkit-readahead-filter(1)>, +L<nbdkit-retry-filter(1)>. + +=head1 AUTHORS + +Richard W.M. Jones + +=head1 COPYRIGHT + +Copyright (C) 2019-2021 Red Hat Inc. diff --git a/filters/retry/nbdkit-retry-filter.pod b/filters/retry/nbdkit-retry-filter.pod index fee4b7e64..babd82bbd 100644 --- a/filters/retry/nbdkit-retry-filter.pod +++ b/filters/retry/nbdkit-retry-filter.pod @@ -16,6 +16,10 @@ make long-running copy operations reliable in the presence of temporary network failures, without requiring any changes to the plugin or the NBD client. +An alternative and more fine-grained filter is +L<nbdkit-retry-request-filter(1)> which will retry only single +requests that fail. + Several optional parameters are available to control: =over 4 @@ -113,7 +117,8 @@ C<nbdkit-retry-filter> first appeared in nbdkit 1.16. L<nbdkit(1)>, L<nbdkit-filter(3)>, -L<nbdkit-readahead-filter(1)>. +L<nbdkit-readahead-filter(1)>, +L<nbdkit-retry-request-filter(1)>. =head1 AUTHORS diff --git a/plugins/curl/nbdkit-curl-plugin.pod b/plugins/curl/nbdkit-curl-plugin.pod index c7acf6225..07f71b389 100644 --- a/plugins/curl/nbdkit-curl-plugin.pod +++ b/plugins/curl/nbdkit-curl-plugin.pod @@ -503,6 +503,7 @@ L<nbdkit-extentlist-filter(1)>, L<nbdkit-file-plugin(1)>, L<nbdkit-readahead-filter(1)>, L<nbdkit-retry-filter(1)>, +L<nbdkit-retry-request-filter(1)>, L<nbdkit-ssh-plugin(1)>, L<nbdkit-torrent-plugin(1)>, L<nbdkit-plugin(3)>, diff --git a/configure.ac b/configure.ac index fd15e2960..3fd8a397e 100644 --- a/configure.ac +++ b/configure.ac @@ -139,6 +139,7 @@ filters="\ rate \ readahead \ retry \ + retry-request \ stats \ swab \ tar \ @@ -1342,6 +1343,7 @@ AC_CONFIG_FILES([Makefile filters/rate/Makefile filters/readahead/Makefile filters/retry/Makefile + filters/retry-request/Makefile filters/stats/Makefile filters/swab/Makefile filters/tar/Makefile diff --git a/filters/retry-request/Makefile.am b/filters/retry-request/Makefile.am new file mode 100644 index 000000000..95fdafdcd --- /dev/null +++ b/filters/retry-request/Makefile.am @@ -0,0 +1,68 @@ +# nbdkit +# Copyright (C) 2019-2021 Red Hat Inc. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +include $(top_srcdir)/common-rules.mk + +EXTRA_DIST = nbdkit-retry-request-filter.pod + +filter_LTLIBRARIES = nbdkit-retry-request-filter.la + +nbdkit_retry_request_filter_la_SOURCES = \ + retry-request.c \ + $(top_srcdir)/include/nbdkit-filter.h \ + $(NULL) + +nbdkit_retry_request_filter_la_CPPFLAGS = \ + -I$(top_srcdir)/include \ + -I$(top_srcdir)/common/include \ + -I$(top_srcdir)/common/utils \ + $(NULL) +nbdkit_retry_request_filter_la_CFLAGS = $(WARNINGS_CFLAGS) +nbdkit_retry_request_filter_la_LDFLAGS = \ + -module -avoid-version -shared $(NO_UNDEFINED_ON_WINDOWS) \ + -Wl,--version-script=$(top_srcdir)/filters/filters.syms \ + $(NULL) +nbdkit_retry_request_filter_la_LIBADD = \ + $(top_builddir)/common/utils/libutils.la \ + $(IMPORT_LIBRARY_ON_WINDOWS) \ + $(NULL) + +if HAVE_POD + +man_MANS = nbdkit-retry-request-filter.1 +CLEANFILES += $(man_MANS) + +nbdkit-retry-request-filter.1: nbdkit-retry-request-filter.pod + $(PODWRAPPER) --section=1 --man $@ \ + --html $(top_builddir)/html/$@.html \ + $< + +endif HAVE_POD diff --git a/tests/Makefile.am b/tests/Makefile.am index 2fb39cf09..9a1485a6c 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -1693,6 +1693,14 @@ EXTRA_DIST += \ test-retry-zero-flags.sh \ $(NULL) +# retry-request filter test. +TESTS += \ + test-retry-request.sh \ + $(NULL) +EXTRA_DIST += \ + test-retry-request.sh \ + $(NULL) + # swab filter test. TESTS += \ test-swab-8.sh \ diff --git a/filters/retry-request/retry-request.c b/filters/retry-request/retry-request.c new file mode 100644 index 000000000..ac7eb017f --- /dev/null +++ b/filters/retry-request/retry-request.c @@ -0,0 +1,278 @@ +/* nbdkit + * Copyright (C) 2019-2021 Red Hat Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of Red Hat nor the names of its contributors may be + * used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A + * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <stdbool.h> +#include <inttypes.h> +#include <string.h> +#include <sys/time.h> + +#include <nbdkit-filter.h> + +#include "cleanup.h" +#include "windows-compat.h" + +static unsigned retries = 2; /* 0 = filter is disabled */ +static unsigned delay = 2; +static bool retry_open_call = true; + +static int +retry_request_thread_model (void) +{ + return NBDKIT_THREAD_MODEL_PARALLEL; +} + +static int +retry_request_config (nbdkit_next_config *next, nbdkit_backend *nxdata, + const char *key, const char *value) +{ + int r; + + if (strcmp (key, "retry-request-retries") == 0) { + if (nbdkit_parse_unsigned ("retry-request-retries", value, &retries) == -1) + return -1; + if (retries > 1000) { + nbdkit_error ("retry-request-retries: value too large"); + return -1; + } + return 0; + } + else if (strcmp (key, "retry-request-delay") == 0) { + if (nbdkit_parse_unsigned ("retry-request-delay", value, &delay) == -1) + return -1; + if (delay == 0) { + nbdkit_error ("retry-request-delay cannot be 0"); + return -1; + } + return 0; + } + else if (strcmp (key, "retry-request-open") == 0) { + r = nbdkit_parse_bool (value); + if (r == -1) + return -1; + retry_open_call = r; + return 0; + } + + return next (nxdata, key, value); +} + +#define retry_request_config_help \ + "retry-request-retries=<N> Number of retries (default: 2).\n" \ + "retry-request-delay=<N> Seconds to wait before retry (default: 2).\n" \ + "retry-request-open=false Do not retry opening the plugin (default: true).\n" + +/* These macros encapsulate the logic of retrying. The code between + * RETRY_START...RETRY_END must set r to 0 or -1 on success or + * failure. + */ +#define RETRY_START \ + { \ + unsigned i; \ + \ + r = -1; \ + for (i = 0; r == -1 && i <= retries; ++i) { \ + if (i > 0) { \ + nbdkit_debug ("retry %u: waiting %u seconds before retrying", \ + i, delay); \ + if (nbdkit_nanosleep (delay, 0) == -1) { \ + if (*err == 0) \ + *err = errno; \ + break; \ + } \ + } \ + do +#define RETRY_END \ + while (0); \ + } \ + } + +static void * +retry_request_open (nbdkit_next_open *next, nbdkit_context *nxdata, + int readonly, const char *exportname, int is_tls) +{ + int r; + + if (retry_open_call) { + int *err = &errno; /* used by the RETRY* macros */ + + RETRY_START + r = next (nxdata, readonly, exportname); + RETRY_END; + } + else { + r = next (nxdata, readonly, exportname); + } + + return r == 0 ? NBDKIT_HANDLE_NOT_NEEDED : NULL; +} + +static int +retry_request_pread (nbdkit_next *next, + void *handle, void *buf, uint32_t count, uint64_t offset, + uint32_t flags, int *err) +{ + int r; + + RETRY_START + r = next->pread (next, buf, count, offset, flags, err); + RETRY_END; + return r; +} + +static int +retry_request_pwrite (nbdkit_next *next, + void *handle, + const void *buf, uint32_t count, uint64_t offset, + uint32_t flags, int *err) +{ + int r; + + RETRY_START + r = next->pwrite (next, buf, count, offset, flags, err); + RETRY_END; + return r; +} + +static int +retry_request_trim (nbdkit_next *next, + void *handle, + uint32_t count, uint64_t offset, uint32_t flags, + int *err) +{ + int r; + + RETRY_START + r = next->trim (next, count, offset, flags, err); + RETRY_END; + return r; +} + +static int +retry_request_flush (nbdkit_next *next, + void *handle, uint32_t flags, + int *err) +{ + int r; + + RETRY_START + r = next->flush (next, flags, err); + RETRY_END; + return r; +} + +static int +retry_request_zero (nbdkit_next *next, + void *handle, + uint32_t count, uint64_t offset, uint32_t flags, + int *err) +{ + int r; + + RETRY_START + r = next->zero (next, count, offset, flags, err); + RETRY_END; + return r; +} + +static int +retry_request_extents (nbdkit_next *next, + void *handle, + uint32_t count, uint64_t offset, uint32_t flags, + struct nbdkit_extents *extents, int *err) +{ + CLEANUP_EXTENTS_FREE struct nbdkit_extents *extents2 = NULL; + int r; + + RETRY_START { + /* Each retry must begin with extents reset to the right beginning. */ + nbdkit_extents_free (extents2); + extents2 = nbdkit_extents_new (offset, next->get_size (next)); + if (extents2 == NULL) { + *err = errno; + return -1; /* Not worth a retry after ENOMEM. */ + } + r = next->extents (next, count, offset, flags, extents2, err); + } RETRY_END; + + if (r == 0) { + size_t i; + + /* Transfer the successful extents back to the caller. */ + for (i = 0; i < nbdkit_extents_count (extents2); ++i) { + struct nbdkit_extent e = nbdkit_get_extent (extents2, i); + + if (nbdkit_add_extent (extents, e.offset, e.length, e.type) == -1) { + *err = errno; + return -1; + } + } + } + + return r; +} + +static int +retry_request_cache (nbdkit_next *next, + void *handle, + uint32_t count, uint64_t offset, uint32_t flags, + int *err) +{ + int r; + + RETRY_START + r = next->cache (next, count, offset, flags, err); + RETRY_END; + return r; +} + +static struct nbdkit_filter filter = { + .name = "retry-request", + .longname = "nbdkit retry request filter", + .thread_model = retry_request_thread_model, + .config = retry_request_config, + .config_help = retry_request_config_help, + .open = retry_request_open, + .pread = retry_request_pread, + .pwrite = retry_request_pwrite, + .trim = retry_request_trim, + .flush = retry_request_flush, + .zero = retry_request_zero, + .extents = retry_request_extents, + .cache = retry_request_cache, +}; + +NBDKIT_REGISTER_FILTER(filter) diff --git a/tests/test-retry-request.sh b/tests/test-retry-request.sh new file mode 100755 index 000000000..96c6a1c15 --- /dev/null +++ b/tests/test-retry-request.sh @@ -0,0 +1,94 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright (C) 2018-2021 Red Hat Inc. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +source ./functions.sh +set -e +set -x + +requires_plugin sh +requires nbdcopy --version +requires dd iflag=count_bytes </dev/null + +files="retry-request.img retry-request-count" +rm -f $files +cleanup_fn rm -f $files + +touch retry-request-count +start_t=$SECONDS + +# Create a custom plugin which will test retrying requests. +nbdkit -v -U - \ + sh - \ + --filter=retry-request retry-request-retries=3 retry-request-delay=1 \ + --run 'nbdcopy --synchronous "$uri" retry-request.img' <<'EOF' +#!/usr/bin/env bash +case "$1" in + get_size) echo 512 ;; + pread) + # Fail 3 times then succeed. + read i < retry-request-count + ((i++)) + echo $i > retry-request-count + if [ $i -le 3 ]; then + echo "EIO pread failed" >&2 + exit 1 + else + dd if=/dev/zero count=$3 iflag=count_bytes + fi + ;; + + *) exit 2 ;; +esac +EOF + +# In this test we should see 3 failures: +# pread FAILS +# retry and wait 1 second +# pread FAILS +# retry and wait 1 second +# pread FAILS +# retry and wait 1 second +# pread succeeds + +# The minimum time for the test should be 3 seconds. +end_t=$SECONDS +if [ $((end_t - start_t)) -lt 3 ]; then + echo "$0: test ran too quickly" + exit 1 +fi + +# Check retry-request-count = 4 (because we write #retries+1 to the file) +read retry_count < retry-request-count +if [ $retry_count -ne 4 ]; then + echo "$0: retry-request-count ($retry_count) != 4" + exit 1 +fi -- 2.32.0

Test the new nbdkit-retry-request-filter with the curl plugin. I have modified our test webserver so it provides a magical "/mirror" path which acts somewhat like a download mirror with occasional broken redirects. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2013000 --- tests/Makefile.am | 24 ++++ tests/test-retry-request-mirror.c | 130 ++++++++++++++++++++ tests/web-server.c | 197 +++++++++++++++++++++++++++--- .gitignore | 1 + 4 files changed, 337 insertions(+), 15 deletions(-) diff --git a/tests/Makefile.am b/tests/Makefile.am index 9a1485a6c..b8a3a654c 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -1701,6 +1701,30 @@ EXTRA_DIST += \ test-retry-request.sh \ $(NULL) +LIBNBD_TESTS += test-retry-request-mirror + +test_retry_request_mirror_SOURCES = \ + test-retry-request-mirror.c \ + web-server.c \ + web-server.h \ + test.h \ + $(NULL) +test_retry_request_mirror_CPPFLAGS = \ + -I$(top_srcdir)/common/utils +test_retry_request_mirror_CFLAGS = \ + $(WARNINGS_CFLAGS) \ + $(PTHREAD_CFLAGS) \ + $(LIBNBD_CFLAGS) \ + $(NULL) +test_retry_request_mirror_LDFLAGS = \ + $(top_builddir)/common/utils/libutils.la \ + $(PTHREAD_LIBS) \ + $(NULL) +test_retry_request_mirror_LDADD = \ + libtest.la \ + $(LIBNBD_LIBS) \ + $(NULL) + # swab filter test. TESTS += \ test-swab-8.sh \ diff --git a/tests/test-retry-request-mirror.c b/tests/test-retry-request-mirror.c new file mode 100644 index 000000000..861e2e0e5 --- /dev/null +++ b/tests/test-retry-request-mirror.c @@ -0,0 +1,130 @@ +/* nbdkit + * Copyright (C) 2013-2021 Red Hat Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of Red Hat nor the names of its contributors may be + * used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A + * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* This is a test of recovering from broken redirects to a mirror + * service. See the following bug for background: + * https://bugzilla.redhat.com/show_bug.cgi?id=2013000 + */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdbool.h> +#include <stdint.h> +#include <inttypes.h> +#include <string.h> +#include <unistd.h> + +#include <libnbd.h> + +#include "cleanup.h" +#include "web-server.h" + +#include "test.h" + +int +main (int argc, char *argv[]) +{ + const char *sockpath; + struct nbd_handle *nbd; + CLEANUP_FREE char *usp_param = NULL; + char buf[512]; + int state, i; + +#ifndef HAVE_CURLOPT_UNIX_SOCKET_PATH + fprintf (stderr, "%s: curl does not support CURLOPT_UNIX_SOCKET_PATH\n", + argv[0]); + exit (77); +#endif + + sockpath = web_server ("disk", NULL); + if (sockpath == NULL) { + fprintf (stderr, "%s: could not start web server thread\n", argv[0]); + exit (EXIT_FAILURE); + } + + /* Start nbdkit. */ + if (asprintf (&usp_param, "unix-socket-path=%s", sockpath) == -1) { + perror ("asprintf"); + exit (EXIT_FAILURE); + } + if (test_start_nbdkit ("--filter=retry-request", + "curl", usp_param, "http://localhost/mirror", + "retry-request-delay=1", + NULL) == -1) + exit (EXIT_FAILURE); + + nbd = nbd_create (); + if (nbd == NULL) { + nbd_error: + fprintf (stderr, "%s: %s\n", argv[0], nbd_get_error ()); + exit (EXIT_FAILURE); + } + + if (nbd_connect_unix (nbd, sock /* NBD socket */) == -1) + goto nbd_error; + + /* The way the test works is we fetch the magic "/mirror" path (see + * web-server.c). This redirects to /mirror1, /mirror2, /mirror3 + * round robin on each request. /mirror1 returns all 1's, /mirror2 + * returns all 2's, and /mirror3 returns a 404 error. The 404 error + * should be transparently skipped by the filter, so we should see + * alternating 1's and 2's buffers. + */ + if (nbd_pread (nbd, buf, sizeof buf, 0, 0) == -1) + goto nbd_error; + + if (buf[0] == 1 && buf[1] == 1 && buf[511] == 1) + state = 2; + else if (buf[0] == 2 && buf[1] == 2 && buf[511] == 2) + state = 1; + else { + fprintf (stderr, "%s: unexpected start state\n", argv[0]); + exit (EXIT_FAILURE); + } + + for (i = 0; i < 10; ++i) { + if (nbd_pread (nbd, buf, sizeof buf, 0, 0) == -1) + goto nbd_error; + if (buf[0] != state || buf[1] != state || buf[511] != state) { + fprintf (stderr, "%s: unexpected state\n", argv[0]); + exit (EXIT_FAILURE); + } + state++; + if (state == 3) + state = 1; + } + + nbd_close (nbd); + exit (EXIT_SUCCESS); +} diff --git a/tests/web-server.c b/tests/web-server.c index ac44d16b2..07a2ec398 100644 --- a/tests/web-server.c +++ b/tests/web-server.c @@ -57,6 +57,8 @@ #define SOCK_CLOEXEC 0 #endif +enum method { HEAD, GET }; + static char tmpdir[] = "/tmp/wsXXXXXX"; static char sockpath[] = "............./sock"; static int listen_sock = -1; @@ -67,7 +69,12 @@ static check_request_t check_request; static void *start_web_server (void *arg); static void handle_requests (int s); -static void handle_request (int s, bool headers_only); +static void handle_file_request (int s, enum method method); +static void handle_mirror_redirect_request (int s); +static void handle_mirror_data_request (int s, enum method method, char byte); +static void send_404_not_found (int s); +static void send_405_method_not_allowed (int s); +static void send_500_internal_server_error (int s); static void xwrite (int s, const char *buf, size_t len); static void xpread (char *buf, size_t count, off_t offset); @@ -177,12 +184,15 @@ start_web_server (void *arg) static void handle_requests (int s) { - size_t r, n, sz; bool eof = false; fprintf (stderr, "web server: accepted connection\n"); while (!eof) { + size_t r, n, sz; + enum method method; + char path[128]; + /* Read request until we see "\r\n\r\n" (end of headers) or EOF. */ n = 0; for (;;) { @@ -214,30 +224,73 @@ handle_requests (int s) /* Call the optional user function to check the request. */ if (check_request) check_request (request); - /* HEAD or GET request? */ - if (strncmp (request, "HEAD ", 5) == 0) - handle_request (s, true); - else if (strncmp (request, "GET ", 4) == 0) - handle_request (s, false); + /* Get the method and path fields from the first line. */ + if (strncmp (request, "HEAD ", 5) == 0) { + method = HEAD; + n = strcspn (&request[5], " \n\t"); + if (n >= sizeof path) { + send_500_internal_server_error (s); + eof = true; + break; + } + memcpy (path, &request[5], n); + path[n] = '\0'; + } + else if (strncmp (request, "GET ", 4) == 0) { + method = GET; + n = strcspn (&request[4], " \n\t"); + if (n >= sizeof path) { + send_500_internal_server_error (s); + eof = true; + break; + } + memcpy (path, &request[4], n); + path[n] = '\0'; + } else { - /* Return 405 Method Not Allowed. */ - const char response[] = - "HTTP/1.1 405 Method Not Allowed\r\n" - "Content-Length: 0\r\n" - "Connection: close\r\n" - "\r\n"; - xwrite (s, response, strlen (response)); + send_405_method_not_allowed (s); eof = true; break; } + + fprintf (stderr, "web server: requested path: %s\n", path); + + /* For testing retry-request + curl: + * /mirror redirects round-robin to /mirror1, /mirror2, /mirror3 + * /mirror1 returns a file of \x01 bytes + * /mirror2 returns a file of \x02 bytes + * /mirror3 returns 404 errors + * Anything else returns a 500 error + */ + if (strcmp (path, "/mirror") == 0) + handle_mirror_redirect_request (s); + else if (strcmp (path, "/mirror1") == 0) + handle_mirror_data_request (s, method, 1); + else if (strcmp (path, "/mirror2") == 0) + handle_mirror_data_request (s, method, 2); + else if (strcmp (path, "/mirror3") == 0) { + send_404_not_found (s); + eof = true; + } + else if (strncmp (path, "/mirror", 7) == 0) { + send_500_internal_server_error (s); + eof = true; + } + + /* Otherwise it's a regular file request. 'path' is ignored, we + * only serve a single file passed to web_server(). + */ + else + handle_file_request (s, method); } close (s); } static void -handle_request (int s, bool headers_only) +handle_file_request (int s, enum method method) { + const bool headers_only = method == HEAD; uint64_t offset, length, end; const char *p; const char response1_ok[] = "HTTP/1.1 200 OK\r\n"; @@ -295,6 +348,120 @@ handle_request (int s, bool headers_only) free (data); } +/* Request for /mirror */ +static void +handle_mirror_redirect_request (int s) +{ + static char rr = '1'; /* round robin '1', '2', '3' */ + /* Note we send 302 (temporary redirect), same as Fedora's mirrorservice. */ + const char found[] = "HTTP/1.1 302 Found\r\nContent-Length: 0\r\n"; + char location[] = "Location: /mirrorX\r\n"; + const char eol[] = "\r\n"; + + location[17] = rr; + rr++; + if (rr == '4') + rr = '1'; + + xwrite (s, found, strlen (found)); + xwrite (s, location, strlen (location)); + xwrite (s, eol, strlen (eol)); +} + +static void +handle_mirror_data_request (int s, enum method method, char byte) +{ + const bool headers_only = method == HEAD; + uint64_t offset, length, end; + const char *p; + const char response1_ok[] = "HTTP/1.1 200 OK\r\n"; + const char response1_partial[] = "HTTP/1.1 206 Partial Content\r\n"; + const char response2[] = + "Accept-rANGES: bytes\r\n" /* See RHBZ#1837337 */ + "Connection: keep-alive\r\n" + "Content-Type: application/octet-stream\r\n"; + char response3[64]; + const char response4[] = "\r\n"; + char *data; + + /* If there's no Range request header then send the full size as the + * content-length. + */ + p = strcasestr (request, "\r\nRange: bytes="); + if (p == NULL) { + offset = 0; + length = statbuf.st_size; + xwrite (s, response1_ok, strlen (response1_ok)); + } + else { + p += 15; + if (sscanf (p, "%" SCNu64 "-%" SCNu64, &offset, &end) != 2) { + fprintf (stderr, "web server: could not parse " + "range request from curl client\n"); + exit (EXIT_FAILURE); + } + /* Unclear but "Range: bytes=0-4" means bytes 0-3. '4' is the + * byte beyond the end of the range. + */ + length = end - offset; + xwrite (s, response1_partial, strlen (response1_partial)); + } + + xwrite (s, response2, strlen (response2)); + snprintf (response3, sizeof response3, + "Content-Length: %" PRIu64 "\r\n", length); + xwrite (s, response3, strlen (response3)); + xwrite (s, response4, strlen (response4)); + + if (headers_only) + return; + + /* Send the file content. */ + data = malloc (length); + if (data == NULL) { + perror ("malloc"); + exit (EXIT_FAILURE); + } + + memset (data, byte, length); + xwrite (s, data, length); + + free (data); +} + +static void +send_404_not_found (int s) +{ + const char response[] = + "HTTP/1.1 404 Not Found\r\n" + "Content-Length: 0\r\n" + "Connection: close\r\n" + "\r\n"; + xwrite (s, response, strlen (response)); +} + +static void +send_405_method_not_allowed (int s) +{ + const char response[] = + "HTTP/1.1 405 Method Not Allowed\r\n" + "Content-Length: 0\r\n" + "Connection: close\r\n" + "\r\n"; + xwrite (s, response, strlen (response)); +} + +static void +send_500_internal_server_error (int s) +{ + const char response[] = + "HTTP/1.1 500 Internal Server Error\r\n" + "Content-Length: 0\r\n" + "Connection: close\r\n" + "\r\n"; + xwrite (s, response, strlen (response)); +} + static void xwrite (int s, const char *buf, size_t len) { diff --git a/.gitignore b/.gitignore index 847b72dd6..e7b07d510 100644 --- a/.gitignore +++ b/.gitignore @@ -155,6 +155,7 @@ plugins/*/*.3 /tests/test-python /tests/test-random /tests/test-readahead +/tests/test-retry-request-mirror /tests/test-ruby /tests/test-S3/boto3/__pycache__/ /tests/test-shell -- 2.32.0

On Mon, Oct 18, 2021 at 08:27:36PM +0200, Laszlo Ersek wrote: I didn't know, but I temporarily modified the test changing #ifndef -> #ifdef above and it did exit (skip) fine. I had to go and check this, and it turns out we do unlink the socket in an at-exit handler (cleanup) in tests/web-server.c, so I think we're good even on error paths. OK, adjusted it as you say. Thanks, Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v