9:37 a.m.
A server may have a reason to reject a request for structured replies,
beyond just not recognizing them as a valid request. It doesn't hurt
us to continue talking to such a server; otherwise 'qemu-nbd --list'
of such a server fails to display all possible details about the
export.
Encountered when temporarily tweaking nbdkit to reply with
NBD_REP_ERR_POLICY. Present since structured reply support was first
added (commit d795299b reused starttls handling, but starttls has to
reject all errors).
Signed-off-by: Eric Blake <eblake(a)redhat.com>
---
nbd/client.c | 39 +++++++++++++++++++++++----------------
1 file changed, 23 insertions(+), 16 deletions(-)
diff --git a/nbd/client.c b/nbd/client.c
index 49bf9906f94b..92444f5e9a62 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2016-2018 Red Hat, Inc.
+ * Copyright (C) 2016-2019 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony(a)codemonkey.ws>
*
* Network Block Device Client Side
@@ -142,17 +142,19 @@ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
return 0;
}
-/* If reply represents success, return 1 without further action.
- * If reply represents an error, consume the optional payload of
- * the packet on ioc. Then return 0 for unsupported (so the client
- * can fall back to other approaches), or -1 with errp set for other
- * errors.
+/*
+ * If reply represents success, return 1 without further action. If
+ * reply represents an error, consume the optional payload of the
+ * packet on ioc. Then return 0 for unsupported (so the client can
+ * fall back to other approaches), where @strict determines if only
+ * ERR_UNSUP or all errors fit that category, or -1 with errp set for
+ * other errors.
*/
static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
- Error **errp)
+ bool strict, Error **errp)
{
char *msg = NULL;
- int result = -1;
+ int result = strict ? -1 : 0;
if (!(reply->type & (1 << 31))) {
return 1;
@@ -163,6 +165,7 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply
*reply,
error_setg(errp, "server error %" PRIu32
" (%s) message is too long",
reply->type, nbd_rep_lookup(reply->type));
+ result = -1;
goto cleanup;
}
msg = g_malloc(reply->length + 1);
@@ -170,6 +173,7 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply
*reply,
error_prepend(errp, "Failed to read option error %" PRIu32
" (%s) message: ",
reply->type, nbd_rep_lookup(reply->type));
+ result = -1;
goto cleanup;
}
msg[reply->length] = '\0';
@@ -258,7 +262,7 @@ static int nbd_receive_list(QIOChannel *ioc, char **name, char
**description,
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
return -1;
}
- error = nbd_handle_reply_err(ioc, &reply, errp);
+ error = nbd_handle_reply_err(ioc, &reply, true, errp);
if (error <= 0) {
return error;
}
@@ -371,7 +375,7 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
return -1;
}
- error = nbd_handle_reply_err(ioc, &reply, errp);
+ error = nbd_handle_reply_err(ioc, &reply, true, errp);
if (error <= 0) {
return error;
}
@@ -546,12 +550,15 @@ static int nbd_receive_query_exports(QIOChannel *ioc,
}
}
-/* nbd_request_simple_option: Send an option request, and parse the reply
+/*
+ * nbd_request_simple_option: Send an option request, and parse the reply.
+ * @strict controls whether ERR_UNSUP or all errors produce 0 status.
* return 1 for successful negotiation,
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
-static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
+static int nbd_request_simple_option(QIOChannel *ioc, int opt, bool strict,
+ Error **errp)
{
NBDOptionReply reply;
int error;
@@ -563,7 +570,7 @@ static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error
**errp)
if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
return -1;
}
- error = nbd_handle_reply_err(ioc, &reply, errp);
+ error = nbd_handle_reply_err(ioc, &reply, strict, errp);
if (error <= 0) {
return error;
}
@@ -595,7 +602,7 @@ static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
- ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, errp);
+ ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, true, errp);
if (ret <= 0) {
if (ret == 0) {
error_setg(errp, "Server don't support STARTTLS option");
@@ -695,7 +702,7 @@ static int nbd_receive_one_meta_context(QIOChannel *ioc,
return -1;
}
- ret = nbd_handle_reply_err(ioc, &reply, errp);
+ ret = nbd_handle_reply_err(ioc, &reply, true, errp);
if (ret <= 0) {
return ret;
}
@@ -951,7 +958,7 @@ static int nbd_start_negotiate(AioContext *aio_context, QIOChannel
*ioc,
if (structured_reply) {
result = nbd_request_simple_option(ioc,
NBD_OPT_STRUCTURED_REPLY,
- errp);
+ false, errp);
if (result < 0) {
return -EINVAL;
}
--
2.21.0