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sd-varlink: fold separate 'protocol_upgrade' flag into state machine

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This commit is contained in:
Lennart Poettering
2026-07-12 22:37:48 +02:00
parent 755f1cff89
commit 260fcf9763
2 changed files with 62 additions and 59 deletions
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src/libsystemd/sd-varlink/sd-varlink.c
+55 -50
View File
@@ -48,27 +48,29 @@
#define VARLINK_COLLECT_MAX 1024U
static const char* const varlink_state_table[_VARLINK_STATE_MAX] = {
[VARLINK_IDLE_CLIENT] = "idle-client",
[VARLINK_AWAITING_REPLY] = "awaiting-reply",
[VARLINK_AWAITING_REPLY_MORE] = "awaiting-reply-more",
[VARLINK_CALLING] = "calling",
[VARLINK_CALLED] = "called",
[VARLINK_COLLECTING] = "collecting",
[VARLINK_COLLECTING_REPLY] = "collecting-reply",
[VARLINK_PROCESSING_REPLY] = "processing-reply",
[VARLINK_IDLE_SERVER] = "idle-server",
[VARLINK_PROCESSING_METHOD] = "processing-method",
[VARLINK_PROCESSING_METHOD_MORE] = "processing-method-more",
[VARLINK_PROCESSING_METHOD_ONEWAY] = "processing-method-oneway",
[VARLINK_PROCESSED_METHOD] = "processed-method",
[VARLINK_PENDING_METHOD] = "pending-method",
[VARLINK_PENDING_METHOD_MORE] = "pending-method-more",
[VARLINK_PENDING_DISCONNECT] = "pending-disconnect",
[VARLINK_PENDING_TIMEOUT] = "pending-timeout",
[VARLINK_PROCESSING_DISCONNECT] = "processing-disconnect",
[VARLINK_PROCESSING_TIMEOUT] = "processing-timeout",
[VARLINK_PROCESSING_FAILURE] = "processing-failure",
[VARLINK_DISCONNECTED] = "disconnected",
[VARLINK_IDLE_CLIENT] = "idle-client",
[VARLINK_AWAITING_REPLY] = "awaiting-reply",
[VARLINK_AWAITING_REPLY_MORE] = "awaiting-reply-more",
[VARLINK_CALLING] = "calling",
[VARLINK_CALLED] = "called",
[VARLINK_COLLECTING] = "collecting",
[VARLINK_COLLECTING_REPLY] = "collecting-reply",
[VARLINK_PROCESSING_REPLY] = "processing-reply",
[VARLINK_IDLE_SERVER] = "idle-server",
[VARLINK_PROCESSING_METHOD] = "processing-method",
[VARLINK_PROCESSING_METHOD_MORE] = "processing-method-more",
[VARLINK_PROCESSING_METHOD_ONEWAY] = "processing-method-oneway",
[VARLINK_PROCESSING_METHOD_UPGRADE] = "processing-method-upgrade",
[VARLINK_PROCESSED_METHOD] = "processed-method",
[VARLINK_PENDING_METHOD] = "pending-method",
[VARLINK_PENDING_METHOD_MORE] = "pending-method-more",
[VARLINK_PENDING_METHOD_UPGRADE] = "pending-method-upgrade",
[VARLINK_PENDING_DISCONNECT] = "pending-disconnect",
[VARLINK_PENDING_TIMEOUT] = "pending-timeout",
[VARLINK_PROCESSING_DISCONNECT] = "processing-disconnect",
[VARLINK_PROCESSING_TIMEOUT] = "processing-timeout",
[VARLINK_PROCESSING_FAILURE] = "processing-failure",
[VARLINK_DISCONNECTED] = "disconnected",
};
DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(varlink_state, VarlinkState);
@@ -112,7 +114,7 @@ static JsonStreamPhase varlink_phase(void *userdata) {
if (v->state == VARLINK_IDLE_CLIENT)
return JSON_STREAM_PHASE_IDLE_CLIENT;
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return JSON_STREAM_PHASE_PENDING_OUTPUT;
return JSON_STREAM_PHASE_OTHER;
@@ -1096,7 +1098,7 @@ static int varlink_fiber_entry(void *userdata) {
* VARLINK_PROCESSING_METHOD{,_MORE} to VARLINK_PENDING_METHOD{,_MORE}, so that's what we match
* here to decide whether the call still needs a reply. Any other state (e.g. IDLE_SERVER after
* the callback replied, or DISCONNECTED after sd_varlink_close()) means no fixup is needed. */
if (!IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
if (!IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return r;
if (r < 0) {
@@ -1118,7 +1120,7 @@ static int varlink_fiber_entry(void *userdata) {
r = 0;
/* If we didn't manage to enqueue a response, then fail the connection completely. */
if (r < 0 && IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
if (r < 0 && IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
goto fail;
return r;
@@ -1264,20 +1266,20 @@ static int varlink_dispatch_method(sd_varlink *v) {
if (r < 0)
goto fail;
varlink_set_state(v, (flags & SD_VARLINK_METHOD_MORE) ? VARLINK_PROCESSING_METHOD_MORE :
(flags & SD_VARLINK_METHOD_ONEWAY) ? VARLINK_PROCESSING_METHOD_ONEWAY :
VARLINK_PROCESSING_METHOD);
varlink_set_state(v, (flags & SD_VARLINK_METHOD_MORE) ? VARLINK_PROCESSING_METHOD_MORE :
(flags & SD_VARLINK_METHOD_ONEWAY) ? VARLINK_PROCESSING_METHOD_ONEWAY :
(flags & SD_VARLINK_METHOD_UPGRADE) ? VARLINK_PROCESSING_METHOD_UPGRADE :
VARLINK_PROCESSING_METHOD);
assert(v->server);
/* Reset the per-call upgrade marker on every dispatch — a previous method's
* UPGRADE flag must not bleed into this one. The transport-level bounded reads
* stay active for SD_VARLINK_SERVER_UPGRADABLE servers regardless. */
v->protocol_upgrade = FLAGS_SET(flags, SD_VARLINK_METHOD_UPGRADE);
json_stream_set_flags(
&v->stream,
JSON_STREAM_BOUNDED_READS,
v->protocol_upgrade || FLAGS_SET(v->server->flags, SD_VARLINK_SERVER_UPGRADABLE));
FLAGS_SET(flags, SD_VARLINK_METHOD_UPGRADE) || FLAGS_SET(v->server->flags, SD_VARLINK_SERVER_UPGRADABLE));
/* First consult user supplied method implementations */
bool is_fiber = false;
@@ -1401,6 +1403,10 @@ static int varlink_dispatch_method(sd_varlink *v) {
varlink_set_state(v, VARLINK_PENDING_METHOD_MORE);
break;
case VARLINK_PROCESSING_METHOD_UPGRADE: /* Method call wasn't replied to, will be replied to later */
varlink_set_state(v, VARLINK_PENDING_METHOD_UPGRADE);
break;
case VARLINK_DISCONNECTED: /* Handler called sd_varlink_close() on us, which is fine */
break;
@@ -1516,7 +1522,7 @@ _public_ int sd_varlink_dispatch_again(sd_varlink *v) {
if (v->state == VARLINK_DISCONNECTED)
return varlink_log_errno(v, SYNTHETIC_ERRNO(ENOTCONN), "Not connected.");
if (!IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
if (!IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EBUSY), "Connection has no pending method.");
varlink_set_state(v, VARLINK_IDLE_SERVER);
@@ -2076,11 +2082,9 @@ _public_ int sd_varlink_call_and_upgrade(
if (r < 0)
return varlink_log_errno(v, r, "Failed to build json message: %m");
v->protocol_upgrade = true;
json_stream_set_flags(&v->stream, JSON_STREAM_BOUNDED_READS, true);
r = varlink_call_internal(v, m);
if (r < 0) {
v->protocol_upgrade = false;
json_stream_set_flags(&v->stream, JSON_STREAM_BOUNDED_READS, false);
return r;
}
@@ -2125,7 +2129,6 @@ _public_ int sd_varlink_call_and_upgrade(
return 1;
finish:
v->protocol_upgrade = false;
json_stream_set_flags(&v->stream, JSON_STREAM_BOUNDED_READS, false);
assert(v->n_pending == 1);
v->n_pending--;
@@ -2360,8 +2363,8 @@ static int varlink_reply_internal(sd_varlink *v, sd_json_variant *parameters, bo
return varlink_log_errno(v, SYNTHETIC_ERRNO(ENOTCONN), "Not connected.");
if (!IN_SET(v->state,
VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE,
VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE, VARLINK_PROCESSING_METHOD_UPGRADE,
VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EBUSY), "Connection busy.");
bool more = IN_SET(v->state, VARLINK_PROCESSING_METHOD_MORE, VARLINK_PENDING_METHOD_MORE);
@@ -2413,7 +2416,7 @@ static int varlink_reply_internal(sd_varlink *v, sd_json_variant *parameters, bo
if (r < 0)
return varlink_log_errno(v, r, "Failed to enqueue json message: %m");
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE)) {
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE)) {
/* We just replied to a method call that was let hanging for a while (i.e. we were outside of
* the varlink_dispatch_method() stack frame), which means with this reply we are ready to
* process further messages. */
@@ -2463,21 +2466,23 @@ _public_ int sd_varlink_reply_and_upgrade(sd_varlink *v, sd_json_variant *parame
if (v->state == VARLINK_DISCONNECTED)
return varlink_log_errno(v, SYNTHETIC_ERRNO(ENOTCONN), "Not connected.");
/* Return -EBUSY if we are not processing methods at all */
if (!IN_SET(v->state,
VARLINK_PROCESSING_METHOD,
VARLINK_PENDING_METHOD))
VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE, VARLINK_PROCESSING_METHOD_ONEWAY, VARLINK_PROCESSING_METHOD_UPGRADE,
VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EBUSY), "Connection busy.");
/* Verify the client actually requested a protocol upgrade */
if (!v->protocol_upgrade)
return varlink_log_errno(v, SYNTHETIC_ERRNO(EPROTO),
"Method call did not request a protocol upgrade.");
/* Return -EPROTO if we are processing methods, but an upgrade was not requested. */
if (!IN_SET(v->state,
VARLINK_PROCESSING_METHOD_UPGRADE,
VARLINK_PENDING_METHOD_UPGRADE))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EPROTO), "Method call did not request a protocol upgrade.");
/* Ensure we did not buffer any data beyond the upgrade request. Check this before sending the
* reply so that we can return a normal error (the framework will send an error reply to the
* client). In normal operation this cannot happen because the client waits for our reply before
* sending raw data, and we set protocol_upgrade=true in dispatch to limit subsequent reads to
* single bytes. But a misbehaving client could pipeline data early. */
/* Ensure we did not buffer any data beyond the upgrade request. Check this before sending the reply
* so that we can return a normal error (the framework will send an error reply to the client). In
* normal operation this cannot happen because the client waits for our reply before sending raw
* data, and we disabled unbounded reads in dispatch to limit subsequent reads to single bytes. But a
* misbehaving client could pipeline data early. */
if (json_stream_has_buffered_input(&v->stream))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EBADMSG),
"Unexpected buffered data from client during protocol upgrade.");
@@ -2548,8 +2553,8 @@ _public_ int sd_varlink_error(sd_varlink *v, const char *error_id, sd_json_varia
if (v->state == VARLINK_DISCONNECTED)
return varlink_log_errno(v, SYNTHETIC_ERRNO(ENOTCONN), "Not connected.");
if (!IN_SET(v->state,
VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE,
VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE))
VARLINK_PROCESSING_METHOD, VARLINK_PROCESSING_METHOD_MORE, VARLINK_PROCESSING_METHOD_UPGRADE,
VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE))
return varlink_log_errno(v, SYNTHETIC_ERRNO(EBUSY), "Connection busy.");
if (v->previous) {
@@ -2601,7 +2606,7 @@ _public_ int sd_varlink_error(sd_varlink *v, const char *error_id, sd_json_varia
if (r < 0)
return varlink_log_errno(v, r, "Failed to enqueue json message: %m");
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE)) {
if (IN_SET(v->state, VARLINK_PENDING_METHOD, VARLINK_PENDING_METHOD_MORE, VARLINK_PENDING_METHOD_UPGRADE)) {
varlink_clear_current(v);
varlink_set_state(v, VARLINK_IDLE_SERVER);
} else
src/libsystemd/sd-varlink/varlink-internal.h
+7 -9
View File
@@ -26,9 +26,11 @@ typedef enum VarlinkState {
VARLINK_PROCESSING_METHOD,
VARLINK_PROCESSING_METHOD_MORE,
VARLINK_PROCESSING_METHOD_ONEWAY,
VARLINK_PROCESSING_METHOD_UPGRADE,
VARLINK_PROCESSED_METHOD,
VARLINK_PENDING_METHOD,
VARLINK_PENDING_METHOD_MORE,
VARLINK_PENDING_METHOD_UPGRADE,
/* Common states (only during shutdown) */
VARLINK_PENDING_DISCONNECT,
@@ -60,16 +62,19 @@ typedef enum VarlinkState {
VARLINK_PROCESSING_METHOD, \
VARLINK_PROCESSING_METHOD_MORE, \
VARLINK_PROCESSING_METHOD_ONEWAY, \
VARLINK_PROCESSING_METHOD_UPGRADE, \
VARLINK_PROCESSED_METHOD, \
VARLINK_PENDING_METHOD, \
VARLINK_PENDING_METHOD_MORE)
VARLINK_PENDING_METHOD_MORE, \
VARLINK_PENDING_METHOD_UPGRADE)
/* Tests whether we are expected to generate a method call reply, i.e. are processing a method call, except
* one with the ONEWAY flag set. */
#define VARLINK_STATE_WANTS_REPLY(state) \
IN_SET(state, \
VARLINK_PROCESSING_METHOD, \
VARLINK_PROCESSING_METHOD_MORE)
VARLINK_PROCESSING_METHOD_MORE, \
VARLINK_PROCESSING_METHOD_UPGRADE)
typedef struct sd_varlink {
unsigned n_ref;
@@ -86,13 +91,6 @@ typedef struct sd_varlink {
unsigned n_pending;
/* Per-call protocol-upgrade marker: set when the *current* method call carries the
* SD_VARLINK_METHOD_UPGRADE flag. Validated by sd_varlink_reply_and_upgrade() to
* ensure the caller's contract is honored. The transport-layer "stop reading at the
* next message boundary" behavior is governed independently by the JsonStream's
* bounded_reads flag. */
bool protocol_upgrade;
sd_varlink_reply_t reply_callback;
sd_json_variant *current;