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protocol-native: extend v3 protocol with message footers

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Extend version 3 protocol with message footers, which are for passing
around global state data that is not addressed to a specific object.

The extension is backward compatible with previous v3 clients, and won't
e.g. result to error spam in logs.

The footer is a single SPA POD, appended after the main message POD.
Because both the protocol message and the message POD record their
length, it's possible to append trailing data. Earlier clients will
ignore any data trailing the message POD.

The footer POD contains a sequence [Id opcode, Struct {...}]*,
so there is room to extend with new opcodes later as necessary.

There are separate marshal/demarshal routines for messages aimed at
resources and proxies.
This commit is contained in:
Pauli Virtanen 2022-02-20 14:03:41 +02:00
parent c4997fc46d
commit 680c33d3eb
7 changed files with 253 additions and 1 deletions
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56
src/modules/module-protocol-native.c
View file

@ -57,6 +57,7 @@
#include "modules/module-protocol-native/connection.h"
#include "modules/module-protocol-native/defs.h"
#include "modules/module-protocol-native/protocol-footer.h"
#define NAME "protocol-native"
@ -115,6 +116,8 @@ struct client {
int ref;
struct footer_proxy_global_state footer_state;
unsigned int connected:1;
unsigned int disconnecting:1;
unsigned int need_flush:1;
@ -151,6 +154,8 @@ struct client_data {
struct pw_protocol_native_connection *connection;
struct spa_hook conn_listener;
struct footer_resource_global_state footer_state;
unsigned int busy:1;
unsigned int need_flush:1;
@ -164,7 +169,7 @@ static void debug_msg(const char *prefix, const struct pw_protocol_native_messag
"%s: id:%d op:%d size:%d seq:%d", prefix,
msg->id, msg->opcode, msg->size, msg->seq);
if ((pod = spa_pod_from_data(msg->data, msg->size, 0, msg->size)) != NULL)
if ((pod = get_first_pod_from_data(msg->data, msg->size, 0)) != NULL)
spa_debug_pod(0, NULL, pod);
else
hex = true;
@ -172,6 +177,49 @@ static void debug_msg(const char *prefix, const struct pw_protocol_native_messag
spa_debug_mem(0, msg->data, msg->size);
}
static void pre_demarshal(struct pw_protocol_native_connection *conn,
const struct pw_protocol_native_message *msg,
void *object, const struct footer_demarshal *opcodes, size_t n_opcodes)
{
struct spa_pod *footer = NULL;
struct spa_pod_parser parser;
struct spa_pod_frame f[2];
uint32_t opcode;
int ret;
footer = pw_protocol_native_connection_get_footer(conn, msg);
if (footer == NULL)
return; /* No valid footer. Ignore silently. */
/*
* Version 3 footer
*
* spa_pod Struct { [Id opcode, Struct { ... }]* }
*/
spa_pod_parser_pod(&parser, footer);
if (spa_pod_parser_push_struct(&parser, &f[0]) < 0) {
pw_log_error("malformed message footer");
return;
}
while (1) {
if (spa_pod_parser_get_id(&parser, &opcode) < 0)
break;
if (spa_pod_parser_push_struct(&parser, &f[1]) < 0)
break;
if (opcode < n_opcodes) {
if ((ret = opcodes[opcode].demarshal(object, &parser)) < 0)
pw_log_error("failed processing message footer (opcode %u): %d (%s)",
opcode, ret, spa_strerror(ret));
} else {
/* Ignore (don't log errors), in case we need to extend this later. */
pw_log_debug("unknown message footer opcode %u", opcode);
}
spa_pod_parser_pop(&parser, &f[1]);
}
}
static int
process_messages(struct client_data *data)
{
@ -249,6 +297,8 @@ process_messages(struct client_data *data)
}
pw_protocol_native_connection_enter(conn);
pre_demarshal(conn, msg, resource, footer_resource_demarshal,
SPA_N_ELEMENTS(footer_resource_demarshal));
res = demarshal[msg->opcode].func(resource, msg);
pw_protocol_native_connection_leave(conn);
if (res < 0) {
@ -794,6 +844,8 @@ process_remote(struct client *impl)
}
proxy->refcount++;
pw_protocol_native_connection_enter(conn);
pre_demarshal(conn, msg, proxy, footer_proxy_demarshal,
SPA_N_ELEMENTS(footer_proxy_demarshal));
res = demarshal[msg->opcode].func(proxy, msg);
pw_protocol_native_connection_leave(conn);
pw_proxy_unref(proxy);
@ -1230,6 +1282,7 @@ static int impl_ext_end_proxy(struct pw_proxy *proxy,
{
struct pw_core *core = proxy->core;
struct client *impl = SPA_CONTAINER_OF(core->conn, struct client, this);
marshal_proxy_footers(&impl->footer_state, proxy, builder);
return core->send_seq = pw_protocol_native_connection_end(impl->connection, builder);
}
@ -1257,6 +1310,7 @@ static int impl_ext_end_resource(struct pw_resource *resource,
{
struct client_data *data = resource->client->user_data;
struct pw_impl_client *client = resource->client;
marshal_resource_footers(&data->footer_state, resource, builder);
return client->send_seq = pw_protocol_native_connection_end(data->connection, builder);
}
static const struct pw_protocol_native_ext protocol_ext_impl = {