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CommandFilter API: REDISMODULE_CMDFILTER_NOSELF.

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Add a flag to automatically protect filters from being called
recursively by their own module.
This commit is contained in:
Yossi Gottlieb 2019-03-21 19:47:43 +02:00
parent b8568a98fd
commit 898677d59e
4 changed files with 62 additions and 15 deletions
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28
src/module.c
View File

@ -50,6 +50,7 @@ struct RedisModule {
list *usedby; /* List of modules using APIs from this one. */
list *using; /* List of modules we use some APIs of. */
list *filters; /* List of filters the module has registered. */
int in_call; /* RM_Call() nesting level */
};
typedef struct RedisModule RedisModule;
@ -283,6 +284,8 @@ typedef struct RedisModuleCommandFilter {
RedisModule *module;
/* Filter callback function */
RedisModuleCommandFilterFunc callback;
/* REDISMODULE_CMDFILTER_* flags */
int flags;
} RedisModuleCommandFilter;
/* Registered filters */
@ -2756,6 +2759,8 @@ RedisModuleCallReply *RM_Call(RedisModuleCtx *ctx, const char *cmdname, const ch
c->db = ctx->client->db;
c->argv = argv;
c->argc = argc;
if (ctx->module) ctx->module->in_call++;
/* We handle the above format error only when the client is setup so that
* we can free it normally. */
if (argv == NULL) goto cleanup;
@ -2822,6 +2827,7 @@ RedisModuleCallReply *RM_Call(RedisModuleCtx *ctx, const char *cmdname, const ch
autoMemoryAdd(ctx,REDISMODULE_AM_REPLY,reply);
cleanup:
if (ctx->module) ctx->module->in_call--;
freeClient(c);
return reply;
}
@ -4857,17 +4863,27 @@ int moduleUnregisterFilters(RedisModule *module) {
*
* Note that in the above use case, if `MODULE.SET` itself uses
* `RedisModule_Call()` the filter will be applied on that call as well. If
* that is not desired, the module itself is responsible for maintaining a flag
* to identify and avoid this form of re-entrancy.
* that is not desired, the `REDISMODULE_CMDFILTER_NOSELF` flag can be set when
* registering the filter.
*
* The `REDISMODULE_CMDFILTER_NOSELF` flag prevents execution flows that
* originate from the module's own `RM_Call()` from reaching the filter. This
* flag is effective for all execution flows, including nested ones, as long as
* the execution begins from the module's command context or a thread-safe
* context that is associated with a blocking command.
*
* Detached thread-safe contexts are *not* associated with the module and cannot
* be protected by this flag.
*
* If multiple filters are registered (by the same or different modules), they
* are executed in the order of registration.
*/
RedisModuleCommandFilter *RM_RegisterCommandFilter(RedisModuleCtx *ctx, RedisModuleCommandFilterFunc callback) {
RedisModuleCommandFilter *RM_RegisterCommandFilter(RedisModuleCtx *ctx, RedisModuleCommandFilterFunc callback, int flags) {
RedisModuleCommandFilter *filter = zmalloc(sizeof(*filter));
filter->module = ctx->module;
filter->callback = callback;
filter->flags = flags;
listAddNodeTail(moduleCommandFilters, filter);
listAddNodeTail(ctx->module->filters, filter);
@ -4908,6 +4924,12 @@ void moduleCallCommandFilters(client *c) {
while((ln = listNext(&li))) {
RedisModuleCommandFilter *f = ln->value;
/* Skip filter if REDISMODULE_CMDFILTER_NOSELF is set and module is
* currently processing a command.
*/
if ((f->flags & REDISMODULE_CMDFILTER_NOSELF) && f->module->in_call) continue;
/* Call filter */
f->callback(&filter);
}

15
src/modules/hellofilter.c
View File

@ -8,7 +8,7 @@ static RedisModuleString *log_key_name;
static const char log_command_name[] = "hellofilter.log";
static const char ping_command_name[] = "hellofilter.ping";
static const char unregister_command_name[] = "hellofilter.unregister";
static int in_module = 0;
static int in_log_command = 0;
static RedisModuleCommandFilter *filter = NULL;
@ -57,7 +57,7 @@ int HelloFilter_LogCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int ar
RedisModule_CloseKey(log);
RedisModule_FreeString(ctx, s);
in_module = 1;
in_log_command = 1;
size_t cmdlen;
const char *cmdname = RedisModule_StringPtrLen(argv[1], &cmdlen);
@ -69,14 +69,14 @@ int HelloFilter_LogCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int ar
RedisModule_ReplyWithSimpleString(ctx, "Unknown command or invalid arguments");
}
in_module = 0;
in_log_command = 0;
return REDISMODULE_OK;
}
void HelloFilter_CommandFilter(RedisModuleCommandFilterCtx *filter)
{
if (in_module) return; /* don't process our own RM_Call() */
if (in_log_command) return; /* don't process our own RM_Call() from HelloFilter_LogCommand() */
/* Fun manipulations:
* - Remove @delme
@ -120,12 +120,14 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
if (RedisModule_Init(ctx,"hellofilter",1,REDISMODULE_APIVER_1)
== REDISMODULE_ERR) return REDISMODULE_ERR;
if (argc != 1) {
if (argc != 2) {
RedisModule_Log(ctx, "warning", "Log key name not specified");
return REDISMODULE_ERR;
}
long long noself = 0;
log_key_name = RedisModule_CreateStringFromString(ctx, argv[0]);
RedisModule_StringToLongLong(argv[1], &noself);
if (RedisModule_CreateCommand(ctx,log_command_name,
HelloFilter_LogCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
@ -139,7 +141,8 @@ int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
HelloFilter_UnregisterCommand,"write deny-oom",1,1,1) == REDISMODULE_ERR)
return REDISMODULE_ERR;
if ((filter = RedisModule_RegisterCommandFilter(ctx, HelloFilter_CommandFilter))
if ((filter = RedisModule_RegisterCommandFilter(ctx, HelloFilter_CommandFilter,
noself ? REDISMODULE_CMDFILTER_NOSELF : 0))
== NULL) return REDISMODULE_ERR;
return REDISMODULE_OK;

7
src/redismodule.h
View File

@ -132,6 +132,11 @@
* of timers that are going to expire, sorted by expire time. */
typedef uint64_t RedisModuleTimerID;
/* CommandFilter Flags */
/* Do filter RedisModule_Call() commands initiated by module itself. */
#define REDISMODULE_CMDFILTER_NOSELF (1<<0)
/* ------------------------- End of common defines ------------------------ */
#ifndef REDISMODULE_CORE
@ -340,7 +345,7 @@ void REDISMODULE_API_FUNC(RedisModule_SetDisconnectCallback)(RedisModuleBlockedC
void REDISMODULE_API_FUNC(RedisModule_SetClusterFlags)(RedisModuleCtx *ctx, uint64_t flags);
int REDISMODULE_API_FUNC(RedisModule_ExportSharedAPI)(RedisModuleCtx *ctx, const char *apiname, void *func);
void *REDISMODULE_API_FUNC(RedisModule_GetSharedAPI)(RedisModuleCtx *ctx, const char *apiname);
RedisModuleCommandFilter *REDISMODULE_API_FUNC(RedisModule_RegisterCommandFilter)(RedisModuleCtx *ctx, RedisModuleCommandFilterFunc cb);
RedisModuleCommandFilter *REDISMODULE_API_FUNC(RedisModule_RegisterCommandFilter)(RedisModuleCtx *ctx, RedisModuleCommandFilterFunc cb, int flags);
int REDISMODULE_API_FUNC(RedisModule_UnregisterCommandFilter)(RedisModuleCtx *ctx, RedisModuleCommandFilter *filter);
int REDISMODULE_API_FUNC(RedisModule_CommandFilterArgsCount)(RedisModuleCommandFilterCtx *fctx);
const RedisModuleString *REDISMODULE_API_FUNC(RedisModule_CommandFilterArgGet)(RedisModuleCommandFilterCtx *fctx, int pos);

27
tests/modules/commandfilter.tcl
View File

@ -1,7 +1,7 @@
set testmodule [file normalize src/modules/hellofilter.so]
start_server {tags {"modules"}} {
r module load $testmodule log-key
r module load $testmodule log-key 0
test {Command Filter handles redirected commands} {
r set mykey @log
@ -50,18 +50,35 @@ start_server {tags {"modules"}} {
r lrange log-key 0 -1
} {}
r module load $testmodule log-key-2
r module load $testmodule log-key 0
test {Command Filter unregister works as expected} {
# Validate reloading succeeded
r del log-key
r set mykey @log
assert_equal "{set mykey @log}" [r lrange log-key-2 0 -1]
assert_equal "{set mykey @log}" [r lrange log-key 0 -1]
# Unregister
r hellofilter.unregister
r del log-key-2
r del log-key
r set mykey @log
r lrange log-key-2 0 -1
r lrange log-key 0 -1
} {}
r module unload hellofilter
r module load $testmodule log-key 1
test {Command Filter REDISMODULE_CMDFILTER_NOSELF works as expected} {
r set mykey @log
assert_equal "{set mykey @log}" [r lrange log-key 0 -1]
r del log-key
r hellofilter.ping
assert_equal {} [r lrange log-key 0 -1]
r eval "redis.call('hellofilter.ping')" 0
assert_equal {} [r lrange log-key 0 -1]
}
}