Allow clients to report name and version (#11758)

This PR allows clients to send information about the client library to redis
to be displayed in CLIENT LIST and CLIENT INFO.

Currently supports:
`CLIENT [lib-name | lib-ver] <value>`
Client libraries are expected to pipeline these right after AUTH, and ignore
the failure in case they're talking to an older version of redis.

These will be shown in CLIENT LIST and CLIENT INFO as:
* `lib-name` - meant to hold the client library name.
* `lib-ver` - meant to hold the client library version.

The values cannot contain spaces, newlines and any wild ASCII characters,
but all other normal chars are accepted, e.g `.`, `=` etc (same as CLIENT NAME).

The RESET command does NOT clear these, but they can be cleared to the
default by sending a command with a blank string.

Co-authored-by: Oran Agra <oran@redislabs.com>

1 files changed, 58 insertions, 11 deletions

diff --git a/src/networking.c b/src/networking.c
index ed14fff72..3b66dd59e 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -147,6 +147,8 @@ client *createClient(connection *conn) {
 #endif
     c->conn = conn;
     c->name = NULL;
+    c->lib_name = NULL;
+    c->lib_ver = NULL;
     c->bufpos = 0;
     c->buf_usable_size = zmalloc_usable_size(c->buf);
     c->buf_peak = c->buf_usable_size;
@@ -1511,6 +1513,9 @@ void clearClientConnectionState(client *c) {
         c->name = NULL;
     }
 
+    /* Note: lib_name and lib_ver are not reset since they still
+     * represent the client library behind the connection. */
+    
     /* Selectively clear state flags not covered above */
     c->flags &= ~(CLIENT_ASKING|CLIENT_READONLY|CLIENT_PUBSUB|CLIENT_REPLY_OFF|
                   CLIENT_REPLY_SKIP_NEXT|CLIENT_NO_TOUCH|CLIENT_NO_EVICT);
@@ -1662,6 +1667,8 @@ void freeClient(client *c) {
     /* Release other dynamically allocated client structure fields,
      * and finally release the client structure itself. */
     if (c->name) decrRefCount(c->name);
+    if (c->lib_name) decrRefCount(c->lib_name);
+    if (c->lib_ver) decrRefCount(c->lib_ver);
     freeClientMultiState(c);
     sdsfree(c->peerid);
     sdsfree(c->sockname);
@@ -2775,7 +2782,7 @@ sds catClientInfoString(sds s, client *client) {
     }
 
     sds ret = sdscatfmt(s,
-        "id=%U addr=%s laddr=%s %s name=%s age=%I idle=%I flags=%s db=%i sub=%i psub=%i ssub=%i multi=%i qbuf=%U qbuf-free=%U argv-mem=%U multi-mem=%U rbs=%U rbp=%U obl=%U oll=%U omem=%U tot-mem=%U events=%s cmd=%s user=%s redir=%I resp=%i",
+        "id=%U addr=%s laddr=%s %s name=%s age=%I idle=%I flags=%s db=%i sub=%i psub=%i ssub=%i multi=%i qbuf=%U qbuf-free=%U argv-mem=%U multi-mem=%U rbs=%U rbp=%U obl=%U oll=%U omem=%U tot-mem=%U events=%s cmd=%s user=%s redir=%I resp=%i lib-name=%s lib-ver=%s",
         (unsigned long long) client->id,
         getClientPeerId(client),
         getClientSockname(client),
@@ -2803,7 +2810,10 @@ sds catClientInfoString(sds s, client *client) {
         client->lastcmd ? client->lastcmd->fullname : "NULL",
         client->user ? client->user->name : "(superuser)",
         (client->flags & CLIENT_TRACKING) ? (long long) client->client_tracking_redirection : -1,
-        client->resp);
+        client->resp,
+        client->lib_name ? (char*)client->lib_name->ptr : "",
+        client->lib_ver ? (char*)client->lib_ver->ptr : ""
+        );
     return ret;
 }
 
@@ -2823,6 +2833,20 @@ sds getAllClientsInfoString(int type) {
     return o;
 }
 
+/* Check validity of an attribute that's gonna be shown in CLIENT LIST. */
+int validateClientAttr(const char *val) {
+    /* Check if the charset is ok. We need to do this otherwise
+     * CLIENT LIST format will break. You should always be able to
+     * split by space to get the different fields. */
+    while (*val) {
+        if (*val < '!' || *val > '~') { /* ASCII is assumed. */
+            return C_ERR;
+        }
+        val++;
+    }
+    return C_OK;
+}
+
 /* Returns C_OK if the name is valid. Returns C_ERR & sets `err` (when provided) otherwise. */
 int validateClientName(robj *name, const char **err) {
     const char *err_msg = "Client names cannot contain spaces, newlines or special characters.";
@@ -2830,15 +2854,9 @@ int validateClientName(robj *name, const char **err) {
     /* We allow setting the client name to an empty string. */
     if (len == 0)
         return C_OK;
-    /* Otherwise check if the charset is ok. We need to do this otherwise
-     * CLIENT LIST format will break. You should always be able to
-     * split by space to get the different fields. */
-    char *p = name->ptr;
-    for (int j = 0; j < len; j++) {
-        if (p[j] < '!' || p[j] > '~') { /* ASCII is assumed. */
-            if (err) *err = err_msg;
-            return C_ERR;
-        }
+    if (validateClientAttr(name->ptr) == C_ERR) {
+        if (err) *err = err_msg;
+        return C_ERR;
     }
     return C_OK;
 }
@@ -2880,6 +2898,35 @@ int clientSetNameOrReply(client *c, robj *name) {
     return result;
 }
 
+/* Set client or connection related info */
+void clientSetinfoCommand(client *c) {
+    sds attr = c->argv[2]->ptr;
+    robj *valob = c->argv[3];
+    sds val = valob->ptr;
+    robj **destvar = NULL;
+    if (!strcasecmp(attr,"lib-name")) {
+        destvar = &c->lib_name;
+    } else if (!strcasecmp(attr,"lib-ver")) {
+        destvar = &c->lib_ver;
+    } else {
+        addReplyStatusFormat(c,"Unrecognized option '%s'", attr);
+        return;
+    }
+
+    if (validateClientAttr(val)==C_ERR) {
+        addReplyStatusFormat(c,
+            "%s cannot contain spaces, newlines or special characters.", attr);
+        return;
+    }
+    if (*destvar) decrRefCount(*destvar);
+    if (sdslen(val)) {
+        *destvar = valob;
+        incrRefCount(valob);
+    } else
+        *destvar = NULL;
+    addReply(c,shared.ok);
+}
+
 /* Reset the client state to resemble a newly connected client.
  */
 void resetCommand(client *c) {