Fix: lttng-ust control protocol handling of variable length command data

[lttng-ust.git] / src / lib / lttng-ust / lttng-ust-comm.c

diff --git a/src/lib/lttng-ust/lttng-ust-comm.c b/src/lib/lttng-ust/lttng-ust-comm.c
index 323ccaea915e8330392c1b1044a23115eec84ca1..5330e5c2a0c9ed2c6e63170203cc862d80199075 100644 (file)
--- a/src/lib/lttng-ust/lttng-ust-comm.c
+++ b/src/lib/lttng-ust/lttng-ust-comm.c
@@ -854,6 +854,49 @@ end:
        return ret;
 }
 
+static
+void prepare_cmd_reply(struct ustcomm_ust_reply *lur, uint32_t handle, uint32_t cmd, int ret)
+{
+       lur->handle = handle;
+       lur->cmd = cmd;
+       lur->ret_val = ret;
+       if (ret >= 0) {
+               lur->ret_code = LTTNG_UST_OK;
+       } else {
+               /*
+                * Use -LTTNG_UST_ERR as wildcard for UST internal
+                * error that are not caused by the transport, except if
+                * we already have a more precise error message to
+                * report.
+                */
+               if (ret > -LTTNG_UST_ERR) {
+                       /* Translate code to UST error. */
+                       switch (ret) {
+                       case -EEXIST:
+                               lur->ret_code = -LTTNG_UST_ERR_EXIST;
+                               break;
+                       case -EINVAL:
+                               lur->ret_code = -LTTNG_UST_ERR_INVAL;
+                               break;
+                       case -ENOENT:
+                               lur->ret_code = -LTTNG_UST_ERR_NOENT;
+                               break;
+                       case -EPERM:
+                               lur->ret_code = -LTTNG_UST_ERR_PERM;
+                               break;
+                       case -ENOSYS:
+                               lur->ret_code = -LTTNG_UST_ERR_NOSYS;
+                               break;
+                       default:
+                               lur->ret_code = -LTTNG_UST_ERR;
+                               break;
+                       }
+               } else {
+                       lur->ret_code = ret;
+               }
+       }
+}
+
 static
 int handle_message(struct sock_info *sock_info,
                int sock, struct ustcomm_ust_msg *lum)
@@ -878,6 +921,52 @@ int handle_message(struct sock_info *sock_info,
                goto error;
        }
 
+       switch (lum->cmd) {
+       case LTTNG_UST_ABI_FILTER:
+       case LTTNG_UST_ABI_EXCLUSION:
+       case LTTNG_UST_ABI_CHANNEL:
+       case LTTNG_UST_ABI_STREAM:
+       case LTTNG_UST_ABI_CONTEXT:
+               /*
+                * Those commands send additional payload after struct
+                * ustcomm_ust_msg, which makes it pretty much impossible to
+                * deal with "unknown command" errors without leaving the
+                * communication pipe in a out-of-sync state. This is part of
+                * the ABI between liblttng-ust-ctl and liblttng-ust, and
+                * should be fixed on the next breaking
+                * LTTNG_UST_ABI_MAJOR_VERSION protocol bump by indicating the
+                * total command message length as part of a message header so
+                * that the protocol can recover from invalid command errors.
+                */
+               break;
+
+       case LTTNG_UST_ABI_CAPTURE:
+       case LTTNG_UST_ABI_COUNTER:
+       case LTTNG_UST_ABI_COUNTER_GLOBAL:
+       case LTTNG_UST_ABI_COUNTER_CPU:
+       case LTTNG_UST_ABI_EVENT_NOTIFIER_CREATE:
+       case LTTNG_UST_ABI_EVENT_NOTIFIER_GROUP_CREATE:
+               /*
+                * Those commands expect a reply to the struct ustcomm_ust_msg
+                * before sending additional payload.
+                */
+               prepare_cmd_reply(&lur, lum->handle, lum->cmd, 0);
+
+               ret = send_reply(sock, &lur);
+               if (ret < 0) {
+                       DBG("error sending reply");
+                       goto error;
+               }
+               break;
+
+       default:
+               /*
+                * Other commands either don't send additional payload, or are
+                * unknown.
+                */
+               break;
+       }
+
        switch (lum->cmd) {
        case LTTNG_UST_ABI_REGISTER_DONE:
                if (lum->handle == LTTNG_UST_ABI_ROOT_HANDLE)
@@ -1295,44 +1384,8 @@ int handle_message(struct sock_info *sock_info,
                break;
        }
 
-       lur.handle = lum->handle;
-       lur.cmd = lum->cmd;
-       lur.ret_val = ret;
-       if (ret >= 0) {
-               lur.ret_code = LTTNG_UST_OK;
-       } else {
-               /*
-                * Use -LTTNG_UST_ERR as wildcard for UST internal
-                * error that are not caused by the transport, except if
-                * we already have a more precise error message to
-                * report.
-                */
-               if (ret > -LTTNG_UST_ERR) {
-                       /* Translate code to UST error. */
-                       switch (ret) {
-                       case -EEXIST:
-                               lur.ret_code = -LTTNG_UST_ERR_EXIST;
-                               break;
-                       case -EINVAL:
-                               lur.ret_code = -LTTNG_UST_ERR_INVAL;
-                               break;
-                       case -ENOENT:
-                               lur.ret_code = -LTTNG_UST_ERR_NOENT;
-                               break;
-                       case -EPERM:
-                               lur.ret_code = -LTTNG_UST_ERR_PERM;
-                               break;
-                       case -ENOSYS:
-                               lur.ret_code = -LTTNG_UST_ERR_NOSYS;
-                               break;
-                       default:
-                               lur.ret_code = -LTTNG_UST_ERR;
-                               break;
-                       }
-               } else {
-                       lur.ret_code = ret;
-               }
-       }
+       prepare_cmd_reply(&lur, lum->handle, lum->cmd, ret);
+
        if (ret >= 0) {
                switch (lum->cmd) {
                case LTTNG_UST_ABI_TRACER_VERSION: