rpc: Switch to dynamically allocated message buffer

Currently, we are allocating buffer for RPC messages statically.
This is not such pain when RPC limits are small. However, if we want
ever to increase those limits, we need to allocate buffer dynamically,
based on RPC message len (= the first 4 bytes). Therefore we will
decrease our mem usage in most cases and still be flexible enough in
corner cases.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/rpc/virnetmessage.c b/src/rpc/virnetmessage.c
index 17ecc90eb7..dc4c2127a8 100644
--- a/src/rpc/virnetmessage.c
+++ b/src/rpc/virnetmessage.c
@@ -61,6 +61,7 @@ void virNetMessageClear(virNetMessagePtr msg)
     for (i = 0 ; i < msg->nfds ; i++)
         VIR_FORCE_CLOSE(msg->fds[i]);
     VIR_FREE(msg->fds);
+    VIR_FREE(msg->buffer);
     memset(msg, 0, sizeof(*msg));
     msg->tracked = tracked;
 }
@@ -79,6 +80,7 @@ void virNetMessageFree(virNetMessagePtr msg)
 
     for (i = 0 ; i < msg->nfds ; i++)
         VIR_FORCE_CLOSE(msg->fds[i]);
+    VIR_FREE(msg->buffer);
     VIR_FREE(msg->fds);
     VIR_FREE(msg);
 }
@@ -144,6 +146,10 @@ int virNetMessageDecodeLength(virNetMessagePtr msg)
     /* Extend our declared buffer length and carry
        on reading the header + payload */
     msg->bufferLength += len;
+    if (VIR_REALLOC_N(msg->buffer, msg->bufferLength) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
 
     VIR_DEBUG("Got length, now need %zu total (%u more)",
               msg->bufferLength, len);
@@ -212,7 +218,11 @@ int virNetMessageEncodeHeader(virNetMessagePtr msg)
     int ret = -1;
     unsigned int len = 0;
 
-    msg->bufferLength = sizeof(msg->buffer);
+    msg->bufferLength = VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX;
+    if (VIR_ALLOC_N(msg->buffer, msg->bufferLength) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
     msg->bufferOffset = 0;
 
     /* Format the header. */