[global] restrict max packet size to 65536 bytes

and apply workaround in data buf allocation while we cleanup
the whole buffer allocation handling situation

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

libknet/handle.c

@@ -997,12 +997,9 @@ ssize_t knet_send(knet_handle_t knet_h, const char *buff, const size_t buff_len)
 	struct iovec iov_out[1];
 	int sock;
 
-	if (!knet_h) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	if ((buff == NULL) || (buff_len == 0)) {
+	if ((!knet_h) ||
+	    (buff == NULL) ||
+	    (buff_len == 0) || (buff_len > KNET_MAX_PACKET_SIZE)) {
 		errno = EINVAL;
 		return -1;
 	}

libknet/internals.h

@@ -17,7 +17,7 @@
 #include "libknet.h"
 #include "onwire.h"
 
-#define KNET_DATABUFSIZE KNET_MAX_PACKET_SIZE + KNET_HEADER_DATA_SIZE
+#define KNET_DATABUFSIZE (KNET_MAX_PACKET_SIZE * 2) + KNET_HEADER_DATA_SIZE
 #define KNET_DATABUFSIZE_CRYPT KNET_DATABUFSIZE * 2
 
 struct knet_listener {

libknet/libknet.h

@@ -34,7 +34,7 @@
  *  see knet_handle_new for details
  */
 
-#define KNET_MAX_PACKET_SIZE 131072
+#define KNET_MAX_PACKET_SIZE 65536
 
 /*
  * buffers used for pretty logging
@@ -63,8 +63,14 @@ typedef struct knet_handle *knet_handle_t;
  *            knet will read data here to send to the other hosts
  *            and will write data received from the network.
  *            Each data packet can be of max size KNET_MAX_PACKET_SIZE!
- *            Applications might be able to write more data at a time
- *            but they will be delivered in KNET_MAX_PACKET_SIZE chunks.
+ *            Applications using knet_send/knet_recv will receive
+ *            proper error in case of packet size is not within boundaries.
+ *            Applications using their own functions to write to the
+ *            datafd should NOT write more than KNET_MAX_PACKET_SIZE
+ *            or the packet will be fragmented by readv inside the
+ *            delivery thread. Be aware that while you can write
+ *            more than KNET_MAX_PACKET_SIZE, that can break any
+ *            custom delivery filters (see below) due to data offset.
  *            Please refer to ping_test.c on how to setup socketpair.
  *            datafd can be 0, and knet_handle_new will create a properly
  *            populated socket pair the same way as ping_test, or a value

libknet/ping_test.c

@@ -273,7 +273,7 @@ static void pmtud_notify(void *private_data, unsigned int link_mtu, unsigned int
 
 int main(int argc, char *argv[])
 {
-	char out_big_buff[64000], out_big_frag[66000], hello_world[16];
+	char out_big_buff[64000], out_big_frag[65536], hello_world[16];
 	char recvbuff[66000];
 	size_t len;
 	fd_set rfds;