RawSocket: handle packets that are larger than a single buffer

VPWS: fix premature exit of push() method after packet discard

src/apps/socket/dev.lua

@@ -28,11 +28,17 @@ end
 
 function dev:receive()
    assert(self.fd)
+   local size = C.msg_size(self.fd)
+   assert(size ~= -1)
    local p = packet.allocate()
-   local b = buffer.allocate()
-   local s = C.receive_packet(self.fd, b)
+   local nbuffers = math.ceil(size/buffer.size)
+   assert(nbuffers <= C.PACKET_IOVEC_MAX)
+   for i = 1, nbuffers do
+      local b = buffer.allocate()
+      packet.add_iovec(p, b, 0)
+   end
+   local s = C.receive_packet(self.fd, p)
    assert(s ~= -1)
-   packet.add_iovec(p, b, s)
    return p
 end
 

src/apps/socket/io.c

@@ -1,6 +1,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/time.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
 #include <stdint.h>
 #include <strings.h>
@@ -31,23 +32,50 @@ int send_packet(int fd, struct packet *p) {
   return(0);
 }
 
-int receive_packet(int fd, struct buffer *b) {
+int receive_packet(int fd, struct packet *p) {
   struct msghdr msg;
-  struct iovec iovec;
-  ssize_t s;
+  struct iovec iovecs[p->niovecs];
+  int i;
+  ssize_t s, len;
 
   bzero(&msg, sizeof(msg));
-  iovec.iov_base = b->pointer;
-  iovec.iov_len  = b->size;
-  msg.msg_iov = &iovec;
-  msg.msg_iovlen = 1;
+  for (i=0; i<p->niovecs; i++) {
+    iovecs[i].iov_base = p->iovecs[i].buffer->pointer;
+    iovecs[i].iov_len  = p->iovecs[i].buffer->size;
+  }
+  msg.msg_iov = iovecs;
+  msg.msg_iovlen = p->niovecs;
   if ((s = recvmsg(fd, &msg, 0)) == -1) {
     perror("recvmsg");
     return(-1);
   }
+  if (msg.msg_flags && MSG_TRUNC) {
+    printf("truncated\n");
+    return(-1);
+  }
+  len = s;
+  for (i=0; i<p->niovecs; i++) {
+    ssize_t iov_len = msg.msg_iov[i].iov_len;
+    if (len > iov_len) {
+      p->iovecs[i].length = iov_len;
+      len -= iov_len;
+    } else {
+      p->iovecs[i].length = len;
+    }
+  }
+  p->length = s;
   return(s);
 }
 
+int msg_size(int fd) {
+  int size;
+  if (ioctl(fd, FIONREAD, &size) == -1) {
+    perror("get message size");
+    return(-1);
+  }
+  return(size);
+}
+
 int can_receive(int fd) {
   fd_set fds;
   struct timeval tv = { .tv_sec = 0, .tv_usec = 0 };

src/apps/socket/io.h

@@ -1,4 +1,5 @@
 int send_packet(int, struct packet *);
-int receive_packet(int, struct buffer *);
+int receive_packet(int, struct packet *);
 int can_transmit(int);
 int can_receive(int);
+int msg_size(int);

src/apps/vpn/vpws.lua

@@ -75,10 +75,10 @@ function vpws:push()
 	    else
 	       -- Packet doesn't belong to VPN, discard
 	       packet.deref(p)
-	       return
+	       p = nil
 	    end
 	 end
-	 app.transmit(l_out, p)
+	 if p then app.transmit(l_out, p) end
       end
    end
 end