[PATCH] fix PXE transmit failure if P_UNKNOWN is not supported

[Andrey Borzenkov <arvidjaar@gmail.com>]

Some PXE stacks do not support P_UNKNOWN in UNDI TRANSMIT; nothing is
sent at all. So strip Ethernet header for known frame types and let PXE
stack add it.

PXE implementation that fail is e.g.

64bit_foxconn with PXE-2.0 (build 082) NIC: SIS900 PXE
BootROM v1.09 Hook Int19

Reported-By: Beeblebrox <zaphod@berentweb.com>
Tested-By: Beeblebrox <zaphod@berentweb.com>

---
 grub-core/net/drivers/i386/pc/pxe.c | 46 ++++++++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/grub-core/net/drivers/i386/pc/pxe.c b/grub-core/net/drivers/i386/pc/pxe.c
index e8c0b22..3d78bdd 100644
--- a/grub-core/net/drivers/i386/pc/pxe.c
+++ b/grub-core/net/drivers/i386/pc/pxe.c
@@ -25,6 +25,7 @@
 #include <grub/env.h>
 #include <grub/i18n.h>
 #include <grub/loader.h>
+#include <grub/net/ethernet.h>
 
 #include <grub/machine/pxe.h>
 #include <grub/machine/int.h>
@@ -38,6 +39,11 @@ GRUB_MOD_LICENSE ("GPLv3+");
 #define SEGOFS(x)	((SEGMENT(x) << 16) + OFFSET(x))
 #define LINEAR(x)	(void *) ((((x) >> 16) << 4) + ((x) & 0xFFFF))
 
+#define P_UNKNOWN	0
+#define P_IP		1
+#define P_ARP		2
+#define P_RARP		3
+
 struct grub_pxe_undi_open
 {
   grub_uint16_t status;
@@ -256,22 +262,56 @@ grub_pxe_send (struct grub_net_card *dev __attribute__ ((unused)),
   struct grub_pxe_undi_transmit *trans;
   struct grub_pxe_undi_tbd *tbd;
   char *buf;
+  grub_uint8_t *dst;
+  grub_uint16_t type;
 
   trans = (void *) GRUB_MEMORY_MACHINE_SCRATCH_ADDR;
   grub_memset (trans, 0, sizeof (*trans));
+  dst = (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 128 - 6);
+  /* First 6 bytes are destination address */
+  grub_memcpy (dst, pack->data, 6);
+
+  /* Some PXE stacks do not support P_UNKNOWN. So strip Ethernet
+     header for known protocols and let PXE implementation add it */
+  grub_memcpy (&type, pack->data + 12, 2);
+  switch (type)
+    {
+    case grub_cpu_to_be16_compile_time (GRUB_NET_ETHERTYPE_IP):
+      trans->protocol = P_IP;
+      break;
+    case grub_cpu_to_be16_compile_time (GRUB_NET_ETHERTYPE_ARP):
+      trans->protocol = P_ARP;
+      break;
+    /* grub does not use RARP */
+    default:
+      trans->protocol = P_UNKNOWN;
+      break;
+    }
+  if (trans->protocol)
+    {
+      grub_err_t err;
+
+      err = grub_netbuff_pull (pack, 14);
+      if (err)
+	return err;
+      if (dst[0] == 0xff && dst[1] == 0xff && dst[2] == 0xff &&
+	  dst[3] == 0xff && dst[4] == 0xff && dst[5] == 0xff)
+	trans->xmitflag = 1;
+      else
+	trans->dest = SEGOFS ((grub_addr_t) dst);
+    }
+    
   tbd = (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 128);
   grub_memset (tbd, 0, sizeof (*tbd));
   buf = (void *) (GRUB_MEMORY_MACHINE_SCRATCH_ADDR + 256);
   grub_memcpy (buf, pack->data, pack->tail - pack->data);
-
   trans->tbd = SEGOFS ((grub_addr_t) tbd);
-  trans->protocol = 0;
   tbd->len = pack->tail - pack->data;
   tbd->buf = SEGOFS ((grub_addr_t) buf);
 
   grub_pxe_call (GRUB_PXENV_UNDI_TRANSMIT, trans, pxe_rm_entry);
   if (trans->status)
-    return grub_error (GRUB_ERR_IO, N_("couldn't send network packet"));
+    return grub_error (GRUB_ERR_IO, N_("couldn't send network packet, PXE status: 0x%04x"), trans->status);
   return 0;
 }
 
-- 
tg: (0901e78..) e/pxe-send-fix (depends on: master)