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/** @file
IP4 option support functions.
Copyright (c) 2005 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "Ip4Impl.h"
/**
Validate the IP4 option format for both the packets we received
and will transmit.
@param[in] Option The first byte of the option
@param[in] OptionLen The length of the whole option
@param[in] Rcvd The option is from the packet we received if TRUE,
otherwise the option we wants to transmit.
@retval TRUE The option is properly formatted
@retval FALSE The option is malformatted
**/
BOOLEAN
Ip4OptionIsValid (
IN UINT8 *Option,
IN UINT32 OptionLen,
IN BOOLEAN Rcvd
)
{
UINT32 Cur;
UINT32 Len;
UINT32 Point;
Cur = 0;
while (Cur < OptionLen) {
switch (Option[Cur]) {
case IP4_OPTION_NOP:
Cur++;
break;
case IP4_OPTION_EOP:
Cur = OptionLen;
break;
case IP4_OPTION_LSRR:
case IP4_OPTION_SSRR:
case IP4_OPTION_RR:
Len = Option[Cur + 1];
Point = Option[Cur + 2];
//
// SRR/RR options are formatted as |Type|Len|Point|Ip1|Ip2|...
//
if ((OptionLen - Cur < Len) || (Len < 3) || ((Len - 3) % 4 != 0)) {
return FALSE;
}
if ((Point > Len + 1) || (Point % 4 != 0)) {
return FALSE;
}
//
// The Point must point pass the last entry if the packet is received
// by us. It must point to 4 if the packet is to be sent by us for
// source route option.
//
if ((Option[Cur] != IP4_OPTION_RR) &&
((Rcvd && (Point != Len + 1)) || (!Rcvd && (Point != 4)))) {
return FALSE;
}
Cur += Len;
break;
default:
Len = Option[Cur + 1];
if ((OptionLen - Cur < Len) || (Len < 2)) {
return FALSE;
}
Cur = Cur + Len;
break;
}
}
return TRUE;
}
/**
Copy the option from the original option to buffer. It
handles the details such as:
1. whether copy the single IP4 option to the first/non-first
fragments.
2. Pad the options copied over to aligned to 4 bytes.
@param[in] Option The original option to copy from
@param[in] OptionLen The length of the original option
@param[in] FirstFragment Whether it is the first fragment
@param[in, out] Buf The buffer to copy options to. NULL
@param[in, out] BufLen The length of the buffer
@retval EFI_SUCCESS The options are copied over
@retval EFI_BUFFER_TOO_SMALL Buf is NULL or BufLen provided is too small.
**/
EFI_STATUS
Ip4CopyOption (
IN UINT8 *Option,
IN UINT32 OptionLen,
IN BOOLEAN FirstFragment,
IN OUT UINT8 *Buf, OPTIONAL
IN OUT UINT32 *BufLen
)
{
UINT8 OptBuf[40];
UINT32 Cur;
UINT32 Next;
UINT8 Type;
UINT32 Len;
ASSERT ((BufLen != NULL) && (OptionLen <= 40));
Cur = 0;
Next = 0;
while (Cur < OptionLen) {
Type = Option[Cur];
Len = Option[Cur + 1];
if (Type == IP4_OPTION_NOP) {
//
// Keep the padding, in case that the sender wants to align
// the option, say, to 4 bytes
//
OptBuf[Next] = IP4_OPTION_NOP;
Next++;
Cur++;
} else if (Type == IP4_OPTION_EOP) {
//
// Don't append the EOP to avoid including only a EOP option
//
break;
} else {
//
// don't copy options that is only valid for the first fragment
//
if (FirstFragment || (Type & IP4_OPTION_COPY_MASK) != 0) {
CopyMem (OptBuf + Next, Option + Cur, Len);
Next += Len;
}
Cur += Len;
}
}
//
// Don't append an EOP only option.
//
if (Next == 0) {
*BufLen = 0;
return EFI_SUCCESS;
}
//
// Append an EOP if the end of option doesn't coincide with the
// end of the IP header, that is, isn't aligned to 4 bytes..
//
if ((Next % 4) != 0) {
OptBuf[Next] = IP4_OPTION_EOP;
Next++;
}
//
// Head length is in the unit of 4 bytes. Now, Len is the
// actual option length to appear in the IP header.
//
Len = ((Next + 3) &~0x03);
//
// If the buffer is too small, set the BufLen then return
//
if ((Buf == NULL) || (*BufLen < Len)) {
*BufLen = Len;
return EFI_BUFFER_TOO_SMALL;
}
//
// Copy the option to the Buf, zero the buffer first to pad
// the options with NOP to align to 4 bytes.
//
ZeroMem (Buf, Len);
CopyMem (Buf, OptBuf, Next);
*BufLen = Len;
return EFI_SUCCESS;
}
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