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Do packet length checks iff they're necessary. 

They're not necessary for most hardware; remove the unnecessary checks,
and add comments indicating why they're not necessary (or fix the
"maximum value of actual_octets is" part of the comment).

They *are* necessary for Series III hardware; put in the check.

Change-Id: Idd64a74099d5cf7398a2ddb850442e53c9206724
Reviewed-on: https://code.wireshark.org/review/21491
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2017-05-04 00:12:07 -07:00
parent dead1b3817
commit 4ca15be3eb
1 changed files with 20 additions and 18 deletions
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38
wiretap/vwr.c
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@ -1227,7 +1227,7 @@ static gboolean vwr_read_s1_W_rec(vwr_t *vwr, struct wtap_pkthdr *phdr,
*
* We include the length of the metadata headers in the packet lengths.
*
* The maximum value of actual_octets is 65535, which, even after
* The maximum value of actual_octets is 8191, which, even after
* adding the lengths of the metadata headers, is less than
* WTAP_MAX_PACKET_SIZE will ever be, so we don't need to check it.
*/
@ -1615,20 +1615,13 @@ static gboolean vwr_read_s2_W_rec(vwr_t *vwr, struct wtap_pkthdr *phdr,
* Fill up the per-packet header.
*
* We include the length of the metadata headers in the packet lengths.
*
* The maximum value of actual_octets is 8191, which, even after
* adding the lengths of the metadata headers, is less than
* WTAP_MAX_PACKET_SIZE will ever be, so we don't need to check it.
*/
phdr->len = STATS_COMMON_FIELDS_LEN + EXT_WLAN_FIELDS_LEN + actual_octets;
phdr->caplen = STATS_COMMON_FIELDS_LEN + EXT_WLAN_FIELDS_LEN + actual_octets;
if (phdr->caplen > WTAP_MAX_PACKET_SIZE) {
/*
* Probably a corrupt capture file; return an error,
* so that our caller doesn't blow up trying to allocate
* space for an immensely-large packet.
*/
*err_info = g_strdup_printf("vwr: File has %u-byte packet, bigger than maximum of %u",
phdr->caplen, WTAP_MAX_PACKET_SIZE);
*err = WTAP_ERR_BAD_FILE;
return FALSE;
}
phdr->ts.secs = (time_t)s_sec;
phdr->ts.nsecs = (int)(s_usec * 1000);
@ -2092,6 +2085,17 @@ static gboolean vwr_read_s3_W_rec(vwr_t *vwr, struct wtap_pkthdr *phdr,
phdr->len = OCTO_TIMESTAMP_FIELDS_LEN + OCTO_LAYER1TO4_LEN + actual_octets;
phdr->caplen = OCTO_TIMESTAMP_FIELDS_LEN + OCTO_LAYER1TO4_LEN + actual_octets;
}
if (phdr->caplen > WTAP_MAX_PACKET_SIZE) {
/*
* Probably a corrupt capture file; return an error,
* so that our caller doesn't blow up trying to allocate
* space for an immensely-large packet.
*/
*err_info = g_strdup_printf("vwr: File has %u-byte packet, bigger than maximum of %u",
phdr->caplen, WTAP_MAX_PACKET_SIZE);
*err = WTAP_ERR_BAD_FILE;
return FALSE;
}
phdr->ts.secs = (time_t)s_sec;
phdr->ts.nsecs = (int)(s_usec * 1000);
@ -2478,12 +2482,6 @@ static gboolean vwr_read_rec_data_ethernet(vwr_t *vwr, struct wtap_pkthdr *phdr,
return FALSE;
}
/*
* The maximum value of actual_octets is 65535, which, even after
* adding the lengths of the metadata headers, is less than
* WTAP_MAX_PACKET_SIZE will ever be, so we don't need to check it.
*/
vc_id = pntoh16(&s_ptr[vwr->VCID_OFF]) & vwr->VCID_MASK;
flow_seq = s_ptr[vwr->FLOWSEQ_OFF];
frame_type = pntoh32(&s_ptr[vwr->FRAME_TYPE_OFF]);
@ -2596,6 +2594,10 @@ static gboolean vwr_read_rec_data_ethernet(vwr_t *vwr, struct wtap_pkthdr *phdr,
* Fill up the per-packet header.
*
* We include the length of the metadata headers in the packet lengths.
*
* The maximum value of actual_octets is 65535, which, even after
* adding the lengths of the metadata headers, is less than
* WTAP_MAX_PACKET_SIZE will ever be, so we don't need to check it.
*/
phdr->len = STATS_COMMON_FIELDS_LEN + EXT_ETHERNET_FIELDS_LEN + actual_octets;
phdr->caplen = STATS_COMMON_FIELDS_LEN + EXT_ETHERNET_FIELDS_LEN + actual_octets;