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Get rid of the stuff to use bitfields to dissect IP and TCP headers - 

bitfields are a pain to use when dealing with structures with a fixed
layout in memory (you have to worry about bit order, for example).

Don't assume that the Ethernet header is aligned on a 2-byte boundary -
use "pntohs()" to extract stuff from it.  (Perhaps C will force it onto
a 2-byte boundary, but why take chances, and why leave the code
vulnerable to changes outside this module?)

Don't assume that the pointers to the IP and TCP headers are nicely
aligned - use "memcpy()", not structure assignment, to copy the headers.
(They're probably *not* nicely aligned on platforms that require 4-byte
alignment of 4-byte integral quantities; the code was dumping core on
SPARC with an alignment error.)

Don't even make those pointers be pointers to structures, as that may
cause the C compiler to generate in-line 4-byte loads and stores for
"memcpy()" (in fact, it *did* do so with GCC 2.95.1 on SPARC), which has
the same problem as structure assignment.

Don't test the IP protocol number twice when handling PPP.

svn path=/trunk/; revision=4378
This commit is contained in:
Guy Harris 2001-12-10 21:19:13 +00:00
parent 156abcce61
commit 3e55e6702f
1 changed files with 12 additions and 62 deletions
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74
gtk/tcp_graph.c
View File

@ -3,7 +3,7 @@
* By Pavel Mores <pvl@uh.cz>
* Win32 port: rwh@unifiedtech.com
*
* $Id: tcp_graph.c,v 1.4 2001/12/10 20:34:52 gram Exp $
* $Id: tcp_graph.c,v 1.5 2001/12/10 21:19:13 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
@ -66,16 +66,9 @@ struct ppp_header {
#define PPPTYPE_IP 0x21
#undef BITFIELDS
/* from <netinet/ip.h> */
struct iphdr {
#ifdef BITFIELDS
unsigned int ihl:4;
unsigned int version:4;
#else /* ! BITFIELDS */
guint8 version_ihl;
#endif /* BITFIELDS */
guint8 tos;
guint16 tot_len;
guint16 id;
@ -87,31 +80,16 @@ struct iphdr {
guint32 daddr;
};
#ifndef BITFIELDS
#define IPHDR_IHL_SHIFT 0
#define IPHDR_IHL_MASK (0xf << IPHDR_IHL_SHIFT)
#define IHL(iphdrptr) ( ((iphdrptr)->version_ihl & IPHDR_IHL_MASK) >> IPHDR_IHL_SHIFT )
#endif /* BITFIELDS */
/* from <netinet/tcp.h> */
struct tcphdr {
guint16 source;
guint16 dest;
guint32 seq;
guint32 ack_seq;
#ifdef BITFIELDS
guint16 res1:4;
guint16 doff:4;
guint16 fin:1;
guint16 syn:1;
guint16 rst:1;
guint16 psh:1;
guint16 ack:1;
guint16 urg:1;
guint16 res2:2;
#else /* ! BITFIELDS */
guint16 flags;
#define TH_FIN 0x01
#define TH_SYN 0x02
@ -119,23 +97,17 @@ struct tcphdr {
#define TH_PUSH 0x08
#define TH_ACK 0x10
#define TH_URG 0x20
#endif /* BITFIELDS */
guint16 window;
guint16 check;
guint16 urg_ptr;
};
#ifndef BITFIELDS
#define TCP_SYN(tcphdr) ( ntohs ((tcphdr).flags) & TH_SYN )
#define TCP_ACK(tcphdr) ( ntohs ((tcphdr).flags) & TH_ACK )
#define TCP_DOFF_SHIFT 12
#define TCP_DOFF_MASK (0xf << TCP_DOFF_SHIFT)
#define DOFF(tcphdr) ( ( ntohs ((tcphdr).flags) & TCP_DOFF_MASK) >> TCP_DOFF_SHIFT )
#endif /* BITFIELDS */
#define TXT_WIDTH 850
#define TXT_HEIGHT 550
@ -679,13 +651,8 @@ static void display_text (struct graph *g)
snprintf ((char *)line, 256, "%10d%15.6f%15.6f%15.6f%15u%15d%15d%10u\n",
ptr->num, time, time-first_time, time-prev_time,
seq, seq_delta_isn, seq_delta_prev,
#ifdef BITFIELDS
ntohs (ptr->iphdr.tot_len) - 4*ptr->iphdr.ihl -
4*ptr->tcphdr.doff);
#else
ntohs (ptr->iphdr.tot_len) - 4*IHL(&(ptr->iphdr)) -
4*DOFF(ptr->tcphdr));
#endif /* BITFIELDS */
gtk_text_insert (GTK_TEXT (g->text), g->font, c, NULL,
(const char * )line, -1);
prev_time = time;
@ -1788,11 +1755,7 @@ static void graph_segment_list_get (struct graph *g)
segment->abs_secs = ptr->abs_secs;
segment->abs_usecs = ptr->abs_usecs;
segment->data = ntohs (segment->iphdr.tot_len) -
#ifdef BITFIELDS
4*segment->iphdr.ihl - 4*segment->tcphdr.doff;
#else
4*IHL(&(segment->iphdr)) - 4*DOFF(segment->tcphdr);
#endif /* BITFIELDS */
if (g->segments) {
last->next = segment;
} else {
@ -1810,34 +1773,29 @@ static int get_headers (char *pd, struct segment *hdrs)
{
struct ether_header *e;
struct ppp_header *p;
struct iphdr *ip;
struct tcphdr *tcp;
void *ip;
void *tcp;
e = (struct ether_header * )pd;
p = (struct ppp_header * )pd;
if (ntohs (e->ether_type) == ETHERTYPE_IP) {
ip = (struct iphdr * )((struct ether_header * )pd + 1);
if (pntohs (&e->ether_type) == ETHERTYPE_IP) {
ip = e + 1;
} else if (((struct iphdr *)e)->protocol == IPPROTO_TCP) {
ip = (struct iphdr *)e;
} else if ( (p->ppp_type == PPPTYPE_IP) && /* IP Protocol over PPP */
(((struct iphdr *)(p+1))->protocol == IPPROTO_TCP) ) { /* TCP Protocol over IP */
ip = (struct iphdr *)(p+1);
ip = e;
} else if (p->ppp_type == PPPTYPE_IP) {
ip = p + 1;
} else {
/* printf ("not IP over Ethernet II or PPP\n"); */
return FALSE;
}
if (ip->protocol != IPPROTO_TCP) {
if (((struct iphdr *)ip)->protocol != IPPROTO_TCP) {
/* printf ("transport protocol not TCP: %#1x\n", ip->protocol); */
return FALSE;
}
#ifdef BITFIELDS
tcp = (struct tcphdr * )((char * )ip + 4*ip->ihl);
#else
tcp = (struct tcphdr * )((char * )ip + 4*IHL(ip));
#endif
tcp = (struct tcphdr * )(ip + 4*IHL((struct iphdr *)ip));
hdrs->iphdr = *ip;
hdrs->tcphdr = *tcp;
memcpy(&hdrs->iphdr, ip, sizeof (struct iphdr));
memcpy(&hdrs->tcphdr, tcp, sizeof (struct tcphdr));
return TRUE;
}
@ -3334,11 +3292,7 @@ static void tseq_tcptrace_make_elmtlist (struct graph *g)
double y1, y2;
seqno = ntohl (tmp->tcphdr.seq);
#ifdef BITFIELDS
if (tmp->tcphdr.syn)
#else
if (TCP_SYN (tmp->tcphdr))
#endif /* BITFIELDS */
data = 1;
else
data = tmp->data;
@ -3368,11 +3322,7 @@ static void tseq_tcptrace_make_elmtlist (struct graph *g)
e1++;
} else {
double ackno, win;
#ifdef BITFIELDS
if (tmp->tcphdr.syn && !tmp->tcphdr.ack)
#else
if (TCP_SYN (tmp->tcphdr) && ! TCP_ACK (tmp->tcphdr))
#endif
/* SYN's have ACK==0 and are useless here */
continue;
/* backward direction -> we need ackno and window */