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Traditionalize ANSI-only constructs; lose if UDP checksum is bad; remove non-portable if_dl.h include; add userland packet filter (yuk); ARPHRD_ETHER - not ETHERTYPE_IP!

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This commit is contained in:
Ted Lemon
1996-05-16 07:26:52 +00:00
parent 10e99bf10e
commit 7bb11ad5af
2 changed files with 88 additions and 30 deletions
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57
common/packet.c
View File

@@ -48,7 +48,6 @@ static char copyright[] =
#include "dhcpd.h" #include "dhcpd.h"
#include <sys/ioctl.h> #include <sys/ioctl.h>
#include <net/if_dl.h>
#include <netinet/in_systm.h> #include <netinet/in_systm.h>
#include <netinet/ip.h> #include <netinet/ip.h>
#include <netinet/udp.h> #include <netinet/udp.h>
@@ -69,14 +68,14 @@ void assemble_hw_header (interface, buf, bufix, to)
struct ether_header eh; struct ether_header eh;
if (to) if (to)
memcpy (eh.ether_dhost, to -> haddr, sizeof eh.ether_dhost); memcpy (ETHER_DEST (&eh), to -> haddr, sizeof eh.ether_dhost);
else else
memset (eh.ether_dhost, 0xff, sizeof (eh.ether_shost)); memset (ETHER_DEST (&eh), 0xff, sizeof (eh.ether_shost));
if (interface -> hw_address.hlen == sizeof (eh.ether_shost)) if (interface -> hw_address.hlen == sizeof (eh.ether_shost))
memcpy (eh.ether_shost, interface -> hw_address.haddr, memcpy (ETHER_SRC (&eh), interface -> hw_address.haddr,
sizeof (eh.ether_shost)); sizeof (eh.ether_shost));
else else
memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost)); memset (ETHER_SRC (&eh), 0x00, sizeof (eh.ether_shost));
eh.ether_type = htons (ETHERTYPE_IP); eh.ether_type = htons (ETHERTYPE_IP);
memcpy (&buf [*bufix], &eh, sizeof eh); memcpy (&buf [*bufix], &eh, sizeof eh);
@@ -152,10 +151,14 @@ size_t decode_hw_header (interface, buf, bufix, from)
{ {
struct ether_header eh; struct ether_header eh;
memcpy (&eh, buf +bufix, sizeof eh); memcpy (&eh, buf + bufix, sizeof eh);
#ifdef USERLAND_FILTER
if (ntohs (eh.ether_type) != ETHERTYPE_IP)
return -1;
#endif
memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost)); memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost));
from -> htype = ETHERTYPE_IP; from -> htype = ARPHRD_ETHER;
from -> hlen = sizeof eh.ether_shost; from -> hlen = sizeof eh.ether_shost;
return sizeof eh; return sizeof eh;
@@ -175,22 +178,42 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
struct udphdr *udp; struct udphdr *udp;
u_int32_t ip_len = (buf [bufix] & 0xf) << 2; u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
u_int32_t sum, usum; u_int32_t sum, usum;
#ifdef USERLAND_FILTER
u_int32_t ibcst = INADDR_BROADCAST;
#endif
ip = (struct ip *)(buf + bufix);
udp = (struct udphdr *)(buf + bufix + ip_len);
#ifdef USERLAND_FILTER
/* Is it a UDP packet? */
if (ip -> ip_p != IPPROTO_UDP)
return -1;
/* Is it to the port we're serving? */
if (udp -> uh_dport != server_port && udp -> uh_dport != server_port + 1)
return -1;
/* Is it to this IP address? */
if (memcmp (&ip -> ip_dst, &ibcst, sizeof ibcst) &&
memcmp (&ip -> ip_dst, interface -> address.iabuf, 4))
return -1;
#endif /* USERLAND_FILTER */
/* Check the IP header checksum - it should be zero. */ /* Check the IP header checksum - it should be zero. */
if (wrapsum (checksum (buf + bufix, ip_len, 0))) { if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
note ("Bad IP checksum: %x", note ("Bad IP checksum: %x",
wrapsum (checksum (buf + bufix, sizeof ip, 0))); wrapsum (checksum (buf + bufix, sizeof *ip, 0)));
return -1;
} }
/* Copy out the IP source address... */ /* Copy out the IP source address... */
ip = (struct ip *)(buf + bufix);
memcpy (&from -> sin_addr, &ip -> ip_src, 4); memcpy (&from -> sin_addr, &ip -> ip_src, 4);
/* Compute UDP checksums, including the ``pseudo-header'', the UDP /* Compute UDP checksums, including the ``pseudo-header'', the UDP
header and the data. If the UDP checksum field is zero, we're header and the data. If the UDP checksum field is zero, we're
not supposed to do a checksum. */ not supposed to do a checksum. */
udp = (struct udphdr *)(buf + bufix + ip_len);
if (!data) { if (!data) {
data = buf + bufix + ip_len + sizeof *udp; data = buf + bufix + ip_len + sizeof *udp;
len -= ip_len + sizeof *udp; len -= ip_len + sizeof *udp;
@@ -198,6 +221,7 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
usum = udp -> uh_sum; usum = udp -> uh_sum;
udp -> uh_sum = 0; udp -> uh_sum = 0;
sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp, sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp,
checksum (data, len, checksum (data, len,
checksum ((unsigned char *) checksum ((unsigned char *)
@@ -220,13 +244,17 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
/* Compute the easy part of the checksum on a range of bytes. */ /* Compute the easy part of the checksum on a range of bytes. */
static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum) static u_int32_t checksum (buf, nbytes, sum)
unsigned char *buf;
int nbytes;
u_int32_t sum;
{ {
int i; int i;
/* Checksum all the pairs of bytes first... */ /* Checksum all the pairs of bytes first... */
for (i = 0; i < (nbytes & ~1); i += 2) for (i = 0; i < (nbytes & ~1); i += 2) {
sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++); sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++);
}
/* If there's a single byte left over, checksum it, too. Network /* If there's a single byte left over, checksum it, too. Network
byte order is big-endian, so the remaining byte is the high byte. */ byte order is big-endian, so the remaining byte is the high byte. */
@@ -240,13 +268,14 @@ static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum)
/* Fold the upper sixteen bits of the checksum down into the lower bits, /* Fold the upper sixteen bits of the checksum down into the lower bits,
complement the sum, and then put it into network byte order. */ complement the sum, and then put it into network byte order. */
static u_int32_t wrapsum (u_int32_t sum) static u_int32_t wrapsum (sum)
u_int32_t sum;
{ {
while (sum > 0x10000) { while (sum > 0x10000) {
sum = (sum >> 16) + (sum & 0xFFFF); sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16); sum += (sum >> 16);
} }
sum = ~sum; sum = sum ^ 0xFFFF;
return htons(sum); return htons(sum);
} }

57
packet.c
View File

@@ -48,7 +48,6 @@ static char copyright[] =
#include "dhcpd.h" #include "dhcpd.h"
#include <sys/ioctl.h> #include <sys/ioctl.h>
#include <net/if_dl.h>
#include <netinet/in_systm.h> #include <netinet/in_systm.h>
#include <netinet/ip.h> #include <netinet/ip.h>
#include <netinet/udp.h> #include <netinet/udp.h>
@@ -69,14 +68,14 @@ void assemble_hw_header (interface, buf, bufix, to)
struct ether_header eh; struct ether_header eh;
if (to) if (to)
memcpy (eh.ether_dhost, to -> haddr, sizeof eh.ether_dhost); memcpy (ETHER_DEST (&eh), to -> haddr, sizeof eh.ether_dhost);
else else
memset (eh.ether_dhost, 0xff, sizeof (eh.ether_shost)); memset (ETHER_DEST (&eh), 0xff, sizeof (eh.ether_shost));
if (interface -> hw_address.hlen == sizeof (eh.ether_shost)) if (interface -> hw_address.hlen == sizeof (eh.ether_shost))
memcpy (eh.ether_shost, interface -> hw_address.haddr, memcpy (ETHER_SRC (&eh), interface -> hw_address.haddr,
sizeof (eh.ether_shost)); sizeof (eh.ether_shost));
else else
memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost)); memset (ETHER_SRC (&eh), 0x00, sizeof (eh.ether_shost));
eh.ether_type = htons (ETHERTYPE_IP); eh.ether_type = htons (ETHERTYPE_IP);
memcpy (&buf [*bufix], &eh, sizeof eh); memcpy (&buf [*bufix], &eh, sizeof eh);
@@ -152,10 +151,14 @@ size_t decode_hw_header (interface, buf, bufix, from)
{ {
struct ether_header eh; struct ether_header eh;
memcpy (&eh, buf +bufix, sizeof eh); memcpy (&eh, buf + bufix, sizeof eh);
#ifdef USERLAND_FILTER
if (ntohs (eh.ether_type) != ETHERTYPE_IP)
return -1;
#endif
memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost)); memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost));
from -> htype = ETHERTYPE_IP; from -> htype = ARPHRD_ETHER;
from -> hlen = sizeof eh.ether_shost; from -> hlen = sizeof eh.ether_shost;
return sizeof eh; return sizeof eh;
@@ -175,22 +178,42 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
struct udphdr *udp; struct udphdr *udp;
u_int32_t ip_len = (buf [bufix] & 0xf) << 2; u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
u_int32_t sum, usum; u_int32_t sum, usum;
#ifdef USERLAND_FILTER
u_int32_t ibcst = INADDR_BROADCAST;
#endif
ip = (struct ip *)(buf + bufix);
udp = (struct udphdr *)(buf + bufix + ip_len);
#ifdef USERLAND_FILTER
/* Is it a UDP packet? */
if (ip -> ip_p != IPPROTO_UDP)
return -1;
/* Is it to the port we're serving? */
if (udp -> uh_dport != server_port && udp -> uh_dport != server_port + 1)
return -1;
/* Is it to this IP address? */
if (memcmp (&ip -> ip_dst, &ibcst, sizeof ibcst) &&
memcmp (&ip -> ip_dst, interface -> address.iabuf, 4))
return -1;
#endif /* USERLAND_FILTER */
/* Check the IP header checksum - it should be zero. */ /* Check the IP header checksum - it should be zero. */
if (wrapsum (checksum (buf + bufix, ip_len, 0))) { if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
note ("Bad IP checksum: %x", note ("Bad IP checksum: %x",
wrapsum (checksum (buf + bufix, sizeof ip, 0))); wrapsum (checksum (buf + bufix, sizeof *ip, 0)));
return -1;
} }
/* Copy out the IP source address... */ /* Copy out the IP source address... */
ip = (struct ip *)(buf + bufix);
memcpy (&from -> sin_addr, &ip -> ip_src, 4); memcpy (&from -> sin_addr, &ip -> ip_src, 4);
/* Compute UDP checksums, including the ``pseudo-header'', the UDP /* Compute UDP checksums, including the ``pseudo-header'', the UDP
header and the data. If the UDP checksum field is zero, we're header and the data. If the UDP checksum field is zero, we're
not supposed to do a checksum. */ not supposed to do a checksum. */
udp = (struct udphdr *)(buf + bufix + ip_len);
if (!data) { if (!data) {
data = buf + bufix + ip_len + sizeof *udp; data = buf + bufix + ip_len + sizeof *udp;
len -= ip_len + sizeof *udp; len -= ip_len + sizeof *udp;
@@ -198,6 +221,7 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
usum = udp -> uh_sum; usum = udp -> uh_sum;
udp -> uh_sum = 0; udp -> uh_sum = 0;
sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp, sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp,
checksum (data, len, checksum (data, len,
checksum ((unsigned char *) checksum ((unsigned char *)
@@ -220,13 +244,17 @@ size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
/* Compute the easy part of the checksum on a range of bytes. */ /* Compute the easy part of the checksum on a range of bytes. */
static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum) static u_int32_t checksum (buf, nbytes, sum)
unsigned char *buf;
int nbytes;
u_int32_t sum;
{ {
int i; int i;
/* Checksum all the pairs of bytes first... */ /* Checksum all the pairs of bytes first... */
for (i = 0; i < (nbytes & ~1); i += 2) for (i = 0; i < (nbytes & ~1); i += 2) {
sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++); sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++);
}
/* If there's a single byte left over, checksum it, too. Network /* If there's a single byte left over, checksum it, too. Network
byte order is big-endian, so the remaining byte is the high byte. */ byte order is big-endian, so the remaining byte is the high byte. */
@@ -240,13 +268,14 @@ static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum)
/* Fold the upper sixteen bits of the checksum down into the lower bits, /* Fold the upper sixteen bits of the checksum down into the lower bits,
complement the sum, and then put it into network byte order. */ complement the sum, and then put it into network byte order. */
static u_int32_t wrapsum (u_int32_t sum) static u_int32_t wrapsum (sum)
u_int32_t sum;
{ {
while (sum > 0x10000) { while (sum > 0x10000) {
sum = (sum >> 16) + (sum & 0xFFFF); sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16); sum += (sum >> 16);
} }
sum = ~sum; sum = sum ^ 0xFFFF;
return htons(sum); return htons(sum);
} }