+/* packet.c
-static void IpChecksum(struct ip *ip);
-static void UdpChecksum(struct ip *ip);
-static u_int32_t Checksum(u_int16_t *buf, int nwords);
-
-struct raw_packet
-{
- u_int16_t space;
- struct ether_header en_hdr;
- struct ip ip;
- struct udphdr udp;
- struct dhcp_packet dhcp;
-};
-
-int sendpkt (in_packet, raw, len, to, tolen)
- struct packet *in_packet;
- struct dhcp_packet *raw;
- size_t len;
- struct sockaddr *to;
- int tolen;
-{
- int i, k;
- struct iaddr dest;
- struct subnet *subnet;
- struct raw_packet out_packet;
- struct raw_packet *const pkt = &out_packet;
-
-/* Find local subnet, or else forward to gateway */
-
- dest.len = 4;
- memcpy(&dest.iabuf, &((struct sockaddr_in *) to)->sin_addr, dest.len);
- if ((subnet = find_subnet(dest)) == NULL)
- return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
-
-/* Find interface corresponding to subnet */
-
- for (i = 0; i < num_ifaces; i++)
- {
- for (k = 0; k < subnet->net.len
- && (dest.iabuf[k] & subnet->netmask.iabuf[k])
- == (subnet->net.iabuf[k] & subnet->netmask.iabuf[k]);
- k++);
- if (k == subnet->net.len)
- break;
- }
- if (i == num_ifaces)
- return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
-
-/* EtherNet header */
-
- memset(pkt->en_hdr.ether_dhost, 0xff, sizeof(pkt->en_hdr.ether_dhost));
- memset(pkt->en_hdr.ether_shost, 0x00, sizeof(pkt->en_hdr.ether_shost));
- pkt->en_hdr.ether_type = ETHERTYPE_IP;
-
-/* IP header (except for checksum) */
-
- pkt->ip.ip_v = 4;
- pkt->ip.ip_hl = 5;
- pkt->ip.ip_tos = IPTOS_LOWDELAY;
- pkt->ip.ip_len = htons(sizeof(pkt->ip) + sizeof(pkt->udp) + len);
- pkt->ip.ip_id = 0;
- pkt->ip.ip_off = 0;
- pkt->ip.ip_ttl = 16;
- pkt->ip.ip_p = IPPROTO_UDP;
- pkt->ip.ip_sum = 0;
- pkt->ip.ip_src = if_list[i].address;
- inet_aton("255.255.255.255", &pkt->ip.ip_dst);
-
-/* UDP header */
-
- pkt->udp.uh_sport = htons(67); /* XXX! */
- pkt->udp.uh_dport = in_packet->client_port;
- pkt->udp.uh_ulen = htons(sizeof(pkt->udp) + len);
- pkt->udp.uh_sum = 0;
-
-/* DHCP packet */
-
- pkt->dhcp = *raw;
-
-/* Compute checksums */
-
- UdpChecksum(&pkt->ip);
- IpChecksum(&pkt->ip);
-
-/* Fire it off */
-
- if (write(if_list[i].bpf, &pkt->en_hdr,
- ntohs(pkt->ip.ip_len) + sizeof(pkt->en_hdr)) < 0)
- warn ("Can't deliver packet: write: %m");
- return(0);
-}
+ Packet assembly code, originally contributed by Archie Cobbs. */
/*
- * UdpChecksum()
+ * Copyright (c) 1995, 1996 The Internet Software Consortium.
+ * All rights reserved.
*
- * Recompute a UDP checksum on a packet
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
*
- * UDP pseudo-header (prot = IPPROTO_UDP = 17):
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of The Internet Software Consortium nor the names
+ * of its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
*
- * | source IP address |
- * | dest. IP address |
- * | zero | prot | UDP leng |
+ * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
+ * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
*
+ * This software has been written for the Internet Software Consortium
+ * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
+ * Enterprises. To learn more about the Internet Software Consortium,
+ * see ``http://www.vix.com/isc''. To learn more about Vixie
+ * Enterprises, see ``http://www.vix.com''.
*/
-static void
-UdpChecksum(struct ip *ip)
-{
- struct udphdr *udp = (struct udphdr *) ((long *) ip + ip->ip_hl);
- u_int32_t sum;
+#ifndef lint
+static char copyright[] =
+"@(#) Copyright (c) 1996 The Internet Software Consortium. All rights reserved.\n";
+#endif /* not lint */
+
+#include "dhcpd.h"
+#include <sys/ioctl.h>
+
+#include <net/if_dl.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <netinet/if_ether.h>
-/* Pad with zero */
+static u_int32_t checksum PROTO ((unsigned char *, int, u_int32_t));
+static u_int32_t wrapsum PROTO ((u_int32_t));
- if (ntohs(udp->uh_ulen) & 0x1)
- *((u_char *) udp + ntohs(udp->uh_ulen)) = 0;
+/* Assemble an hardware header... */
+/* XXX currently only supports ethernet; doesn't check for other types. */
-/* Do pseudo-header first */
+void assemble_hw_header (interface, buf, bufix, to)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int *bufix;
+ struct hardware *to;
+{
+ struct ether_header eh;
+
+ if (to)
+ memcpy (eh.ether_dhost, to -> haddr, sizeof eh.ether_dhost);
+ else
+ memset (eh.ether_dhost, 0xff, sizeof (eh.ether_shost));
+ if (interface -> hw_address.hlen == sizeof (eh.ether_shost))
+ memcpy (eh.ether_shost, interface -> hw_address.haddr,
+ sizeof (eh.ether_shost));
+ else
+ memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost));
+ eh.ether_type = htons (ETHERTYPE_IP);
+
+ memcpy (&buf [*bufix], &eh, sizeof eh);
+ *bufix += sizeof eh;
+}
+
+/* UDP header and IP header assembled together for convenience. */
- sum = Checksum((u_int16_t *) &ip->ip_src, 4);
- sum += (u_int16_t) IPPROTO_UDP;
- sum += (u_int16_t) ntohs(udp->uh_ulen);
+void assemble_udp_ip_header (interface, buf, bufix, addr, port, data, len)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int *bufix;
+ u_int32_t addr;
+ u_int16_t port;
+ unsigned char *data;
+ int len;
+{
+ struct ip ip;
+ struct udphdr udp;
+
+ /* Fill out the IP header */
+ ip.ip_v = 4;
+ ip.ip_hl = 5;
+ ip.ip_tos = IPTOS_LOWDELAY;
+ ip.ip_len = htons(sizeof(ip) + sizeof(udp) + len);
+ ip.ip_id = 0;
+ ip.ip_off = 0;
+ ip.ip_ttl = 16;
+ ip.ip_p = IPPROTO_UDP;
+ ip.ip_sum = 0;
+ memcpy (&ip.ip_src, interface -> address.iabuf, 4);
+ ip.ip_dst.s_addr = addr;
+
+ /* Checksum the IP header... */
+ ip.ip_sum = wrapsum (checksum ((unsigned char *)&ip, sizeof ip, 0));
+
+ /* Copy the ip header into the buffer... */
+ memcpy (&buf [*bufix], &ip, sizeof ip);
+ *bufix += sizeof ip;
+
+ /* Fill out the UDP header */
+ udp.uh_sport = htons (67); /* XXX */
+ udp.uh_dport = port; /* XXX */
+ udp.uh_ulen = htons(sizeof(udp) + len);
+ memset (&udp.uh_sum, 0, sizeof udp.uh_sum);
+
+ /* Compute UDP checksums, including the ``pseudo-header'', the UDP
+ header and the data. */
+
+ udp.uh_sum =
+ wrapsum (checksum ((unsigned char *)&udp, sizeof udp,
+ checksum (data, len,
+ checksum ((unsigned char *)
+ &ip.ip_src,
+ sizeof ip.ip_src,
+ IPPROTO_UDP +
+ (u_int32_t)
+ ntohs (udp.uh_ulen)))));
+
+ /* Copy the udp header into the buffer... */
+ memcpy (&buf [*bufix], &udp, sizeof udp);
+ *bufix += sizeof udp;
+}
-/* Now do UDP packet itself */
+/* Decode a hardware header... */
+/* XXX currently only supports ethernet; doesn't check for other types. */
- udp->uh_sum = 0;
- sum += Checksum((u_int16_t *) udp,
- ((u_int16_t) ntohs(udp->uh_ulen) + 1) >> 1);
+size_t decode_hw_header (interface, buf, bufix, from)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int bufix;
+ struct hardware *from;
+{
+ struct ether_header eh;
-/* Flip it & stick it */
+ memcpy (&eh, buf +bufix, sizeof eh);
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- sum = ~sum;
+ memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost));
+ from -> htype = ETHERTYPE_IP;
+ from -> hlen = sizeof eh.ether_shost;
- udp->uh_sum = htons(sum);
+ return sizeof eh;
}
-/*
- * IpChecksum()
- *
- * Recompute an IP header checksum
- *
- */
+/* UDP header and IP header decoded together for convenience. */
-static void
-IpChecksum(struct ip *ip)
+size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int bufix;
+ struct sockaddr_in *from;
+ unsigned char *data;
+ int len;
{
- u_int32_t sum;
+ struct ip *ip;
+ struct udphdr *udp;
+ u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
+ u_int32_t sum, usum;
+
+ /* Check the IP header checksum - it should be zero. */
+ if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
+ note ("Bad IP checksum: %x",
+ wrapsum (checksum (buf + bufix, sizeof ip, 0)));
+ }
-/* Sum up IP header words */
+ /* Copy out the IP source address... */
+ ip = (struct ip *)(buf + bufix);
+ memcpy (&from -> sin_addr, &ip -> ip_src, 4);
- ip->ip_sum = 0;
- sum = Checksum((u_int16_t *) ip, ip->ip_hl * 2);
+ /* Compute UDP checksums, including the ``pseudo-header'', the UDP
+ header and the data. If the UDP checksum field is zero, we're
+ not supposed to do a checksum. */
-/* Flip it & stick it */
+ udp = (struct udphdr *)(buf + bufix + ip_len);
+ if (!data) {
+ data = buf + bufix + ip_len + sizeof *udp;
+ len -= ip_len + sizeof *udp;
+ }
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- sum = ~sum;
+ usum = udp -> uh_sum;
+ udp -> uh_sum = 0;
+ sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp,
+ checksum (data, len,
+ checksum ((unsigned char *)
+ &ip -> ip_src,
+ sizeof ip -> ip_src,
+ IPPROTO_UDP +
+ (u_int32_t)
+ ntohs (udp -> uh_ulen)))));
+
+ if (usum && usum != sum) {
+ note ("Bad udp checksum: %x %x", usum, sum);
+ return -1;
+ }
- ip->ip_sum = htons(sum);
+ /* Copy out the port... */
+ memcpy (&from -> sin_port, &udp -> uh_sport, sizeof udp -> uh_sport);
+
+ return ip_len + sizeof *udp;
}
-/*
- * Checksum()
- *
- * Do the one's complement sum thing over a range of words
- * Ideally, this should get replaced by an assembly version.
- */
+/* Compute the easy part of the checksum on a range of bytes. */
-static u_int32_t
-Checksum(u_int16_t *buf, int nwords)
+static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum)
{
- u_int32_t sum = 0;
+ int i;
+
+ /* Checksum all the pairs of bytes first... */
+ for (i = 0; i < (nbytes & ~1); i += 2)
+ sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++);
+
+ /* 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. */
+ if (i < nbytes) {
+ sum += (*buf) << 8;
+ }
+
+ return sum;
+}
- while (nwords--)
- sum += (u_int16_t) ntohs(*buf++);
- return(sum);
+/* Fold the upper sixteen bits of the checksum down into the lower bits,
+ complement the sum, and then put it into network byte order. */
+
+static u_int32_t wrapsum (u_int32_t sum)
+{
+ while (sum > 0x10000) {
+ sum = (sum >> 16) + (sum & 0xFFFF);
+ sum += (sum >> 16);
+ }
+ sum = ~sum;
+
+ return htons(sum);
}
+/* packet.c
-static void IpChecksum(struct ip *ip);
-static void UdpChecksum(struct ip *ip);
-static u_int32_t Checksum(u_int16_t *buf, int nwords);
-
-struct raw_packet
-{
- u_int16_t space;
- struct ether_header en_hdr;
- struct ip ip;
- struct udphdr udp;
- struct dhcp_packet dhcp;
-};
-
-int sendpkt (in_packet, raw, len, to, tolen)
- struct packet *in_packet;
- struct dhcp_packet *raw;
- size_t len;
- struct sockaddr *to;
- int tolen;
-{
- int i, k;
- struct iaddr dest;
- struct subnet *subnet;
- struct raw_packet out_packet;
- struct raw_packet *const pkt = &out_packet;
-
-/* Find local subnet, or else forward to gateway */
-
- dest.len = 4;
- memcpy(&dest.iabuf, &((struct sockaddr_in *) to)->sin_addr, dest.len);
- if ((subnet = find_subnet(dest)) == NULL)
- return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
-
-/* Find interface corresponding to subnet */
-
- for (i = 0; i < num_ifaces; i++)
- {
- for (k = 0; k < subnet->net.len
- && (dest.iabuf[k] & subnet->netmask.iabuf[k])
- == (subnet->net.iabuf[k] & subnet->netmask.iabuf[k]);
- k++);
- if (k == subnet->net.len)
- break;
- }
- if (i == num_ifaces)
- return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
-
-/* EtherNet header */
-
- memset(pkt->en_hdr.ether_dhost, 0xff, sizeof(pkt->en_hdr.ether_dhost));
- memset(pkt->en_hdr.ether_shost, 0x00, sizeof(pkt->en_hdr.ether_shost));
- pkt->en_hdr.ether_type = ETHERTYPE_IP;
-
-/* IP header (except for checksum) */
-
- pkt->ip.ip_v = 4;
- pkt->ip.ip_hl = 5;
- pkt->ip.ip_tos = IPTOS_LOWDELAY;
- pkt->ip.ip_len = htons(sizeof(pkt->ip) + sizeof(pkt->udp) + len);
- pkt->ip.ip_id = 0;
- pkt->ip.ip_off = 0;
- pkt->ip.ip_ttl = 16;
- pkt->ip.ip_p = IPPROTO_UDP;
- pkt->ip.ip_sum = 0;
- pkt->ip.ip_src = if_list[i].address;
- inet_aton("255.255.255.255", &pkt->ip.ip_dst);
-
-/* UDP header */
-
- pkt->udp.uh_sport = htons(67); /* XXX! */
- pkt->udp.uh_dport = in_packet->client_port;
- pkt->udp.uh_ulen = htons(sizeof(pkt->udp) + len);
- pkt->udp.uh_sum = 0;
-
-/* DHCP packet */
-
- pkt->dhcp = *raw;
-
-/* Compute checksums */
-
- UdpChecksum(&pkt->ip);
- IpChecksum(&pkt->ip);
-
-/* Fire it off */
-
- if (write(if_list[i].bpf, &pkt->en_hdr,
- ntohs(pkt->ip.ip_len) + sizeof(pkt->en_hdr)) < 0)
- warn ("Can't deliver packet: write: %m");
- return(0);
-}
+ Packet assembly code, originally contributed by Archie Cobbs. */
/*
- * UdpChecksum()
+ * Copyright (c) 1995, 1996 The Internet Software Consortium.
+ * All rights reserved.
*
- * Recompute a UDP checksum on a packet
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
*
- * UDP pseudo-header (prot = IPPROTO_UDP = 17):
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of The Internet Software Consortium nor the names
+ * of its contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
*
- * | source IP address |
- * | dest. IP address |
- * | zero | prot | UDP leng |
+ * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
+ * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
*
+ * This software has been written for the Internet Software Consortium
+ * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
+ * Enterprises. To learn more about the Internet Software Consortium,
+ * see ``http://www.vix.com/isc''. To learn more about Vixie
+ * Enterprises, see ``http://www.vix.com''.
*/
-static void
-UdpChecksum(struct ip *ip)
-{
- struct udphdr *udp = (struct udphdr *) ((long *) ip + ip->ip_hl);
- u_int32_t sum;
+#ifndef lint
+static char copyright[] =
+"@(#) Copyright (c) 1996 The Internet Software Consortium. All rights reserved.\n";
+#endif /* not lint */
+
+#include "dhcpd.h"
+#include <sys/ioctl.h>
+
+#include <net/if_dl.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <netinet/if_ether.h>
-/* Pad with zero */
+static u_int32_t checksum PROTO ((unsigned char *, int, u_int32_t));
+static u_int32_t wrapsum PROTO ((u_int32_t));
- if (ntohs(udp->uh_ulen) & 0x1)
- *((u_char *) udp + ntohs(udp->uh_ulen)) = 0;
+/* Assemble an hardware header... */
+/* XXX currently only supports ethernet; doesn't check for other types. */
-/* Do pseudo-header first */
+void assemble_hw_header (interface, buf, bufix, to)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int *bufix;
+ struct hardware *to;
+{
+ struct ether_header eh;
+
+ if (to)
+ memcpy (eh.ether_dhost, to -> haddr, sizeof eh.ether_dhost);
+ else
+ memset (eh.ether_dhost, 0xff, sizeof (eh.ether_shost));
+ if (interface -> hw_address.hlen == sizeof (eh.ether_shost))
+ memcpy (eh.ether_shost, interface -> hw_address.haddr,
+ sizeof (eh.ether_shost));
+ else
+ memset (eh.ether_shost, 0x00, sizeof (eh.ether_shost));
+ eh.ether_type = htons (ETHERTYPE_IP);
+
+ memcpy (&buf [*bufix], &eh, sizeof eh);
+ *bufix += sizeof eh;
+}
+
+/* UDP header and IP header assembled together for convenience. */
- sum = Checksum((u_int16_t *) &ip->ip_src, 4);
- sum += (u_int16_t) IPPROTO_UDP;
- sum += (u_int16_t) ntohs(udp->uh_ulen);
+void assemble_udp_ip_header (interface, buf, bufix, addr, port, data, len)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int *bufix;
+ u_int32_t addr;
+ u_int16_t port;
+ unsigned char *data;
+ int len;
+{
+ struct ip ip;
+ struct udphdr udp;
+
+ /* Fill out the IP header */
+ ip.ip_v = 4;
+ ip.ip_hl = 5;
+ ip.ip_tos = IPTOS_LOWDELAY;
+ ip.ip_len = htons(sizeof(ip) + sizeof(udp) + len);
+ ip.ip_id = 0;
+ ip.ip_off = 0;
+ ip.ip_ttl = 16;
+ ip.ip_p = IPPROTO_UDP;
+ ip.ip_sum = 0;
+ memcpy (&ip.ip_src, interface -> address.iabuf, 4);
+ ip.ip_dst.s_addr = addr;
+
+ /* Checksum the IP header... */
+ ip.ip_sum = wrapsum (checksum ((unsigned char *)&ip, sizeof ip, 0));
+
+ /* Copy the ip header into the buffer... */
+ memcpy (&buf [*bufix], &ip, sizeof ip);
+ *bufix += sizeof ip;
+
+ /* Fill out the UDP header */
+ udp.uh_sport = htons (67); /* XXX */
+ udp.uh_dport = port; /* XXX */
+ udp.uh_ulen = htons(sizeof(udp) + len);
+ memset (&udp.uh_sum, 0, sizeof udp.uh_sum);
+
+ /* Compute UDP checksums, including the ``pseudo-header'', the UDP
+ header and the data. */
+
+ udp.uh_sum =
+ wrapsum (checksum ((unsigned char *)&udp, sizeof udp,
+ checksum (data, len,
+ checksum ((unsigned char *)
+ &ip.ip_src,
+ sizeof ip.ip_src,
+ IPPROTO_UDP +
+ (u_int32_t)
+ ntohs (udp.uh_ulen)))));
+
+ /* Copy the udp header into the buffer... */
+ memcpy (&buf [*bufix], &udp, sizeof udp);
+ *bufix += sizeof udp;
+}
-/* Now do UDP packet itself */
+/* Decode a hardware header... */
+/* XXX currently only supports ethernet; doesn't check for other types. */
- udp->uh_sum = 0;
- sum += Checksum((u_int16_t *) udp,
- ((u_int16_t) ntohs(udp->uh_ulen) + 1) >> 1);
+size_t decode_hw_header (interface, buf, bufix, from)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int bufix;
+ struct hardware *from;
+{
+ struct ether_header eh;
-/* Flip it & stick it */
+ memcpy (&eh, buf +bufix, sizeof eh);
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- sum = ~sum;
+ memcpy (from -> haddr, eh.ether_shost, sizeof (eh.ether_shost));
+ from -> htype = ETHERTYPE_IP;
+ from -> hlen = sizeof eh.ether_shost;
- udp->uh_sum = htons(sum);
+ return sizeof eh;
}
-/*
- * IpChecksum()
- *
- * Recompute an IP header checksum
- *
- */
+/* UDP header and IP header decoded together for convenience. */
-static void
-IpChecksum(struct ip *ip)
+size_t decode_udp_ip_header (interface, buf, bufix, from, data, len)
+ struct interface_info *interface;
+ unsigned char *buf;
+ int bufix;
+ struct sockaddr_in *from;
+ unsigned char *data;
+ int len;
{
- u_int32_t sum;
+ struct ip *ip;
+ struct udphdr *udp;
+ u_int32_t ip_len = (buf [bufix] & 0xf) << 2;
+ u_int32_t sum, usum;
+
+ /* Check the IP header checksum - it should be zero. */
+ if (wrapsum (checksum (buf + bufix, ip_len, 0))) {
+ note ("Bad IP checksum: %x",
+ wrapsum (checksum (buf + bufix, sizeof ip, 0)));
+ }
-/* Sum up IP header words */
+ /* Copy out the IP source address... */
+ ip = (struct ip *)(buf + bufix);
+ memcpy (&from -> sin_addr, &ip -> ip_src, 4);
- ip->ip_sum = 0;
- sum = Checksum((u_int16_t *) ip, ip->ip_hl * 2);
+ /* Compute UDP checksums, including the ``pseudo-header'', the UDP
+ header and the data. If the UDP checksum field is zero, we're
+ not supposed to do a checksum. */
-/* Flip it & stick it */
+ udp = (struct udphdr *)(buf + bufix + ip_len);
+ if (!data) {
+ data = buf + bufix + ip_len + sizeof *udp;
+ len -= ip_len + sizeof *udp;
+ }
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- sum = ~sum;
+ usum = udp -> uh_sum;
+ udp -> uh_sum = 0;
+ sum = wrapsum (checksum ((unsigned char *)udp, sizeof *udp,
+ checksum (data, len,
+ checksum ((unsigned char *)
+ &ip -> ip_src,
+ sizeof ip -> ip_src,
+ IPPROTO_UDP +
+ (u_int32_t)
+ ntohs (udp -> uh_ulen)))));
+
+ if (usum && usum != sum) {
+ note ("Bad udp checksum: %x %x", usum, sum);
+ return -1;
+ }
- ip->ip_sum = htons(sum);
+ /* Copy out the port... */
+ memcpy (&from -> sin_port, &udp -> uh_sport, sizeof udp -> uh_sport);
+
+ return ip_len + sizeof *udp;
}
-/*
- * Checksum()
- *
- * Do the one's complement sum thing over a range of words
- * Ideally, this should get replaced by an assembly version.
- */
+/* Compute the easy part of the checksum on a range of bytes. */
-static u_int32_t
-Checksum(u_int16_t *buf, int nwords)
+static u_int32_t checksum (unsigned char *buf, int nbytes, u_int32_t sum)
{
- u_int32_t sum = 0;
+ int i;
+
+ /* Checksum all the pairs of bytes first... */
+ for (i = 0; i < (nbytes & ~1); i += 2)
+ sum += (u_int16_t) ntohs(*((u_int16_t *)buf)++);
+
+ /* 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. */
+ if (i < nbytes) {
+ sum += (*buf) << 8;
+ }
+
+ return sum;
+}
- while (nwords--)
- sum += (u_int16_t) ntohs(*buf++);
- return(sum);
+/* Fold the upper sixteen bits of the checksum down into the lower bits,
+ complement the sum, and then put it into network byte order. */
+
+static u_int32_t wrapsum (u_int32_t sum)
+{
+ while (sum > 0x10000) {
+ sum = (sum >> 16) + (sum & 0xFFFF);
+ sum += (sum >> 16);
+ }
+ sum = ~sum;
+
+ return htons(sum);
}
projects / thirdparty / dhcp.git / commitdiff
