mirror of
https://gitlab.isc.org/isc-projects/dhcp
synced 2025-08-31 14:25:41 +00:00
Various user-provided patches
This commit is contained in:
Ted Lemon
260
common/socket.c
260
common/socket.c
@@ -48,6 +48,27 @@ static char copyright[] =
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#include "dhcpd.h"
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#include <sys/ioctl.h>
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#ifdef USE_BPF
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#include <net/bpf.h>
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#include <net/if.h>
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#include <net/if_arp.h>
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#include <net/if_dl.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/udp.h>
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#include <netinet/if_ether.h>
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struct interface {
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struct in_addr address;
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int bpf;
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};
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static struct interface *if_list;
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static int num_ifaces;
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#endif
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/* List of sockets we're accepting packets on... */
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struct socklist {
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struct socklist *next;
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@@ -86,17 +107,48 @@ u_int32_t *get_interface_list (count)
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second time to copy them into an array of addresses. */
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for (i = 0; i < ic.ifc_len;) {
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struct ifreq *ifp = (struct ifreq *)((caddr_t)ic.ifc_req + i);
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#ifdef HAVE_SIN_LEN
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i += (sizeof ifp -> ifr_name) + ifp -> ifr_addr.sa_len;
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#else
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i += sizeof *ifp;
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#endif
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if (ifp -> ifr_addr.sa_family == AF_INET) {
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struct sockaddr_in *foo =
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(struct sockaddr_in *)(&ifp -> ifr_addr);
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/* We don't want the loopback interface. */
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if (foo -> sin_addr.s_addr == INADDR_LOOPBACK)
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continue;
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if (intbuf)
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intbuf [ifix++] = foo -> sin_addr.s_addr;
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else
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if (intbuf) {
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intbuf [ifix] = foo -> sin_addr.s_addr;
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#ifdef USE_BPF
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/* Open a bpf device for this interface */
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{
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int b;
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char filename[50];
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for (b = 0; 1; b++)
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{
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snprintf(filename, sizeof(filename),
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"/dev/bpf%d", b);
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if ((if_list[ifix].bpf =
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open(filename, O_RDWR, 0)) < 0)
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if (errno == EBUSY)
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continue;
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else
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error ("Can't find free bpf: %m");
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else
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break;
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}
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if (ioctl(if_list[ifix].bpf,
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BIOCSETIF, ifp) < 0)
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error ("Can't BIOCSETIF on bpf: %m");
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}
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if_list[ifix].address = foo->sin_addr;
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#endif
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ifix++;
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} else {
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++ifcount;
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}
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}
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}
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/* If we haven't already filled our array, allocate it and go
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@@ -107,6 +159,13 @@ u_int32_t *get_interface_list (count)
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"get_interface_list");
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if (!intbuf)
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return intbuf;
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#ifdef USE_BPF
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num_ifaces = ifcount;
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if (!(if_list = (struct interface *)dmalloc
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(num_ifaces * sizeof(*if_list),
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"get_interface_list")))
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error ("Can't allocate memory for if_list");
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#endif
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goto again;
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}
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*count = ifcount;
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@@ -215,3 +274,198 @@ void dispatch ()
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} while (1);
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}
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#ifndef USE_BPF
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int sendpkt (packet, raw, len, to, tolen)
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struct packet *packet;
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struct dhcp_packet *raw;
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size_t len;
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struct sockaddr *to;
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int tolen;
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{
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return(sendto(packet->client_sock, raw, len, 0, to, tolen));
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}
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#else
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static void IpChecksum(struct ip *ip);
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static void UdpChecksum(struct ip *ip);
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static u_int32_t Checksum(u_int16_t *buf, int nwords);
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struct raw_packet
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{
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u_int16_t space;
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struct ether_header en_hdr;
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struct ip ip;
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struct udphdr udp;
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struct dhcp_packet dhcp;
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};
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int sendpkt (in_packet, raw, len, to, tolen)
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struct packet *in_packet;
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struct dhcp_packet *raw;
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size_t len;
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struct sockaddr *to;
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int tolen;
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{
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int i, k;
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struct iaddr dest;
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struct subnet *subnet;
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struct raw_packet out_packet;
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struct raw_packet *const pkt = &out_packet;
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/* Find local subnet, or else forward to gateway */
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dest.len = 4;
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memcpy(&dest.iabuf, &((struct sockaddr_in *) to)->sin_addr, dest.len);
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if ((subnet = find_subnet(dest)) == NULL)
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return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
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/* Find interface corresponding to subnet */
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for (i = 0; i < num_ifaces; i++)
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{
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for (k = 0; k < subnet->net.len
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&& (dest.iabuf[k] & subnet->netmask.iabuf[k])
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== (subnet->net.iabuf[k] & subnet->netmask.iabuf[k]);
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k++);
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if (k == subnet->net.len)
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break;
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}
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if (i == num_ifaces)
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return(sendto(in_packet->client_sock, raw, len, 0, to, tolen));
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/* EtherNet header */
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memset(pkt->en_hdr.ether_dhost, 0xff, sizeof(pkt->en_hdr.ether_dhost));
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memset(pkt->en_hdr.ether_shost, 0x00, sizeof(pkt->en_hdr.ether_shost));
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pkt->en_hdr.ether_type = ETHERTYPE_IP;
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/* IP header (except for checksum) */
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pkt->ip.ip_v = 4;
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pkt->ip.ip_hl = 5;
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pkt->ip.ip_tos = IPTOS_LOWDELAY;
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pkt->ip.ip_len = htons(sizeof(pkt->ip) + sizeof(pkt->udp) + len);
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pkt->ip.ip_id = 0;
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pkt->ip.ip_off = 0;
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pkt->ip.ip_ttl = 16;
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pkt->ip.ip_p = IPPROTO_UDP;
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pkt->ip.ip_sum = 0;
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pkt->ip.ip_src = if_list[i].address;
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inet_aton("255.255.255.255", &pkt->ip.ip_dst);
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/* UDP header */
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pkt->udp.uh_sport = htons(67); /* XXX! */
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pkt->udp.uh_dport = in_packet->client_port;
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pkt->udp.uh_ulen = htons(sizeof(pkt->udp) + len);
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pkt->udp.uh_sum = 0;
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/* DHCP packet */
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pkt->dhcp = *raw;
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/* Compute checksums */
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UdpChecksum(&pkt->ip);
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IpChecksum(&pkt->ip);
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/* Fire it off */
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if (write(if_list[i].bpf, &pkt->en_hdr,
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ntohs(pkt->ip.ip_len) + sizeof(pkt->en_hdr)) < 0)
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warn ("Can't deliver packet: write: %m");
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return(0);
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}
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/*
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* UdpChecksum()
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*
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* Recompute a UDP checksum on a packet
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*
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* UDP pseudo-header (prot = IPPROTO_UDP = 17):
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*
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* | source IP address |
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* | dest. IP address |
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* | zero | prot | UDP leng |
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*
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*/
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static void
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UdpChecksum(struct ip *ip)
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{
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struct udphdr *udp = (struct udphdr *) ((long *) ip + ip->ip_hl);
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u_int32_t sum;
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/* Pad with zero */
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if (ntohs(udp->uh_ulen) & 0x1)
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*((u_char *) udp + ntohs(udp->uh_ulen)) = 0;
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/* Do pseudo-header first */
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sum = Checksum((u_int16_t *) &ip->ip_src, 4);
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sum += (u_int16_t) IPPROTO_UDP;
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sum += (u_int16_t) ntohs(udp->uh_ulen);
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/* Now do UDP packet itself */
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udp->uh_sum = 0;
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sum += Checksum((u_int16_t *) udp,
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((u_int16_t) ntohs(udp->uh_ulen) + 1) >> 1);
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/* Flip it & stick it */
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sum = (sum >> 16) + (sum & 0xFFFF);
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sum += (sum >> 16);
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sum = ~sum;
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udp->uh_sum = htons(sum);
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}
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/*
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* IpChecksum()
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*
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* Recompute an IP header checksum
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*
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*/
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static void
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IpChecksum(struct ip *ip)
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{
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u_int32_t sum;
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/* Sum up IP header words */
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ip->ip_sum = 0;
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sum = Checksum((u_int16_t *) ip, ip->ip_hl * 2);
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/* Flip it & stick it */
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sum = (sum >> 16) + (sum & 0xFFFF);
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sum += (sum >> 16);
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sum = ~sum;
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ip->ip_sum = htons(sum);
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}
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/*
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* Checksum()
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*
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* Do the one's complement sum thing over a range of words
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* Ideally, this should get replaced by an assembly version.
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*/
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static u_int32_t
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Checksum(u_int16_t *buf, int nwords)
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{
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u_int32_t sum = 0;
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while (nwords--)
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sum += (u_int16_t) ntohs(*buf++);
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return(sum);
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}
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#endif
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