main.c

freebsd v4.4内核源码

default_netmask()
{
	int net = arptable[ARP_CLIENT].ipaddr >> 24;
	if (net <= 127)
		netmask = htonl(0xff000000);
	else if (net < 192)
		netmask = htonl(0xffff0000);
	else
		netmask = htonl(0xffffff00);
}
/**************************************************************************
UDP_TRANSMIT - Send a UDP datagram
**************************************************************************/
udp_transmit(destip, srcsock, destsock, len, buf)
	unsigned long destip;
	unsigned short srcsock, destsock;
	int len;
	char *buf;
{
	struct iphdr *ip;
	struct udphdr *udp;
	struct arprequest arpreq;
	int arpentry, i;
	unsigned long time;
	int retry = MAX_ARP_RETRIES;

	ip = (struct iphdr *)buf;
	udp = (struct udphdr *)(buf + sizeof(struct iphdr));
	ip->verhdrlen = 0x45;
	ip->service = 0;
	ip->len = htons(len);
	ip->ident = 0;
	ip->frags = 0;
	ip->ttl = 60;
	ip->protocol = IP_UDP;
	ip->chksum = 0;
	convert_ipaddr(ip->src, &arptable[ARP_CLIENT].ipaddr);
	convert_ipaddr(ip->dest, &destip);
	ip->chksum = ipchksum(buf, sizeof(struct iphdr));
	udp->src = htons(srcsock);
	udp->dest = htons(destsock);
	udp->len = htons(len - sizeof(struct iphdr));
	udp->chksum = 0;
	if (destip == IP_BROADCAST) {
		eth_transmit(broadcast, IP, len, buf);
	} else {
		long h_netmask = ntohl(netmask);
				/* Check to see if we need gateway */
		if (((destip & h_netmask) !=
			(arptable[ARP_CLIENT].ipaddr & h_netmask)) &&
			arptable[ARP_GATEWAY].ipaddr)
				destip = arptable[ARP_GATEWAY].ipaddr;
		for(arpentry = 0; arpentry<MAX_ARP; arpentry++)
			if (arptable[arpentry].ipaddr == destip) break;
		if (arpentry == MAX_ARP) {
			printf("%I is not in my arp table!\n");
			return(0);
		}
		for (i = 0; i<ETHER_ADDR_LEN; i++)
			if (arptable[arpentry].node[i]) break;
		if (i == ETHER_ADDR_LEN) {	/* Need to do arp request */
			arpreq.hwtype = htons(1);
			arpreq.protocol = htons(IP);
			arpreq.hwlen = ETHER_ADDR_LEN;
			arpreq.protolen = 4;
			arpreq.opcode = htons(ARP_REQUEST);
			bcopy(arptable[ARP_CLIENT].node, arpreq.shwaddr,
				ETHER_ADDR_LEN);
			convert_ipaddr(arpreq.sipaddr,
				&arptable[ARP_CLIENT].ipaddr);
			bzero(arpreq.thwaddr, ETHER_ADDR_LEN);
			convert_ipaddr(arpreq.tipaddr, &destip);
			while (retry--) {
				eth_transmit(broadcast, ARP, sizeof(arpreq),
					&arpreq);
				if (await_reply(AWAIT_ARP, arpentry,
					arpreq.tipaddr)) goto xmit;
			}
			return(0);
		}
xmit:		eth_transmit(arptable[arpentry].node, IP, len, buf);
	}
	return(1);
}

/**************************************************************************
TFTP - Try to load configuation file
**************************************************************************/
tftp(name)
	char *name;
{
	struct	tftp_t	*tr;
	int retry = MAX_TFTP_RETRIES;
	static unsigned short isocket = 2000;
	unsigned short osocket = TFTP;
	unsigned short len, block=1;
	struct tftp_t tp;
	int code;
	printf("Loading %s...\r\n",name);
	isocket++;
	tp.opcode = htons(TFTP_RRQ);
	len = (sprintf((char *)tp.u.rrq,"%s%c%s",name,0,"octet")
		- ((char *)&tp)) + 1;
	while(retry--) {
		if (!udp_transmit(arptable[ARP_SERVER].ipaddr, isocket, osocket,
			len, &tp)) return(0);
		if (await_reply(AWAIT_TFTP, isocket, NULL)) {
			tr = (struct tftp_t *)&packet[ETHER_HDR_LEN];
			if (tr->opcode == ntohs(TFTP_ERROR)) {
				printf("TFTP error %d (%s)\r\n",
					ntohs(tr->u.err.errcode),
					tr->u.err.errmsg);
				return(0);
			}			/* ACK PACKET */
			if (tr->opcode != ntohs(TFTP_DATA)) return(0);
			tp.opcode = htons(TFTP_ACK);
			tp.u.ack.block = tr->u.data.block;
			udp_transmit(arptable[ARP_SERVER].ipaddr, isocket,
				osocket, TFTP_MIN_PACKET_SIZE, &tp);
			len = ntohs(tr->udp.len) - sizeof(struct udphdr) - 4;
			if (len >= 512) {
				printf("Config file too large.\r\n");
				config_buffer[0] = 0;
				return(0);
			} else {
				bcopy(tr->u.data.download, config_buffer, len);
				config_buffer[len] = 0;
			}
			return(1);
		}
	}
	return(0);
}

/**************************************************************************
BOOTP - Get my IP address and load information
**************************************************************************/
bootp()
{
	int retry = MAX_BOOTP_RETRIES;
	struct bootp_t bp;
	unsigned long  starttime;
	bzero(&bp, sizeof(struct bootp_t));
	bp.bp_op = BOOTP_REQUEST;
	bp.bp_htype = 1;
	bp.bp_hlen = ETHER_ADDR_LEN;
	bp.bp_xid = starttime = currticks();
	bcopy(arptable[ARP_CLIENT].node, bp.bp_hwaddr, ETHER_ADDR_LEN);
	while(retry--) {
		udp_transmit(IP_BROADCAST, 0, BOOTP_SERVER,
			sizeof(struct bootp_t), &bp);
		if (await_reply(AWAIT_BOOTP, 0, NULL))
			return(1);
		bp.bp_secs = htons((currticks()-starttime)/20);
	}
	return(0);
}


/**************************************************************************
AWAIT_REPLY - Wait until we get a response for our request
**************************************************************************/
await_reply(type, ival, ptr)
	int type, ival;
	char *ptr;
{
	unsigned long time;
	struct	iphdr *ip;
	struct	udphdr *udp;
	struct	arprequest *arpreply;
	struct	bootp_t *bootpreply;
	struct	rpc_t *rpc;

	int	protohdrlen = ETHER_HDR_LEN + sizeof(struct iphdr) +
				sizeof(struct udphdr);
	time = currticks() + TIMEOUT;
	while(time > currticks()) {
		pollkbd();
		if (eth_poll()) {	/* We have something! */
					/* Check for ARP - No IP hdr */
			if ((type == AWAIT_ARP) &&
			   (packetlen >= ETHER_HDR_LEN +
				sizeof(struct arprequest)) &&
			   (((packet[12] << 8) | packet[13]) == ARP)) {
				arpreply = (struct arprequest *)
					&packet[ETHER_HDR_LEN];
				if ((arpreply->opcode == ntohs(ARP_REPLY)) &&
				   bcompare(arpreply->sipaddr, ptr, 4)) {
					bcopy(arpreply->shwaddr,
						arptable[ival].node,
						ETHER_ADDR_LEN);
					return(1);
				}
				continue;
			}

					/* Anything else has IP header */
			if ((packetlen < protohdrlen) ||
			   (((packet[12] << 8) | packet[13]) != IP)) continue;
			ip = (struct iphdr *)&packet[ETHER_HDR_LEN];
			if ((ip->verhdrlen != 0x45) ||
				ipchksum(ip, sizeof(struct iphdr)) ||
				(ip->protocol != IP_UDP)) continue;
			udp = (struct udphdr *)&packet[ETHER_HDR_LEN +
				sizeof(struct iphdr)];

					/* BOOTP ? */
			bootpreply = (struct bootp_t *)&packet[ETHER_HDR_LEN];
			if ((type == AWAIT_BOOTP) &&
			   (packetlen >= (ETHER_HDR_LEN +
					  sizeof(struct iphdr) +
					  sizeof(struct udphdr) +
					  BOOTP_MIN_LEN)) &&
			   (ntohs(udp->dest) == BOOTP_CLIENT) &&
			   (bootpreply->bp_op == BOOTP_REPLY)) {
				convert_ipaddr(&arptable[ARP_CLIENT].ipaddr,
					bootpreply->bp_yiaddr);
				default_netmask();
				convert_ipaddr(&arptable[ARP_SERVER].ipaddr,
					bootpreply->bp_siaddr);
				bzero(arptable[ARP_SERVER].node,
					ETHER_ADDR_LEN);  /* Kill arp */
				convert_ipaddr(&arptable[ARP_GATEWAY].ipaddr,
					bootpreply->bp_giaddr);
				bzero(arptable[ARP_GATEWAY].node,
					ETHER_ADDR_LEN);  /* Kill arp */
				if (bootpreply->bp_file[0]) {
					bcopy(bootpreply->bp_file,
						kernel_buf, 128);
					kernel = kernel_buf;
				}
				decode_rfc1048(bootpreply->bp_vend);
				return(1);
			}

					/* TFTP ? */
			if ((type == AWAIT_TFTP) &&
				(ntohs(udp->dest) == ival)) return(1);

					/* RPC */
			rpc = (struct rpc_t *)&packet[ETHER_HDR_LEN];
			if ((type == AWAIT_RPC) &&
			   (ntohs(udp->dest) == RPC_SOCKET) &&
			   (ntohl(rpc->u.reply.id) == ival) &&
			   (ntohl(rpc->u.reply.type) == MSG_REPLY)) {
				rpc_id++;
				return(1);
			}
		}
	}
	return(0);
}

void
bootp_string(char *name, char *bootp_ptr)
{       
	char tmp_buf[512]; /* oversized, but who cares ! */
	bzero(tmp_buf, sizeof(tmp_buf));
	bcopy(bootp_ptr+2, tmp_buf, TAG_LEN(bootp_ptr));
	sprintf(config_buffer+strlen(config_buffer),
	    "%s %s\n", name, tmp_buf);
}


/**************************************************************************
DECODE_RFC1048 - Decodes RFC1048 header
**************************************************************************/
decode_rfc1048(p)
	unsigned char *p;
{
	static char rfc1048_cookie[4] = RFC1048_COOKIE;
	unsigned char *end = p + BOOTP_VENDOR_LEN,*q;
	if (bcompare(p, rfc1048_cookie, 4)) { /* RFC 1048 header */
		p += 4;
		while(p < end) {
			switch (*p) {
			case RFC1048_PAD:
				p++;
				continue;
			case RFC1048_END:
				p = end;
				continue;
			case RFC1048_GATEWAY:
				convert_ipaddr(&arptable[ARP_GATEWAY].ipaddr,
					p+2);
				break;
			case RFC1048_NETMASK:
				bcopy(p+2,&netmask,4);
				break;
			case RFC1048_HOSTNAME:
				bcopy(p+2, &nfsdiskless.my_hostnam, TAG_LEN(p));
				hostnamelen = (TAG_LEN(p) + 3) & ~3;
				break;
			case RFC1048_ROOT_PATH: /* XXX check len */
				bootp_string("rootfs", p);
				break;
			case RFC1048_SWAP_PATH:
				bootp_string("swapfs", p);
				break;
			case RFC1048_SWAP_LEN: /* T129 */
				sprintf(config_buffer+strlen(config_buffer),
				    "swapsize %d\n", ntohl(*(long *)(p+2)) );
				break;
			case 130:       /* root mount options */
				bootp_string("rootopts", p);
				break;
			case 131:       /* swap mount options */
				bootp_string("swapopts", p);
				break;
			default:
				printf("Unknown RFC1048-tag ");
				for(q=p;q<p+2+TAG_LEN(p);q++)
					printf("%x ",*q);
				printf("\n\r");
			}
			p += TAG_LEN(p) + 2;
		}
	}
}

/**************************************************************************
IPCHKSUM - Checksum IP Header
**************************************************************************/
ipchksum(ip, len)
	unsigned short *ip;
	int len;
{
	unsigned long sum = 0;
	len >>= 1;
	while (len--) {
		sum += *(ip++);
		if (sum > 0xFFFF)
			sum -= 0xFFFF;
	}
	return((~sum) & 0x0000FFFF);
}


/**************************************************************************
CONVERT_IPADDR - Convert IP address from net to machine order
**************************************************************************/
convert_ipaddr(d, s)
	char *d,*s;
{
	*(d+3) = *s;
	*(d+2) = *(s+1);
	*(d+1) = *(s+2);
	*d     = *(s+3);
}