nfs.c

linux下从网卡远程启动

#ifdef	DOWNLOAD_PROTO_NFS

#include "etherboot.h"
#include "nic.h"

/* NOTE: the NFS code is heavily inspired by the NetBSD netboot code (read:
 * large portions are copied verbatim) as distributed in OSKit 0.97.  A few
 * changes were necessary to adapt the code to Etherboot and to fix several
 * inconsistencies.  Also the RPC message preparation is done "by hand" to
 * avoid adding netsprintf() which I find hard to understand and use.  */

/* NOTE 2: Etherboot does not care about things beyond the kernel image, so
 * it loads the kernel image off the boot server (ARP_SERVER) and does not
 * access the client root disk (root-path in dhcpd.conf), which would use
 * ARP_ROOTSERVER.  The root disk is something the operating system we are
 * about to load needs to use.  This is different from the OSKit 0.97 logic.  */

/* NOTE 3: Symlink handling introduced by Anselm M Hoffmeister, 2003-July-14
 * If a symlink is encountered, it is followed as far as possible (recursion
 * possible, maximum 16 steps). There is no clearing of ".."'s inside the
 * path, so please DON'T DO THAT. thx. */

#define START_OPORT 700		/* mountd usually insists on secure ports */
#define OPORT_SWEEP 200		/* make sure we don't leave secure range */

static int oport = START_OPORT;
static int mount_port = -1;
static int nfs_port = -1;
static int fs_mounted = 0;
static unsigned long rpc_id;

/**************************************************************************
RPC_INIT - set up the ID counter to something fairly random
**************************************************************************/
void rpc_init(void)
{
	unsigned long t;

	t = currticks();
	rpc_id = t ^ (t << 8) ^ (t << 16);
}


/**************************************************************************
RPC_PRINTERROR - Print a low level RPC error message
**************************************************************************/
static void rpc_printerror(struct rpc_t *rpc)
{
	if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
	    rpc->u.reply.astatus) {
		/* rpc_printerror() is called for any RPC related error,
		 * suppress output if no low level RPC error happened.  */
		printf("RPC error: (%d,%d,%d)\n", ntohl(rpc->u.reply.rstatus),
			ntohl(rpc->u.reply.verifier),
			ntohl(rpc->u.reply.astatus));
	}
}

/**************************************************************************
AWAIT_RPC - Wait for an rpc packet
**************************************************************************/
static int await_rpc(int ival, void *ptr,
	unsigned short ptype, struct iphdr *ip, struct udphdr *udp)
{
	struct rpc_t *rpc;
	if (!udp) 
		return 0;
	if (arptable[ARP_CLIENT].ipaddr.s_addr != ip->dest.s_addr)
		return 0;
	if (ntohs(udp->dest) != ival)
		return 0;
	if (nic.packetlen < ETH_HLEN + sizeof(struct iphdr) + sizeof(struct udphdr) + 8)
		return 0;
	rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
	if (*(unsigned long *)ptr != ntohl(rpc->u.reply.id))
		return 0;
	if (MSG_REPLY != ntohl(rpc->u.reply.type))
		return 0;
	return 1;
}

/**************************************************************************
RPC_LOOKUP - Lookup RPC Port numbers
**************************************************************************/
static int rpc_lookup(int addr, int prog, int ver, int sport)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	int retries;
	long *p;

	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_PORTMAP);
	buf.u.call.vers = htonl(2);	/* portmapper is version 2 */
	buf.u.call.proc = htonl(PORTMAP_GETPORT);
	p = (long *)buf.u.call.data;
	*p++ = 0; *p++ = 0;				/* auth credential */
	*p++ = 0; *p++ = 0;				/* auth verifier */
	*p++ = htonl(prog);
	*p++ = htonl(ver);
	*p++ = htonl(IP_UDP);
	*p++ = 0;
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout;
		udp_transmit(arptable[addr].ipaddr.s_addr, sport, SUNRPC_PORT,
			(char *)p - (char *)&buf, &buf);
		timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		if (await_reply(await_rpc, sport, &id, timeout)) {
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus) {
				rpc_printerror(rpc);
				return -1;
			} else {
				return ntohl(rpc->u.reply.data[0]);
			}
		}
	}
	return -1;
}

/**************************************************************************
RPC_ADD_CREDENTIALS - Add RPC authentication/verifier entries
**************************************************************************/
static long *rpc_add_credentials(long *p)
{
	int hl;

	/* Here's the executive summary on authentication requirements of the
	 * various NFS server implementations:  Linux accepts both AUTH_NONE
	 * and AUTH_UNIX authentication (also accepts an empty hostname field
	 * in the AUTH_UNIX scheme).  *BSD refuses AUTH_NONE, but accepts
	 * AUTH_UNIX (also accepts an empty hostname field in the AUTH_UNIX
	 * scheme).  To be safe, use AUTH_UNIX and pass the hostname if we have
	 * it (if the BOOTP/DHCP reply didn't give one, just use an empty
	 * hostname).  */

	hl = (hostnamelen + 3) & ~3;

	/* Provide an AUTH_UNIX credential.  */
	*p++ = htonl(1);		/* AUTH_UNIX */
	*p++ = htonl(hl+20);		/* auth length */
	*p++ = htonl(0);		/* stamp */
	*p++ = htonl(hostnamelen);	/* hostname string */
	if (hostnamelen & 3) {
		*(p + hostnamelen / 4) = 0; /* add zero padding */
	}
	memcpy(p, hostname, hostnamelen);
	p += hl / 4;
	*p++ = 0;			/* uid */
	*p++ = 0;			/* gid */
	*p++ = 0;			/* auxiliary gid list */

	/* Provide an AUTH_NONE verifier.  */
	*p++ = 0;			/* AUTH_NONE */
	*p++ = 0;			/* auth length */

	return p;
}

/**************************************************************************
NFS_PRINTERROR - Print a NFS error message
**************************************************************************/
static void nfs_printerror(int err)
{
	switch (-err) {
	case NFSERR_PERM:
		printf("Not owner\n");
		break;
	case NFSERR_NOENT:
		printf("No such file or directory\n");
		break;
	case NFSERR_ACCES:
		printf("Permission denied\n");
		break;
	case NFSERR_ISDIR:
		printf("Directory given where filename expected\n");
		break;
	case NFSERR_INVAL:
		printf("Invalid filehandle\n");
		break; // INVAL is not defined in NFSv2, some NFS-servers
		// seem to use it in answers to v2 nevertheless.
	case 9998:
		printf("low-level RPC failure (parameter decoding problem?)\n");
		break;
	case 9999:
		printf("low-level RPC failure (authentication problem?)\n");
		break;
	default:
		printf("Unknown NFS error %d\n", -err);
	}
}

/**************************************************************************
NFS_MOUNT - Mount an NFS Filesystem
**************************************************************************/
static int nfs_mount(int server, int port, char *path, char *fh, int sport)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	int retries;
	long *p;
	int pathlen = strlen(path);

	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_MOUNT);
	buf.u.call.vers = htonl(1);	/* mountd is version 1 */
	buf.u.call.proc = htonl(MOUNT_ADDENTRY);
	p = rpc_add_credentials((long *)buf.u.call.data);
	*p++ = htonl(pathlen);
	if (pathlen & 3) {
		*(p + pathlen / 4) = 0;	/* add zero padding */
	}
	memcpy(p, path, pathlen);
	p += (pathlen + 3) / 4;
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout;
		udp_transmit(arptable[server].ipaddr.s_addr, sport, port,
			(char *)p - (char *)&buf, &buf);
		timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		if (await_reply(await_rpc, sport, &id, timeout)) {
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus || rpc->u.reply.data[0]) {
				rpc_printerror(rpc);
				if (rpc->u.reply.rstatus) {
					/* RPC failed, no verifier, data[0] */
					return -9999;
				}
				if (rpc->u.reply.astatus) {
					/* RPC couldn't decode parameters */
					return -9998;
				}
				return -ntohl(rpc->u.reply.data[0]);
			} else {
				fs_mounted = 1;
				memcpy(fh, rpc->u.reply.data + 1, NFS_FHSIZE);
				return 0;
			}
		}
	}
	return -1;
}

/**************************************************************************
NFS_UMOUNTALL - Unmount all our NFS Filesystems on the Server
**************************************************************************/
void nfs_umountall(int server)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	int retries;
	long *p;

	if (!arptable[server].ipaddr.s_addr) {
		/* Haven't sent a single UDP packet to this server */
		return;
	}
	if ((mount_port == -1) || (!fs_mounted)) {
		/* Nothing mounted, nothing to umount */
		return;
	}
	id = rpc_id++;
	buf.u.call.id = htonl(id);
	buf.u.call.type = htonl(MSG_CALL);
	buf.u.call.rpcvers = htonl(2);	/* use RPC version 2 */
	buf.u.call.prog = htonl(PROG_MOUNT);
	buf.u.call.vers = htonl(1);	/* mountd is version 1 */
	buf.u.call.proc = htonl(MOUNT_UMOUNTALL);
	p = rpc_add_credentials((long *)buf.u.call.data);
	for (retries = 0; retries < MAX_RPC_RETRIES; retries++) {
		long timeout = rfc2131_sleep_interval(TIMEOUT, retries);
		udp_transmit(arptable[server].ipaddr.s_addr, oport, mount_port,
			(char *)p - (char *)&buf, &buf);
		if (await_reply(await_rpc, oport, &id, timeout)) {
			rpc = (struct rpc_t *)&nic.packet[ETH_HLEN];
			if (rpc->u.reply.rstatus || rpc->u.reply.verifier ||
			    rpc->u.reply.astatus) {
				rpc_printerror(rpc);
			}
			fs_mounted = 0;
			return;
		}
	}
}
/***************************************************************************
 * NFS_READLINK (AH 2003-07-14)
 * This procedure is called when read of the first block fails -
 * this probably happens when it's a directory or a symlink
 * In case of successful readlink(), the dirname is manipulated,
 * so that inside the nfs() function a recursion can be done.
 **************************************************************************/
static int nfs_readlink(int server, int port, char *fh, char *path, char *nfh,
	int sport)
{
	struct rpc_t buf, *rpc;
	unsigned long id;
	long *p;
	int retries;
	int pathlen = strlen(path);