2001-09-27 Roland McGrath <roland@frob.com>

	* nbd.c: New file.
	* Makefile (SRCS): Add it.
	* store.h (store_nbd_open, _store_nbd_create): Declare them.

1 files changed, 409 insertions, 0 deletions

diff --git a/libstore/nbd.c b/libstore/nbd.c
new file mode 100644
index 00000000..9484f0b7
--- /dev/null
+++ b/libstore/nbd.c
@@ -0,0 +1,409 @@
+/* "Network Block Device" store backend compatible with Linux `nbd' driver
+   Copyright (C) 2001 Free Software Foundation, Inc.
+
+   This task is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
+
+#include <hurd.h>
+#include <hurd/store.h>
+#include <hurd/io.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+
+// Avoid dragging in the resolver when linking statically.
+#pragma weak gethostbyname
+
+
+/* The nbd protocol, such as it is, is not really specified anywhere.
+   These message layouts and constants were culled from the nbd-server and
+   Linux kernel nbd module sources.  */
+
+#define NBD_INIT_MAGIC		"NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53"
+
+#define NBD_REQUEST_MAGIC	htonl(0x25609513)
+#define NBD_REPLY_MAGIC		htonl(0x67446698)
+
+struct nbd_startup
+{
+  char magic[16];		/* NBD_INIT_MAGIC */
+  uint32_t sizehi;		/* size in bytes, 64 bits in net order */
+  uint32_t sizelo;
+  char reserved[128];		/* zeros, we don't check it */
+};
+
+struct nbd_request
+{
+  uint32_t magic;		/* NBD_REQUEST_MAGIC */
+  uint32_t type;		/* 0 read, 1 write, 2 disconnect */
+  uint64_t handle;		/* returned in reply */
+  uint64_t from;
+  uint32_t len;
+} __attribute__ ((packed));
+
+struct nbd_reply
+{
+  uint32_t magic;		/* NBD_REPLY_MAGIC */
+  uint32_t error;
+  uint64_t handle;		/* value from request */
+} __attribute__ ((packed));
+
+
+/* i/o functions.  */
+
+static inline uint64_t
+htonll (uint64_t x)
+{
+#if BYTE_ORDER == BIG_ENDIAN
+  return x;
+#elif BYTE_ORDER == LITTLE_ENDIAN
+  union { uint64_t ll; uint32_t l[2]; } u;
+  u.l[0] = htonl ((uint32_t) (x >> 32));
+  u.l[1] = htonl ((uint32_t) x);
+  return u.ll;
+#else
+# error what endian?
+#endif
+}
+#define ntohll htonll
+
+
+static inline error_t
+read_reply (struct store *store, uint64_t handle)
+{
+  struct nbd_reply reply;
+  char *buf = (void *) &reply;
+  mach_msg_type_number_t cc = sizeof reply;
+  error_t err = io_read (store->port, &buf, &cc, -1, cc);
+  if (err)
+    return err;
+  if (buf != (void *) &reply)
+    {
+      memcpy (&reply, buf, sizeof reply);
+      munmap (buf, cc);
+    }
+  if (cc != sizeof reply)
+    return EIO;
+  if (reply.magic != NBD_REPLY_MAGIC)
+    return EIO;
+  if (reply.handle != handle)
+    return EIO;
+  if (reply.error != 0)
+    return EIO;
+  return 0;
+}
+
+static error_t
+nbd_write (struct store *store,
+	   store_offset_t addr, size_t index, const void *buf, size_t len,
+	   size_t *amount)
+{
+  struct nbd_request req =
+  {
+    magic: NBD_REQUEST_MAGIC,
+    type: htonl (1),		/* WRITE */
+    from: htonll (addr << store->log2_block_size),
+    len: htonl (len)
+  };
+  error_t err;
+  mach_msg_type_number_t cc;
+
+  err = io_write (store->port, (char *) &req, sizeof req, -1, &cc);
+  if (err)
+    return err;
+  if (cc != sizeof req)
+    return EIO;
+
+  *amount = 0;
+  do
+    {
+      err = io_write (store->port, (char *) buf, len - *amount, -1, &cc);
+      if (err)
+	return err;
+      buf += cc;
+      *amount += cc;
+    } while (*amount < len);
+
+  return read_reply (store, req.handle);
+}
+
+static error_t
+nbd_read (struct store *store,
+	  store_offset_t addr, size_t index, size_t amount, void **buf,
+	  size_t *len)
+{
+  struct nbd_request req =
+  {
+    magic: NBD_REQUEST_MAGIC,
+    type: htonl (0),		/* READ */
+    from: htonll (addr << store->log2_block_size),
+    len: htonl (amount),
+  };
+  error_t err;
+  mach_msg_type_number_t cc;
+
+  err = io_write (store->port, (char *) &req, sizeof req, -1, &cc);
+  if (err)
+    return err;
+  if (cc != sizeof req)
+    return EIO;
+
+  err = read_reply (store, req.handle);
+  if (err == 0)
+    err = io_read (store->port, (char **) buf, len, (off_t) -1, amount);
+  return err;
+}
+
+
+
+/* Setup hooks.  */
+
+static error_t
+nbd_decode (struct store_enc *enc, const struct store_class *const *classes,
+	    struct store **store)
+{
+  return store_std_leaf_decode (enc, _store_nbd_create, store);
+}
+
+static error_t
+nbd_open (const char *name, int flags,
+	  const struct store_class *const *classes,
+	  struct store **store)
+{
+  return store_nbd_open (name, flags, store);
+}
+
+/* Valid name syntax is HOSTNAME:PORT[/BLOCKSIZE].
+   If "/BLOCKSIZE" is omitted, the block size is 1.  */
+static error_t
+nbd_validate_name (const char *name,
+		   const struct store_class *const *classes)
+{
+  char *p = strchr (name, ':'), *endp;
+  if (p == 0)
+    return EINVAL;
+  endp = 0;
+  strtoul (p, &endp, 0);
+  if (endp == 0 || endp == p)
+    return EINVAL;
+  switch (*endp)
+    {
+    default:
+      return EINVAL;
+    case '\0':
+      break;
+    case '/':
+      p = endp + 1;
+      strtoul (p, &endp, 0);
+      if (endp == 0 || endp == p)
+	return EINVAL;
+      if (*endp != '\0')
+	return EINVAL;
+    }
+  return 0;
+}
+
+static error_t
+nbdopen (const char *name, int *mod_flags,
+	 socket_t *sockport, size_t *blocksize, store_offset_t *size)
+{
+  int sock;
+  struct sockaddr_in sin;
+  const struct hostent *he;
+  char **ap;
+  struct nbd_startup ns;
+  ssize_t cc;
+
+  /* First we have to parse the store name to get the host name and TCP
+     port number to connect to and the block size to use.  */
+
+  unsigned long int port;
+  char *hostname = strdupa (name);
+  char *p = strchr (hostname, ':'), *endp;
+
+  if (p == 0)
+    return EINVAL;
+  *p++ = '\0';
+  port = strtoul (p, &endp, 0);
+  if (endp == 0 || endp == p || port > 0xffffUL)
+    return EINVAL;
+  switch (*endp)
+    {
+    default:
+      return EINVAL;
+    case '\0':
+      *blocksize = 1;
+      break;
+    case '/':
+      p = endp + 1;
+      *blocksize = strtoul (p, &endp, 0);
+      if (endp == 0 || endp == p)
+	return EINVAL;
+      if (*endp != '\0')
+	return EINVAL;
+    }
+
+  /* Now look up the host name and get a TCP connection.  */
+
+  he = gethostbyname (hostname);
+  if (he == 0)			/* XXX emit an error message? */
+    return errno;		/* XXX what value will this have? */
+
+  sock = socket (PF_INET, SOCK_STREAM, 0);
+  if (sock < 0)
+    return errno;
+
+  sin.sin_family = AF_INET;
+  sin.sin_port = htons (port);
+  for (ap = he->h_addr_list; *ap != 0; ++ap)
+    {
+      sin.sin_addr = *(const struct in_addr *) *ap;
+      if (connect (sock, &sin, sizeof sin) == 0 || errno == ECONNREFUSED)
+	break;
+    }
+  if (*ap != 0)			/* last connect failed */
+    {
+      error_t err = errno;
+      close (sock);
+      return err;
+    }
+
+  /* Read the startup packet, which tells us the size of the store.  */
+
+  cc = read (sock, &ns, sizeof ns);
+  if (cc < 0)
+    {
+      error_t err = errno;
+      close (sock);
+      return err;
+    }
+  if (cc != sizeof ns
+      || memcmp (ns.magic, NBD_INIT_MAGIC, sizeof ns.magic) != 0)
+    {
+      close (sock);
+      return EGRATUITOUS;	/* ? */
+    }
+
+  *size = ((uint64_t) ntohl (ns.sizehi) << 32) | ntohl (ns.sizelo);
+  *sockport = getdport (sock);
+  close (sock);
+
+  return 0;
+}
+
+static void
+nbdclose (struct store *store)
+{
+  if (store->port != MACH_PORT_NULL)
+    {
+      /* Send a disconnect message, but don't wait for a reply.  */
+      struct nbd_request req =
+      {
+	magic: NBD_REQUEST_MAGIC,
+	type: htonl (2),	/* disconnect */
+      };
+      mach_msg_type_number_t cc;
+      (void) io_write (store->port, (char *) &req, sizeof req, -1, &cc);
+
+      /* Close the socket.  */
+      mach_port_deallocate (mach_task_self (), store->port);
+      store->port = MACH_PORT_NULL;
+    }
+}
+
+static error_t
+nbd_set_flags (struct store *store, int flags)
+{
+  if ((flags & ~STORE_INACTIVE) != 0)
+    /* Trying to set flags we don't support.  */
+    return EINVAL;
+
+  nbdclose (store);
+  store->flags |= STORE_INACTIVE;
+
+  return 0;
+}
+
+static error_t
+nbd_clear_flags (struct store *store, int flags)
+{
+  error_t err = 0;
+  if ((flags & ~STORE_INACTIVE) != 0)
+    err = EINVAL;
+  err = store->name
+    ? nbdopen (store->name, &store->flags,
+	       &store->port, &store->block_size, &store->size)
+    : ENOENT;
+  if (! err)
+    store->flags &= ~STORE_INACTIVE;
+  return err;
+}
+
+struct store_class store_nbd_class =
+{
+  STORAGE_NETWORK, "nbd",
+  open: nbd_open,
+  validate_name: nbd_validate_name,
+  read: nbd_read,
+  write: nbd_write,
+  allocate_encoding: store_std_leaf_allocate_encoding,
+  encode: store_std_leaf_encode,
+  decode: nbd_decode,
+  set_flags: nbd_set_flags, clear_flags: nbd_clear_flags,
+};
+
+/* Create a store from an existing socket to an nbd server.
+   The initial handshake has already been done.  */
+error_t
+_store_nbd_create (mach_port_t port, int flags, size_t block_size,
+		   const struct store_run *runs, size_t num_runs,
+		   struct store **store)
+{
+  return _store_create (&store_nbd_class,
+			port, flags, block_size, runs, num_runs, 0, store);
+}
+
+/* Open a new store backed by the named nbd server.  */
+error_t
+store_nbd_open (const char *name, int flags, struct store **store)
+{
+  error_t err;
+  socket_t sock;
+  struct store_run run;
+  size_t blocksize;
+
+  run.start = 0;
+  err = nbdopen (name, &flags, &sock, &blocksize, &run.length);
+  if (!err)
+    {
+      err = _store_nbd_create (sock, flags, blocksize, &run, 1, store);
+      if (! err)
+	{
+	  err = store_set_name (*store, name);
+	  if (err)
+	    store_free (*store);
+	}
+      if (err)
+	mach_port_deallocate (mach_task_self (), sock);
+    }
+  return err;
+}