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Re: [Qemu-devel] [PATCH 2/3] nbd: Add exports listing support.


From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH 2/3] nbd: Add exports listing support.
Date: Tue, 03 Jun 2014 13:36:35 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0

Il 31/05/2014 23:39, Hani Benhabiles ha scritto:
This is added by handling the NBD_OPT_LIST and NBD_OPT_ABORT options.

NBD_REP_ERR_UNSUP is also sent for unknown NBD option values.

Signed-off-by: Hani Benhabiles <address@hidden>
---
 include/block/nbd.h |   5 ++
 nbd.c               | 197 +++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 162 insertions(+), 40 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 95d52ab..fd7e057 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -51,6 +51,11 @@ struct nbd_reply {
 /* New-style client flags. */
 #define NBD_FLAG_C_FIXED_NEWSTYLE   (1 << 0)    /* Fixed newstyle protocol. */

+/* Reply types. */
+#define NBD_REP_ACK             (1)             /* Data sending finished. */
+#define NBD_REP_SERVER          (2)             /* Export description. */
+#define NBD_REP_ERR_UNSUP       ((1 << 31) | 1) /* Unknown option. */
+
 #define NBD_CMD_MASK_COMMAND   0x0000ffff
 #define NBD_CMD_FLAG_FUA       (1 << 16)

diff --git a/nbd.c b/nbd.c
index aa2e552..012e5da 100644
--- a/nbd.c
+++ b/nbd.c
@@ -64,6 +64,7 @@
 #define NBD_REPLY_MAGIC         0x67446698
 #define NBD_OPTS_MAGIC          0x49484156454F5054LL
 #define NBD_CLIENT_MAGIC        0x0000420281861253LL
+#define NBD_REP_MAGIC           0x3e889045565a9LL

 #define NBD_SET_SOCK            _IO(0xab, 0)
 #define NBD_SET_BLKSIZE         _IO(0xab, 1)
@@ -77,7 +78,9 @@
 #define NBD_SET_TIMEOUT         _IO(0xab, 9)
 #define NBD_SET_FLAGS           _IO(0xab, 10)

-#define NBD_OPT_EXPORT_NAME     (1 << 0)
+#define NBD_OPT_EXPORT_NAME     (1)
+#define NBD_OPT_ABORT           (2)
+#define NBD_OPT_LIST            (3)

 /* Definitions for opaque data types */

@@ -215,54 +218,98 @@ static ssize_t write_sync(int fd, void *buffer, size_t 
size)

 */

-static int nbd_receive_options(NBDClient *client)
+static int nbd_send_rep(int csock, uint32_t type, uint32_t opt)
 {
-    int csock = client->sock;
-    char name[256];
-    uint32_t tmp, length;
     uint64_t magic;
-    int rc;
-
-    /* Client sends:
-        [ 0 ..   3]   client flags
-        [ 4 ..  11]   NBD_OPTS_MAGIC
-        [12 ..  15]   NBD_OPT_EXPORT_NAME
-        [16 ..  19]   length
-        [20 ..  xx]   export name (length bytes)
-     */
+    uint32_t len;

-    rc = -EINVAL;
-    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
-        LOG("read failed");
-        goto fail;
+    magic = cpu_to_be64(NBD_REP_MAGIC);
+    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
+        LOG("write failed (rep magic)");
+        return -EINVAL;
     }
-    TRACE("Checking client flags");
-    tmp = be32_to_cpu(tmp);
-    if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
-        LOG("Bad client flags received");
-        goto fail;
+    opt = cpu_to_be32(opt);
+    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
+        LOG("write failed (rep opt)");
+        return -EINVAL;
     }
-
-    if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
-        LOG("read failed");
-        goto fail;
+    type = cpu_to_be32(type);
+    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
+        LOG("write failed (rep type)");
+        return -EINVAL;
     }
-    TRACE("Checking opts magic");
-    if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
-        LOG("Bad magic received");
-        goto fail;
+    len = cpu_to_be32(0);
+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
+        LOG("write failed (rep data length)");
+        return -EINVAL;
     }
+    return 0;
+}

-    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
-        LOG("read failed");
-        goto fail;
+static int nbd_send_rep_list(int csock, NBDExport *exp)
+{
+    uint64_t magic, name_len;
+    uint32_t opt, type, len;
+
+    name_len = strlen(exp->name);
+    magic = cpu_to_be64(NBD_REP_MAGIC);
+    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
+        LOG("write failed (magic)");
+        return -EINVAL;
     }
-    TRACE("Checking option");
-    if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
-        LOG("Bad option received");
-        goto fail;
+    opt = cpu_to_be32(NBD_OPT_LIST);
+    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
+        LOG("write failed (opt)");
+        return -EINVAL;
+    }
+    type = cpu_to_be32(NBD_REP_SERVER);
+    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
+        LOG("write failed (reply type)");
+        return -EINVAL;
+    }
+    len = cpu_to_be32(name_len + sizeof(len));
+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
+        LOG("write failed (length)");
+        return -EINVAL;
+    }
+    len = cpu_to_be32(name_len);
+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
+        LOG("write failed (length)");
+        return -EINVAL;
+    }
+    if (write_sync(csock, exp->name, name_len) != name_len) {
+        LOG("write failed (buffer)");
+        return -EINVAL;
+    }
+    return 0;
+}
+
+static int nbd_send_list(NBDClient *client)
+{
+    int csock;
+    NBDExport *exp;
+
+    csock = client->sock;
+    /* For each export, send a NBD_REP_SERVER reply. */
+    QTAILQ_FOREACH(exp, &exports, next) {
+        if (nbd_send_rep_list(csock, exp)) {
+            return -EINVAL;
+        }
     }
+    /* Finish with a NBD_REP_ACK. */
+    return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST);
+}
+
+static int nbd_handle_export_name(NBDClient *client)
+{
+    int rc = -EINVAL, csock = client->sock;
+    char name[256];
+    uint32_t length;

+    /* Client sends:
+        [16 ..  19]   length
+        [20 ..  xx]   export name (length bytes)
+     */
     if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
         LOG("read failed");
         goto fail;
@@ -287,8 +334,76 @@ static int nbd_receive_options(NBDClient *client)

     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
     nbd_export_get(client->exp);
+    rc = 0;
+fail:
+    return rc;
+}
+
+static int nbd_receive_options(NBDClient *client)
+{
+    int rc = -EINVAL;

-    TRACE("Option negotiation succeeded.");
+    while (1) {
+        int csock = client->sock;
+        uint32_t tmp;
+        uint64_t magic;
+
+        /* Client sends:
+            [ 0 ..   3]   client flags
+            [ 4 ..  11]   NBD_OPTS_MAGIC
+            [12 ..  15]   NBD option
+            ...           Rest of request
+        */
+
+        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
+            LOG("read failed");
+            goto fail;
+        }
+        TRACE("Checking client flags");
+        tmp = be32_to_cpu(tmp);
+        if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
+            LOG("Bad client flags received");
+            goto fail;
+        }
+
+        if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
+            LOG("read failed");
+            goto fail;
+        }
+        TRACE("Checking opts magic");
+        if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
+            LOG("Bad magic received");
+            goto fail;
+        }
+
+        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
+            LOG("read failed");
+            goto fail;
+        }
+
+        TRACE("Checking option");
+        switch (be32_to_cpu(tmp)) {
+        case NBD_OPT_LIST:
+            if (nbd_send_list(client) < 0) {
+                return -EINVAL;
+            }
+            break;

You can just do "return nbd_send_list(client);" here. You probably should also rename the function to nbd_handle_list.

+        case NBD_OPT_ABORT:
+            return 1;
+
+        case NBD_OPT_EXPORT_NAME:
+            return nbd_handle_export_name(client);

Part of this patch belongs in patch 1. This one should only add nbd_send_rep_list, nbd_handle_list and the NBD_OPT_LIST case.

Paolo

+        default:
+            tmp = be32_to_cpu(tmp);
+            LOG("Unsupported option 0x%x", tmp);
+            if (nbd_send_rep(client->sock, NBD_REP_ERR_UNSUP, tmp)) {
+                return -EINVAL;
+            }
+            return 1;
+        }
+    }
     rc = 0;
 fail:
     return rc;
@@ -351,6 +466,8 @@ static int nbd_send_negotiate(NBDClient *client)
         if (rc < 0) {
             LOG("option negotiation failed");
             goto fail;
+        } else if (rc > 0) {
+            goto fail;
         }

         assert ((client->exp->nbdflags & ~65535) == 0);
@@ -1175,7 +1292,7 @@ NBDClient *nbd_client_new(NBDExport *exp, int csock,
     client->refcount = 1;
     client->exp = exp;
     client->sock = csock;
-    if (nbd_send_negotiate(client) < 0) {
+    if (nbd_send_negotiate(client)) {
         g_free(client);
         return NULL;
     }





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