[Qemu-devel] [PATCH 2/2] nbd: Handle NBD_OPT_LIST option.

[Hani Benhabiles <kroosec@gmail.com>]

Signed-off-by: Hani Benhabiles <hani@linux.com>
---
 include/block/nbd.h |  4 +++
 nbd.c               | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 99 insertions(+), 2 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 95d52ab..23e9a84 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -51,6 +51,10 @@ 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_CMD_MASK_COMMAND	0x0000ffff
 #define NBD_CMD_FLAG_FUA	(1 << 16)
 
diff --git a/nbd.c b/nbd.c
index fb0a9cf..9150fa6 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 +78,8 @@
 #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_LIST            (3)
 
 /* Definitions for opaque data types */
 
@@ -215,6 +217,88 @@ static ssize_t write_sync(int fd, void *buffer, size_t size)
 
 */
 
+static int nbd_send_rep_ack(int csock)
+{
+    uint64_t magic;
+    uint32_t opt, type, len;
+
+    magic = cpu_to_be64(NBD_REP_MAGIC);
+    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
+        LOG("write failed (rep magic)");
+        return -EINVAL;
+    }
+    opt = cpu_to_be32(NBD_OPT_LIST);
+    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
+        LOG("write failed (opt list)");
+        return -EINVAL;
+    }
+    type = cpu_to_be32(NBD_REP_ACK);
+    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
+        LOG("write failed (rep ack)");
+        return -EINVAL;
+    }
+    len = cpu_to_be32(0);
+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
+        LOG("write failed (rep data length)");
+        return -EINVAL;
+    }
+    return 0;
+}
+
+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;
+    }
+    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_ack(csock);
+}
+
 static int nbd_receive_options(NBDClient *client)
 {
     int csock = client->sock;
@@ -258,6 +342,13 @@ static int nbd_receive_options(NBDClient *client)
         goto fail;
     }
     TRACE("Checking option");
+    if (tmp == be32_to_cpu(NBD_OPT_LIST)) {
+        if (nbd_send_list(client) < 0) {
+            return -EINVAL;
+        } else {
+            return 1;
+        }
+    }
     if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
         LOG("Bad option received");
         goto fail;
@@ -351,6 +442,8 @@ 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 +1268,7 @@ 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;
     }
-- 
1.8.3.2