Re: [linux-minidisc] "netmdcli send" does not break on errors

[Thomas Arp <manner.moe@gmx.de>]

Am 17/09/2011 20:51, schrieb John Paul Adrian Glaubitz:
> However, before we make any bigger changes to netmdcli/libnetmd, the
> code will need some further cleanup first. There is some code in netmdcli
> which I think should rather go into libnetmd. I was particularly thinking
> about the code which sets up the secure session and sends a track
> to the device. That should probably better go into libnetmd, so we
> avoid reinventing the wheel over and over again when using libnetmd
> in other applications.
> ...
> Adrian
As it seems that reading disc flags is generally missing in the current 
status of libnetmd i first made a small patch to implement this.
But you are right. The key generation/exchange mechanism should go into 
libnetmd. Maybe we should provide something like netmd_start_session() 
and netmd_end_session() externally which set up and clean a secure 
session  inside libnetmd.

Thomas

>From 8d5780c60f4694ce8468dd44e3bc684a09ad010d Mon Sep 17 00:00:00 2001
From: Thomas Arp <manner.moe@gmx.de>
Date: Sun, 18 Sep 2011 16:25:00 +0200
Subject: [PATCH] integrate reading disc flags in netmd_initialize_disc_info()

---
 libnetmd/libnetmd.c |   25 +++++++++++++++++++++++++
 libnetmd/libnetmd.h |    1 +
 netmdcli/netmdcli.c |   18 +++++++++++++++++-
 3 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/libnetmd/libnetmd.c b/libnetmd/libnetmd.c
index 0291cbe..6d57ad1 100644
--- a/libnetmd/libnetmd.c
+++ b/libnetmd/libnetmd.c
@@ -131,6 +131,25 @@ static int request_disc_title(netmd_dev_handle* dev, char* buffer, size_t size)
     return (int)title_size - 25;
 }
 
+int request_disc_flags(netmd_dev_handle* dev)
+{
+    int ret = -1;
+    unsigned char disc_flags_request[] = {0x00, 0x18, 0x06, 0x01, 0x10, 0x10,
+                                          0x00, 0xff, 0x00, 0x00, 0x01, 0x00,
+                                          0x0b  };
+    unsigned char flags[14];
+
+    ret = netmd_exch_message(dev, disc_flags_request, 0x0d, flags);
+
+    if(ret < 0 || flags[7] != 0x10)
+    {
+        fprintf(stderr, "request_disc_flags: bad ret code\n");
+        return 0;
+    }
+
+    return flags[13] & 0xff;
+}
+
 int netmd_request_track_time(netmd_dev_handle* dev, const uint16_t track, struct netmd_track* buffer)
 {
     int ret = 0;
@@ -329,6 +348,12 @@ int netmd_initialize_disc_info(netmd_dev_handle* devh, minidisc* md)
         set_group_data(md, 0, "<Untitled>", 0, 0);
     }
 
+    disc_flags = request_disc_flags(devh);
+    if (disc_flags & NETMD_DISC_FLAG_WRITE_PROTECTED)
+        md->writable = 0;
+    else
+        md->writable = 1; /* try to use disc as not write protected else if disc flags cannot be read */
+
     return disc_size;
 }
 
diff --git a/libnetmd/libnetmd.h b/libnetmd/libnetmd.h
index 52f7edb..2becb8e 100644
--- a/libnetmd/libnetmd.h
+++ b/libnetmd/libnetmd.h
@@ -81,6 +81,7 @@ typedef struct {
     size_t header_length;
     struct netmd_group *groups;
     unsigned int group_count;
+    int writable;
 } minidisc;
 
 
diff --git a/netmdcli/netmdcli.c b/netmdcli/netmdcli.c
index 60f1d81..ed43e8b 100644
--- a/netmdcli/netmdcli.c
+++ b/netmdcli/netmdcli.c
@@ -168,6 +168,13 @@ void retailmac(unsigned char *rootkey, unsigned char *hostnonce,
     gcry_cipher_close(handle2);
 }
 
+static void cleanup(minidisc *md, netmd_dev_handle *devh, netmd_device *device_list)
+{
+    netmd_clean_disc_info(md);
+    netmd_close(devh);
+    netmd_clean(&device_list);
+}
+
 int main(int argc, char* argv[])
 {
     netmd_dev_handle* devh;
@@ -212,7 +219,8 @@ int main(int argc, char* argv[])
     printf("%s\n", name);
 
     netmd_initialize_disc_info(devh, md);
-    printf("Disc Title: %s\n\n", md->groups[0].name);
+    printf("Disc Title: %s\n", md->groups[0].name);
+    printf("Protection status: %s\n\n", (md->writable ? "writable" : "write protected"));
 
     /* by default, log only errors */
     netmd_set_log_level(NETMD_LOG_ERROR);
@@ -441,6 +449,14 @@ int main(int argc, char* argv[])
             unsigned char uuid[8] = { 0 };
             unsigned char new_contentid[20] = { 0 };
 
+            /* check if disc is write protected first */
+            if(!md->writable)
+            {
+                printf("Cannot send track: disc is write protected\n");
+                cleanup(md, devh, device_list);
+                return -1;
+            }
+
             error = netmd_secure_leave_session(devh);
             puts(netmd_strerror(error));
 
-- 
1.7.6.msysgit.0