commit f7616315ea0caf514b2e2927f196392891748e2f
author Orit Kashany <okashany@nvidia.com> Sun Aug 24 04:48:41 2025 -0700
committer Orit Kashany <okashany@nvidia.com> Tue Aug 26 01:36:32 2025 -0700
tree 645b244a8dded4e762cdf5b5be6b3571e26011aa
parent 5659dda70999bc6ca9fb52fb22dac1f2fb6c47a7

Fix handling of 16-byte IPMI username without null terminator

The IPMI spec defines username as a fixed 16-byte field,
which may not contain a null terminator if the name length
is exactly 16 characters.
Several places in the code assumed C-string semantics
(null terminated), causing incorrect user data reading and
comparisons.

This change:
1. Replaces incorrect
std::string(const char *, size_t pos, size_t count),
which does not exist, with length-safe
strnlen + std::string(char *, size_t count).
These are the relevant constructors exist:
std::string(const char* s, size_t count)
std::string(const std::string& str, size_t pos, size_t count).
The old code used the second constructor with char *,
which led to unexpected behaviors.

2. Replaces strncpy and unsafe std::fill casts with
explicit zero padding memset and memcpy.

3. Ensures reads stop at the first null or take the full
16 bytes in case there is no null.

This ensures storage, retrieval and comparison of all valid
IPMI usernames, including the edge case of exactly 16
characters with no null terminator.

Tested on bluefield BMC platform:
```
root@dpu-bmc:~# ipmitool user set name 10 firmware_updater
root@dpu-bmc:~# ipmitool user list 1
ID  Name             Call    Link Auth  IPMI Msg   Channel Priv Limit
1   root             false   true       true       ADMINISTRATOR
2                    true    false      false      NO ACCESS
3                    true    false      false      NO ACCESS
4                    true    false      false      NO ACCESS
5                    true    false      false      NO ACCESS
6                    true    false      false      NO ACCESS
7                    true    false      false      NO ACCESS
8                    true    false      false      NO ACCESS
9                    true    false      false      NO ACCESS
10  firmware_updater true    false      false      USER
11                   true    false      false      NO ACCESS
12                   true    false      false      NO ACCESS
13                   true    false      false      NO ACCESS
14                   true    false      false      NO ACCESS
15                   true    false      false      NO ACCESS
root@dpu-bmc:~# ipmitool user set name 10 ""
root@dpu-bmc:~# ipmitool user list 1
ID  Name             Call    Link Auth  IPMI Msg   Channel Priv Limit
1   root             false   true       true       ADMINISTRATOR
2                    true    false      false      NO ACCESS
3                    true    false      false      NO ACCESS
4                    true    false      false      NO ACCESS
5                    true    false      false      NO ACCESS
6                    true    false      false      NO ACCESS
7                    true    false      false      NO ACCESS
8                    true    false      false      NO ACCESS
9                    true    false      false      NO ACCESS
10                   true    false      false      NO ACCESS
11                   true    false      false      NO ACCESS
12                   true    false      false      NO ACCESS
13                   true    false      false      NO ACCESS
14                   true    false      false      NO ACCESS
15                   true    false      false      NO ACCESS
root@dpu-bmc:~# ipmitool user set name 4 testuser
root@dpu-bmc:~# ipmitool user set password 4 "Aa1234567890!!"
Set User Password command successful (user 4)
root@dpu-bmc:~# ipmitool channel setaccess 1 4 link=on ipmi=on privilege=4
Set User Access (channel 1 id 4) successful.
root@dpu-bmc:~# ipmitool user enable 4
root@dpu-bmc:~# ipmitool channel getaccess 1 4
Maximum User IDs     : 15
Enabled User IDs     : 2

User ID              : 4
User Name            : testuser
Fixed Name           : No
Access Available     : callback
Link Authentication  : enabled
IPMI Messaging       : enabled
Privilege Level      : ADMINISTRATOR
Enable Status        : enabled

On host:

root@ldev-platform-12:~# ipmitool -I lanplus -H <bmc_ip> -U testuser -P 'Aa1234567890!!' -C 17 power status
Chassis Power is on
```

Change-Id: Ib678bdcca1d88289d5c8ce414876563d5fead4ad
Signed-off-by: Orit Kashany <okashany@nvidia.com>