A key-value database (For miniLCTF 2022)

A CTF challenge for miniLCTF 2022：https://github.com/XDSEC/miniLCTF_2022/tree/main/Challenges/kvdb

Easy key-value database written in C/C++ language.

Doc

0x00 Opcodes

• ADD: Add a new kvpair to database.
• DEL: Delete a kvpair fromm database by key.
• MDF: Modify a kvpair's value.
• RNM: Rename a kvpair's key.
• CPY: Copy kvpair.
• GET: Get value by key.
• DUMP: Dump all kvpair in an array.
• SHUT: Close current TCP connection.

In kvdb.h:

#define OPCODE_ADD "ADD"
#define OPCODE_DELETE "DEL"
#define OPCODE_MODIFY "MDF"
#define OPCODE_RENAME "RNM"
#define OPCODE_COPY "CPY"
#define OPCODE_GET "GET"
#define OPCODE_DUMP "DUMP"
#define OPCODE_CLEAR "CLR"
#define OPCODE_SHUTDOWN "SHUT"

0x01 Protocol (TCP)

In big endian

Data Format

1. Integer data format

<data_type(16 bits)>|<integer(64 bits)>

2. Float data format

<data_type(16 bits)>|<float(64 bits)>

3. String data format (integer, float, string)

<data_type(16 bits)>|<str_len(32 bits)>|[char(8 bits)]*str_len

4. Array format

<data_type(16 bits)>|<counts(32 bits)>|[data]*counts

5. Empty data

<data_type>

In kvdb.h:

#define DATA_TYPE_EMPTY 0x0
#define DATA_TYPE_INTEGER 0x1
#define DATA_TYPE_FLOAT 0x2
#define DATA_TYPE_STRING 0x3
#define DATA_TYPE_ARRAY 0x4
#define DATA_TYPE_TERM 0xff

Clitnt Message Format

"KVDB"|<op len(16 bits)>|<opcode>|[data]*n

N indicates the number of parameters. Please refer to supported methods.

Server Message Format

"KVDB"|data

The reason for the query failure will be returned in string data format

Supported methods

1. ADD(KEY,VALUE)
2. DEL(KEY)
3. MDF(KEY)
4. RNM(OLD_KEY, NEW_KEY)
5. CPY(SRC_KEY, DST, KEY)
6. GET(KEY)
7. DUMP()
8. CLR()
9. SHUT()

0x02 Build

1. git clone https://github.com/yikesoftware/kvdb

2. cd kvdb

3. make

   • Release: make
   • Debug: make debug
     • This will show data_t construction info and handler return in stderr.
   • Disable optimization: make noopt