From 0d054955d48711279e152e123a5aa75cbb49b60c Mon Sep 17 00:00:00 2001
From: drfrugal <drfrugal@karazhan>
Date: Fri, 7 Mar 2025 21:15:18 +0100
Subject: init

---
 cli/Cargo.toml  |   8 ++++
 cli/src/main.rs | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 cli/Cargo.toml
 create mode 100644 cli/src/main.rs

(limited to 'cli')

diff --git a/cli/Cargo.toml b/cli/Cargo.toml
new file mode 100644
index 0000000..e84f99e
--- /dev/null
+++ b/cli/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "zlib-header-cli"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+clap = { version = "4.5.30", features = ["derive"] }
+zlib-header = { path = "../lib" }
diff --git a/cli/src/main.rs b/cli/src/main.rs
new file mode 100644
index 0000000..9392372
--- /dev/null
+++ b/cli/src/main.rs
@@ -0,0 +1,112 @@
+//! CLI to print details about the 2 Byte zlib header, as defined in
+//! [RFC 1950](https://datatracker.ietf.org/doc/html/rfc1950).  
+//! This was initially written to reverse-engineer more details about Blizzard's proprietary MPQ
+//! archive format, which uses zlib streams to store data.  
+//! ```
+//! Usage: zlib-header-cli [OPTIONS] [HEX4CHAR]
+//!
+//! Arguments:
+//! [HEX4CHAR]  A four-character hex string representing the ZlibHeader (Big Endian)
+//!
+//! Options:
+//!   -e, --explain  Explain the ZlibHeader struct and abbreviations
+//!   -h, --help     Print help
+//! ```
+//! ```
+//! drfrugal@karazhan:~$ zlib-header-cli 789C
+//! CM      8 (DEFLATE)
+//! CINFO   7 (Window: 32768 Bytes)
+//! FCHECK  28 (valid)
+//! FDICT   false (Preset Dictionary not used)
+//! FLEVEL  2 (default)
+//! ```
+//! ```
+//! drfrugal@karazhan:~$ zlib-header-cli --explain
+//! 2 Byte zlib header according to https://datatracker.ietf.org/doc/html/rfc1950
+//! 1st Byte - CMF (Compression Method and Flags)
+//!   0000_1111  CM      Compression Method   8, _ (DEFLATE, UNDEFINED)
+//!   1111_0000  CINFO   Compression Info     window size is 2.pow(CINFO + 8)
+//! 2nd Byte - FLG (Flags)
+//!   0001_1111  FCHECK  Checksum Adjustment  valid if (CMF * 256 + FLG) % 31 == 0
+//!   0010_0000  FDICT   Preset Dictionary    a preset dictionary was used
+//!   1100_0000  FLEVEL  Compression Level    0, 1, 2, 3 (fastest, fast, default, best)
+//! ```
+
+use clap::Parser;
+use zlib_header::ZlibHeader;
+
+#[derive(Debug, Parser)]
+pub struct Cli {
+    /// Explain the ZlibHeader struct and abbreviations
+    #[arg(short, long)]
+    explain: bool,
+
+    /// A four-character hex string representing the ZlibHeader (Big Endian)
+    #[arg(required_unless_present = "explain")]
+    hex4char: Option<String>,
+}
+
+pub fn main() {
+    let args = Cli::parse();
+    if args.explain {
+        explain();
+    }
+    let header = match args.hex4char {
+        Some(hex) => match ZlibHeader::from_hex(&hex) {
+            Ok(header) => header,
+            Err(err) => {
+                eprintln!("{}", err);
+                return;
+            }
+        },
+        None => {
+            return;
+        }
+    };
+    if args.explain {
+        println!();
+    }
+    let cm = header.get_cm();
+    let algorithm = header.get_cm_str();
+    let cinfo = header.get_cinfo();
+    let window = header.get_window_size();
+    let fcheck = header.get_fcheck();
+    let valid = if header.is_valid() {
+        "valid"
+    } else {
+        "not valid"
+    };
+    let fdict = header.get_fdict();
+    let dict = if fdict { "used" } else { "not used" };
+    let flevel = header.get_flevel();
+    let level = header.get_flevel_str();
+    println!("CM      {} ({})", cm, algorithm);
+    println!("CINFO   {} (Window: {} Bytes)", cinfo, window);
+    println!("FCHECK  {} ({})", fcheck, valid);
+    println!("FDICT   {} (Preset Dictionary {})", fdict, dict);
+    println!("FLEVEL  {} ({})", flevel, level);
+
+    let cm = 8;
+    let cinfo = 7;
+    let fdict = false;
+    let flevel = 2;
+    let header = ZlibHeader::new(cm, cinfo, fdict, flevel);
+    match header {
+      Ok(header) => {
+        println!("header is valid (strict): {}", header.is_valid_strict()); // 
+      },
+      Err(err) => eprintln!("Unable to initialize zlib header: {:?}", err)
+    }
+}
+
+/// Prints a few lines in order to explain the ZlibHeader struct.
+pub fn explain() {
+    println!("2 Byte zlib header as defined in https://datatracker.ietf.org/doc/html/rfc1950");
+    println!("1st Byte - CMF (Compression Method and Flags)");
+    println!("  0000_1111  CM      Compression Method   8, _ (DEFLATE, UNDEFINED)");
+    println!("  1111_0000  CINFO   Compression Info     window size is 2.pow(CINFO + 8)");
+    println!("2nd Byte - FLG (Flags)");
+    println!("  0001_1111  FCHECK  Checksum Adjustment  valid if (CMF * 256 + FLG) % 31 == 0");
+    println!("  0010_0000  FDICT   Preset Dictionary    a preset dictionary was used");
+    println!("  1100_0000  FLEVEL  Compression Level    0, 1, 2, 3 (fastest, fast, default, best)");
+}
-- 
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