feat: add cmd_elf

.gitignore

@@ -2,7 +2,7 @@
 # Generated by Cargo
 # will have compiled files and executables
 /target/
-
+sample_elf
 
 # These are backup files generated by rustfmt
 **/*.rs.bk

README.md

@@ -2,3 +2,11 @@
 
 Rust Cli - Rust command line util
 
+ELF
+* https://fasterthanli.me/series/making-our-own-executable-packer/part-1
+
+
+ELF format:
+![](https://playsecurity.org/getdoc/3969_4D1E689A0A238F3244FA46D98AF1C404/elf64-file-header.a08515d63bdb6e35.safe.svg)
+
+

src/cmd_elf.rs

@@ -0,0 +1,89 @@
+use std::io::Read;
+use std::fs::File;
+use clap::{ ArgMatches, SubCommand, App, Arg };
+use crate::cmd::{ Command, CommandError };
+
+pub struct CommandElf;
+
+// https://fasterthanli.me/series/making-our-own-executable-packer/part-1
+impl Command for CommandElf {
+
+    fn name(&self) -> &str { "elf" }
+
+    fn subcommand<'a>(&self) -> App<'a, 'a> {
+        SubCommand::with_name(self.name()).about("ELF subcommand")
+            .arg(Arg::with_name("FILE").required(true).index(1).help("ELF file"))
+    }
+
+    fn run(&self, _arg_matches: &ArgMatches, sub_arg_matches: &ArgMatches) -> CommandError {
+        let file_name = sub_arg_matches.value_of("FILE").unwrap();
+        let mut file = File::open(file_name)?;
+        let mut buf = vec![];
+        let len = file.read_to_end(&mut buf)?;
+
+        information!("File: {}, length: {}", file_name, len);
+
+        let elf_magic_number = buf.drain(0..4).collect::<Vec<_>>();
+        if vec![0x7f, 0x45/*'E'*/, 0x4c/*'L'*/, 0x46/*'F'*/] != elf_magic_number {
+            failure!("File not ELF file: {}", file_name);
+            return Ok(());
+        }
+        let class = buf.remove(0);
+        if class == 0x01 || class == 0x02 {
+            information!("File class is: {}", iff!(class == 0x01, "x86", "x64"));
+        } else {
+            failure!("File is not x86 or x64: {}", file_name);
+            return Ok(());
+        }
+        let endian = buf.remove(0);
+        if endian == 0x01 || endian == 0x02 {
+            information!("File endian is: {}", iff!(class == 0x01, "LittleEndian", "BigEndian"));
+        } else {
+            failure!("File is not Little or Big Endian: {}", file_name);
+            return Ok(());
+        }
+        let version = buf.remove(0);
+        information!("File version: {}", version);
+        let abi = buf.remove(0);
+        information!("File ABI: {}", abi);
+        let padding = buf.drain(0..8).collect::<Vec<_>>();
+        information!("File padding: {:?}", padding);
+        let ty = u16::from_le_bytes([buf.remove(0), buf.remove(0)]);
+        information!("File type: {}", match ty {
+            0x0 => "NONE".into(),
+            0x1 => "REL".into(),
+            0x2 => "EXEC".into(),
+            0x3 => "DYN".into(),
+            0x4 => "CORE".into(),
+            _ => format!("unknown: {}", ty),
+        });
+        let machine = u16::from_le_bytes([buf.remove(0), buf.remove(0)]);
+        information!("File machine: {}", match machine {
+            0x03 => "x86".into(),
+            0x3e => "x86-64".into(),
+            _ => format!("unknown: {}", machine),
+        });
+        let encore_version = u32::from_le_bytes([buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0)]);
+        information!("File encore version: {}", encore_version);
+        let entry_point = u64::from_le_bytes([buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0),
+                                              buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0)]);
+        information!("File entry point: {}", entry_point);
+        let table_offset_first_program_header_entry = u64::from_le_bytes([buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0),
+                                              buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0)]);
+        information!("File table offset fist program header entry: {}", table_offset_first_program_header_entry);
+        let table_offset_first_section_header_entry = u64::from_le_bytes([buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0),
+                                              buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0)]);
+        information!("File table offset fist section header entry: {}", table_offset_first_section_header_entry);
+        let flags = u32::from_le_bytes([buf.remove(0), buf.remove(0), buf.remove(0), buf.remove(0)]);
+        information!("File flags: {}", flags);
+        let header_size = u16::from_le_bytes([buf.remove(0), buf.remove(0)]);
+        information!("File header size: {}", header_size);
+        let entry_size = u16::from_le_bytes([buf.remove(0), buf.remove(0)]);
+        information!("File entry size: {}", entry_size);
+        let number_of_entries = u16::from_le_bytes([buf.remove(0), buf.remove(0)]);
+        information!("File number of entries: {}", number_of_entries);
+
+
+        Ok(())
+    }
+}

src/main.rs

@@ -1,16 +1,19 @@
+#[macro_use] extern crate rust_util;
+
 use clap::App;
 
 mod cmd;
+mod cmd_elf;
 mod cmd_show;
 mod cmd_default;
 
-use cmd::{ Command, CommandError, };
+use cmd::{ Command, CommandError };
-use cmd_show::CommandShow;
 use cmd_default::CommandDefault;
 
 fn main() -> CommandError {
     let commands: Vec<Box<dyn Command>> = vec![
-        Box::new(CommandShow),
+        Box::new(cmd_elf::CommandElf),
+        Box::new(cmd_show::CommandShow),
     ];
     let mut app = App::new(env!("CARGO_PKG_NAME"))
                     .version(env!("CARGO_PKG_VERSION"))