From 735fd57bba83a356e5975001d6ca8df414413eec Mon Sep 17 00:00:00 2001
From: ohaddahan <ohaddahan@gmail.com>
Date: Fri, 2 Sep 2022 09:55:34 +0300
Subject: [PATCH] init

---
 .gitignore     |  3 +++
 Cargo.toml     |  9 +++++++++
 src/errors.rs  |  0
 src/lib.rs     | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 src/structs.rs | 15 +++++++++++++++
 src/utils.rs   | 33 +++++++++++++++++++++++++++++++++
 6 files changed, 107 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 src/errors.rs
 create mode 100644 src/lib.rs
 create mode 100644 src/structs.rs
 create mode 100644 src/utils.rs

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..df49965
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/target
+/Cargo.lock
+.idea
\ No newline at end of file
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..3f21994
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "solana-sandwich"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+solana-program = "1.11.10"
diff --git a/src/errors.rs b/src/errors.rs
new file mode 100644
index 0000000..e69de29
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..689dd9c
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,47 @@
+mod errors;
+mod structs;
+mod utils;
+
+use crate::structs::{AllowedRules, InstructionsData};
+use crate::utils::load_instruction_data;
+use solana_program::account_info::AccountInfo;
+use solana_program::program_error::ProgramError;
+use solana_program::sysvar::instructions::load_instruction_at_checked;
+
+pub fn allowed_only<'a>(
+    instruction_sysvar_account: &'a AccountInfo<'a>,
+    rules: Vec<AllowedRules>,
+) -> Result<bool, ProgramError> {
+    let instruction_data = load_instruction_data(instruction_sysvar_account)?;
+
+    for index in 0..instruction_data.num_of_instructions {
+        let instruction = load_instruction_at_checked(index as usize, instruction_sysvar_account)?;
+        let rule: &AllowedRules = match rules
+            .iter()
+            .find(|rule| rule.program == instruction.program_id)
+        {
+            Some(r) => r,
+            None => {
+                return Ok(false);
+            }
+        };
+
+        if !rule.before && index > instruction_data.current_index {
+            return Ok(false);
+        }
+        if !rule.after && index < instruction_data.current_index {
+            return Ok(false);
+        }
+    }
+
+    Ok(true)
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        let result = 2 + 2;
+        assert_eq!(result, 4);
+    }
+}
diff --git a/src/structs.rs b/src/structs.rs
new file mode 100644
index 0000000..a4afa57
--- /dev/null
+++ b/src/structs.rs
@@ -0,0 +1,15 @@
+use solana_program::account_info::AccountInfo;
+use solana_program::pubkey::Pubkey;
+
+pub struct AllowedRules {
+    pub program: Pubkey,
+    pub before: bool,
+    pub after: bool,
+}
+
+pub struct InstructionsData<'a> {
+    pub current_program: Pubkey,
+    pub current_index: u16,
+    pub num_of_instructions: u16,
+    pub instruction_sysvar_account: &'a AccountInfo<'a>,
+}
diff --git a/src/utils.rs b/src/utils.rs
new file mode 100644
index 0000000..027f293
--- /dev/null
+++ b/src/utils.rs
@@ -0,0 +1,33 @@
+use crate::InstructionsData;
+use solana_program::account_info::AccountInfo;
+use solana_program::program_error::ProgramError;
+use solana_program::serialize_utils::read_u16;
+use solana_program::sysvar::instructions::{
+    load_current_index_checked, load_instruction_at_checked,
+};
+
+pub fn load_instruction_data<'a>(
+    instruction_sysvar_account: &'a AccountInfo<'a>,
+) -> Result<InstructionsData<'a>, ProgramError> {
+    let data = instruction_sysvar_account.try_borrow_data()?;
+    let current_index = load_current_index_checked(instruction_sysvar_account)?;
+    let instruction =
+        load_instruction_at_checked(current_index as usize, instruction_sysvar_account)?;
+    let mut current = 0;
+    let num_of_instructions= match read_u16(&mut current, &**data) {
+        Ok(index) => {
+            index
+        }
+        Err(_) => {
+            return Err(ProgramError::InvalidArgument);
+            // return Err(ReadingNumInstructionsError);
+        }
+    };
+
+    Ok(InstructionsData {
+        current_program: instruction.program_id,
+        current_index,
+        num_of_instructions,
+        instruction_sysvar_account,
+    })
+}