From 085777ee9c739895b15b8db17a629826c469facd Mon Sep 17 00:00:00 2001
From: Andrew Walbran <qwandor@google.com>
Date: Tue, 21 Nov 2023 14:06:43 +0000
Subject: Import asn1-rs-impl crate.

Request Document: go/android-rust-importing-crates
For CL Reviewers: go/android3p#cl-review
For Build Team: go/ab-third-party-imports
Bug: 312436741
Test: Treehugger

Change-Id: Ie6e96450b8bd28dfaec21f2a9af7d3827af8c2ca
---
 src/lib.rs | 126 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 src/lib.rs

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..ea635cc
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,126 @@
+extern crate proc_macro;
+use proc_macro::{Span, TokenStream};
+use syn::{parse_macro_input, Error, LitInt};
+
+#[proc_macro]
+pub fn encode_oid(input: TokenStream) -> TokenStream {
+    let token_stream = input.to_string();
+    let (s, relative) = if token_stream.starts_with("rel ") {
+        (&token_stream[4..], true)
+    } else {
+        (token_stream.as_ref(), false)
+    };
+    let items: Result<Vec<_>, _> = s.split('.').map(|x| x.trim().parse::<u128>()).collect();
+    let mut items: &[_] = match items.as_ref() {
+        Ok(v) => v.as_ref(),
+        Err(_) => return create_error("Could not parse OID"),
+    };
+    let mut v = Vec::new();
+    if !relative {
+        if items.len() < 2 {
+            if items.len() == 1 && items[0] == 0 {
+                return "[0]".parse().unwrap();
+            }
+            return create_error("Need at least two components for non-relative oid");
+        }
+        if items[0] > 2 || items[1] > 39 {
+            return create_error("First components are too big");
+        }
+        let first_byte = (items[0] * 40 + items[1]) as u8;
+        v.push(first_byte);
+        items = &items[2..];
+    }
+    for &int in items {
+        let enc = encode_base128(int);
+        v.extend_from_slice(&enc);
+    }
+    // "fn answer() -> u32 { 42 }".parse().unwrap()
+    let mut s = String::with_capacity(2 + 6 * v.len());
+    s.push('[');
+    for byte in v.iter() {
+        s.insert_str(s.len(), &format!("0x{:02x}, ", byte));
+    }
+    s.push(']');
+    s.parse().unwrap()
+}
+
+#[inline]
+fn create_error(msg: &str) -> TokenStream {
+    let s = format!("Invalid OID({})", msg);
+    Error::new(Span::call_site().into(), &s)
+        .to_compile_error()
+        .into()
+}
+
+// encode int as base128
+fn encode_base128(int: u128) -> Vec<u8> {
+    let mut val = int;
+    let mut base128 = Vec::new();
+    let lo = val & 0x7f;
+    base128.push(lo as u8);
+    val >>= 7;
+    loop {
+        if val == 0 {
+            base128.reverse();
+            return base128;
+        }
+        let lo = val & 0x7f;
+        base128.push(lo as u8 | 0x80);
+        val >>= 7;
+    }
+}
+
+#[proc_macro]
+pub fn encode_int(input: TokenStream) -> TokenStream {
+    let lit = parse_macro_input!(input as LitInt);
+
+    match impl_encode_int(lit) {
+        Ok(ts) => ts,
+        Err(e) => e.to_compile_error().into(),
+    }
+
+    // let token_stream = input.to_string();
+    // let items: Result<Vec<_>, _> = token_stream
+    //     .split('.')
+    //     .map(|x| x.trim().parse::<u64>())
+    //     .collect();
+    // let err = Error::new(Span::call_site().into(), "invalid OID");
+    // if let Ok(items) = items {
+    //     let mut v = Vec::new();
+    //     if items.len() < 2 || items[0] > 2 || items[1] > 39 {
+    //         return err.to_compile_error().into();
+    //     }
+    //     let first_byte = (items[0] * 40 + items[1]) as u8;
+    //     v.push(first_byte);
+    //     for &int in &items[2..] {
+    //         let enc = encode_base128(int);
+    //         v.extend_from_slice(&enc);
+    //     }
+    //     // "fn answer() -> u32 { 42 }".parse().unwrap()
+    //     let mut s = String::with_capacity(2 + 6 * v.len());
+    //     s.push('[');
+    //     for byte in v.iter() {
+    //         s.insert_str(s.len(), &format!("0x{:02x}, ", byte));
+    //     }
+    //     s.push(']');
+    //     s.parse().unwrap()
+    // } else {
+    //     eprintln!("could not parse OID '{}'", token_stream);
+    //     err.to_compile_error().into()
+    // }
+}
+
+fn impl_encode_int(lit: LitInt) -> Result<TokenStream, Error> {
+    let value = lit.base10_parse::<u64>()?;
+
+    let bytes = value.to_be_bytes();
+    let v: Vec<_> = bytes.iter().skip_while(|&c| *c == 0).collect();
+
+    let mut s = String::with_capacity(2 + 6 * v.len());
+    s.push('[');
+    for byte in v.iter() {
+        s.insert_str(s.len(), &format!("0x{:02x}, ", byte));
+    }
+    s.push(']');
+    Ok(s.parse().unwrap())
+}
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