Category: Rust

【Rust】Option型のunwrap

unwrap()は、OptionがSomeの場合はその中の値を返し、Noneの場合はパニックを引き起こす。

fn main(){
    let value = Some(10);
    let v = value.unwrap();
    println!("v: {}", v);
}

【Rust】Rustのunwrapとは？

Rustの「unwrap」と「?」はエラーハンドリングに使われる方法
unwrapはOption型やResult型の値がSomeやOkであることを前提として値を取り出す。NoneやErrだった場合は、panic!マクロが呼ばれてプログラムがクラッシュする。
?演算子は、Okの場合は値を返し、Errの場合はそのErrを呼び出し元に返す。

なるほど、OptionとResultがわかってないと、unwrapと?もさっぱり理解できませんね。。

【Rust】Result型

Resultは、失敗するかもしれない処理の結果を表現する列挙型。

enum Result<T, E>{
    Ok(T),
    Err(E),
}

fn get_value_bad(v: bool, result: &mut usize) -> usize {
    if v {
        *result = 100;
        true
    } else {
        false
    }
}

fn get_value_good(v: bool) -> Result<usize, &'static str> {
    if v {
        OK(100)
    } else {
        Err("error message")
    }
}

fn main(){
    let mut result = 0;
    if get_value_bad(true, &mut result){
        println!("success: {}", result);
    } else {
        println!("failure");
    }

    match get_value_good(true){
        Ok(result) => println!("success: {}", result),
        Err(msg) => println!("failure")
    }
}

fn plus_one(x: Option<i32>) -> Option<i32> {
    match x {
        None => None,
        Some(i) => Some(i + 1),
    }
}

fn main(){
    let five = Some(5);
    let six = plus_one(five);
    let none = plus_one(None);
}

use std::fs::File;

fn main(){
    let f = File::open("hello.txt");

    let _f = match f {
        Ok(file) => file,
        Err(error) => {
            panic!("There was a problem opening the file: {:?}", error);
        }
    };
}

OptionはSome, None, ResultはOk, Errで共にエラーハンドリングなどで使うのね。

【Rust】Option型

無効な値を取ることができる便利な列挙型としてOption型がある。

enum Option<T>{
    Some(T),
    None,
}

まず列挙型について
C++の列挙型

#include <stdio.h>

enum week {
    Mon,
    Tue,
    Wed,
    Thu,
    Fri,
    Sat,
    Sun,
};

int main(void) {
    enum week wk0, wk1, wk2;

    wk0 = Mon;
    wk1 = Tue;
    wk2 = Thu;

    printf("Monの値は:%d\n", wk0);
    printf("Tueの値は:%d\n", wk1);
    printf("Thuの値は:%d\n", wk2);
}

#[derive(Debug)]
enum Week {
    Mon,
    Tue,
    Wed,
    Thu,
    Fri,
    Sat,
    Sun
}

fn main(){
    let wk0 = Week::Mon;
    let wk1 = Week::Tue;
    let wk2 = Week::Thu;

    println!("Monの値は{:?}", wk0);
    println!("Tueの値は{:?}", wk1);
    println!("Wedの値は{:?}", wk2);
}

$ ./main
Monの値はMon
Tueの値はTue
Wedの値はThu
rustだと、c++のように0,1,2…ではなく、値がそのまま出てくる。

### Option
取得できないかもしれない値を表現する列挙型
値が無いことを示すNoneと、あることを示すSome(T)のどちらかを取る

pub enum Option<T> {
    None,
    Some(T),
}

fn get_value_bad(v: bool, result: &mut usize) -> bool {
    if v {
        *result = 100;
        true
    } else {
        false
    }
}

fn get_value_good(v: bool) -> Option<usize> {
    if v {
        Some(100)
    } else {
        None
    }
}

fn main(){
    let mut result = 0;
    if get_value_bad(true, &mut result){
        println!("success: {}", result);
    } else {
        println!("failure");
    }

    match get_value_good(true){
        Some(result) => println!("success: {}", result),
        None => println!("failure")
    }
}

【Rust】RustでWebサーバを作る

$ cargo new hello –bin

use std::net::TcpListener;

fn main() {
    let listner = TcpListener::bind("127.0.0.1:7878").unwrap();

    for stream in listner.incoming() {
        let stream = stream.unwrap();
        println!("Connection established!");
    }
}

ターミナルから、リクエストを送信する
$ ping http://127.0.0.1:7878/
ping: http://127.0.0.1:7878/: Name or service not known

すると、サーバ側では、
Running `target/debug/hello`
Connection established!
Connection established!
Connection established!
Connection established!
…

use std::io::prelude::*;
use std::net::TcpStream;
use std::net::TcpListener;

fn main() {
    let listner = TcpListener::bind("127.0.0.1:7878").unwrap();

    for stream in listner.incoming() {
        let stream = stream.unwrap();
        handle_connection(stream);
    }
}

fn handle_connection(mut stream: TcpStream) {
    let mut buffer = [0; 1024];

    stream.read(&mut buffer).unwrap();

    println!("Request: {}", String::from_utf8_lossy(&buffer[..]));
}

fn handle_connection(mut stream: TcpStream) {
    let mut buffer = [0; 1024];
    stream.read(&mut buffer).unwrap();

    let mut file = File::open("hello.html").unwrap();

    let mut contents = String::new();
    file.read_to_string(&mut contents).unwrap();

    let response = format!("HTTP/1.1 200 OK\r\n\r\n", contents);
    stream.write(response.as_bytes()).unwrap();
    stream.flush().unwrap();
}

fn handle_connection(mut stream: TcpStream) {
    let mut buffer = [0; 1024];
    stream.read(&mut buffer).unwrap();

    let mut file = File::open("hello.html").unwrap();

    let mut contents = String::new();
    file.read_to_string(&mut contents).unwrap();

    let response = format!("HTTP/1.1 200 OK\r\n\r\n{}", contents);
    stream.write(response.as_bytes()).unwrap();
    stream.flush().unwrap();
}

これで、curl http://127.0.0.1:7878を打つと、htmlが返ってくる

fn handle_connection(mut stream: TcpStream) {
    let mut buffer = [0; 1024];
    stream.read(&mut buffer).unwrap();

    let get = b"GET / HTTP/1.1\r\n"; 

    if buffer.starts_with(get) {
        let mut file = File::open("hello.html").unwrap();
        let mut contents = String::new();
        file.read_to_string(&mut contents).unwrap();

        let response = format!("HTTP/1.1 200 OK\r\n\r\n{}", contents);
        stream.write(response.as_bytes()).unwrap();
        stream.flush().unwrap();
    } else {
        let status_line = "HTTP/1.1 404 NOT FOUND\r\n\r\n";
        let mut file = File::open("404.html").unwrap();
        let mut contents = String::new();

        file.read_to_string(&mut contents).unwrap();

        let response = format!("{} {}", status_line, contents);

        stream.write(response.as_bytes()).unwrap();
        stream.flush().unwrap();
    }    
}

【Rust】Rustでjsonに読み書き

### jsonの読み込み

use serde::{Serialize, Deserialize};
use std::fs;
use std::io::prelude::*;

#[derive(Serialize, Deserialize, Debug)]
#[allow(non_snake_case)]
struct Rotator {
    Pitch:f32,
    Roll:f32,
    Yaw:f32,
}

#[derive(Serialize, Deserialize, Debug)]
#[allow(non_snake_case)]
struct CharaParam {
    Name: String,
    Id: i32,
    ItemIdList: Vec<u32>,
    RotData:Rotator,
}

fn main(){
    let input_fn = fs::read_to_string("src/test_input.json")
        .expect("JSON Read Failed.");
    let deserialized: Vec<CharaParam> = serde_json::from_str(&input_fn).unwrap();

    for data in &deserialized {
        println!("{:?}", data);
    }
}

### jsonの書き出し

use serde::{Serialize, Deserialize};
use std::fs::File;
use std::io::prelude::*;

#[derive(Serialize, Deserialize, Debug)]
#[allow(non_snake_case)]
struct Rotator {
    Pitch:f32,
    Roll:f32,
    Yaw:f32,
}

#[derive(Serialize, Deserialize, Debug)]
#[allow(non_snake_case)]
struct CharaParam {
    Name: String,
    Id: i32,
    ItemIdList: Vec<u32>,
    RotData:Rotator,
}

fn main(){
    let chara00 = CharaParam{Name:String::from("Apple"), Id:0x01, ItemIdList:vec![1000, 1001], RotData:Rotator{Pitch:0.0, Roll:0.0, Yaw:32.0} };
    let chara01 = CharaParam{Name:String::from("Banana"), Id:0x02, ItemIdList:vec![1002, 1003], RotData:Rotator{Pitch:0.0, Roll:-70.0, Yaw:66.0} };

    let mut param_list:Vec<CharaParam> = Vec::new();
    param_list.push(chara00);
    param_list.push(chara01);

    let output_fn = String::from("src/test_output.json");
    let result = output_json(&output_fn, param_list);
    match result {
        Ok(..) => {println!("Json Output Finished. [{}]", output_fn)}
        Err(err) => {println!("Error! : {}", err)}
    }
}

fn output_json(output_fn: &str, charaparam_list: Vec<CharaParam>) -> std::io::Result<()> {
    let serialized: String = serde_json::to_string(&charaparam_list).unwrap();
    let mut file = File::create(output_fn)?;
    file.write_all(serialized.as_bytes())?;
    Ok(())
}

serde_json::to_string(&charaparam_list).unwrap();　でstring型にしていますね。

つまりこういうことかな？

use serde::{Serialize, Deserialize};
use std::io::prelude::*;
use hex_literal::hex;
use k256::{ecdsa::{SigningKey, Signature, signature::Signer, signature::Verifier, VerifyingKey}};
use chrono::{Utc, Local, DateTime, Date};

#[derive(Serialize, Deserialize, Debug)]
struct UnsignedTransaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
}

#[derive(Serialize, Deserialize, Debug)]
struct SignedTransaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
    signature: String,
}

fn hex(bytes: &[u8]) -> String {
    bytes.iter().fold("".to_owned(), |s, b| format!("{}{:x}", s, b))
}

fn main(){
    let private_key: SigningKey = SigningKey::from_bytes(&hex!(
        "DCDFF4B7CA287CC7BD30ECAEF0622265DB4E14054E12954225457C3A6B84F135"
    ).into()).unwrap();
    let public_key: &VerifyingKey = private_key.verifying_key();
    let public_key_str = hex(&public_key.to_encoded_point(false).to_bytes());
    let public_key_b_str = "4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991124";

    let utc_datetime: DateTime<Utc> = Utc::now();
    let ut1 = UnsignedTransaction {time: utc_datetime.to_string(), sender: public_key_str.to_string(), receiver: public_key_b_str.to_string(), amount: 10};
    println!("{:?}", ut1);
    let serialized: String = serde_json::to_string(&ut1).unwrap();
    let sig1: Signature = private_key.sign(serialized.as_bytes());
    let signed_ut1 = SignedTransaction {time: utc_datetime.to_string(), sender: public_key_str.to_string(), receiver: public_key_b_str.to_string(), amount: 10, signature: sig1.to_string()};
    println!("{:?}", signed_ut1);

}

UnsignedTransaction { time: “2024-12-22 00:30:45.843926032 UTC”, sender: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991123”, receiver: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991124”, amount: 10 }
SignedTransaction { time: “2024-12-22 00:30:45.843926032 UTC”, sender: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991123”, receiver: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991124”, amount: 10, signature: “301DC132F45B1F8D0734A51E73F6725260B5365FBC9C2C405B9A12C70B97E47842366C2EC589F05AF8715268BC5A954B487F234F5FD3157ADBE8940AF2037B60” }

シリアライズしてバイトにしてsignする。。
しかし、これだとうまくいかん…

    let pubkey = signed_ut1.sender;
    let sig = signed_ut1.signature;

    let verified = pubkey.verify(ut1, &sig).is_ok();

    if verified {
        println!("文章は改竄されていません。");
    } else {
        println!("文章が改竄されています。");
    }

【Rust】Rustのtry & catch

#![feature(catch_expr)]

use std::fs::File;
use std::io::{self, BufReader, Read};

fn main(){
    try {
        let f = File::open("foo.txt")?;
        let mut f = BufReader::new(f);
        let mut buf = String::new();
        f.read_to_string(&mut buf)?;
        println!("{}", buf);
        Ok(())
    }.unwrap_or_else(|err: io::Error| {
        eprintln!("An error occured: {}", err);
    })
}

try & catchではなく、matchで実装する

fn main(){
    let file_path = "foo.txt";
    match std::fs::remove_file(file_path) {
        Ok(()) => {},
        Err(e) => {
            eprintln!("Failed deleting file{}. Error caut:", file_path);
            // return Err(e);
        }
    }
}

$ ./main
Failed deleting filefoo.txt. Error caut:

true or falseの場合はifで大丈夫

fn main(){
    let private_key: SigningKey = SigningKey::from_bytes(&hex!(
        "DCDFF4B7CA287CC7BD30ECAEF0622265DB4E14054E12954225457C3A6B84F135"
    ).into()).unwrap();

    let public_key: &VerifyingKey = private_key.verifying_key();

    let message = b"hello, world";
    let signature: Signature = private_key.sign(message);

    let verified = public_key.verify(message, &signature).is_ok();

    println!("private key: {:X?}", hex(&private_key.to_bytes()));
    println!("public key: {:X?}", hex(&public_key.to_encoded_point(false).to_bytes()));
    println!("Signature: {:X?}", hex(&signature.to_bytes()));

    if verified {
            println!("文章は改竄されていません。");
        } else {
            println!("文章が改竄されています。");
        }

}

private key: “dcdff4b7ca287cc7bd30ecaef0622265db4e1454e12954225457c3a6b84f135”
public key: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991123”
Signature: “f690afffd24623627bfa97996873a6a9d8ca8e9bb7ab6ad269c929453b42985573cdc4c05b8522224065757fef6c181c8418ffd3debdab4be22a73b2e5b6ce”
文章は改竄されていません。

【Rust】u8のバイト列を16進数hexに変換

fn hex(bytes: &[u8]) -> String {
    bytes.iter().fold("".to_owned(), |s, b| format!("{}{:x}", s, b))
}

fn main(){
    let s = hex(&[10, 32, 123]);
    println!("{:?}", s);
}

$ ./main
“a207b”

これを秘密鍵、公開鍵のコードに実装します。

use hex_literal::hex;
use k256::{ecdsa::{SigningKey, Signature, signature::Signer, signature::Verifier, VerifyingKey}};

fn hex(bytes: &[u8]) -> String {
    bytes.iter().fold("".to_owned(), |s, b| format!("{}{:x}", s, b))
}

fn main(){
    let private_key: SigningKey = SigningKey::from_bytes(&hex!(
        "DCDFF4B7CA287CC7BD30ECAEF0622265DB4E14054E12954225457C3A6B84F135"
    ).into()).unwrap();

    let public_key: &VerifyingKey = private_key.verifying_key();

    let message = b"hello, world";
    let signature: Signature = private_key.sign(message);

    let verified = public_key.verify(message, &signature).is_ok();

    println!("private key: {:X?}", hex(&private_key.to_bytes()));
    println!("public key: {:X?}", hex(&public_key.to_encoded_point(false).to_bytes()));
    println!("message: {:X?}", message);
    println!("Signature: {:X?}", hex(&signature.to_bytes()));
    println!("verified: {:X?}", verified);

}

private key: “dcdff4b7ca287cc7bd30ecaef0622265db4e1454e12954225457c3a6b84f135”
public key: “4bac6cb0f4ad6397752c3d73b88c5c86e3d88ac695118494a1732e2abd16c76acad3d6586c37c8db7e69c2f812f99275198936957d72c38d71981991123”
message: [68, 65, 6C, 6C, 6F, 2C, 20, 77, 6F, 72, 6C, 64]
Signature: “f690afffd24623627bfa97996873a6a9d8ca8e9bb7ab6ad269c929453b42985573cdc4c05b8522224065757fef6c181c8418ffd3debdab4be22a73b2e5b6ce”
verified: true

うん、いい感じ

【Rust】RustでSECP256k1

$ cargo add hex-literal k256

[dependencies]
chrono = "0.4.23"
hex-literal = "0.4.1"
k256 = "0.13.4"

use hex_literal::hex;
use k256::{ecdsa::{SigningKey, Signature, signature::Signer, signature::Verifier, VerifyingKey}};

fn main(){
    let private_key: SigningKey = SigningKey::from_bytes(&hex!(
        "DCDFF4B7CA287CC7BD30ECAEF0622265DB4E14054E12954225457C3A6B84F135"
    ).into()).unwrap();

    let public_key: &VerifyingKey = private_key.verifying_key();

    let message = b"hello, world";
    let signature: Signature = private_key.sign(message);

    let verified = public_key.verify(message, &signature).is_ok();

    println!("private key: {:X?}", private_key.to_bytes());
    println!("public key: {:X?}", public_key.to_encoded_point(false).to_bytes());
    println!("message: {:X?}", message);
    println!("Signature: {:X?}", signature.to_bytes());
    println!("verified: {:X?}", verified);

}

private key: [DC, DF, F4, B7, CA, 28, 7C, C7, BD, 30, EC, AE, F0, 62, 22, 65, DB, 4E, 14, 5, 4E, 12, 95, 42, 25, 45, 7C, 3A, 6B, 84, F1, 35]
public key: [4, BA, C6, CB, 0, F, 4, AD, 63, 97, 7, 52, C3, D7, 3B, 88, C5, C8, 6E, 3D, 88, AC, 69, 51, 18, 49, 4A, 1, 73, 2E, 2A, BD, 16, C7, 6A, CA, D3, D6, 58, 6C, 37, C8, DB, 7E, 69, C2, F8, 12, F9, 92, 75, 19, 89, 36, 95, 7D, 72, C3, 8D, 71, 9, 81, 99, 11, 23]
message: [68, 65, 6C, 6C, 6F, 2C, 20, 77, 6F, 72, 6C, 64]
Signature: [F6, 90, AF, FF, D2, 46, 23, 62, 7B, FA, 97, 99, 68, 73, A6, A9, D8, CA, 8E, 9B, B7, AB, 6A, D2, 69, C9, 29, 45, 3B, 42, 98, 55, 73, CD, C4, C0, 5B, 85, 22, 22, 40, 65, 75, 7F, EF, 6C, 18, 1, C8, 41, 8F, FD, 3D, EB, DA, B, 4B, E2, 2A, 73, B2, E5, B6, CE]
verified: true

【Rust】rustでblockchain

### トランザクション

use std::collections::HashMap;

fn main(){
    let transaction = HashMap::from([
        ("Time", "2024-12-20 13:58"),
        ("sender", "A"),
        ("receiver", "B"),
        ("amount", "1")
    ]);
    for (k, v) in &transaction {
        println!("{} {}", k, v);
    }
}

Hashmapだとkey, valueが全て同じ型になってしまうので、構造体を使用する。

#[derive(Debug)]

struct Transaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
}

fn main(){
    let t1 = Transaction {time: "2024-12-20 13:58".to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};

    println!("{:?}", t1);
}

$ ./main
Transaction { time: “2024-12-20 13:58”, sender: “A”, receiver: “B”, amount: 10 }

複数トランザクションの場合は配列を使用する

fn main(){
    let t1 = Transaction {time: "2024-12-20 13:58".to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};
    let t2 = Transaction {time: "2024-12-21 13:58".to_string(), sender: "B".to_string(), receiver: "C".to_string(), amount: 5};

    let transactions = [t1, t2];
    println!("{:?}", transactions);
}

### Rustで日時を扱う

use chrono::{Utc, Local, DateTime, Date};

fn main(){
    let utc_datetime: DateTime<Utc> = Utc::now();
    let utc_date: Date<Utc> = Utc::today();

    println!("{}", utc_datetime);
    println!("{}", utc_date);
}

2024-12-20 05:46:43.775637762 UTC
2024-12-20UTC

crateを使うには、Cargo.tomlを利用する

[package]
name = "hoge"
version = "0.1.0"
edition = "2021"

[dependencies]
chrono = "0.4.23"

凄い基本的なことを書くだけでも時間がかかりますな。。

use chrono::{Utc, Local, DateTime, Date};
#[derive(Debug)]

struct Transaction {
    time: String,
    sender: String,
    receiver: String,
    amount: i32,
}

fn main(){
    let utc_datetime: DateTime<Utc> = Utc::now();
    let t1 = Transaction {time: utc_datetime.to_string(), sender: "A".to_string(), receiver: "B".to_string(), amount: 10};
    let t2 = Transaction {time: utc_datetime.to_string(), sender: "B".to_string(), receiver: "C".to_string(), amount: 5};

    let transactions = [t1, t2];
    println!("{:?}", transactions);
}

[Transaction { time: “2024-12-21 06:09:35.567867379 UTC”, sender: “A”, receiver: “B”, amount: 10 }, Transaction { time: “2024-12-21 06:09:35.567867379 UTC”, sender: “B”, receiver: “C”, amount: 5 }]