canteen 0.5.6

A Flask-like microframework for Rust
Documentation 
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// Copyright (c) 2016
// Jeff Nettleton
//
// Licensed under the MIT license (http://opensource.org/licenses/MIT). This
// file may not be copied, modified, or distributed except according to those
// terms

use std::env;
use std::fs::File;
use std::path::PathBuf;
use std::io::prelude::*;
use chrono::{Utc, DateTime, TimeZone};
use mime_guess::MimeGuess;
use std::time::{UNIX_EPOCH, SystemTime};
use crate::response::{ToOutput, Response};
use crate::request::Request;

/// Convenience method for creating a response from the basic components
/// required (a request body, content type, and response status).
///
/// # Examples
///
/// ```rust
/// use canteen::{Request, Response};
/// use canteen::utils;
///
/// fn handler(_: &Request) -> Response {
///     utils::make_response("Hello, world!", "text/plain", 200)
/// }
/// ```
pub fn make_response<T: ToOutput>(body: T, c_type: &str, status: u16) -> Response {
    let mut res = Response::new();

    res.set_status(status);
    res.set_content_type(c_type);
    res.append(body);

    res
}

/// Converts std::time::SystemTime to chrono::DateTime<Utc>
///
/// Code from: https://users.rust-lang.org/t/convert-std-time-systemtime-to-chrono-datetime-datetime/7684/4
pub fn _conv_systemtime(t: SystemTime) -> DateTime<Utc> {
    let (sec, nsec) = match t.duration_since(UNIX_EPOCH) {
        Ok(dur) => (dur.as_secs() as i64, dur.subsec_nanos()),
        Err(e) => {
            let dur = e.duration();
            let (sec, nsec) = (dur.as_secs() as i64, dur.subsec_nanos());

            if nsec == 0 {
                (-sec, 0)
            } else {
                (-sec - 1, 1_000_000_000 - nsec)
            }
        },
    };

    Utc.timestamp(sec, nsec)
}

/// Replace the URI escape codes with their ASCII equivalents.
pub fn replace_escape(path: &str) -> String {
    let mut fixed = String::from(path);
    let replaces: [(&str, &str); 175] = [
        ("%20", " "),  ("%21", "!"),  ("%22", "\""), ("%23", "#"),  ("%24", "$"),
        ("%25", "%"),  ("%26", "&"),  ("%27", "'"),  ("%28", "("),  ("%29", ")"),
        ("%2A", "*"),  ("%2B", "+"),  ("%2C", ","),  ("%2D", "-"),  ("%2E", "."),
        ("%2F", "/"),  ("%30", "0"),  ("%31", "1"),  ("%32", "2"),  ("%33", "3"),
        ("%34", "4"),  ("%35", "5"),  ("%36", "6"),  ("%37", "7"),  ("%38", "8"),
        ("%39", "9"),  ("%3A", ":"),  ("%3B", ";"),  ("%3C", "<"),  ("%3D", "="),
        ("%3E", ">"),  ("%3F", "?"),  ("%40", "@"),  ("%41", "A"),  ("%42", "B"),
        ("%43", "C"),  ("%44", "D"),  ("%45", "E"),  ("%46", "F"),  ("%47", "G"),
        ("%48", "H"),  ("%49", "I"),  ("%4A", "J"),  ("%4B", "K"),  ("%4C", "L"),
        ("%4D", "M"),  ("%4E", "N"),  ("%4F", "O"),  ("%50", "P"),  ("%51", "Q"),
        ("%52", "R"),  ("%53", "S"),  ("%54", "T"),  ("%55", "U"),  ("%56", "V"),
        ("%57", "W"),  ("%58", "X"),  ("%59", "Y"),  ("%5A", "Z"),  ("%5B", "["),
        ("%5C", "\\"), ("%5D", "]"),  ("%5E", "^"),  ("%5F", "_"),  ("%60", "`"),
        ("%61", "a"),  ("%62", "b"),  ("%63", "c"),  ("%64", "d"),  ("%65", "e"),
        ("%66", "f"),  ("%67", "g"),  ("%68", "h"),  ("%69", "i"),  ("%6A", "j"),
        ("%6B", "k"),  ("%6C", "l"),  ("%6D", "m"),  ("%6E", "n"),  ("%6F", "o"),
        ("%70", "p"),  ("%71", "q"),  ("%72", "r"),  ("%73", "s"),  ("%74", "t"),
        ("%75", "u"),  ("%76", "v"),  ("%77", "w"),  ("%78", "x"),  ("%79", "y"),
        ("%7A", "z"),  ("%7B", "{"),  ("%7C", "|"),  ("%7D", "}"),  ("%7E", "~"),
        ("%A2", "¢"),  ("%A3", "£"),  ("%A5", "¥"),  ("%A6", "|"),  ("%A7", "§"),
        ("%AB", "«"),  ("%AC", "¬"),  ("%AD", "¯"),  ("%B0", "º"),  ("%B1", "±"),
        ("%B2", "ª"),  ("%B4", ","),  ("%B5", "µ"),  ("%BB", "»"),  ("%BC", "¼"),
        ("%BD", "½"),  ("%BF", "¿"),  ("%C0", "À"),  ("%C1", "Á"),  ("%C2", "Â"),
        ("%C3", "Ã"),  ("%C4", "Ä"),  ("%C5", "Å"),  ("%C6", "Æ"),  ("%C7", "Ç"),
        ("%C8", "È"),  ("%C9", "É"),  ("%CA", "Ê"),  ("%CB", "Ë"),  ("%CC", "Ì"),
        ("%CD", "Í"),  ("%CE", "Î"),  ("%CF", "Ï"),  ("%D0", "Ð"),  ("%D1", "Ñ"),
        ("%D2", "Ò"),  ("%D3", "Ó"),  ("%D4", "Ô"),  ("%D5", "Õ"),  ("%D6", "Ö"),
        ("%D8", "Ø"),  ("%D9", "Ù"),  ("%DA", "Ú"),  ("%DB", "Û"),  ("%DC", "Ü"),
        ("%DD", "Ý"),  ("%DE", "Þ"),  ("%DF", "ß"),  ("%E0", "à"),  ("%E1", "á"),
        ("%E2", "â"),  ("%E3", "ã"),  ("%E4", "ä"),  ("%E5", "å"),  ("%E6", "æ"),
        ("%E7", "ç"),  ("%E8", "è"),  ("%E9", "é"),  ("%EA", "ê"),  ("%EB", "ë"),
        ("%EC", "ì"),  ("%ED", "í"),  ("%EE", "î"),  ("%EF", "ï"),  ("%F0", "ð"),
        ("%F1", "ñ"),  ("%F2", "ò"),  ("%F3", "ó"),  ("%F4", "ô"),  ("%F5", "õ"),
        ("%F6", "ö"),  ("%F7", "÷"),  ("%F8", "ø"),  ("%F9", "ù"),  ("%FA", "ú"),
        ("%FB", "û"),  ("%FC", "ü"),  ("%FD", "ý"),  ("%FE", "þ"),  ("%FF", "ÿ"),
    ];

    if !fixed.contains('%') {
        return fixed;
    }

    for &(from, to) in replaces.iter() {
        fixed = fixed.replace(from, to);
    }

    fixed
}

fn err_body(message: &str, path: &str) -> String {
    format!("<html><head>\
             <style>body {{ font-family: helvetica, sans-serif; }} p {{ font-size: 14 }}</style>\
             </head><body><h3>Your request failed</h3><p>{}: {}</p></body></html>", message, path)
}

/// Default handler function for HTTP 403 errors.
pub fn err_403(req: &Request) -> Response {
    make_response(err_body("forbidden", &req.path), "text/html", 403)
}

/// Default handler function for HTTP 403 errors for XHR.
pub fn err_403_json(message: &str) -> Response {
    make_response(format!("{{ message: 'forbidden: {}' }}", message), "application/json", 403)
}

/// Default handler function for HTTP 404 errors.
pub fn err_404(req: &Request) -> Response {
    make_response(err_body("not found", &req.path), "text/html", 404)
}

/// Default handler function for HTTP 500 errors for XHR.
pub fn err_404_json(message: &str) -> Response {
    make_response(format!("{{ message: 'not found: {}' }}", message), "application/json", 404)
}

/// Default handler function for HTTP 500 errors.
pub fn err_500(req: &Request) -> Response {
    make_response(err_body("internal server error", &req.path), "text/html", 500)
}

/// Default handler function for HTTP 500 errors for XHR.
pub fn err_500_json(message: &str) -> Response {
    make_response(format!("{{ message: 'internal server error: {}' }}", message), "application/json", 500)
}

/// Handler that sends static files relative to the current working directory.
pub fn static_file(req: &Request) -> Response {
    let mut res = Response::new();

    let cwd = env::current_dir().unwrap();
    let clean = replace_escape(&req.path);
    let mut fpath = PathBuf::from(&cwd);
    let mut fbuf: Vec<u8> = Vec::new();

    for chunk in clean.split('/') {
        if chunk == "" || chunk == "." || chunk == ".." {
            /* bzzzzt */
            continue;
        }

        fpath.push(&chunk);
    }

    let file = File::open(&fpath);

    match file {
        Ok(mut f)   => {
            let last = match f.metadata() {
                Err(_)  => Utc::now(),
                Ok(md)  => {
                    match md.modified() {
                        Err(_)  => Utc::now(), // should never happen...
                        Ok(st)  => _conv_systemtime(st),
                    }
                }
            };

            if let Some(hdr) = req.get_header("If-Modified-Since") {
                if let Ok(dt_utc) = Utc.datetime_from_str(&hdr, "%a, %d %b %Y, %H:%M:%S UTC") {
                    if dt_utc >= last {
                        // it hasn't been modified, return a 304
                        res.set_status(304);
                        return res;
                    }
                }
            }

            match f.read_to_end(&mut fbuf) {
                Ok(_)   => {
                    res.add_header("Last-Modified", &last.format("%a, %d %b %Y, %H:%M:%S %Z").to_string());
                    res.set_status(200);

                    match MimeGuess::from_path(&fpath).first_raw() {
                        Some(ftype) => res.set_content_type(ftype),
                        None        => res.set_content_type("text/plain"),
                    };

                    res.append(fbuf);
                },
                Err(_)  => {
                    return err_500(&req);
                },
            }
        },
        Err(_)      => {
            return err_404(&req);
        }
    }

    res
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::{Utc, TimeZone};
    use std::time::UNIX_EPOCH;

    #[test]
    fn test_replace_escape() {
        let path = "%61%62%63%64%65%66%67%68%69%6A%6B%6C%6D%6E%6F%70%71%72%73%74%75%76%77%78%79%7A";
        assert_eq!("abcdefghijklmnopqrstuvwxyz", replace_escape(&path));
    }

    #[test]
    fn test_conv_systemtime() {
        assert_eq!(_conv_systemtime(UNIX_EPOCH), Utc.timestamp(0, 0));
    }
}