rsurl 0.0.7

A pure-Rust implementation of curl. Library, C FFI, and CLI for HTTP/HTTPS/FTP/FTPS.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219

//! End-to-end test for `--parallel-segments`: the `rsurl` binary downloads a
//! single file over several concurrent HTTP range requests and reassembles it
//! correctly. A small in-process server supports HEAD (Content-Length +
//! Accept-Ranges) and ranged GET (206), and counts the range requests it
//! serves so the test can confirm the download was actually segmented.

use std::io::{Read, Write};
use std::net::TcpListener;
use std::process::Command;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::thread;

/// 4 MiB of a deterministic pattern.
fn payload() -> Vec<u8> {
    (0..4 * 1024 * 1024).map(|i| (i % 251) as u8).collect()
}

struct Server {
    port: u16,
    range_gets: Arc<AtomicUsize>,
    accept_ranges: bool,
}

/// Spawn a server. When `accept_ranges` is false it advertises no range support
/// (and ignores Range), so the client must fall back to a single stream.
fn start(accept_ranges: bool) -> Server {
    let listener = TcpListener::bind("127.0.0.1:0").unwrap();
    let port = listener.local_addr().unwrap().port();
    let body = Arc::new(payload());
    let range_gets = Arc::new(AtomicUsize::new(0));
    let counter = Arc::clone(&range_gets);

    thread::spawn(move || {
        for stream in listener.incoming() {
            let Ok(mut s) = stream else { continue };
            let body = Arc::clone(&body);
            let counter = Arc::clone(&counter);
            thread::spawn(move || {
                // Read request head.
                let mut buf = Vec::new();
                let mut tmp = [0u8; 1024];
                loop {
                    let n = match s.read(&mut tmp) {
                        Ok(0) | Err(_) => return,
                        Ok(n) => n,
                    };
                    buf.extend_from_slice(&tmp[..n]);
                    if buf.windows(4).any(|w| w == b"\r\n\r\n") {
                        break;
                    }
                    if buf.len() > 64 * 1024 {
                        return;
                    }
                }
                let head = String::from_utf8_lossy(&buf);
                let method = head.split_whitespace().next().unwrap_or("");
                let range = head.lines().find_map(|l| {
                    let (k, v) = l.split_once(':')?;
                    if k.eq_ignore_ascii_case("range") {
                        Some(v.trim().to_string())
                    } else {
                        None
                    }
                });
                let total = body.len();

                if method == "HEAD" {
                    let ar = if accept_ranges {
                        "Accept-Ranges: bytes\r\n"
                    } else {
                        ""
                    };
                    let resp = format!(
                        "HTTP/1.1 200 OK\r\nContent-Length: {total}\r\n{ar}Connection: close\r\n\r\n"
                    );
                    let _ = s.write_all(resp.as_bytes());
                    return;
                }

                // GET
                if accept_ranges {
                    if let Some(r) = range.as_deref().and_then(|r| r.strip_prefix("bytes=")) {
                        if let Some((a, b)) = r.split_once('-') {
                            let a: usize = a.parse().unwrap_or(0);
                            let b: usize = b.parse().unwrap_or(total - 1);
                            let b = b.min(total - 1);
                            counter.fetch_add(1, Ordering::SeqCst);
                            let slice = &body[a..=b];
                            let hdr = format!(
                                "HTTP/1.1 206 Partial Content\r\nContent-Range: bytes {a}-{b}/{total}\r\nContent-Length: {}\r\nConnection: close\r\n\r\n",
                                slice.len()
                            );
                            let _ = s.write_all(hdr.as_bytes());
                            let _ = s.write_all(slice);
                            return;
                        }
                    }
                }
                // Full body (no range / ranges unsupported).
                let hdr = format!(
                    "HTTP/1.1 200 OK\r\nContent-Length: {total}\r\nConnection: close\r\n\r\n"
                );
                let _ = s.write_all(hdr.as_bytes());
                let _ = s.write_all(&body);
            });
        }
    });

    Server {
        port,
        range_gets,
        accept_ranges,
    }
}

static OUT_SEQ: AtomicUsize = AtomicUsize::new(0);

struct Run {
    data: Vec<u8>,
    stderr: String,
    ok: bool,
}

/// Run `rsurl --parallel-segments[ n] [-#] -o tmp url`. `segments == None` omits
/// the count (exercising the default of 4); `progress` adds `-#`.
fn run_download_ex(url: &str, segments: Option<u32>, progress: bool) -> Run {
    let bin = env!("CARGO_BIN_EXE_rsurl");
    let uniq = OUT_SEQ.fetch_add(1, Ordering::SeqCst);
    let out = std::env::temp_dir().join(format!("rsurl_par_{}_{}", std::process::id(), uniq));
    let mut cmd = Command::new(bin);
    cmd.arg("--parallel-segments");
    if let Some(n) = segments {
        cmd.arg(n.to_string());
    }
    if progress {
        cmd.arg("-#");
    }
    let output = cmd
        .arg("-o")
        .arg(&out)
        .arg(url)
        .output()
        .expect("spawn rsurl");
    let data = std::fs::read(&out).unwrap_or_default();
    let _ = std::fs::remove_file(&out);
    Run {
        data,
        stderr: String::from_utf8_lossy(&output.stderr).into_owned(),
        ok: output.status.success(),
    }
}

fn run_download(url: &str, segments: u32) -> (Vec<u8>, bool) {
    let r = run_download_ex(url, Some(segments), false);
    (r.data, r.ok)
}

#[test]
fn parallel_segments_reassembles_file() {
    let server = start(true);
    let url = format!("http://127.0.0.1:{}/big", server.port);
    let (data, ok) = run_download(&url, 4);
    assert!(ok, "rsurl exited non-zero");
    assert_eq!(data, payload(), "downloaded file does not match");
    // It actually used multiple range requests (not a single stream).
    assert!(
        server.range_gets.load(Ordering::SeqCst) >= 2,
        "expected >=2 range GETs, saw {}",
        server.range_gets.load(Ordering::SeqCst)
    );
}

#[test]
fn bare_flag_defaults_to_four_segments() {
    let server = start(true);
    let url = format!("http://127.0.0.1:{}/big", server.port);
    // No count given → defaults to 4 segments.
    let r = run_download_ex(&url, None, false);
    assert!(r.ok, "rsurl exited non-zero: {}", r.stderr);
    assert_eq!(r.data, payload(), "downloaded file does not match");
    assert_eq!(
        server.range_gets.load(Ordering::SeqCst),
        4,
        "default should split into 4 segments, saw {}",
        server.range_gets.load(Ordering::SeqCst)
    );
}

#[test]
fn progress_flag_renders_and_keeps_file_intact() {
    let server = start(true);
    let url = format!("http://127.0.0.1:{}/big", server.port);
    let r = run_download_ex(&url, Some(4), true);
    assert!(r.ok, "rsurl exited non-zero: {}", r.stderr);
    assert_eq!(r.data, payload(), "progress mode corrupted the file");
    // stderr (not a TTY here) carries the aggregate progress line; the file is
    // unaffected by the display going to stderr.
    assert!(
        r.stderr.contains("rsurl:"),
        "expected a progress line on stderr, got {:?}",
        r.stderr
    );
}

#[test]
fn falls_back_to_single_stream_without_range_support() {
    let server = start(false);
    let url = format!("http://127.0.0.1:{}/big", server.port);
    let (data, ok) = run_download(&url, 4);
    assert!(ok, "rsurl exited non-zero");
    assert_eq!(data, payload(), "fallback download does not match");
    assert!(!server.accept_ranges);
    assert_eq!(
        server.range_gets.load(Ordering::SeqCst),
        0,
        "no range GETs expected on the fallback path"
    );
}