rustlavel-client 0.1.0

Rustlavel outbound HTTP client, written on Tokio with TLS from rustls
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
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336

//! Streaming response bodies, and the server-sent events AI providers use.

use crate::{Connection, find_head_end, parse_head};
use rustlavel_core::{Error, Json, Result};
use rustlavel_http::{Headers, Status};
use std::time::Duration;

/// A response whose body is read as it arrives.
pub struct Body {
    pub status: Status,
    pub headers: Headers,
    source: Source,
    buffer: Vec<u8>,
    /// Set once the transfer is complete, so `chunk` stops asking for more.
    finished: bool,
    /// Bytes still expected, when the body is chunked.
    chunk_remaining: Option<usize>,
    chunked: bool,
    timeout: Duration,
}

enum Source {
    Live(Box<Connection>),
    /// A faked body, already complete.
    Memory,
}

/// Send a request and hand back the body before it has finished arriving.
pub(crate) async fn open(
    mut connection: Connection,
    request: Vec<u8>,
    timeout: Duration,
) -> Result<Body> {
    connection.write_all(&request).await.map_err(Error::Io)?;
    connection.flush().await.map_err(Error::Io)?;

    let mut buffer = Vec::with_capacity(8 * 1024);
    let head_end = loop {
        if let Some(at) = find_head_end(&buffer) {
            break at;
        }
        let mut chunk = [0u8; 4096];
        let read = tokio::time::timeout(timeout, connection.read(&mut chunk))
            .await
            .map_err(|_| Error::msg("timed out waiting for response headers"))?
            .map_err(Error::Io)?;
        if read == 0 {
            return Err(Error::Protocol("the server closed before sending headers".into()));
        }
        buffer.extend_from_slice(&chunk[..read]);
    };

    let (status, headers) = parse_head(&buffer[..head_end])?;
    let rest = buffer.split_off(head_end);
    let chunked = headers.get("transfer-encoding").is_some_and(|te| te.contains("chunked"));

    Ok(Body {
        status,
        headers,
        source: Source::Live(Box::new(connection)),
        buffer: rest,
        finished: false,
        chunk_remaining: None,
        chunked,
        timeout,
    })
}

impl Body {
    /// A body that is already in memory, for fakes and tests.
    pub fn from_bytes(status: Status, headers: Headers, body: Vec<u8>) -> Body {
        Body {
            status,
            headers,
            source: Source::Memory,
            buffer: body,
            finished: true,
            chunk_remaining: None,
            chunked: false,
            timeout: Duration::from_secs(30),
        }
    }

    /// The next piece of the body, or `None` when it is complete.
    pub async fn chunk(&mut self) -> Result<Option<Vec<u8>>> {
        loop {
            if self.chunked {
                if let Some(chunk) = self.take_chunked()? {
                    return Ok(Some(chunk));
                }
            } else if !self.buffer.is_empty() {
                return Ok(Some(std::mem::take(&mut self.buffer)));
            }

            if self.finished {
                return Ok(None);
            }
            if !self.fill().await? {
                self.finished = true;
                if !self.chunked && !self.buffer.is_empty() {
                    return Ok(Some(std::mem::take(&mut self.buffer)));
                }
                return Ok(None);
            }
        }
    }

    /// Read the rest of the body into memory.
    pub async fn bytes(mut self) -> Result<Vec<u8>> {
        let mut out = Vec::new();
        while let Some(chunk) = self.chunk().await? {
            out.extend_from_slice(&chunk);
        }
        Ok(out)
    }

    pub async fn text(self) -> Result<String> {
        Ok(String::from_utf8_lossy(&self.bytes().await?).into_owned())
    }

    /// Read the body as a server-sent event stream.
    pub fn events(self) -> SseReader {
        SseReader { body: self, pending: String::new() }
    }

    /// Pull one chunk out of a chunked transfer, if a whole one is buffered.
    fn take_chunked(&mut self) -> Result<Option<Vec<u8>>> {
        loop {
            match self.chunk_remaining {
                None => {
                    let Some(line_end) = find_crlf(&self.buffer) else { return Ok(None) };
                    let header: Vec<u8> = self.buffer.drain(..line_end + 2).collect();
                    let text = String::from_utf8_lossy(&header[..line_end]);
                    let size =
                        usize::from_str_radix(text.split(';').next().unwrap_or("").trim(), 16)
                            .map_err(|_| Error::Protocol("invalid chunk size".into()))?;
                    if size == 0 {
                        self.finished = true;
                        return Ok(None);
                    }
                    self.chunk_remaining = Some(size);
                }
                Some(size) => {
                    if self.buffer.len() < size + 2 {
                        return Ok(None);
                    }
                    let chunk: Vec<u8> = self.buffer.drain(..size).collect();
                    self.buffer.drain(..2);
                    self.chunk_remaining = None;
                    return Ok(Some(chunk));
                }
            }
        }
    }

    async fn fill(&mut self) -> Result<bool> {
        let Source::Live(connection) = &mut self.source else {
            return Ok(false);
        };

        let mut chunk = [0u8; 8192];
        let read = tokio::time::timeout(self.timeout, connection.read(&mut chunk))
            .await
            .map_err(|_| Error::msg("timed out reading the response body"))?
            .map_err(Error::Io)?;

        self.buffer.extend_from_slice(&chunk[..read]);
        Ok(read > 0)
    }
}

fn find_crlf(buffer: &[u8]) -> Option<usize> {
    buffer.windows(2).position(|w| w == b"\r\n")
}

/// One server-sent event.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct ServerSentEvent {
    pub event: Option<String>,
    pub data: String,
    pub id: Option<String>,
}

impl ServerSentEvent {
    /// The data parsed as JSON, which is how every AI provider sends it.
    pub fn json(&self) -> Result<Json> {
        Json::parse(&self.data)
    }

    /// Whether this is the conventional end-of-stream marker.
    pub fn is_done(&self) -> bool {
        self.data.trim() == "[DONE]"
    }
}

/// Reads a body as a sequence of server-sent events.
pub struct SseReader {
    body: Body,
    /// Text received but not yet ending in a blank line.
    pending: String,
}

impl SseReader {
    /// The next event, or `None` at the end of the stream.
    pub async fn next(&mut self) -> Result<Option<ServerSentEvent>> {
        loop {
            if let Some(event) = self.take_event() {
                return Ok(Some(event));
            }
            match self.body.chunk().await? {
                Some(bytes) => self.pending.push_str(&String::from_utf8_lossy(&bytes)),
                None => return Ok(self.take_event().or_else(|| self.take_remainder())),
            }
        }
    }

    /// Collect every event, for a caller that does not need them as they arrive.
    pub async fn collect(mut self) -> Result<Vec<ServerSentEvent>> {
        let mut events = Vec::new();
        while let Some(event) = self.next().await? {
            events.push(event);
        }
        Ok(events)
    }

    fn take_event(&mut self) -> Option<ServerSentEvent> {
        // An event ends at a blank line; both line endings appear in the wild.
        let end = self
            .pending
            .find("\n\n")
            .map(|at| (at, 2))
            .or_else(|| self.pending.find("\r\n\r\n").map(|at| (at, 4)))?;

        let block: String = self.pending.drain(..end.0 + end.1).collect();
        parse_event(&block)
    }

    fn take_remainder(&mut self) -> Option<ServerSentEvent> {
        if self.pending.trim().is_empty() {
            return None;
        }
        let block = std::mem::take(&mut self.pending);
        parse_event(&block)
    }
}

fn parse_event(block: &str) -> Option<ServerSentEvent> {
    let mut event = ServerSentEvent::default();
    let mut data_lines: Vec<&str> = Vec::new();

    for line in block.lines() {
        let line = line.trim_end_matches('\r');
        // A line starting with `:` is a comment, used as a keep-alive.
        if line.is_empty() || line.starts_with(':') {
            continue;
        }
        let (field, value) = match line.split_once(':') {
            Some((field, value)) => (field, value.strip_prefix(' ').unwrap_or(value)),
            None => (line, ""),
        };
        match field {
            "event" => event.event = Some(value.to_string()),
            "data" => data_lines.push(value),
            "id" => event.id = Some(value.to_string()),
            _ => {}
        }
    }

    if data_lines.is_empty() && event.event.is_none() {
        return None;
    }
    event.data = data_lines.join("\n");
    Some(event)
}

#[cfg(test)]
mod tests {
    use super::*;

    fn body(text: &str) -> Body {
        Body::from_bytes(Status::OK, Headers::new(), text.as_bytes().to_vec())
    }

    #[tokio::test]
    async fn reads_a_stream_of_events() {
        let mut events = body("data: one\n\ndata: two\n\ndata: [DONE]\n\n").events();

        assert_eq!(events.next().await.unwrap().unwrap().data, "one");
        assert_eq!(events.next().await.unwrap().unwrap().data, "two");
        assert!(events.next().await.unwrap().unwrap().is_done());
        assert!(events.next().await.unwrap().is_none());
    }

    #[tokio::test]
    async fn keeps_named_events_and_ids() {
        let events = body("event: message_start\nid: 42\ndata: {\"a\":1}\n\n")
            .events()
            .collect()
            .await
            .unwrap();

        assert_eq!(events.len(), 1);
        assert_eq!(events[0].event.as_deref(), Some("message_start"));
        assert_eq!(events[0].id.as_deref(), Some("42"));
        assert_eq!(events[0].json().unwrap().get("a").unwrap().as_i64(), Some(1));
    }

    #[tokio::test]
    async fn joins_multi_line_data_and_skips_comments() {
        let events = body(": keep-alive\n\ndata: first\ndata: second\n\n").events().collect().await.unwrap();

        assert_eq!(events.len(), 1);
        assert_eq!(events[0].data, "first\nsecond");
    }

    #[tokio::test]
    async fn handles_crlf_line_endings() {
        let events = body("data: one\r\n\r\ndata: two\r\n\r\n").events().collect().await.unwrap();

        assert_eq!(events.len(), 2);
        assert_eq!(events[1].data, "two");
    }

    #[tokio::test]
    async fn an_unterminated_final_event_is_still_delivered() {
        let events = body("data: one\n\ndata: trailing").events().collect().await.unwrap();

        assert_eq!(events.len(), 2);
        assert_eq!(events[1].data, "trailing");
    }

    #[tokio::test]
    async fn reads_a_whole_body_as_text() {
        assert_eq!(body("hello").text().await.unwrap(), "hello");
    }
}