io_jmap/rfc8620/
blob_download.rs

1//! JMAP blob download coroutine (RFC 8620 §6.2): GETs from the caller-resolved
2//! `download_url` and returns the response body bytes.
3//!
4//! A 3xx response surfaces as [`JmapRedirectYield::WantsRedirect`]; the caller
5//! must open a new connection to the redirect target and build a fresh
6//! coroutine.
7//!
8//! # Example
9//!
10//! ```rust,no_run
11//! use std::{
12//!     io::{Read, Write},
13//!     net::TcpStream,
14//! };
15//!
16//! use io_jmap::{
17//!     coroutine::{JmapCoroutine, JmapCoroutineState},
18//!     rfc8620::{blob_download::JmapBlobDownload, coroutine::JmapRedirectYield},
19//! };
20//! use secrecy::SecretString;
21//! use url::Url;
22//!
23//! // Ready stream needed (TCP-connected, TLS-negociated)
24//! let mut stream = TcpStream::connect("api.example.com:443").unwrap();
25//! let mut buf = [0u8; 4096];
26//!
27//! let url: Url = "https://api.example.com/jmap/download/a1/b1/blob".parse().unwrap();
28//! let auth = SecretString::from("Bearer xyz");
29//! let mut coroutine = JmapBlobDownload::new(&auth, &url);
30//! let mut arg = None;
31//!
32//! let out = loop {
33//!     match coroutine.resume(arg.take()) {
34//!         JmapCoroutineState::Yielded(JmapRedirectYield::WantsWrite(bytes)) => {
35//!             stream.write_all(&bytes).unwrap();
36//!         }
37//!         JmapCoroutineState::Yielded(JmapRedirectYield::WantsRead) => {
38//!             let n = stream.read(&mut buf).unwrap();
39//!             arg = Some(&buf[..n]);
40//!         }
41//!         JmapCoroutineState::Yielded(JmapRedirectYield::WantsRedirect { .. }) => {
42//!             unimplemented!("open a new connection and start over");
43//!         }
44//!         JmapCoroutineState::Complete(Ok(out)) => break out,
45//!         JmapCoroutineState::Complete(Err(err)) => panic!("{err}"),
46//!     }
47//! };
48//!
49//! println!("{} bytes", out.data.len());
50//! ```
51
52use alloc::vec::Vec;
53
54use io_http::{
55    coroutine::*,
56    rfc9110::{request::HttpRequest, send::HttpSendOutput},
57    rfc9112::send::{Http11Send, Http11SendError},
58};
59use log::{debug, trace};
60use secrecy::{ExposeSecret, SecretString};
61use thiserror::Error;
62use url::Url;
63
64use crate::{coroutine::*, rfc8620::coroutine::JmapRedirectYield};
65
66/// Failure causes during the JMAP blob-download flow.
67#[derive(Debug, Error)]
68pub enum JmapBlobDownloadError {
69    /// The server answered with a non-2xx status.
70    #[error("JMAP blob-download failed: HTTP {0}")]
71    HttpStatus(u16),
72    /// The inner HTTP/1.1 send coroutine failed.
73    #[error("JMAP blob-download failed: {0}")]
74    Send(#[from] Http11SendError),
75}
76
77/// Successful terminal output of [`JmapBlobDownload`].
78#[derive(Clone, Debug)]
79pub struct JmapBlobDownloadOutput {
80    /// The downloaded blob bytes.
81    pub data: Vec<u8>,
82    /// Whether the server indicated the connection can be reused.
83    pub keep_alive: bool,
84}
85
86/// I/O-free coroutine downloading a blob from a JMAP server (RFC 8620 §6.2).
87pub struct JmapBlobDownload {
88    state: State,
89}
90
91impl JmapBlobDownload {
92    /// `download_url` is the fully resolved download URL (no template
93    /// placeholders).
94    pub fn new(http_auth: &SecretString, download_url: &Url) -> Self {
95        let host = download_url.host_str().unwrap_or("localhost");
96
97        let http_request = HttpRequest::get(download_url.clone())
98            .header("Host", host)
99            .header("Authorization", http_auth.expose_secret());
100
101        debug!("prepare blob download request");
102        trace!("download url: {download_url}");
103
104        Self {
105            state: State::Send(Http11Send::new(http_request)),
106        }
107    }
108}
109
110impl JmapCoroutine for JmapBlobDownload {
111    type Yield = JmapRedirectYield;
112    type Return = Result<JmapBlobDownloadOutput, JmapBlobDownloadError>;
113
114    fn resume(&mut self, arg: Option<&[u8]>) -> JmapCoroutineState<Self::Yield, Self::Return> {
115        match &mut self.state {
116            State::Send(send) => match send.resume(arg) {
117                HttpCoroutineState::Yielded(y) => JmapCoroutineState::Yielded(y.into()),
118                HttpCoroutineState::Complete(Err(err)) => {
119                    JmapCoroutineState::Complete(Err(err.into()))
120                }
121                HttpCoroutineState::Complete(Ok(HttpSendOutput {
122                    response,
123                    keep_alive,
124                    ..
125                })) => {
126                    if !response.status.is_success() {
127                        let err = JmapBlobDownloadError::HttpStatus(*response.status);
128                        return JmapCoroutineState::Complete(Err(err));
129                    }
130
131                    JmapCoroutineState::Complete(Ok(JmapBlobDownloadOutput {
132                        data: response.body,
133                        keep_alive,
134                    }))
135                }
136            },
137        }
138    }
139}
140
141enum State {
142    Send(Http11Send),
143}
144
145#[cfg(test)]
146mod tests {
147    use alloc::format;
148
149    use crate::rfc8620::blob_download::*;
150
151    fn make_auth() -> SecretString {
152        SecretString::from("Bearer test")
153    }
154
155    fn make_url() -> Url {
156        "https://api.example.com/jmap/download/a1/b1/blob"
157            .parse()
158            .unwrap()
159    }
160
161    fn build_http_reply(status: u16, body: &[u8]) -> Vec<u8> {
162        let head = format!(
163            "HTTP/1.1 {} OK\r\nContent-Length: {}\r\n\r\n",
164            status,
165            body.len()
166        );
167        let mut bytes = head.into_bytes();
168        bytes.extend_from_slice(body);
169        bytes
170    }
171
172    #[test]
173    fn success_returns_ok() {
174        let mut cor = JmapBlobDownload::new(&make_auth(), &make_url());
175
176        expect_wants_write(&mut cor, None);
177        expect_wants_read(&mut cor);
178
179        let reply = build_http_reply(200, b"hello blob");
180        let out = expect_complete_ok(&mut cor, &reply);
181        assert_eq!(out.data, b"hello blob");
182    }
183
184    #[test]
185    fn http_error_returns_status() {
186        let mut cor = JmapBlobDownload::new(&make_auth(), &make_url());
187
188        expect_wants_write(&mut cor, None);
189        expect_wants_read(&mut cor);
190
191        let reply = b"HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n";
192        let err = expect_complete_err(&mut cor, reply);
193        assert!(matches!(err, JmapBlobDownloadError::HttpStatus(404)));
194    }
195
196    #[test]
197    fn redirect_yields_redirect() {
198        let mut cor = JmapBlobDownload::new(&make_auth(), &make_url());
199
200        expect_wants_write(&mut cor, None);
201        expect_wants_read(&mut cor);
202
203        let reply = b"HTTP/1.1 302 Found\r\nLocation: https://cdn.example.com/blob\r\nContent-Length: 0\r\n\r\n";
204        match cor.resume(Some(reply)) {
205            JmapCoroutineState::Yielded(JmapRedirectYield::WantsRedirect { url, .. }) => {
206                assert_eq!(url.host_str(), Some("cdn.example.com"));
207            }
208            state => panic!("expected WantsRedirect, got {state:?}"),
209        }
210    }
211
212    #[test]
213    fn empty_body_succeeds() {
214        let mut cor = JmapBlobDownload::new(&make_auth(), &make_url());
215
216        expect_wants_write(&mut cor, None);
217        expect_wants_read(&mut cor);
218
219        let reply = build_http_reply(200, b"");
220        let out = expect_complete_ok(&mut cor, &reply);
221        assert!(out.data.is_empty());
222    }
223
224    #[test]
225    fn request_uses_get_method() {
226        let mut cor = JmapBlobDownload::new(&make_auth(), &make_url());
227        let bytes = expect_wants_write(&mut cor, None);
228        let req = core::str::from_utf8(&bytes).expect("utf8 request");
229        assert!(req.starts_with("GET "));
230    }
231
232    fn expect_wants_write(cor: &mut JmapBlobDownload, arg: Option<&[u8]>) -> Vec<u8> {
233        match cor.resume(arg) {
234            JmapCoroutineState::Yielded(JmapRedirectYield::WantsWrite(bytes)) => bytes,
235            state => panic!("expected WantsWrite, got {state:?}"),
236        }
237    }
238
239    fn expect_wants_read(cor: &mut JmapBlobDownload) {
240        match cor.resume(None) {
241            JmapCoroutineState::Yielded(JmapRedirectYield::WantsRead) => {}
242            state => panic!("expected WantsRead, got {state:?}"),
243        }
244    }
245
246    fn expect_complete_ok(cor: &mut JmapBlobDownload, reply: &[u8]) -> JmapBlobDownloadOutput {
247        match cor.resume(Some(reply)) {
248            JmapCoroutineState::Complete(Ok(out)) => out,
249            state => panic!("expected Complete(Ok), got {state:?}"),
250        }
251    }
252
253    fn expect_complete_err(cor: &mut JmapBlobDownload, reply: &[u8]) -> JmapBlobDownloadError {
254        match cor.resume(Some(reply)) {
255            JmapCoroutineState::Complete(Err(err)) => err,
256            state => panic!("expected Complete(Err), got {state:?}"),
257        }
258    }
259}
io_jmap/rfc8620/blob_download.rs

io_jmap/rfc8620/
blob_download.rs
