proxyapi 0.2.0

Core library for the Proxelar MITM proxy
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

use async_trait::async_trait;
use bytes::Bytes;
use http_body_util::{BodyExt, Limited};
use hyper::{Request, Response};
use proxyapi_models::{ProxiedRequest, ProxiedResponse};
use tokio::sync::mpsc;

use crate::body::{self, ProxyBody};
use crate::event::{next_id, ProxyEvent};
use crate::{HttpContext, HttpHandler, RequestOrResponse};

/// Maximum body size the proxy will collect (100 MB).
///
/// Bodies exceeding this limit are replaced with an empty body in the
/// captured event. The proxied traffic itself is unaffected.
const MAX_BODY_SIZE: usize = 100 * 1024 * 1024;

fn now_millis() -> i64 {
    chrono::Local::now().timestamp_millis()
}

/// Collect the response body, emit a [`ProxyEvent`], and return the reconstructed response.
///
/// This is the single source of truth for response capture, used by both
/// forward and reverse proxy paths.
pub fn collect_and_emit(
    handler: &mut CapturingHandler,
    parts: http::response::Parts,
    body_bytes: Bytes,
) -> Response<ProxyBody> {
    let proxied_response = ProxiedResponse::new(
        parts.status,
        parts.version,
        parts.headers.clone(),
        body_bytes.clone(),
        now_millis(),
    );

    if let Some(request) = handler.take_captured_request() {
        let event = ProxyEvent::RequestComplete {
            id: next_id(),
            request: Box::new(request),
            response: Box::new(proxied_response),
        };
        handler.send_event(event);
    }

    Response::from_parts(parts, body::full(body_bytes))
}

/// Collect response body bytes up to [`MAX_BODY_SIZE`], logging a warning on failure.
pub async fn collect_body(body: hyper::body::Incoming) -> Bytes {
    Limited::new(body, MAX_BODY_SIZE)
        .collect()
        .await
        .map(http_body_util::Collected::to_bytes)
        .unwrap_or_else(|e| {
            tracing::warn!(
                "Failed to collect response body (possibly exceeds {}MB limit): {e}",
                MAX_BODY_SIZE / (1024 * 1024)
            );
            Bytes::new()
        })
}

/// Default handler that captures request/response pairs and emits [`ProxyEvent`]s.
#[derive(Clone, Debug)]
pub struct CapturingHandler {
    event_tx: mpsc::Sender<ProxyEvent>,
    captured_request: Option<ProxiedRequest>,
}

impl CapturingHandler {
    /// Create a new handler that sends events to the given channel.
    #[must_use]
    pub fn new(event_tx: mpsc::Sender<ProxyEvent>) -> Self {
        Self {
            event_tx,
            captured_request: None,
        }
    }

    pub(crate) fn take_captured_request(&mut self) -> Option<ProxiedRequest> {
        self.captured_request.take()
    }

    pub(crate) fn send_event(&self, event: ProxyEvent) {
        match self.event_tx.try_send(event) {
            Ok(()) => {}
            Err(mpsc::error::TrySendError::Full(_)) => {
                tracing::warn!("Event channel full, dropping event");
            }
            Err(mpsc::error::TrySendError::Closed(_)) => {
                tracing::debug!("Event channel closed");
            }
        }
    }
}

#[async_trait]
impl HttpHandler for CapturingHandler {
    async fn handle_request(
        &mut self,
        _ctx: &HttpContext,
        req: Request<hyper::body::Incoming>,
    ) -> RequestOrResponse {
        let (parts, incoming) = req.into_parts();
        let body_bytes = Limited::new(incoming, MAX_BODY_SIZE)
            .collect()
            .await
            .map(http_body_util::Collected::to_bytes)
            .unwrap_or_else(|e| {
                tracing::warn!("Failed to collect request body: {e}");
                Bytes::new()
            });

        let proxied_request = ProxiedRequest::new(
            parts.method.clone(),
            parts.uri.clone(),
            parts.version,
            parts.headers.clone(),
            body_bytes.clone(),
            now_millis(),
        );
        self.captured_request = Some(proxied_request);

        let req = Request::from_parts(parts, body::full(body_bytes));
        RequestOrResponse::Request(req)
    }

    async fn handle_response(
        &mut self,
        _ctx: &HttpContext,
        res: Response<hyper::body::Incoming>,
    ) -> Response<ProxyBody> {
        let (parts, incoming) = res.into_parts();
        let body_bytes = collect_body(incoming).await;
        collect_and_emit(self, parts, body_bytes)
    }
}