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

//! An HTTP endpoint for dynamically setting tracing filters.

use std::net::SocketAddr;

use abscissa_core::{Component, FrameworkError};

use crate::config::ZebradConfig;

#[cfg(feature = "filter-reload")]
use hyper::{Body, Request, Response};

#[cfg(feature = "filter-reload")]
use crate::{components::tokio::TokioComponent, prelude::*};

/// Abscissa component which runs a tracing filter endpoint.
#[derive(Debug, Component)]
#[cfg_attr(
    feature = "filter-reload",
    component(inject = "init_tokio(zebrad::components::tokio::TokioComponent)")
)]
pub struct TracingEndpoint {
    #[allow(dead_code)]
    addr: Option<SocketAddr>,
}

#[cfg(feature = "filter-reload")]
async fn read_filter(req: Request<Body>) -> Result<String, String> {
    std::str::from_utf8(
        &hyper::body::to_bytes(req.into_body())
            .await
            .map_err(|_| "Error reading body".to_owned())?,
    )
    .map(|s| s.to_owned())
    .map_err(|_| "Filter must be UTF-8".to_owned())
}

impl TracingEndpoint {
    /// Create the component.
    pub fn new(config: &ZebradConfig) -> Result<Self, FrameworkError> {
        if config.tracing.endpoint_addr.is_some() && !cfg!(feature = "filter-reload") {
            warn!(addr = ?config.tracing.endpoint_addr,
                  "unable to activate configured tracing filter endpoint: \
                   enable the 'filter-reload' feature when compiling zebrad",
            );
        }

        Ok(Self {
            addr: config.tracing.endpoint_addr,
        })
    }

    #[cfg(feature = "filter-reload")]
    #[allow(clippy::unwrap_in_result)]
    pub fn init_tokio(&mut self, tokio_component: &TokioComponent) -> Result<(), FrameworkError> {
        use hyper::{
            service::{make_service_fn, service_fn},
            Server,
        };

        let addr = if let Some(addr) = self.addr {
            addr
        } else {
            return Ok(());
        };

        let service =
            make_service_fn(|_| async { Ok::<_, hyper::Error>(service_fn(request_handler)) });

        info!("Trying to open tracing endpoint at {}...", addr);
        tokio_component
            .rt
            .as_ref()
            .expect("runtime should not be taken")
            .spawn(async move {
                // try_bind uses the tokio runtime, so we
                // need to construct it inside the task.
                let server = match Server::try_bind(&addr) {
                    Ok(s) => s,
                    Err(e) => panic!(
                        "Opening tracing endpoint listener {addr:?} failed: {e:?}. \
                         Hint: Check if another zebrad or zcashd process is running. \
                         Try changing the tracing endpoint_addr in the Zebra config.",
                    ),
                }
                .serve(service);

                info!("Opened tracing endpoint at {}", server.local_addr());

                if let Err(e) = server.await {
                    error!("Server error: {}", e);
                }
            });

        Ok(())
    }
}

#[cfg(feature = "filter-reload")]
#[instrument]
async fn request_handler(req: Request<Body>) -> Result<Response<Body>, hyper::Error> {
    use hyper::{Method, StatusCode};

    use super::Tracing;

    let rsp = match (req.method(), req.uri().path()) {
        (&Method::GET, "/") => Response::new(Body::from(
            r#"
This HTTP endpoint allows dynamic control of the filter applied to
tracing events.

To get the current filter, GET /filter:

    curl -X GET localhost:3000/filter

To set the filter, POST the new filter string to /filter:

    curl -X POST localhost:3000/filter -d "zebrad=trace"
"#,
        )),
        (&Method::GET, "/filter") => Response::builder()
            .status(StatusCode::OK)
            .body(Body::from(
                APPLICATION
                    .state()
                    .components()
                    .get_downcast_ref::<Tracing>()
                    .expect("Tracing component should be available")
                    .filter(),
            ))
            .expect("response with known status code cannot fail"),
        (&Method::POST, "/filter") => match read_filter(req).await {
            Ok(filter) => {
                APPLICATION
                    .state()
                    .components()
                    .get_downcast_ref::<Tracing>()
                    .expect("Tracing component should be available")
                    .reload_filter(filter);

                Response::new(Body::from(""))
            }
            Err(e) => Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .body(Body::from(e))
                .expect("response with known status code cannot fail"),
        },
        _ => Response::builder()
            .status(StatusCode::NOT_FOUND)
            .body(Body::from(""))
            .expect("response with known status cannot fail"),
    };
    Ok(rsp)
}