webhookey/src/main.rs

mod cli;
mod config;
mod filters;
mod metrics;

use crate::{
    cli::Opts,
    config::Config,
    filters::{FilterType, IpFilter},
    metrics::Metrics,
};
use anyhow::{anyhow, bail, Result};
use clap::Parser;
use hmac::{Hmac, Mac, NewMac};
use log::{debug, error, info, trace, warn};
use rocket::{
    data::{FromData, ToByteUnit},
    futures::TryFutureExt,
    http::{HeaderMap, Status},
    outcome::Outcome::{self, Failure, Success},
    post, routes,
    tokio::io::AsyncReadExt,
    Data, Request, State,
};
use run_script::ScriptOptions;
use serde::{Deserialize, Serialize};
use sha2::Sha256;
use std::{
    collections::BTreeMap,
    fs::File,
    io::BufReader,
    net::{IpAddr, Ipv4Addr, SocketAddr},
    sync::atomic::Ordering,
};
use thiserror::Error;

#[derive(Debug, Error)]
pub enum WebhookeyError {
    #[error("Could not extract signature from header")]
    InvalidSignature,
    #[error("Unauthorized request from `{0}`")]
    Unauthorized(IpAddr),
    #[error("Unmatched hook from `{0}`")]
    UnmatchedHook(IpAddr),
    #[error("Could not evaluate filter request")]
    InvalidFilter,
    #[error("IO Error")]
    Io(std::io::Error),
    #[error("Serde Error")]
    Serde(serde_json::Error),
}

#[derive(Debug, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct Hook {
    command: String,
    signature: String,
    ip_filter: Option<IpFilter>,
    secrets: Vec<String>,
    filter: FilterType,
}

impl Hook {
    fn get_command(
        &self,
        hook_name: &str,
        request: &Request,
        data: &mut serde_json::Value,
    ) -> Result<String> {
        debug!("Replacing parameters for command of  hook `{}`", hook_name);

        Hook::replace_parameters(&self.command, request.headers(), data)
    }

    fn replace_parameters(
        input: &str,
        headers: &HeaderMap,
        data: &serde_json::Value,
    ) -> Result<String> {
        let mut command = String::new();
        let command_template = &mut input.chars();

        while let Some(i) = command_template.next() {
            if i == '{' {
                if let Some('{') = command_template.next() {
                    let mut token = String::new();

                    while let Some(i) = command_template.next() {
                        if i == '}' {
                            if let Some('}') = command_template.next() {
                                let expr = token.trim().split(' ').collect::<Vec<&str>>();

                                let replaced = match expr.get(0) {
                                    Some(&"header") => get_header_field(
                                        headers,
                                        expr.get(1).ok_or_else(|| {
                                            anyhow!("Missing parameter for `header` expression")
                                        })?,
                                    )?
                                    .to_string(),
                                    Some(pointer) => {
                                        get_string(data.pointer(pointer).ok_or_else(|| {
                                            anyhow!(
                                                "Could not find field refered to in parameter `{}`",
                                                pointer
                                            )
                                        })?)?
                                    }
                                    None => bail!("Missing expression in variable `{}`", token),
                                };

                                command.push_str(&replaced);

                                trace!("Replace `{}` with: {}", token, replaced);

                                break;
                            } else {
                                command.push('}');
                                command.push(i);
                            }
                        } else {
                            token.push(i);
                        }
                    }
                } else {
                    command.push('{');
                    command.push(i);
                }
            } else {
                command.push(i);
            }
        }

        Ok(command)
    }
}

#[derive(Debug)]
struct Hooks {
    inner: BTreeMap<String, String>,
}

impl Hooks {
    async fn get_commands(request: &Request<'_>, data: Data<'_>) -> Result<Self, WebhookeyError> {
        let mut buffer = Vec::new();
        let size = data
            .open(256_i32.kilobytes())
            .read_to_end(&mut buffer)
            .map_err(WebhookeyError::Io)
            .await?;
        info!("Data of size {} received", size);

        let config = request.guard::<&State<Config>>().await.unwrap(); // should never fail
        let mut valid = false;
        let mut result = BTreeMap::new();
        let client_ip = &request
            .client_ip()
            .unwrap_or(IpAddr::V4(Ipv4Addr::UNSPECIFIED));

        let hooks = config.hooks.iter().filter(|(name, hook)| {
            if let Some(ip) = &hook.ip_filter {
                accept_ip(name, client_ip, ip)
            } else {
                info!(
                    "Allow hook `{}` from {}, no IP filter was configured",
                    &name, &client_ip
                );
                true
            }
        });

        for (hook_name, hook) in hooks {
            let signature = request
                .headers()
                .get_one(&hook.signature)
                .ok_or(WebhookeyError::InvalidSignature)?;

            let secrets = hook
                .secrets
                .iter()
                .map(|secret| validate_request(secret, signature, &buffer));

            for secret in secrets {
                match secret {
                    Ok(()) => {
                        trace!("Valid signature found for hook `{}`", hook_name);

                        valid = true;

                        let mut data: serde_json::Value =
                            serde_json::from_slice(&buffer).map_err(WebhookeyError::Serde)?;

                        match hook.filter.evaluate(request, &data) {
                            Ok(true) => match hook.get_command(hook_name, request, &mut data) {
                                Ok(command) => {
                                    info!("Filter for `{}` matched", &hook_name);
                                    result.insert(hook_name.to_string(), command);
                                    break;
                                }
                                Err(e) => error!("{}", e),
                            },
                            Ok(false) => info!("Filter for `{}` did not match", &hook_name),
                            Err(error) => {
                                error!("Could not match filter for `{}`: {}", &hook_name, error)
                            }
                        }
                    }
                    Err(e) => trace!("Hook `{}` could not validate request: {}", &hook_name, e),
                }
            }
        }

        if !valid {
            return Err(WebhookeyError::Unauthorized(*client_ip));
        }

        Ok(Hooks { inner: result })
    }
}

fn accept_ip(hook_name: &str, client_ip: &IpAddr, ip: &IpFilter) -> bool {
    if ip.validate(client_ip) {
        info!("Allow hook `{}` from {}", &hook_name, &client_ip);
        return true;
    }

    warn!("Deny hook `{}` from {}", &hook_name, &client_ip);
    false
}

fn validate_request(secret: &str, signature: &str, data: &[u8]) -> Result<()> {
    let mut mac = Hmac::<Sha256>::new_from_slice(secret.as_bytes())
        .map_err(|e| anyhow!("Could not create hasher with secret: {}", e))?;
    mac.update(data);
    let raw_signature = hex::decode(signature.as_bytes())?;
    mac.verify(&raw_signature).map_err(|e| anyhow!("{}", e))
}

fn get_header_field<'a>(headers: &'a HeaderMap, param: &str) -> Result<&'a str> {
    headers
        .get_one(param)
        .ok_or_else(|| anyhow!("Could not extract event parameter from header"))
}

pub fn get_string(data: &serde_json::Value) -> Result<String, WebhookeyError> {
    match &data {
        serde_json::Value::Bool(bool) => Ok(bool.to_string()),
        serde_json::Value::Number(number) => Ok(number.to_string()),
        serde_json::Value::String(string) => Ok(string.as_str().to_string()),
        x => {
            error!("Could not get string from: {:?}", x);
            unimplemented!()
        }
    }
}

#[rocket::async_trait]
impl<'r> FromData<'r> for Hooks {
    type Error = WebhookeyError;

    async fn from_data(
        request: &'r Request<'_>,
        data: Data<'r>,
    ) -> Outcome<Self, (Status, Self::Error), Data<'r>> {
        {
            request
                .guard::<&State<Metrics>>()
                .await
                .unwrap() // TODO: Check if unwrap need to be fixed
                .requests_received
                .fetch_add(1, Ordering::Relaxed);
        }

        match Hooks::get_commands(request, data).await {
            Ok(hooks) => {
                if hooks.inner.is_empty() {
                    let client_ip = &request
                        .client_ip()
                        .unwrap_or(IpAddr::V4(Ipv4Addr::UNSPECIFIED));

                    request
                        .guard::<&State<Metrics>>()
                        .await
                        .unwrap() // TODO: Check if unwrap need to be fixed
                        .hooks_unmatched
                        .fetch_add(1, Ordering::Relaxed);

                    warn!("Unmatched hook from {}", &client_ip);
                    return Failure((Status::NotFound, WebhookeyError::UnmatchedHook(*client_ip)));
                }

                Success(hooks)
            }
            Err(WebhookeyError::Unauthorized(e)) => {
                error!("{}", WebhookeyError::Unauthorized(e));

                request
                    .guard::<&State<Metrics>>()
                    .await
                    .unwrap() // TODO: Check if unwrap need to be fixed
                    .hooks_forbidden
                    .fetch_add(1, Ordering::Relaxed);

                Failure((Status::Unauthorized, WebhookeyError::Unauthorized(e)))
            }
            Err(e) => {
                error!("{}", e);

                request
                    .guard::<&State<Metrics>>()
                    .await
                    .unwrap() // TODO: Check if unwrap need to be fixed
                    .requests_invalid
                    .fetch_add(1, Ordering::Relaxed);

                Failure((Status::BadRequest, e))
            }
        }
    }
}

#[post("/", format = "json", data = "<hooks>")]
async fn receive_hook<'a>(address: SocketAddr, hooks: Hooks, metrics: &State<Metrics>) -> Status {
    info!("Post request received from: {}", address);

    hooks.inner.iter().for_each(|(name, command)| {
        info!("Execute `{}` from hook `{}`", &command, &name);

        match run_script::run(command, &vec![], &ScriptOptions::new()) {
            Ok((status, stdout, stderr)) => {
                info!("Command `{}` exited with return code: {}", &command, status);
                trace!("Output of command `{}` on stdout: {:?}", &command, &stdout);
                debug!("Output of command `{}` on stderr: {:?}", &command, &stderr);

                metrics.commands_executed.fetch_add(1, Ordering::Relaxed);

                let _ = match status {
                    0 => metrics.commands_successful.fetch_add(1, Ordering::Relaxed),
                    _ => metrics.commands_failed.fetch_add(1, Ordering::Relaxed),
                };
            }
            Err(e) => {
                error!("Execution of `{}` failed: {}", &command, e);

                metrics
                    .commands_execution_failed
                    .fetch_add(1, Ordering::Relaxed);
            }
        }
    });

    Status::Ok
}

#[rocket::main]
async fn main() -> Result<()> {
    env_logger::init();

    let cli: Opts = Opts::parse();

    let config: Config = match cli.config {
        Some(config) => serde_yaml::from_reader(BufReader::new(File::open(config)?))?,
        _ => serde_yaml::from_reader(BufReader::new(config::get_config()?))?,
    };

    trace!("Parsed configuration:\n{}", serde_yaml::to_string(&config)?);

    if cli.command.is_some() {
        debug!("Configtest succeded.");
        println!("Config is OK");
        return Ok(());
    }

    rocket::build()
        .mount("/", routes![receive_hook, metrics::metrics])
        .manage(config)
        .manage(Metrics::default())
        .launch()
        .await?;

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::MetricsConfig;
    use filters::{AddrType, HeaderFilter, JsonFilter};
    use regex::Regex;
    use rocket::{
        http::{ContentType, Header},
        local::asynchronous::Client,
    };
    use serde_json::json;

    #[rocket::async_test]
    async fn secret() {
        let mut hooks = BTreeMap::new();

        hooks.insert(
            "test_hook".to_string(),
            Hook {
                command: "".to_string(),
                signature: "X-Gitea-Signature".to_string(),
                ip_filter: None,
                secrets: vec!["valid".to_string()],
                filter: FilterType::JsonFilter(JsonFilter {
                    pointer: "*".to_string(),
                    regex: Regex::new(".*").unwrap(),
                }),
            },
        );

        let config = Config {
            metrics: None,
            hooks: hooks,
        };

        let rocket = rocket::build()
            .mount("/", routes![receive_hook])
            .manage(config)
            .manage(Metrics::default());

        let client = Client::tracked(rocket).await.unwrap();
        let response = client
            .post("/")
            .header(Header::new(
                "X-Gitea-Signature",
                "28175a0035f637f3cbb85afee9f9d319631580e7621cf790cd16ca063a2f820e",
            ))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .body(&serde_json::to_string(&json!({ "foo": "bar" })).unwrap())
            .dispatch();

        assert_eq!(response.await.status(), Status::NotFound);

        let response = client
            .post("/")
            .header(Header::new("X-Gitea-Signature", "beef"))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .body(&serde_json::to_string(&json!({ "foo": "bar" })).unwrap())
            .dispatch();

        assert_eq!(response.await.status(), Status::Unauthorized);

        let response = client
            .post("/")
            .header(Header::new(
                "X-Gitea-Signature",
                "c5c315d76318362ec129ca629b50b626bba09ad3d7ba4cc0f4c0afe4a90537a0",
            ))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .body(r#"{ "not_secret": "invalid" "#)
            .dispatch();

        assert_eq!(response.await.status(), Status::BadRequest);

        let response = client
            .post("/")
            .header(Header::new("X-Gitea-Signature", "foobar"))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .dispatch();

        assert_eq!(response.await.status(), Status::Unauthorized);
    }

    #[test]
    fn parse_command() {
        let mut headers = HeaderMap::new();
        headers.add_raw("X-Gitea-Event", "something");

        assert_eq!(
            Hook::replace_parameters("command", &headers, &serde_json::Value::Null).unwrap(),
            "command"
        );

        assert_eq!(
            Hook::replace_parameters("    command", &headers, &serde_json::Value::Null).unwrap(),
            "    command"
        );

        assert_eq!(
            Hook::replace_parameters("command    ", &headers, &serde_json::Value::Null).unwrap(),
            "command    "
        );

        assert_eq!(
            Hook::replace_parameters("    command    ", &headers, &serde_json::Value::Null)
                .unwrap(),
            "    command    "
        );

        assert_eq!(
            Hook::replace_parameters("command command    ", &headers, &serde_json::Value::Null)
                .unwrap(),
            "command command    "
        );

        assert_eq!(
            Hook::replace_parameters("{{ /foo }}   command", &headers, &json!({ "foo": "bar" }))
                .unwrap(),
            "bar   command"
        );

        assert_eq!(
            Hook::replace_parameters(
                "   command  {{ /foo }}  ",
                &headers,
                &json!({ "foo": "bar" })
            )
            .unwrap(),
            "   command  bar  "
        );

        assert_eq!(
            Hook::replace_parameters(
                "{{ /foo }}   command{{/field1/foo}}",
                &headers,
                &json!({ "foo": "bar", "field1": { "foo": "baz" } })
            )
            .unwrap(),
            "bar   commandbaz"
        );

        assert_eq!(
            Hook::replace_parameters(
                "   command  {{ /foo }}  ",
                &headers,
                &json!({ "foo": "bar" })
            )
            .unwrap(),
            "   command  bar  "
        );

        assert_eq!(
            Hook::replace_parameters(
                "   {{ /field1/foo }}   command",
                &headers,
                &json!({ "field1": { "foo": "bar" } })
            )
            .unwrap(),
            "   bar   command"
        );

        assert_eq!(
            Hook::replace_parameters(
                "   {{ header X-Gitea-Event }}   command",
                &headers,
                &json!({ "field1": { "foo": "bar" } })
            )
            .unwrap(),
            "   something   command"
        );

        assert_eq!(
            Hook::replace_parameters(
                "   {{ header X-Gitea-Event }} {{ /field1/foo }}  command",
                &headers,
                &json!({ "field1": { "foo": "bar" } })
            )
            .unwrap(),
            "   something bar  command"
        );

        assert_eq!(
            Hook::replace_parameters(
                "   {{ header X-Gitea-Event }} {{ /field1/foo }} {{ /field1/bar }} {{ /field2/foo }} --command{{ /cmd }}",
                &headers,
                &json!({ "field1": { "foo": "bar", "bar": "baz" }, "field2": { "foo": "qux" }, "cmd": " else"})
            )
            .unwrap(),
            "   something bar baz qux --command else"
        );
    }

    #[rocket::async_test]
    async fn parse_command_request() {
        let mut hooks = BTreeMap::new();

        hooks.insert(
            "test_hook0".to_string(),
            Hook {
                command:
                    "/usr/bin/echo {{ /repository/full_name }} --foo {{ /pull_request/base/ref }}"
                        .to_string(),
                signature: "X-Gitea-Signature".to_string(),
                ip_filter: None,
                secrets: vec!["valid".to_string()],
                filter: FilterType::JsonFilter(JsonFilter {
                    pointer: "/foo".to_string(),
                    regex: Regex::new("bar").unwrap(),
                }),
            },
        );

        hooks.insert(
            "test_hook2".to_string(),
            Hook {
                command: "/usr/bin/echo {{ /repository/full_name }} {{ /pull_request/base/ref }}"
                    .to_string(),
                signature: "X-Gitea-Signature".to_string(),
                ip_filter: None,
                secrets: vec!["valid".to_string()],
                filter: FilterType::JsonFilter(JsonFilter {
                    pointer: "/foo".to_string(),
                    regex: Regex::new("bar").unwrap(),
                }),
            },
        );

        hooks.insert(
            "test_hook3".to_string(),
            Hook {
                command: "/usr/bin/echo {{ /repository/full_name }} {{ /pull_request/base/ref }}"
                    .to_string(),
                signature: "X-Gitea-Signature".to_string(),
                ip_filter: None,
                secrets: vec!["valid".to_string()],
                filter: FilterType::Not(Box::new(FilterType::JsonFilter(JsonFilter {
                    pointer: "/foobar".to_string(),
                    regex: Regex::new("bar").unwrap(),
                }))),
            },
        );

        let config = Config {
            metrics: None,
            hooks: hooks,
        };

        let rocket = rocket::build()
            .mount("/", routes![receive_hook])
            .manage(config)
            .manage(Metrics::default());

        let client = Client::tracked(rocket).await.unwrap();

        let response = client
            .post("/")
            .header(Header::new(
                "X-Gitea-Signature",
                "693b733871ecb684651a813c82936df683c9e4a816581f385353e06170545400",
            ))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .body(
                &serde_json::to_string(&json!({
                    "foo": "bar",
                    "repository": {
                        "full_name": "keith"
                    },
                    "pull_request": {
                        "base": {
                            "ref": "main"
                        }
                    }
                }))
                .unwrap(),
            )
            .dispatch();

        assert_eq!(response.await.status(), Status::Ok);
    }

    #[rocket::async_test]
    async fn parse_invalid_command_request() {
        let mut hooks = BTreeMap::new();

        hooks.insert(
            "test_hook".to_string(),
            Hook {
                command: "/usr/bin/echo {{ /repository/full }} {{ /pull_request/base/ref }}"
                    .to_string(),
                signature: "X-Gitea-Signature".to_string(),
                ip_filter: None,
                secrets: vec!["valid".to_string()],
                filter: FilterType::JsonFilter(JsonFilter {
                    pointer: "/foo".to_string(),
                    regex: Regex::new("bar").unwrap(),
                }),
            },
        );

        let config = Config {
            metrics: None,
            hooks: hooks,
        };

        let rocket = rocket::build()
            .mount("/", routes![receive_hook])
            .manage(config)
            .manage(Metrics::default());

        let client = Client::tracked(rocket).await.unwrap();

        let response = client
            .post("/")
            .header(Header::new(
                "X-Gitea-Signature",
                "693b733871ecb684651a813c82936df683c9e4a816581f385353e06170545400",
            ))
            .header(ContentType::JSON)
            .remote("127.0.0.1:8000".parse().unwrap())
            .body(
                &serde_json::to_string(&json!({
                    "foo": "bar",
                    "repository": {
                        "full_name": "keith"
                    },
                    "pull_request": {
                        "base": {
                            "ref": "main"
                        }
                    }
                }))
                .unwrap(),
            )
            .dispatch();

        assert_eq!(response.await.status(), Status::NotFound);
    }

    #[test]
    fn parse_config() {
        let config: Config = serde_yaml::from_str(
            r#"---
hooks:
  hook1:
    command: /usr/bin/local/script_xy.sh {{ /field2/foo }} asdfasdf
    signature: X-Gitea-Signature
    ip_filter:
      allow:
        - 127.0.0.1/31
    secrets:
      - secret_key_01
      - secret_key_02
    filter:
      json:
        pointer: /ref
        regex: refs/heads/master
  hook2:
    command: /usr/bin/local/script_xy.sh asdfasdf
    signature: X-Gitea-Signature
    secrets:
      - secret_key_01
      - secret_key_02
    filter:
      and:
        - json:
            pointer: /ref
            regex: refs/heads/master
        - header:
            field: X-Gitea-Signature
            regex: f6e5fe4fe37df76629112d55cc210718b6a55e7e"#,
        )
        .unwrap();

        assert_eq!(
            serde_yaml::to_string(&config).unwrap(),
            serde_yaml::to_string(&Config {
                metrics: None,
                hooks: BTreeMap::from([
                    (
                        "hook1".to_string(),
                        Hook {
                            command: "/usr/bin/local/script_xy.sh {{ /field2/foo }} asdfasdf"
                                .to_string(),
                            signature: "X-Gitea-Signature".to_string(),
                            ip_filter: Some(IpFilter::Allow(vec![AddrType::IpNet(
                                "127.0.0.1/31".parse().unwrap()
                            )])),
                            secrets: vec!["secret_key_01".to_string(), "secret_key_02".to_string()],
                            filter: FilterType::JsonFilter(JsonFilter {
                                pointer: "/ref".to_string(),
                                regex: Regex::new("refs/heads/master").unwrap(),
                            }),
                        }
                    ),
                    (
                        "hook2".to_string(),
                        Hook {
                            command: "/usr/bin/local/script_xy.sh asdfasdf".to_string(),
                            signature: "X-Gitea-Signature".to_string(),
                            ip_filter: None,
                            secrets: vec!["secret_key_01".to_string(), "secret_key_02".to_string()],
                            filter: FilterType::And(vec![
                                FilterType::JsonFilter(JsonFilter {
                                    pointer: "/ref".to_string(),
                                    regex: Regex::new("refs/heads/master").unwrap(),
                                }),
                                FilterType::HeaderFilter(HeaderFilter {
                                    field: "X-Gitea-Signature".to_string(),
                                    regex: Regex::new("f6e5fe4fe37df76629112d55cc210718b6a55e7e")
                                        .unwrap(),
                                }),
                            ]),
                        }
                    )
                ])
            })
            .unwrap()
        );

        let config: Config = serde_yaml::from_str(
            r#"---
metrics:
  enabled: true
hooks:
  hook1:
    command: /usr/bin/local/script_xy.sh {{ /field2/foo }} asdfasdf
    signature: X-Gitea-Signature
    ip_filter:
      allow:
        - 127.0.0.1/31
    secrets:
      - secret_key_01
      - secret_key_02
    filter:
      json:
        pointer: /ref
        regex: refs/heads/master"#,
        )
        .unwrap();

        assert_eq!(
            serde_yaml::to_string(&config).unwrap(),
            serde_yaml::to_string(&Config {
                metrics: Some(MetricsConfig {
                    enabled: true,
                    ip_filter: None
                }),
                hooks: BTreeMap::from([(
                    "hook1".to_string(),
                    Hook {
                        command: "/usr/bin/local/script_xy.sh {{ /field2/foo }} asdfasdf"
                            .to_string(),
                        signature: "X-Gitea-Signature".to_string(),
                        ip_filter: Some(IpFilter::Allow(vec![AddrType::IpNet(
                            "127.0.0.1/31".parse().unwrap()
                        )])),
                        secrets: vec!["secret_key_01".to_string(), "secret_key_02".to_string()],
                        filter: FilterType::JsonFilter(JsonFilter {
                            pointer: "/ref".to_string(),
                            regex: Regex::new("refs/heads/master").unwrap(),
                        }),
                    }
                ),])
            })
            .unwrap()
        );
    }
}