systemprompt_api/services/gateway/service/
mod.rs

1//! Gateway dispatch entry point: route resolution, policy and quota checks,
2//! upstream send, and response finalization.
3//!
4//! Copyright (c) systemprompt.io — Business Source License 1.1.
5//! See <https://systemprompt.io> for licensing details.
6#![expect(
7    clippy::clone_on_ref_ptr,
8    reason = "Arc::clone usage is intentional and ergonomic in this gateway dispatch path"
9)]
10
11mod finalize;
12mod resolve;
13
14#[cfg(feature = "test-api")]
15pub mod test_api {
16    pub use super::finalize::{apply_system_prompt_override, attach_request_id};
17}
18
19use std::sync::Arc;
20
21use anyhow::{Result, anyhow};
22use axum::body::Body;
23use axum::response::Response;
24use bytes::Bytes;
25use systemprompt_ai::SafetyConfig;
26use systemprompt_database::DbPool;
27use systemprompt_identifiers::{AiRequestId, UserId};
28use systemprompt_models::profile::{GatewayConfig, ProviderRegistry};
29
30use self::finalize::{
31    FinalizeCtx, apply_system_prompt_override, attach_request_id, finalize, run_request_safety_scan,
32};
33use self::resolve::{ResolvedUpstream, resolve_upstream};
34use super::audit::{GatewayAudit, GatewayRequestContext};
35use super::policy::{PolicyResolver, QuotaWindow};
36use super::protocol::canonical::CanonicalRequest;
37use super::protocol::inbound::InboundAdapter;
38use super::protocol::outbound::{OutboundCtx, OutboundOutcome};
39use super::quota;
40
41pub const REQUEST_ID_HEADER: &str = "x-systemprompt-request-id";
42
43#[derive(Debug, Clone, Copy)]
44pub struct GatewayService;
45
46#[derive(Debug)]
47pub struct DispatchInputs {
48    pub request: CanonicalRequest,
49    pub raw_body: Bytes,
50    pub ctx: GatewayRequestContext,
51    pub inbound: Arc<dyn InboundAdapter>,
52}
53
54#[derive(Debug, thiserror::Error)]
55pub enum DispatchError {
56    #[error(transparent)]
57    PreAudit(anyhow::Error),
58    #[error(transparent)]
59    Recorded(anyhow::Error),
60}
61
62#[derive(Debug, thiserror::Error)]
63#[error("{0}")]
64pub struct PolicyDenied(pub String);
65
66#[derive(Debug, thiserror::Error)]
67#[error("{message}")]
68pub struct QuotaExceeded {
69    pub message: String,
70    pub retry_after_seconds: i32,
71}
72
73#[derive(Debug, thiserror::Error)]
74#[error("{message}")]
75pub struct SafetyBlocked {
76    pub category: String,
77    pub message: String,
78}
79
80impl GatewayService {
81    pub async fn dispatch(
82        config: &GatewayConfig,
83        registry: &ProviderRegistry,
84        db: &DbPool,
85        inputs: DispatchInputs,
86    ) -> Result<Response<Body>, DispatchError> {
87        let DispatchInputs {
88            mut request,
89            raw_body,
90            ctx,
91            inbound,
92        } = inputs;
93        if ctx.session_id.is_none() {
94            return Err(DispatchError::PreAudit(anyhow!(
95                "gateway dispatch missing conversation binding (session_id)"
96            )));
97        }
98
99        let ai_request_id = ctx.ai_request_id.clone();
100        let upstream = resolve_upstream(config, registry, &request, &ai_request_id).await?;
101
102        tracing::info!(
103            ai_request_id = %ai_request_id,
104            user_id = %ctx.user_id,
105            model = %request.model,
106            provider = %upstream.route.provider,
107            upstream = %upstream.provider.endpoint,
108            wire_protocol = %ctx.wire_protocol,
109            streaming = request.stream,
110            "Gateway request dispatched"
111        );
112
113        let resolver = PolicyResolver::new(db).map_err(DispatchError::PreAudit)?;
114        let policy = resolver.resolve().await;
115
116        let audit = Arc::new(
117            GatewayAudit::new(db, ctx.clone())
118                .map_err(|e| DispatchError::PreAudit(anyhow!("audit init failed: {e}")))?,
119        );
120
121        if let Err(e) = audit.open(&request, &raw_body).await {
122            tracing::error!(error = %e, "audit open failed — proceeding without audit row");
123        }
124
125        if let Some(descriptor) = upstream.route_match_descriptor.as_deref() {
126            audit.set_route_match(descriptor).await;
127        }
128
129        enforce_quota(db, &ctx.user_id, &policy.quota_windows, &audit).await?;
130        enforce_request_safety(db, &ai_request_id, &request, &policy.safety, &audit).await?;
131
132        let outcome = send_to_upstream(config, &upstream, &mut request, &audit).await?;
133
134        let response = finalize(
135            outcome,
136            FinalizeCtx {
137                audit: Arc::clone(&audit),
138                db: db.clone(),
139                ai_request_id: ai_request_id.clone(),
140                policy,
141                inbound,
142                request_model: request.model.clone(),
143            },
144        )
145        .await;
146        Ok(attach_request_id(response, &ai_request_id))
147    }
148}
149
150async fn send_to_upstream(
151    config: &GatewayConfig,
152    upstream: &ResolvedUpstream<'_>,
153    request: &mut CanonicalRequest,
154    audit: &GatewayAudit,
155) -> Result<OutboundOutcome, DispatchError> {
156    let upstream_model = upstream
157        .route
158        .effective_upstream_model(&request.model)
159        .to_owned();
160    if let Some(descriptor) =
161        apply_system_prompt_override(config, &upstream.provider.name, &upstream_model, request)
162            .await
163    {
164        audit.set_system_prompt_override(&descriptor).await;
165    }
166    let model_limits = upstream
167        .provider
168        .find_model(&upstream_model)
169        .map(|m| m.limits);
170    let outbound_ctx = OutboundCtx {
171        route: upstream.route.as_ref(),
172        endpoint: &upstream.provider.endpoint,
173        api_key: upstream.api_key,
174        request,
175        upstream_model: &upstream_model,
176        model_limits,
177    };
178
179    match upstream.adapter.send(outbound_ctx).await {
180        Ok(o) => Ok(o),
181        Err(e) => {
182            audit_upstream_failure(audit, upstream.provider.name.as_str(), &request.model, &e)
183                .await;
184            Err(DispatchError::Recorded(e))
185        },
186    }
187}
188
189async fn enforce_quota(
190    db: &DbPool,
191    user_id: &UserId,
192    quota_windows: &[QuotaWindow],
193    audit: &GatewayAudit,
194) -> Result<(), DispatchError> {
195    let reservation = quota::precheck_and_reserve(db, user_id, quota_windows)
196        .await
197        .map_err(DispatchError::Recorded)?;
198    let Some(decision) = reservation else {
199        return Ok(());
200    };
201    if decision.allow {
202        return Ok(());
203    }
204    let msg = format!(
205        "quota exceeded for window {}s (used {}/{:?})",
206        decision.window_seconds, decision.state.requests, decision.limit_requests
207    );
208    if let Err(e) = audit.fail(&msg).await {
209        tracing::warn!(error = %e, "quota audit fail failed");
210    }
211    Err(DispatchError::Recorded(
212        QuotaExceeded {
213            message: msg,
214            retry_after_seconds: decision.window_seconds,
215        }
216        .into(),
217    ))
218}
219
220async fn enforce_request_safety(
221    db: &DbPool,
222    ai_request_id: &AiRequestId,
223    request: &CanonicalRequest,
224    safety: &SafetyConfig,
225    audit: &GatewayAudit,
226) -> Result<(), DispatchError> {
227    let findings = run_request_safety_scan(db, ai_request_id, request, safety).await;
228    let Some(finding) = findings
229        .iter()
230        .find(|f| safety.block_categories.contains(&f.category))
231    else {
232        return Ok(());
233    };
234    let msg = format!(
235        "request blocked by safety policy: category '{}'",
236        finding.category
237    );
238    tracing::warn!(
239        ai_request_id = %ai_request_id,
240        category = %finding.category,
241        scanner = %finding.scanner,
242        "Gateway blocked request by safety policy"
243    );
244    if let Err(e) = audit.fail(&msg).await {
245        tracing::warn!(error = %e, "safety-block audit fail failed");
246    }
247    Err(DispatchError::Recorded(
248        SafetyBlocked {
249            category: finding.category.clone(),
250            message: msg,
251        }
252        .into(),
253    ))
254}
255
256async fn audit_upstream_failure(
257    audit: &GatewayAudit,
258    provider: &str,
259    model: &str,
260    error: &anyhow::Error,
261) {
262    tracing::warn!(
263        provider = %provider,
264        model = %model,
265        error = %error,
266        "gateway upstream call failed"
267    );
268    if let Err(audit_err) = audit.fail(&error.to_string()).await {
269        tracing::warn!(error = %audit_err, "upstream audit fail failed");
270    }
271}
systemprompt_api/services/gateway/service/mod.rs

systemprompt_api/services/gateway/service/
mod.rs
