a2a_client/
lib.rs

1// Copyright AGNTCY Contributors (https://github.com/agntcy)
2// SPDX-License-Identifier: Apache-2.0
3pub mod agent_card;
4pub mod auth;
5pub mod client;
6pub mod factory;
7pub mod jsonrpc;
8pub mod middleware;
9mod push_config_compat;
10pub mod rest;
11pub mod transport;
12
13pub use client::A2AClient;
14pub use factory::A2AClientFactory;
15pub use futures::stream::BoxStream;
16pub use transport::{ServiceParams, Transport, TransportFactory};
17
18/// Build a `reqwest::Client` whose TLS layer matches this crate's feature
19/// selection, optionally adding extra root certificates from a PEM bundle.
20///
21/// - When `rustls-tls-aws-lc-rs` or `rustls-tls-ring` is enabled, a
22///   `rustls::ClientConfig` is constructed with the corresponding provider
23///   and handed to `reqwest::ClientBuilder::use_preconfigured_tls`. Custom
24///   PEM certificates are parsed and added to the rustls root store
25///   alongside the webpki roots. No process-global `CryptoProvider` is
26///   installed.
27/// - When only `rustls-tls` is enabled (no provider variant), reqwest
28///   falls back to whatever `CryptoProvider` the application installed via
29///   `install_default()`. If none is installed, `reqwest::Client::new()`
30///   panics; that is the contract the consumer accepted by disabling the
31///   provider variants.
32/// - When the rustls features are off (e.g. only `native-tls`), extra
33///   certificates are added via `reqwest::ClientBuilder::add_root_certificate`.
34pub fn default_reqwest_client(
35    extra_root_pem: Option<&[u8]>,
36) -> Result<reqwest::Client, a2a::A2AError> {
37    let builder = reqwest::Client::builder();
38
39    #[cfg(any(feature = "rustls-tls-aws-lc-rs", feature = "rustls-tls-ring"))]
40    let builder = builder.use_preconfigured_tls(rustls_client_config(extra_root_pem)?);
41
42    #[cfg(not(any(feature = "rustls-tls-aws-lc-rs", feature = "rustls-tls-ring")))]
43    let builder = match extra_root_pem {
44        Some(pem) => {
45            let cert = reqwest::Certificate::from_pem(pem)
46                .map_err(|e| a2a::A2AError::internal(format!("invalid PEM certificate: {e}")))?;
47            builder.add_root_certificate(cert)
48        }
49        None => builder,
50    };
51
52    builder
53        .build()
54        .map_err(|e| a2a::A2AError::internal(format!("failed to build HTTP client: {e}")))
55}
56
57#[cfg(any(feature = "rustls-tls-aws-lc-rs", feature = "rustls-tls-ring"))]
58fn rustls_client_config(
59    extra_root_pem: Option<&[u8]>,
60) -> Result<rustls::ClientConfig, a2a::A2AError> {
61    let provider = std::sync::Arc::new(selected_crypto_provider());
62    let mut roots = rustls::RootCertStore::empty();
63    roots.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
64    if let Some(pem) = extra_root_pem {
65        for cert in rustls_pemfile::certs(&mut std::io::Cursor::new(pem)) {
66            let der =
67                cert.map_err(|e| a2a::A2AError::internal(format!("invalid PEM certificate: {e}")))?;
68            roots
69                .add(der)
70                .map_err(|e| a2a::A2AError::internal(format!("failed to add CA: {e}")))?;
71        }
72    }
73    Ok(rustls::ClientConfig::builder_with_provider(provider)
74        .with_safe_default_protocol_versions()
75        .expect("safe default protocol versions are supported")
76        .with_root_certificates(roots)
77        .with_no_client_auth())
78}
79
80#[cfg(feature = "rustls-tls-aws-lc-rs")]
81fn selected_crypto_provider() -> rustls::crypto::CryptoProvider {
82    rustls::crypto::aws_lc_rs::default_provider()
83}
84
85#[cfg(all(feature = "rustls-tls-ring", not(feature = "rustls-tls-aws-lc-rs")))]
86fn selected_crypto_provider() -> rustls::crypto::CryptoProvider {
87    rustls::crypto::ring::default_provider()
88}
89
90pub(crate) fn a2a_error_from_details(
91    code: i32,
92    message: String,
93    details: Vec<a2a::TypedDetail>,
94) -> a2a::A2AError {
95    use a2a::{error_code, errordetails, reason_to_error_code};
96    use serde_json::Value;
97
98    let mut code = code;
99    let mut message = message;
100
101    for detail in &details {
102        match detail.type_url.as_str() {
103            errordetails::BAD_REQUEST_TYPE => {
104                if let Some(Value::Array(violations)) = detail.value.get("fieldViolations") {
105                    let violation_strs: Vec<String> = violations
106                        .iter()
107                        .filter_map(|v| {
108                            let field = v.get("field")?.as_str()?;
109                            let desc = v.get("description")?.as_str()?;
110                            if field.is_empty() {
111                                Some(desc.to_string())
112                            } else {
113                                Some(format!("{field}: {desc}"))
114                            }
115                        })
116                        .collect();
117                    if !violation_strs.is_empty() {
118                        message = format!("{}: {}", message, violation_strs.join("; "));
119                    }
120                }
121                if code == error_code::INTERNAL_ERROR {
122                    code = error_code::INVALID_PARAMS;
123                }
124            }
125            errordetails::ERROR_INFO_TYPE => {
126                if let Some(Value::String(domain)) = detail.value.get("domain") {
127                    if domain == errordetails::PROTOCOL_DOMAIN {
128                        if let Some(Value::String(reason)) = detail.value.get("reason") {
129                            if let Some(c) = reason_to_error_code(reason) {
130                                code = c;
131                            }
132                        }
133                    }
134                }
135            }
136            _ => {}
137        }
138    }
139
140    a2a::A2AError {
141        code,
142        message,
143        details: (!details.is_empty()).then_some(details),
144    }
145}
146
147#[cfg(test)]
148pub(crate) mod test_utils {
149    pub fn rcgen_self_signed_ca_pem() -> Vec<u8> {
150        let mut params = rcgen::CertificateParams::new(Vec::<String>::new()).unwrap();
151        params.is_ca = rcgen::IsCa::Ca(rcgen::BasicConstraints::Unconstrained);
152        params
153            .distinguished_name
154            .push(rcgen::DnType::CommonName, "Test CA");
155        let key = rcgen::KeyPair::generate().unwrap();
156        let cert = params.self_signed(&key).unwrap();
157        cert.pem().into_bytes()
158    }
159}
a2a_client/lib.rs

a2a_client/
lib.rs
