feat(lsp): respect IDE user proxy settings / forward trust store

plugins/amazonq/shared/jetbrains-community/src/software/aws/toolkits/jetbrains/services/amazonq/lsp/TrustChainUtil.kt

@@ -0,0 +1,119 @@
+// Copyright 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.jetbrains.services.amazonq.lsp
+
+import com.intellij.util.io.DigestUtil
+import com.intellij.util.net.JdkProxyProvider
+import com.intellij.util.net.ssl.CertificateManager
+import org.apache.http.client.methods.RequestBuilder
+import org.apache.http.conn.ssl.DefaultHostnameVerifier
+import org.apache.http.impl.client.HttpClientBuilder
+import org.apache.http.impl.client.SystemDefaultCredentialsProvider
+import org.apache.http.impl.conn.SystemDefaultRoutePlanner
+import software.aws.toolkits.core.utils.getLogger
+import software.aws.toolkits.core.utils.warn
+import java.net.URI
+import java.security.KeyStore
+import java.security.cert.CertPathBuilder
+import java.security.cert.CertStore
+import java.security.cert.Certificate
+import java.security.cert.CollectionCertStoreParameters
+import java.security.cert.PKIXBuilderParameters
+import java.security.cert.PKIXCertPathBuilderResult
+import java.security.cert.X509CertSelector
+import java.security.cert.X509Certificate
+import kotlin.collections.ifEmpty
+
+object TrustChainUtil {
+    private val LOG = getLogger<TrustChainUtil>()
+
+    /**
+     * Build and validate the complete certificate chain
+     * @param certs The end-entity certificate
+     * @param trustAnchors The truststore containing trusted CA certificates
+     * @return The complete certificate chain
+     */
+    fun resolveTrustChain(certs: Collection<X509Certificate>, trustAnchors: KeyStore): List<X509Certificate> {
+        // Create the selector for the certificate
+        val selector = X509CertSelector()
+        selector.certificate = certs.first()
+
+        // Create the parameters for path validation
+        val pkixParams = PKIXBuilderParameters(trustAnchors, selector)
+
+        // Disable CRL checking since we just want to build the path
+        pkixParams.isRevocationEnabled = false
+
+        // Create a CertStore containing the certificate we want to validate
+        val ccsp = CollectionCertStoreParameters(certs)
+        val certStore = CertStore.getInstance("Collection", ccsp)
+        pkixParams.addCertStore(certStore)
+
+        // Get the certification path
+        val builder = CertPathBuilder.getInstance("PKIX")
+        val result = builder.build(pkixParams) as PKIXCertPathBuilderResult
+        val certPath = result.certPath
+        val chain = (certPath.certificates as List<X509Certificate>).toMutableList()
+
+        // Add the trust anchor (root CA) to complete the chain
+        val trustAnchorCert = result.trustAnchor.trustedCert
+        if (trustAnchorCert != null) {
+            chain.add(trustAnchorCert)
+        }
+
+        return chain
+    }
+
+    fun getTrustChain(uri: URI): List<X509Certificate> {
+        val proxyProvider = JdkProxyProvider.getInstance()
+        var peerCerts: Array<Certificate> = emptyArray()
+        val verifierDelegate = DefaultHostnameVerifier()
+        val client = HttpClientBuilder.create()
+            .setRoutePlanner(SystemDefaultRoutePlanner(proxyProvider.proxySelector))
+            .setDefaultCredentialsProvider(SystemDefaultCredentialsProvider())
+            .setSSLHostnameVerifier { hostname, sslSession ->
+                peerCerts = sslSession.peerCertificates
+
+                verifierDelegate.verify(hostname, sslSession)
+            }
+            // prompt user via modal to accept certificate if needed; otherwise need to prompt separately prior to launching flare
+            .setSSLContext(CertificateManager.getInstance().sslContext)
+
+        // client request will fail if user did not accept cert
+        client.build().execute(RequestBuilder.options(uri).build())
+
+        val certificates = peerCerts as Array<X509Certificate>
+
+        // java default + custom system
+        // excluding leaf cert for case where user has both leaf and issuing CA as trusted roots
+        val allAccepted = CertificateManager.getInstance().trustManager.acceptedIssuers.toSet() - certificates.first()
+        val ks = keystoreFromCertificates(allAccepted)
+
+        // if this throws then there is a bug because it passed PKIX validation in apache client
+        val trustChain = try {
+            resolveTrustChain(certificates.toList(), ks)
+        } catch (e: Exception) {
+            LOG.warn(e) { "Passed Apache PKIX verification but could not build trust anchor via CertPathBuilder" }
+            emptyList()
+        }
+
+        // if trust chain is empty, then somehow user only trusts the leaf cert???
+        return trustChain.ifEmpty {
+            // so return the served certificate chain from the server and hope that works
+            certificates.toList()
+        }
+    }
+
+    private fun keystoreFromCertificates(certificates: Collection<X509Certificate>): KeyStore {
+        val ks = KeyStore.getInstance(KeyStore.getDefaultType())
+        ks.load(null, null)
+        certificates.forEachIndexed { index, cert ->
+            ks.setCertificateEntry(
+                cert.getSubjectX500Principal().toString() + "-" + DigestUtil.sha256Hex(cert.encoded),
+                cert
+            )
+        }
+        return ks
+    }
+}