Display TLS session information in level DEBUG2.

diff --git a/src/connection.c b/src/connection.c
index 3056aa79a9a34f24fd87d3ebb9e16c9e859267de..a473873d65800ce890be26c5ffbc27fe989593d2 100644 (file)
--- a/src/connection.c
+++ b/src/connection.c
@@ -28,6 +28,8 @@
 #include <poll.h>
 #include <unistd.h>
 
+#include <gnutls/x509.h>
+
 
 /* Maximum length of a HTTP request line. Longer request lines are aborted
  * with an error. The standard doesn't specify a maximum line length but this
@@ -84,6 +86,8 @@ static int connect_to_host(const char *hostname, const char *port);
 static int parse_request(const char *buffer, char *host, char *port,
                                              int *version_minor);
 
+static void log_session_information(gnutls_session_t session);
+
 
 void handle_connection(int client_socket) {
     int server_socket;
@@ -253,6 +257,10 @@ void handle_connection(int client_socket) {
 
     LOG(DEBUG1, "server TLS handshake finished");
 
+    if (global_log_level >= LOG_DEBUG2_LEVEL) {
+        log_session_information(server_session);
+    }
+
     /* Make sure the server certificate is valid and known. */
     if (verify_tls_connection(server_session, host) != 0) {
         LOG(ERROR, "server certificate validation failed!");
@@ -296,6 +304,10 @@ void handle_connection(int client_socket) {
 
     LOG(DEBUG1, "client TLS handshake finished");
 
+    if (global_log_level >= LOG_DEBUG2_LEVEL) {
+        log_session_information(client_session);
+    }
+
     /* Tell the client that the verification failed. Shouldn't be necessary as
      * the client should terminate the connection because he received the
      * invalid certificate but better be sure. */
@@ -886,3 +898,71 @@ static int parse_request(const char *request, char *host, char *port,
 
     return 0;
 }
+
+
+static void log_session_information(gnutls_session_t session) {
+    /* From doc/examples/ex-session-info.c of GnuTLS 3.2.3's tarball and
+     * modified, thanks. */
+
+    const char *tmp;
+    gnutls_credentials_type_t cred;
+    gnutls_kx_algorithm_t kx;
+    int dhe, ecdh;
+
+    dhe = 0;
+    ecdh = 0;
+
+    /* Key exchange algorithm. */
+    kx = gnutls_kx_get(session);
+    LOG(DEBUG2, "- key exchange: %s", gnutls_kx_get_name(kx));
+
+    /* Authentication type. */
+    cred = gnutls_auth_get_type(session);
+    switch (cred) {
+        case GNUTLS_CRD_CERTIFICATE:
+            if (kx == GNUTLS_KX_DHE_RSA
+                    || kx == GNUTLS_KX_DHE_DSS) {
+                dhe = 1;
+#ifdef GNUTLS_KX_ECDHE_RSA
+            } else if (kx == GNUTLS_KX_ECDHE_RSA
+                    || kx == GNUTLS_KX_ECDHE_ECDSA) {
+                ecdh = 1;
+#endif
+            }
+            break;
+
+        case GNUTLS_CRD_IA:
+        case GNUTLS_CRD_SRP:
+        case GNUTLS_CRD_PSK:
+        case GNUTLS_CRD_ANON:
+            /* This shouldn't occur. */
+            LOG(WARNING, "unexpected authentication method: %d", cred);
+            break;
+    }
+
+    /* Information about key exchange. */
+    if (dhe) {
+        LOG(DEBUG2, "- ephemeral DH using prime of %d bits",
+                    gnutls_dh_get_prime_bits(session));
+    } else if (ecdh) {
+#ifdef GNUTLS_KX_ECDHE_RSA
+        LOG(DEBUG2, "- ephemeral ECDH using curve %s",
+                    gnutls_ecc_curve_get_name(gnutls_ecc_curve_get(session)));
+#endif
+    }
+
+    tmp = gnutls_protocol_get_name(gnutls_protocol_get_version(session));
+    LOG(DEBUG2, "- protocol: %s", tmp); /* e.g. TLS 1.0 */
+
+    tmp = gnutls_certificate_type_get_name(gnutls_certificate_type_get(session));
+    LOG(DEBUG2, "- certificate type: %s", tmp);
+
+    tmp = gnutls_compression_get_name(gnutls_compression_get(session));
+    LOG(DEBUG2, "- compression: %s", tmp);
+
+    tmp = gnutls_cipher_get_name(gnutls_cipher_get(session));
+    LOG(DEBUG2, "- cipher: %s", tmp);
+
+    tmp = gnutls_mac_get_name(gnutls_mac_get(session));
+    LOG(DEBUG2, "- MAC: %s", tmp);
+}