gnutls-cli: Add option "--logfile" to redirect information message output

First, add an option "--logfile" so user could choose a specific file to
store all the informational messages. In some cases, informational
messages may cause unexpected result if the output is standard output.

With this option, user could redirect these messages to a specific
file. This will be helpful in testing and tracking.

Second, replace printf() function with log_msg() function

This log_msg() function is used when "--logfile" is enabled.

Third, add a functionality test for "--logfile" option

Add a test script to test if "--logfile" option works as it should be.

Signed-off-by: Ke Zhao <kzhao@redhat.com>

1 files changed, 148 insertions, 127 deletions

diff --git a/src/common.c b/src/common.c
index b1cb519e2f..f0fdf9e00d 100644
--- a/src/common.c
+++ b/src/common.c
@@ -52,6 +52,7 @@
 
 const char str_unknown[] = "(unknown)";
 
+static FILE *logfile = NULL;
 /* Hex encodes the given data adding a semicolon between hex bytes.
  */
 const char *raw_to_string(const unsigned char *raw, size_t raw_size)
@@ -145,7 +146,7 @@ static void print_x509_info_compact(gnutls_session_t session, int print_crt_stat
 
 	ret = gnutls_x509_crt_print(crt, GNUTLS_CRT_PRINT_COMPACT, &cinfo);
 	if (ret == 0) {
-		printf("- X.509 cert: %s\n", cinfo.data);
+		log_msg(stdout, "- X.509 cert: %s\n", cinfo.data);
 		gnutls_free(cinfo.data);
 	}
 
@@ -249,12 +250,12 @@ int cert_verify(gnutls_session_t session, const char *hostname, const char *purp
 
 	rc = gnutls_certificate_verify_peers(session, data, elements, &status);
 	if (rc == GNUTLS_E_NO_CERTIFICATE_FOUND) {
-		printf("- Peer did not send any certificate.\n");
+		log_msg(stdout, "- Peer did not send any certificate.\n");
 		return 0;
 	}
 
 	if (rc < 0) {
-		printf("- Could not verify certificate (err: %s)\n",
+		log_msg(stdout, "- Could not verify certificate (err: %s)\n",
 		       gnutls_strerror(rc));
 		return 0;
 	}
@@ -263,12 +264,12 @@ int cert_verify(gnutls_session_t session, const char *hostname, const char *purp
 	rc = gnutls_certificate_verification_status_print(status, type,
 							  &out, 0);
 	if (rc < 0) {
-		printf("- Could not print verification flags (err: %s)\n",
+		log_msg(stdout, "- Could not print verification flags (err: %s)\n",
 		       gnutls_strerror(rc));
 		return 0;
 	}
 
-	printf("- Status: %s\n", out.data);
+	log_msg(stdout, "- Status: %s\n", out.data);
 
 	gnutls_free(out.data);
 
@@ -298,12 +299,12 @@ print_dh_info(gnutls_session_t session, const char *str, int print)
 		return;
 	}
 
-	printf("- %sDiffie-Hellman parameters\n", str);
-	printf(" - Using prime: %d bits\n",
+	log_msg(stdout, "- %sDiffie-Hellman parameters\n", str);
+	log_msg(stdout, " - Using prime: %d bits\n",
 	       gnutls_dh_get_prime_bits(session));
-	printf(" - Secret key: %d bits\n",
+	log_msg(stdout, " - Secret key: %d bits\n",
 	       gnutls_dh_get_secret_bits(session));
-	printf(" - Peer's public key: %d bits\n",
+	log_msg(stdout, " - Peer's public key: %d bits\n",
 	       gnutls_dh_get_peers_public_bits(session));
 
 	ret = gnutls_dh_get_group(session, &raw_gen, &raw_prime);
@@ -354,7 +355,7 @@ print_dh_info(gnutls_session_t session, const char *str, int print)
 		goto out;
 	}
 
-	printf(" - PKCS#3 format:\n\n%.*s\n",
+	log_msg(stdout, " - PKCS#3 format:\n\n%.*s\n",
 	       (int) params_data_size, params_data);
 
       out:
@@ -372,12 +373,12 @@ static void print_ecdh_info(gnutls_session_t session, const char *str, int print
 	if (!print)
 		return;
 
-	printf("- %sEC Diffie-Hellman parameters\n", str);
+	log_msg(stdout, "- %sEC Diffie-Hellman parameters\n", str);
 
 	curve = gnutls_ecc_curve_get(session);
 
-	printf(" - Using curve: %s\n", gnutls_ecc_curve_get_name(curve));
-	printf(" - Curve size: %d bits\n",
+	log_msg(stdout, " - Using curve: %s\n", gnutls_ecc_curve_get_name(curve));
+	log_msg(stdout, " - Curve size: %d bits\n",
 	       gnutls_ecc_curve_get_size(curve) * 8);
 
 }
@@ -396,13 +397,13 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 	int rc;
 
 	desc = gnutls_session_get_desc(session);
-	printf("- Description: %s\n", desc);
+	log_msg(stdout, "- Description: %s\n", desc);
 	gnutls_free(desc);
 
 	/* print session ID */
 	gnutls_session_get_id(session, session_id, &session_id_size);
 	if (session_id_size > 0) {
-		printf("- Session ID: %s\n",
+		log_msg(stdout, "- Session ID: %s\n",
 		       raw_to_string(session_id, session_id_size));
 	}
 
@@ -426,7 +427,7 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 		 * side.
 		 */
 		if (gnutls_srp_server_get_username(session) != NULL)
-			printf("- SRP authentication. Connected as '%s'\n",
+			log_msg(stdout, "- SRP authentication. Connected as '%s'\n",
 			       gnutls_srp_server_get_username(session));
 		break;
 #endif
@@ -435,12 +436,12 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 		/* This returns NULL in server side.
 		 */
 		if (gnutls_psk_client_get_hint(session) != NULL)
-			printf("- PSK authentication. PSK hint '%s'\n",
+			log_msg(stdout, "- PSK authentication. PSK hint '%s'\n",
 			       gnutls_psk_client_get_hint(session));
 		/* This returns NULL in client side.
 		 */
 		if (gnutls_psk_server_get_username(session) != NULL)
-			printf("- PSK authentication. Connected as '%s'\n",
+			log_msg(stdout, "- PSK authentication. Connected as '%s'\n",
 			       gnutls_psk_server_get_username(session));
 		if (kx == GNUTLS_KX_DHE_PSK)
 			print_dh_info(session, "Ephemeral ", verbose);
@@ -449,7 +450,7 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 		break;
 #endif
 	case GNUTLS_CRD_IA:
-		printf("- TLS/IA authentication\n");
+		log_msg(stdout, "- TLS/IA authentication\n");
 		break;
 	case GNUTLS_CRD_CERTIFICATE:
 		{
@@ -460,13 +461,13 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 			/* This fails in client side */
 			if (gnutls_server_name_get
 			    (session, dns, &dns_size, &type, 0) == 0) {
-				printf("- Given server name[%d]: %s\n",
+				log_msg(stdout, "- Given server name[%d]: %s\n",
 				       type, dns);
 			}
 		}
 
 		if ((flags & P_WAIT_FOR_CERT) && gnutls_certificate_get_ours(session) == 0)
-			printf("- No certificate was sent to peer\n");
+			log_msg(stdout, "- No certificate was sent to peer\n");
 
 		if (flags& P_PRINT_CERT)
 			print_cert_info(session, verbose, (flags&P_PRINT_CERT));
@@ -483,18 +484,18 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 		version = gnutls_protocol_get_version(session);
 		tmp =
 		    SU(gnutls_protocol_get_name(version));
-		printf("- Version: %s\n", tmp);
+		log_msg(stdout, "- Version: %s\n", tmp);
 
 		if (version < GNUTLS_TLS1_3) {
 			tmp = SU(gnutls_kx_get_name(kx));
-			printf("- Key Exchange: %s\n", tmp);
+			log_msg(stdout, "- Key Exchange: %s\n", tmp);
 		}
 
 		if (gnutls_sign_algorithm_get(session) != GNUTLS_SIGN_UNKNOWN) {
 			tmp =
 			    SU(gnutls_sign_get_name
 			       (gnutls_sign_algorithm_get(session)));
-			printf("- Server Signature: %s\n", tmp);
+			log_msg(stdout, "- Server Signature: %s\n", tmp);
 		}
 
 		if (gnutls_sign_algorithm_get_client(session) !=
@@ -502,41 +503,41 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 			tmp =
 			    SU(gnutls_sign_get_name
 			       (gnutls_sign_algorithm_get_client(session)));
-			printf("- Client Signature: %s\n", tmp);
+			log_msg(stdout, "- Client Signature: %s\n", tmp);
 		}
 
 		tmp = SU(gnutls_cipher_get_name(gnutls_cipher_get(session)));
-		printf("- Cipher: %s\n", tmp);
+		log_msg(stdout, "- Cipher: %s\n", tmp);
 
 		tmp = SU(gnutls_mac_get_name(gnutls_mac_get(session)));
-		printf("- MAC: %s\n", tmp);
+		log_msg(stdout, "- MAC: %s\n", tmp);
 	}
 
-	printf("- Options:");
+	log_msg(stdout, "- Options:");
 	if (gnutls_session_ext_master_secret_status(session)!=0)
-		printf(" extended master secret,");
+		log_msg(stdout, " extended master secret,");
 	if (gnutls_safe_renegotiation_status(session)!=0)
-		printf(" safe renegotiation,");
+		log_msg(stdout, " safe renegotiation,");
 	if (gnutls_session_etm_status(session)!=0)
-		printf(" EtM,");
+		log_msg(stdout, " EtM,");
 #ifdef ENABLE_OCSP
 	if (gnutls_ocsp_status_request_is_checked(session, GNUTLS_OCSP_SR_IS_AVAIL)!=0) {
-		printf(" OCSP status request%s,", gnutls_ocsp_status_request_is_checked(session,0)!=0?"":"[ignored]");
+		log_msg(stdout, " OCSP status request%s,", gnutls_ocsp_status_request_is_checked(session,0)!=0?"":"[ignored]");
 	}
 #endif
-	printf("\n");
+	log_msg(stdout, "\n");
 
 #ifdef ENABLE_DTLS_SRTP
 	rc = gnutls_srtp_get_selected_profile(session, &srtp_profile);
 	if (rc == 0)
-		printf("- SRTP profile: %s\n",
+		log_msg(stdout, "- SRTP profile: %s\n",
 		       gnutls_srtp_get_profile_name(srtp_profile));
 #endif
 
 #ifdef ENABLE_ALPN
 	rc = gnutls_alpn_get_selected_protocol(session, &p);
 	if (rc == 0)
-		printf("- Application protocol: %.*s\n", p.size, p.data);
+		log_msg(stdout, "- Application protocol: %.*s\n", p.size, p.data);
 #endif
 
 	if (verbose) {
@@ -551,10 +552,10 @@ int print_info(gnutls_session_t session, int verbose, int flags)
 		else {
 			size_t i;
 
-			printf("- Channel binding 'tls-unique': ");
+			log_msg(stdout, "- Channel binding 'tls-unique': ");
 			for (i = 0; i < cb.size; i++)
-				printf("%02x", cb.data[i]);
-			printf("\n");
+				log_msg(stdout, "%02x", cb.data[i]);
+			log_msg(stdout, "\n");
 			gnutls_free(cb.data);
 		}
 	}
@@ -579,7 +580,7 @@ void print_cert_info2(gnutls_session_t session, int verbose, FILE *out, int prin
 		flag = GNUTLS_CRT_PRINT_COMPACT;
 
 	if (gnutls_certificate_client_get_request_status(session) != 0) {
-		printf("- Server has requested a certificate.\n");
+		log_msg(stdout, "- Server has requested a certificate.\n");
 		print_crt_status = 1;
 	}
 
@@ -597,7 +598,7 @@ void print_cert_info_compact(gnutls_session_t session)
 	int verbose = 0;
 
 	if (gnutls_certificate_client_get_request_status(session) != 0) {
-		printf("- Server has requested a certificate.\n");
+		log_msg(stdout, "- Server has requested a certificate.\n");
 		verbose = 1;
 	}
 
@@ -626,7 +627,7 @@ void print_list(const char *priorities, int verbose)
 	const unsigned int *list;
 
 	if (priorities != NULL) {
-		printf("Cipher suites for %s\n", priorities);
+		log_msg(stdout, "Cipher suites for %s\n", priorities);
 
 		ret = gnutls_priority_init(&pcache, priorities, &err);
 		if (ret < 0) {
@@ -652,13 +653,13 @@ void print_list(const char *priorities, int verbose)
 						     NULL, &version);
 
 			if (name != NULL)
-				printf("%-50s\t0x%02x, 0x%02x\t%s\n",
+				log_msg(stdout, "%-50s\t0x%02x, 0x%02x\t%s\n",
 				       name, (unsigned char) id[0],
 				       (unsigned char) id[1],
 				       gnutls_protocol_get_name(version));
 		}
 
-		printf("\n");
+		log_msg(stdout, "\n");
 #if 0
 		{
 			ret =
@@ -666,17 +667,17 @@ void print_list(const char *priorities, int verbose)
 								  &list,
 								  GNUTLS_CTYPE_CLIENT);
 
-			printf("Certificate types: ");
+			log_msg(stdout, "Certificate types: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("CTYPE-%s",
+				log_msg(stdout, "CTYPE-%s",
 				       gnutls_certificate_type_get_name
 				       (list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 #endif
@@ -684,64 +685,64 @@ void print_list(const char *priorities, int verbose)
 		{
 			ret = gnutls_priority_protocol_list(pcache, &list);
 
-			printf("Protocols: ");
+			log_msg(stdout, "Protocols: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("VERS-%s",
+				log_msg(stdout, "VERS-%s",
 				       gnutls_protocol_get_name(list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
 		{
 			ret = gnutls_priority_cipher_list(pcache, &list);
 
-			printf("Ciphers: ");
+			log_msg(stdout, "Ciphers: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("%s",
+				log_msg(stdout, "%s",
 				       gnutls_cipher_get_name(list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
 		{
 			ret = gnutls_priority_mac_list(pcache, &list);
 
-			printf("MACs: ");
+			log_msg(stdout, "MACs: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("%s",
+				log_msg(stdout, "%s",
 				       gnutls_mac_get_name(list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
 		{
 			ret = gnutls_priority_kx_list(pcache, &list);
 
-			printf("Key Exchange Algorithms: ");
+			log_msg(stdout, "Key Exchange Algorithms: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("%s",
+				log_msg(stdout, "%s",
 				       gnutls_kx_get_name(list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
@@ -749,33 +750,33 @@ void print_list(const char *priorities, int verbose)
 			ret =
 			    gnutls_priority_group_list(pcache, &list);
 
-			printf("Groups: ");
+			log_msg(stdout, "Groups: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("GROUP-%s",
+				log_msg(stdout, "GROUP-%s",
 				       gnutls_group_get_name(list[i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
 		{
 			ret = gnutls_priority_sign_list(pcache, &list);
 
-			printf("PK-signatures: ");
+			log_msg(stdout, "PK-signatures: ");
 			if (ret == 0)
-				printf("none\n");
+				log_msg(stdout, "none\n");
 			for (i = 0; i < (unsigned) ret; i++) {
-				printf("SIGN-%s",
+				log_msg(stdout, "SIGN-%s",
 				       gnutls_sign_algorithm_get_name(list
 								      [i]));
 				if (i + 1 != (unsigned) ret)
-					printf(", ");
+					log_msg(stdout, ", ");
 				else
-					printf("\n");
+					log_msg(stdout, "\n");
 			}
 		}
 
@@ -783,99 +784,99 @@ void print_list(const char *priorities, int verbose)
 		return;
 	}
 
-	printf("Cipher suites:\n");
+	log_msg(stdout, "Cipher suites:\n");
 	for (i = 0; (name = gnutls_cipher_suite_info
 		     (i, id, &kx, &cipher, &mac, &version)); i++) {
-		printf("%-50s\t0x%02x, 0x%02x\t%s\n",
+		log_msg(stdout, "%-50s\t0x%02x, 0x%02x\t%s\n",
 		       name,
 		       (unsigned char) id[0], (unsigned char) id[1],
 		       gnutls_protocol_get_name(version));
 		if (verbose)
-			printf
-			    ("\tKey exchange: %s\n\tCipher: %s\n\tMAC: %s\n\n",
+			log_msg
+			    (stdout, "\tKey exchange: %s\n\tCipher: %s\n\tMAC: %s\n\n",
 			     gnutls_kx_get_name(kx),
 			     gnutls_cipher_get_name(cipher),
 			     gnutls_mac_get_name(mac));
 	}
 
-	printf("\n");
+	log_msg(stdout, "\n");
 	{
 		const gnutls_certificate_type_t *p =
 		    gnutls_certificate_type_list();
 
-		printf("Certificate types: ");
+		log_msg(stdout, "Certificate types: ");
 		for (; *p; p++) {
-			printf("CTYPE-%s",
+			log_msg(stdout, "CTYPE-%s",
 			       gnutls_certificate_type_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_protocol_t *p = gnutls_protocol_list();
 
-		printf("Protocols: ");
+		log_msg(stdout, "Protocols: ");
 		for (; *p; p++) {
-			printf("VERS-%s", gnutls_protocol_get_name(*p));
+			log_msg(stdout, "VERS-%s", gnutls_protocol_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_cipher_algorithm_t *p = gnutls_cipher_list();
 
-		printf("Ciphers: ");
+		log_msg(stdout, "Ciphers: ");
 		for (; *p; p++) {
-			printf("%s", gnutls_cipher_get_name(*p));
+			log_msg(stdout, "%s", gnutls_cipher_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_mac_algorithm_t *p = gnutls_mac_list();
 
-		printf("MACs: ");
+		log_msg(stdout, "MACs: ");
 		for (; *p; p++) {
-			printf("%s", gnutls_mac_get_name(*p));
+			log_msg(stdout, "%s", gnutls_mac_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_digest_algorithm_t *p = gnutls_digest_list();
 
-		printf("Digests: ");
+		log_msg(stdout, "Digests: ");
 		for (; *p; p++) {
-			printf("%s", gnutls_digest_get_name(*p));
+			log_msg(stdout, "%s", gnutls_digest_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_kx_algorithm_t *p = gnutls_kx_list();
 
-		printf("Key exchange algorithms: ");
+		log_msg(stdout, "Key exchange algorithms: ");
 		for (; *p; p++) {
-			printf("%s", gnutls_kx_get_name(*p));
+			log_msg(stdout, "%s", gnutls_kx_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
@@ -883,53 +884,53 @@ void print_list(const char *priorities, int verbose)
 		const gnutls_compression_method_t *p =
 		    gnutls_compression_list();
 
-		printf("Compression: ");
+		log_msg(stdout, "Compression: ");
 		for (; *p; p++) {
-			printf("COMP-%s", gnutls_compression_get_name(*p));
+			log_msg(stdout, "COMP-%s", gnutls_compression_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_group_t *p = gnutls_group_list();
 
-		printf("Groups: ");
+		log_msg(stdout, "Groups: ");
 		for (; *p; p++) {
-			printf("GROUP-%s", gnutls_group_get_name(*p));
+			log_msg(stdout, "GROUP-%s", gnutls_group_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_pk_algorithm_t *p = gnutls_pk_list();
 
-		printf("Public Key Systems: ");
+		log_msg(stdout, "Public Key Systems: ");
 		for (; *p; p++) {
-			printf("%s", gnutls_pk_algorithm_get_name(*p));
+			log_msg(stdout, "%s", gnutls_pk_algorithm_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 
 	{
 		const gnutls_sign_algorithm_t *p = gnutls_sign_list();
 
-		printf("PK-signatures: ");
+		log_msg(stdout, "PK-signatures: ");
 		for (; *p; p++) {
-			printf("SIGN-%s",
+			log_msg(stdout, "SIGN-%s",
 			       gnutls_sign_algorithm_get_name(*p));
 			if (*(p + 1))
-				printf(", ");
+				log_msg(stdout, ", ");
 			else
-				printf("\n");
+				log_msg(stdout, "\n");
 		}
 	}
 }
@@ -1069,16 +1070,16 @@ pin_callback(void *user, int attempt, const char *token_url,
 
 	if (flags & GNUTLS_PIN_FINAL_TRY) {
 		cache = 0;
-		printf("*** This is the final try before locking!\n");
+		log_msg(stdout, "*** This is the final try before locking!\n");
 	}
 	if (flags & GNUTLS_PIN_COUNT_LOW) {
 		cache = 0;
-		printf("*** Only few tries left before locking!\n");
+		log_msg(stdout, "*** Only few tries left before locking!\n");
 	}
 
 	if (flags & GNUTLS_PIN_WRONG) {
 		cache = 0;
-		printf("*** Wrong PIN has been provided!\n");
+		log_msg(stdout, "*** Wrong PIN has been provided!\n");
 	}
 
 	if (cache > 0 && cached_url != NULL) {
@@ -1166,7 +1167,7 @@ token_callback(void *user, const char *label, const unsigned retry)
 		fprintf(stderr, "Could not find token %s\n", label);
 		return -1;
 	}
-	printf("Please insert token '%s' in slot and press enter\n",
+	log_msg(stdout, "Please insert token '%s' in slot and press enter\n",
 	       label);
 	if (fgets(buf, sizeof(buf), stdin) == NULL) {
 		fprintf(stderr, "error reading input\n");
@@ -1200,3 +1201,23 @@ void sockets_init(void)
 	signal(SIGPIPE, SIG_IGN);
 #endif
 }
+
+
+int log_msg(FILE *file, const char *message, ...)
+{
+	va_list args;
+	int rv;
+
+	va_start(args, message);
+
+	rv = vfprintf(logfile ? logfile : file, message, args);
+
+	va_end(args);
+
+	return rv;
+}
+
+void log_set(FILE *file)
+{
+	logfile = file;
+}