Improve SAML authentication

In the initial implementation there were still some issues that needed
to be fixed.
One main improvement is that the http server thread does not run the
tunnel thread. Instead the http server is first shut down and then
the tunnel is started as usual.

README.md

@@ -238,7 +238,7 @@ solution requires a graphic session.
 When started using `--saml-login` the program creates a web server that
 accepts SAML login requests. To login using SAML you just have to open
 `<your-vpn-domain>/remote/saml/start?redirect=1` and follow the login steps.
-At the end of the login process the page will be redirected to 
+At the end of the login process the page will be redirected to
 `http://127.0.0.1:8020/?id=<session-id>`
 
 Contributing

src/config.c

@@ -45,6 +45,8 @@ const struct vpn_config invalid_cfg = {
 	.password = {'\0'},
 	.password_set = 0,
 	.cookie = NULL,
+	.saml_port = 0,
+	.saml_session_id = {'\0'},
 	.otp = {'\0'},
 	.otp_prompt = NULL,
 	.otp_delay = -1,
@@ -418,9 +420,13 @@ int load_config(struct vpn_config *cfg, const char *filename)
 			if (strncmp(cfg->user_cert, "pkcs11:", 7) == 0)
 				cfg->use_engine = 1;
 		} else if (strcmp(key, "saml-login") == 0) {
-			free(cfg->saml_port);
-			cfg->saml_port = atol(val);
-			continue;
+			long port = strtol(val, NULL, 0);
+
+			if (port < 1 || port > 65535) {
+				log_error("Bad SAML listen port: \"%s\".\n", val);
+        goto err_free;
+      }
+			cfg->saml_port = (uint16_t)port;
 		} else if (strcmp(key, "user-key") == 0) {
 			free(cfg->user_key);
 			cfg->user_key = strdup(val);

src/config.h

@@ -81,6 +81,7 @@ struct x509_digest {
  * We believe we are on the safe side using this value.
  */
 #define MAX_DOMAIN_LENGTH 256
+#define MAX_SAML_SESSION_ID_LENGTH 1024
 
 struct vpn_config {
 	char			gateway_host[GATEWAY_HOST_SIZE + 1];
@@ -91,8 +92,8 @@ struct vpn_config {
 	int			password_set;
 	char			otp[OTP_SIZE + 1];
 	char			*cookie;
-	int			    saml_port;
-	char			saml_session_id[1024];
+	int			saml_port;
+	char			saml_session_id[MAX_SAML_SESSION_ID_LENGTH];
 	char			*otp_prompt;
 	unsigned int		otp_delay;
 	int			no_ftm_push;

src/http.c

@@ -621,42 +621,6 @@ static int try_otp_auth(struct tunnel *tunnel, const char *buffer,
 }
 
 
-/*
- * Authenticates to gateway by sending username and password.
- *
- * @return  1   in case of success
- *          < 0 in case of error
- */
-int saml_login(struct tunnel *tunnel)
-{
-	log_debug("SAML login\n");
-
-	int ret;
-	ssl_connect(tunnel);
-
-	char uri[1024];
-	snprintf(uri, sizeof(uri), "/remote/saml/auth_id?id=%s", tunnel->config->saml_session_id);
-	char *response;
-	uint32_t response_size = 0;
-	ret = http_request(tunnel, "GET", uri, "", &response, &response_size);
-	if(ret != 1 || response_size <= 15) return ret;
-	if (memcmp(response, "HTTP/1.1 200 OK", 15) != 0){
-		log_error("SAML login failed: %s\n", response);
-		return ret;
-	}
-	auth_get_cookie(tunnel, response, response_size);
-	if (ret == ERR_HTTP_NO_COOKIE){
-		log_error("SAML login failed: no cookie\n");
-		return ret;
-	}	
-
-	// free(response);
-
-
-
-	return ret;
-}
-
 /*
  * Authenticates to gateway by sending username and password.
  *
@@ -703,7 +667,15 @@ int auth_log_in(struct tunnel *tunnel)
 
 	tunnel->cookie[0] = '\0';
 
-	if (username[0] == '\0' && tunnel->config->password[0] == '\0') {
+	if (strlen(tunnel->config->saml_session_id) > 0) {
+		// SAML login
+		static const char *uri_pattern = "/remote/saml/auth_id?id=%s";
+		int required_size = snprintf(NULL, 0, uri_pattern, tunnel->config->saml_session_id) + 1;
+		char *uri = alloca(required_size);
+		snprintf(uri, required_size, uri_pattern, tunnel->config->saml_session_id);
+		log_debug("Using SAML authentication URL %s\n", uri);
+		ret = http_request(tunnel, "GET", uri, "", &res, &response_size);
+	} else if (username[0] == '\0' && tunnel->config->password[0] == '\0') {
 		ret = http_request(tunnel, "GET", "/remote/login",
 		                   data, &res, &response_size);
 	} else {

src/http.h

@@ -19,7 +19,6 @@
 #define OPENFORTIVPN_HTTP_H
 
 #include "tunnel.h"
-#include "config.h"
 
 #include <stdint.h>
 
@@ -56,7 +55,6 @@ static inline const char *err_http_str(int code)
 int http_send(struct tunnel *tunnel, const char *request, ...);
 int http_receive(struct tunnel *tunnel, char **response, uint32_t *response_size);
 
-int saml_login(struct tunnel *tunnel);
 int auth_log_in(struct tunnel *tunnel);
 int auth_log_out(struct tunnel *tunnel);
 int auth_request_vpn_allocation(struct tunnel *tunnel);