Avoid possible crashes caused by passing NULL pointers to str*() functions

README.md

@@ -144,7 +144,7 @@ client IP address from the arp cache of the system, then compares it with
 the value in the users table. If the ethernet addresses do not match, the 
 connection is redirected to the login page. SSLproxy also compares the atime 
 value in the users table with the current system time. If the difference is 
-larger than the configured value of the user timeout option, then the 
+greater than the configured value of the user timeout option, then the 
 connection is redirected to the login page. The atime of the IP address in the 
 users table is updated with the system time while the connection is being 
 terminated. Since this atime update is run using a privsep command, it is 

src/sslproxy.1

@@ -146,7 +146,7 @@ client IP address from the arp cache of the system, then compares it with
 the value in the users table. If the ethernet addresses do not match, the 
 connection is redirected to the login page. SSLproxy also compares the atime 
 value in the users table with the current system time. If the difference is 
-larger than the configured value of the user timeout option, then the 
+greater than the configured value of the user timeout option, then the 
 connection is redirected to the login page. The atime of the IP address in the 
 users table is updated with the system time while the connection is being 
 terminated. Since this atime update is run using a privsep command, it is 

tests/testproxy/lp/prototcp.c

@@ -142,33 +142,53 @@ prototcp_parse_sslproxy_line(char *line, pxy_conn_ctx_t *ctx)
 			log_dbg_printf("%s\n", line);
 		}
 
-		char *ip_start = strchr(line, '[') + 1;
+		// The checks here cannot cover all possible error conditions
+		// But we should at least avoid crashes, for example caused by passing NULL pointers to str*() functions
+		char *ip_start = strchr(line, '[');
+		if (!ip_start) {
+			log_err_level_printf(LOG_ERR, "Unable to find sslproxy ip_start: %s\n", line);
+			return -1;
+		}
+		ip_start++;
+
 		char *ip_end = strchr(ip_start, ']');
-		char *port_start = strchr(ip_end, ':') + 1;
-		char *port_end = strchr(port_start, ',');
+		if (!ip_end) {
+			log_err_level_printf(LOG_ERR, "Unable to find sslproxy ip_end: %s\n", line);
+			return -1;
+		}
 
-		if (!ip_start || !ip_end || !port_start || !port_end) {
-			log_err_level_printf(LOG_ERR, "Unable to find sslproxy addr: %s", line);
+		char *port_start = strchr(ip_end, ':');
+		if (!port_start) {
+			log_err_level_printf(LOG_ERR, "Unable to find sslproxy port_start: %s\n", line);
+			return -1;
+		}
+		port_start++;
+
+		char *port_end = strchr(port_start, ',');
+		if (!port_end) {
+			log_err_level_printf(LOG_ERR, "Unable to find sslproxy port_end: %s\n", line);
 			return -1;
 		}
 
 		int addr_len = ip_end - ip_start;
 		if (addr_len > MAX_IPADDR_LEN) {
-			log_err_level_printf(LOG_ERR, "sslproxy addr_len larger than MAX_IPADDR_LEN: %d\n", addr_len);
+			log_err_level_printf(LOG_ERR, "sslproxy addr_len greater than MAX_IPADDR_LEN: %d\n", addr_len);
 			return -1;
 		}
 
-		char addr[MAX_IPADDR_LEN + 1];
+		// We can use addr_len for size restriction here, because we check it against MAX_IPADDR_LEN above
+		char addr[addr_len + 1];
 		strncpy(addr, ip_start, addr_len);
 		addr[addr_len] = '\0';
 
 		int port_len = port_end - port_start;
 		if (port_len > MAX_PORT_LEN) {
-			log_err_level_printf(LOG_ERR, "sslproxy port_len larger than MAX_PORT_LEN: %d\n", port_len);
+			log_err_level_printf(LOG_ERR, "sslproxy port_len greater than MAX_PORT_LEN: %d\n", port_len);
 			return -1;
 		}
 
-		char port[MAX_PORT_LEN + 1];
+		// We can use port_len for size restriction here, because we check it against MAX_PORT_LEN above
+		char port[port_len + 1];
 		strncpy(port, port_start, port_len);
 		port[port_len] = '\0';