Support for TCP comm blocks on Runtime

webserver/core/client.cpp

@@ -0,0 +1,147 @@
+//-----------------------------------------------------------------------------
+// Copyright 2022 Thiago Alves
+// This file is part of the OpenPLC Software Stack.
+//
+// OpenPLC is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// OpenPLC is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with OpenPLC.  If not, see <http://www.gnu.org/licenses/>.
+//------
+//
+// This is the file for the network routines of the OpenPLC. It has procedures
+// to create a socket and connect to a server.
+// Thiago Alves, Nov 2022
+//-----------------------------------------------------------------------------
+
+
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include "ladder.h"
+
+int connect_to_tcp_server(uint8_t *ip_address, uint16_t port)
+{
+    int sockfd, connfd;
+    unsigned char log_msg[1000];
+    struct sockaddr_in servaddr, cli;
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockfd == -1)
+    {
+        sprintf(log_msg, "TCP Client: error creating TCP socket => %s\n", strerror(errno));
+        log(log_msg);
+        return -1;
+    }
+    bzero(&servaddr, sizeof(servaddr));
+    
+    //Configure socket
+    servaddr.sin_family = AF_INET;
+    servaddr.sin_addr.s_addr = inet_addr(ip_address);
+    servaddr.sin_port = htons(port);
+    
+    //Connect to server
+    if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0)
+    {
+        sprintf(log_msg, "TCP Client: error connecting to server => %s\n", strerror(errno));
+        log(log_msg);
+        close(sockfd);
+        return -1;
+    }
+    
+    //Set non-blocking socket
+    int flags = fcntl(sockfd, F_GETFL, 0);
+    if (flags == -1)
+    {
+        sprintf(log_msg, "TCP Client: error reading flags from TCP socket => %s\n", strerror(errno));
+        log(log_msg);
+        return -1;
+    }
+    flags = (flags | O_NONBLOCK);
+    if (fcntl(sockfd, F_SETFL, flags) != 0)
+    {
+        sprintf(log_msg, "TCP Client: error setting flags for TCP socket => %s\n", strerror(errno));
+        log(log_msg);
+        return -1;
+    }
+    
+    return sockfd;
+}
+
+int send_tcp_message(uint8_t *msg, size_t msg_size, int socket_id)
+{
+    int bytes_sent = 0;
+    unsigned char log_msg[1000];
+    bytes_sent = write(socket_id, msg, msg_size);
+    if (bytes_sent < 0)
+    {
+        sprintf(log_msg, "TCP Client: error sending msg to server => %s\n", strerror(errno));
+        log(log_msg);
+        return -1;
+    }
+    
+    return bytes_sent;
+}
+
+int receive_tcp_message(uint8_t *msg_buffer, size_t buffer_size, int socket_id)
+{
+    int bytes_received = 0;
+    unsigned char log_msg[1000];
+    bytes_received = read(socket_id, msg_buffer, buffer_size);
+    
+    if (bytes_received < 0 && bytes_received != EAGAIN && bytes_received != EWOULDBLOCK)
+    {
+        //sprintf(log_msg, "TCP Client: error receiving msg from server => %s\n", strerror(errno));
+        //log(log_msg);
+        return -1;
+    }
+    else
+    {
+        msg_buffer[bytes_received] = 0;
+        sprintf(log_msg, "TCP Client: msg from server => %s\n", msg_buffer);
+        log(log_msg);
+    }
+    
+    return bytes_received;
+}
+
+int close_tcp_connection(int socket_id)
+{
+    return close(socket_id);
+}
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