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w8/rsh_cli.c

+
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/un.h>
+#include <fcntl.h>
+
+#include "dshlib.h"
+#include "rshlib.h"
+
+
+
+
+/*
+ * exec_remote_cmd_loop(server_ip, port)
+ *      server_ip:  a string in ip address format, indicating the servers IP
+ *                  address.  Note 127.0.0.1 is the default meaning the server
+ *                  is running on the same machine as the client
+ *              
+ *      port:   The port the server will use.  Note the constant 
+ *              RDSH_DEF_PORT which is 1234 in rshlib.h.  If you are using
+ *              tux you may need to change this to your own default, or even
+ *              better use the command line override -c implemented in dsh_cli.c
+ *              For example ./dsh -c 10.50.241.18:5678 where 5678 is the new port
+ *              number and the server address is 10.50.241.18    
+ * 
+ *      This function basically implements the network version of 
+ *      exec_local_cmd_loop() from the last assignemnt.  It will:
+ *  
+ *          1. Allocate buffers for sending and receiving data over the 
+ *             network
+ *          2. Create a network connection to the server, getting an active
+ *             socket by calling the start_client(server_ip, port) function.
+ *          2. Go into an infinite while(1) loop prompting the user for
+ *             input commands. 
+ * 
+ *             a. Accept a command from the user via fgets()
+ *             b. Send that command to the server using send() - it should
+ *                be a null terminated string
+ *             c. Go into a loop and receive client requests.  Note each
+ *                receive might not be a C string so you need to print it
+ *                out using:
+ *                     printf("%.*s", (int)bytes_received, rsp_buff);
+ *                this version of printf() uses the "%.*s" flag that indicates
+ *                that the rsp_buff might be a null terminated string, or
+ *                it might not be, if its not, print exactly bytes_received
+ *                bytes. 
+ *             d. In the recv() loop described above. Each time you receive
+ *                data from the server, see if the last byte received is the
+ *                EOF character. This indicates the server is done and you can
+ *                send another command by going to the top of the loop.  The
+ *                best way to do this is as follows assuming you are receiving
+ *                data into a buffer called recv_buff, and you received
+ *                recv_bytes in the call to recv:
+ * 
+ *                  recv_bytes = recv(sock, recv_buff, recv_buff_sz, 0)
+ *                  
+ *                if recv_bytes:
+ *                  <negative_number>: communication error
+ *                    0:    Didn't receive anything, likely server down
+ *                  > 0:    Got some data. Check if the last byte is EOF
+ *                          is_eof = (recv_buff[recv_bytes-1] == RDSH_EOF_CHAR) ? 1 : 0;
+ *                    if is_eof is true, this is the last part of the transmission
+ *                    from the server and you can break out of the recv() loop. 
+ * 
+ *   returns:
+ *          OK:      The client executed all of its commands and is exiting
+ *                   either by the `exit` command that terminates the client
+ *                   or the `stop-server` command that terminates both the
+ *                   client and the server. 
+ *          ERR_MEMORY:             If this function cannot allocate memory via
+ *                                  malloc for the send and receive buffers
+ *          ERR_RDSH_CLIENT:        If the client cannot connect to the server. 
+ *                                  AKA the call to start_client() fails.
+ *          ERR_RDSH_COMMUNICATION: If there is a communication error, AKA
+ *                                  any failures from send() or recv().
+ * 
+ *   NOTE:  Since there are several exit points and each exit point must
+ *          call free() on the buffers allocated, close the socket, and
+ *          return an appropriate error code.  Its suggested you use the
+ *          helper function client_cleanup() for these purposes.  For example:
+ * 
+ *   return client_cleanup(cli_socket, request_buff, resp_buff, ERR_RDSH_COMMUNICATION);
+ *   return client_cleanup(cli_socket, request_buff, resp_buff, OK);
+ *
+ *   The above will return ERR_RDSH_COMMUNICATION and OK respectively to the main()
+ *   function after cleaning things up.  See the documentation for client_cleanup()
+ *      
+ */
+int exec_remote_cmd_loop(char *address, int port)
+{
+    
+    int cli_socket;
+    char *cmd_buff, *rsp_buff;
+    ssize_t recv_size;
+
+    // Allocate buffers for command input and response storage
+    cmd_buff = (char *)malloc(SH_CMD_MAX);
+    rsp_buff = (char *)malloc(RDSH_COMM_BUFF_SZ);
+
+    if (!cmd_buff || !rsp_buff) {
+        fprintf(stderr, "Error: Memory allocation failed\n");
+        return client_cleanup(-1, cmd_buff, rsp_buff, ERR_MEMORY);
+    }
+
+    // Start the client (connect to the server)
+    cli_socket = start_client(address, port);
+    if (cli_socket < 0) {
+        return client_cleanup(cli_socket, cmd_buff, rsp_buff, ERR_RDSH_CLIENT);
+    }
+
+    // Main client loop
+    while (1) {
+        // Print prompt and read user input
+        printf("%s", SH_PROMPT);
+        if (fgets(cmd_buff, SH_CMD_MAX, stdin) == NULL) {
+            printf("\n");
+            break;  // Exit loop on EOF (Ctrl+D)
+        }
+
+        // Remove trailing newline
+        cmd_buff[strcspn(cmd_buff, "\n")] = '\0';
+
+        // Ignore empty input
+        if (strlen(cmd_buff) == 0) continue;
+
+        // Send command to the server (including null terminator)
+        if (send(cli_socket, cmd_buff, strlen(cmd_buff) + 1, 0) < 0) {
+            perror("Error sending command to server");
+            return client_cleanup(cli_socket, cmd_buff, rsp_buff, ERR_RDSH_COMMUNICATION);
+        }
+
+        // Receive response from server
+        while ((recv_size = recv(cli_socket, rsp_buff, RDSH_COMM_BUFF_SZ, 0)) > 0) {
+            // Check if last byte is the EOF character
+            int is_last_chunk = (rsp_buff[recv_size - 1] == RDSH_EOF_CHAR) ? 1 : 0;
+            
+            // Replace EOF character with null terminator
+            if (is_last_chunk) {
+                rsp_buff[recv_size - 1] = '\0';
+            }
+
+            // Print response (handles both raw data and null-terminated strings)
+            printf("%.*s", (int)recv_size, rsp_buff);
+
+            // If EOF character received, stop receiving
+            if (is_last_chunk) break;
+        }
+
+        if (recv_size < 0) {
+            perror("Error receiving response from server");
+            return client_cleanup(cli_socket, cmd_buff, rsp_buff, ERR_RDSH_COMMUNICATION);
+        }
+    }
+
+    // Cleanup before exiting
+    return client_cleanup(cli_socket, cmd_buff, rsp_buff, OK);
+    
+    //return WARN_RDSH_NOT_IMPL;
+}
+
+/*
+ * start_client(server_ip, port)
+ *      server_ip:  a string in ip address format, indicating the servers IP
+ *                  address.  Note 127.0.0.1 is the default meaning the server
+ *                  is running on the same machine as the client
+ *              
+ *      port:   The port the server will use.  Note the constant 
+ *              RDSH_DEF_PORT which is 1234 in rshlib.h.  If you are using
+ *              tux you may need to change this to your own default, or even
+ *              better use the command line override -c implemented in dsh_cli.c
+ *              For example ./dsh -c 10.50.241.18:5678 where 5678 is the new port
+ *              number and the server address is 10.50.241.18    
+ * 
+ *      This function basically runs the client by: 
+ *          1. Creating the client socket via socket()
+ *          2. Calling connect()
+ *          3. Returning the client socket after connecting to the server
+ * 
+ *   returns:
+ *          client_socket:      The file descriptor fd of the client socket
+ *          ERR_RDSH_CLIENT:    If socket() or connect() fail
+ * 
+ */
+int start_client(char *server_ip, int port) {
+    int client_socket;
+    struct sockaddr_in server_addr;
+
+    // Step 1: Create the client socket
+    client_socket = socket(AF_INET, SOCK_STREAM, 0);
+    if (client_socket < 0) {
+        perror("Error creating client socket");
+        return ERR_RDSH_CLIENT;
+    }
+
+    // Step 2: Set up the server address struct
+    memset(&server_addr, 0, sizeof(server_addr));
+    server_addr.sin_family = AF_INET;
+    server_addr.sin_port = htons(port);  // Convert port to network byte order
+
+    // Step 3: Convert and assign the server IP address
+    if (inet_pton(AF_INET, server_ip, &server_addr.sin_addr) <= 0) {
+        perror("Invalid server IP address");
+        close(client_socket);
+        return ERR_RDSH_CLIENT;
+    }
+
+    // Step 4: Connect to the server
+    if (connect(client_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
+        perror("Error connecting to the server");
+        close(client_socket);
+        return ERR_RDSH_CLIENT;
+    }
+
+    printf("Connected to server at %s:%d\n", server_ip, port);
+    return client_socket;  // Return the connected socket descriptor
+}
+
+
+/*
+ * client_cleanup(int cli_socket, char *cmd_buff, char *rsp_buff, int rc)
+ *      cli_socket:   The client socket
+ *      cmd_buff:     The buffer that will hold commands to send to server
+ *      rsp_buff:     The buffer that will hld server responses
+ * 
+ *   This function does the following: 
+ *      1. If cli_socket > 0 it calls close(cli_socket) to close the socket
+ *      2. It calls free() on cmd_buff and rsp_buff
+ *      3. It returns the value passed as rc
+ *  
+ *   Note this function is intended to be helper to manage exit conditions
+ *   from the exec_remote_cmd_loop() function given there are several
+ *   cleanup steps.  We provide it to you fully implemented as a helper.
+ *   You do not have to use it if you want to develop an alternative
+ *   strategy for cleaning things up in your exec_remote_cmd_loop()
+ *   implementation. 
+ * 
+ *   returns:
+ *          rc:   This function just returns the value passed as the 
+ *                rc parameter back to the caller.  This way the caller
+ *                can just write return client_cleanup(...)
+ *      
+ */
+int client_cleanup(int cli_socket, char *cmd_buff, char *rsp_buff, int rc){
+    //If a valid socket number close it.
+    if(cli_socket > 0){
+        close(cli_socket);
+    }
+
+    //Free up the buffers 
+    free(cmd_buff);
+    free(rsp_buff);
+
+    //Echo the return value that was passed as a parameter
+    return rc;
+}
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