init

client.cpp

@@ -0,0 +1,170 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+
+// open ssl
+#include <openssl/conf.h>
+#include <openssl/evp.h>
+#include <openssl/err.h>
+
+#include <errno.h>  // error handling
+#include <unistd.h> // for close()
+
+#include <string>
+#include <cstring>
+#include <cstdlib> // for atoi()
+#include <vector>
+
+#include "helper.h"
+
+// block cipher encryption function
+int block_encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key, unsigned char *iv, unsigned char *ciphertext)
+{
+    /* Declare cipher context */
+    EVP_CIPHER_CTX *ctx;
+
+    int len, ciphertext_len;
+
+    /* Create and initialise the context */
+    ctx = EVP_CIPHER_CTX_new();
+    if (!ctx)
+    {
+        ERR_print_errors_fp(stderr);
+    }
+
+    /* Initialise the encryption operation. */
+    // choice for aes_256 ref: https://stackoverflow.com/questions/1220751/how-to-choose-an-aes-encryption-mode-cbc-ecb-ctr-ocb-cfb
+    if (EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv) != 1)
+    {
+        ERR_print_errors_fp(stderr);
+    }
+
+    /* Provide the message to be encrypted, and obtain the encrypted output. EVP_EncryptUpdate can be called multiple times if necessary */
+    if (EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len) != 1)
+    {
+        ERR_print_errors_fp(stderr);
+    }
+
+    /* Finalize the encryption. Further cipher text bytes may be written at this stage. */
+    if (EVP_EncryptFinal_ex(ctx, ciphertext + len, &ciphertext_len) != 1)
+    {
+        ERR_print_errors_fp(stderr);
+    }
+
+    /* Clean up */
+    EVP_CIPHER_CTX_free(ctx);
+
+    return ciphertext_len + len;
+}
+
+int main(void)
+{
+    load_env(".env");
+    // Declare variables
+    const char *server_ip = std::getenv("SERVER_IP");
+    const int server_port = std::atoi(std::getenv("SERVER_PORT"));
+    printf("Connecting to server %s:%d\n", server_ip, server_port);
+
+    char client_message[1024];
+    char server_message[1024];
+    const char *custom_message = "Zheyuan Wu: ";
+
+    // Create socket:
+    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
+    if (client_socket == -1)
+    {
+        perror("Failed to create socket");
+        return 1;
+    }
+    else
+    {
+        printf("Socket created successfully\n");
+    }
+
+    // Send connection request to server, be sure to set por tand IP the same as server-side
+    struct sockaddr_in server_addr;
+    server_addr.sin_family = AF_INET;
+    server_addr.sin_port = htons(server_port);
+    inet_pton(AF_INET, server_ip, &server_addr.sin_addr);
+
+    if (connect(client_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1)
+    {
+        perror("Failed to connect to server");
+        close(client_socket);
+        return 1;
+    }
+    else
+    {
+        printf("Connected to server successfully\n");
+    }
+
+    // Get input from the user:
+    printf("Enter message sent to the server (type \\quit to exit): ");
+    // clean the buffer
+    memset(client_message, 0, sizeof(client_message));
+    if (fgets(client_message, sizeof(client_message), stdin) == NULL)
+    {
+        // EOF or error reading from stdin, exit the loop
+        perror("Error reading from stdin");
+        return 1;
+    }
+
+    while (strcmp(client_message, "\\quit\n") != 0)
+    {
+
+        // Send the message to server:
+        // add my name in the front
+        char buffer[2048];
+        std::snprintf(buffer, sizeof(buffer), "%s%s", custom_message, client_message);
+        printf("Message sent to server: %s, length: %d \n", byte_to_hex((unsigned char *)buffer, strlen(buffer)), (int)strlen(buffer));
+
+        ssize_t sent = send(client_socket, buffer, strlen(buffer), 0);
+        if (sent <= 0)
+        {
+            perror("No message sent to server");
+            break;
+        }
+        // send hmac of the message
+        unsigned char hmac[20];
+        memset(hmac, 0, sizeof(hmac));
+        cal_hmac(hmac, buffer);
+        printf("HMAC sent to server: %s\n", byte_to_hex(hmac, 20));
+
+        ssize_t sent_hmac = send(client_socket, hmac, strlen((char *)hmac), 0);
+        if (sent_hmac <= 0)        {
+            perror("No HMAC sent to server");
+            break;
+        }
+
+        // Receive the server's response:
+        // add terminator for string
+        ssize_t recvd = recv(client_socket, server_message, sizeof(server_message) - 1, 0);
+        if (recvd <= 0)
+        {
+            perror("No message received from server");
+            break;
+        }
+        server_message[recvd] = '\0';
+
+        printf("Server's response: %s\n", server_message);
+
+        printf("Enter message sent to the server (type \\quit to exit): ");
+
+        // clean the buffer
+        memset(client_message, 0, sizeof(client_message));
+        memset(server_message, 0, sizeof(server_message));
+
+        if (fgets(client_message, sizeof(client_message), stdin) == NULL)
+        {
+            // EOF or error reading from stdin, exit the loop
+            perror("Error reading from stdin");
+            break;
+        }
+    }
+
+    // Close the socket
+    close(client_socket);
+
+    return 0;
+}