some improvements and fixed intendations
This commit is contained in:
parent
ddef20a8e7
commit
c4a3ddae50
394
client.cpp
394
client.cpp
@ -17,213 +17,215 @@
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int main(int argc, char **argv)
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int main(int argc, char **argv)
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{
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{
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int create_socket;
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int create_socket;
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char buffer[BUF];
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char buffer[BUF];
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struct sockaddr_in address;
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struct sockaddr_in address;
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int size;
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int size;
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int isQuit;
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int isQuit;
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////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////
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// CREATE A SOCKET
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// CREATE A SOCKET
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// https://man7.org/linux/man-pages/man2/socket.2.html
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// https://man7.org/linux/man-pages/man2/socket.2.html
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// https://man7.org/linux/man-pages/man7/ip.7.html
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// https://man7.org/linux/man-pages/man7/ip.7.html
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// https://man7.org/linux/man-pages/man7/tcp.7.html
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// https://man7.org/linux/man-pages/man7/tcp.7.html
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// IPv4, TCP (connection oriented), IP (same as server)
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// IPv4, TCP (connection oriented), IP (same as server)
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if ((create_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1)
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if ((create_socket = socket(AF_INET, SOCK_STREAM, 0)) == -1)
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{
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{
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perror("Socket error");
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perror("Socket error");
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return EXIT_FAILURE;
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return EXIT_FAILURE;
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}
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}
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////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////
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// INIT ADDRESS
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// INIT ADDRESS
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// Attention: network byte order => big endian
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// Attention: network byte order => big endian
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memset(&address, 0, sizeof(address)); // init storage with 0
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memset(&address, 0, sizeof(address)); // init storage with 0
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address.sin_family = AF_INET; // IPv4
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address.sin_family = AF_INET; // IPv4
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// https://man7.org/linux/man-pages/man3/htons.3.html
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// https://man7.org/linux/man-pages/man3/htons.3.html
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address.sin_port = htons(PORT);
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address.sin_port = htons(PORT);
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// https://man7.org/linux/man-pages/man3/inet_aton.3.html
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// https://man7.org/linux/man-pages/man3/inet_aton.3.html
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if (argc < 2)
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if (argc < 2)
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{
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{
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inet_aton("127.0.0.1", &address.sin_addr);
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inet_aton("127.0.0.1", &address.sin_addr);
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}
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}
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else
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else
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{
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{
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inet_aton(argv[1], &address.sin_addr);
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inet_aton(argv[1], &address.sin_addr);
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}
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}
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////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////
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// CREATE A CONNECTION
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// CREATE A CONNECTION
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// https://man7.org/linux/man-pages/man2/connect.2.html
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// https://man7.org/linux/man-pages/man2/connect.2.html
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if (connect(create_socket,
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if (connect(create_socket,
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(struct sockaddr *)&address,
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(struct sockaddr *)&address,
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sizeof(address)) == -1)
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sizeof(address)) == -1)
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{
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{
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// https://man7.org/linux/man-pages/man3/perror.3.html
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// https://man7.org/linux/man-pages/man3/perror.3.html
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perror("Connect error - no server available");
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perror("Connect error - no server available");
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return EXIT_FAILURE;
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return EXIT_FAILURE;
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}
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}
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// ignore return value of printf
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// ignore return value of printf
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printf("Connection with server (%s) established\n",
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printf("Connection with server (%s) established\n",
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inet_ntoa(address.sin_addr));
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inet_ntoa(address.sin_addr));
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////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////
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// RECEIVE DATA
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// RECEIVE DATA
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// https://man7.org/linux/man-pages/man2/recv.2.html
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// https://man7.org/linux/man-pages/man2/recv.2.html
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size = recv(create_socket, buffer, BUF - 1, 0);
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/*
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if (size == -1)
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size = recv(create_socket, buffer, BUF - 1, 0);
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{
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if (size == -1)
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perror("recv error");
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{
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}
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perror("recv error");
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else if (size == 0)
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}
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{
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else if (size == 0)
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printf("Server closed remote socket\n"); // ignore error
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{
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}
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printf("Server closed remote socket\n"); // ignore error
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else
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}
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{
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else
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buffer[size] = '\0';
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{
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printf("%s", buffer); // ignore error
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buffer[size] = '\0';
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}
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printf("%s", buffer); // ignore error
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}
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*/
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do {
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do {
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printf("Please specify a command (SEND, LIST, READ, DEL, QUIT): ");
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printf("Please specify a command (SEND, LIST, READ, DEL, QUIT): ");
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if (fgets(buffer, BUF - 1, stdin) != NULL)
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if (fgets(buffer, BUF - 1, stdin) != NULL)
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{
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{
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size = strlen(buffer);
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size = strlen(buffer);
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if (buffer[size - 2] == '\r' && buffer[size - 1] == '\n')
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if (buffer[size - 2] == '\r' && buffer[size - 1] == '\n')
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{
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{
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size -= 2;
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size -= 2;
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buffer[size] = 0;
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buffer[size] = 0;
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}
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}
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else if (buffer[size - 1] == '\n')
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else if (buffer[size - 1] == '\n')
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{
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{
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--size;
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--size;
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buffer[size] = 0;
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buffer[size] = 0;
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}
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}
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isQuit = strcmp(buffer, "QUIT") == 0;
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isQuit = strcmp(buffer, "QUIT") == 0;
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if (strcmp(buffer, "SEND") == 0)
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if (strcmp(buffer, "SEND") == 0)
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{
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{
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char sender[BUF], receiver[BUF], subject[81], message[BUF * 10];
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char sender[BUF], receiver[BUF], subject[81], message[BUF * 10];
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printf("Sender: ");
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printf("Sender: ");
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fgets(sender, BUF - 1, stdin);
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fgets(sender, BUF - 1, stdin);
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printf("Receiver: ");
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printf("Receiver: ");
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fgets(receiver, BUF - 1, stdin);
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fgets(receiver, BUF - 1, stdin);
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printf("Subject: ");
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printf("Subject: ");
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fgets(subject, 80, stdin);
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fgets(subject, 80, stdin);
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printf("Message: \n");
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printf("Message: ");
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char line[BUF];
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char line[BUF];
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message[0] = '\0';
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message[0] = '\0';
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while (true)
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while (true)
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{
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{
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fgets(line, BUF - 1, stdin);
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fgets(line, BUF - 1, stdin);
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if (strcmp(line, ".\n") == 0)
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if (strcmp(line, ".\n") == 0)
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break;
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break;
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strcat(message, line);
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strcat(message, line);
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}
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}
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snprintf(buffer, sizeof(buffer), "SEND\n%s%s%s%s.\n", sender, receiver, subject, message);
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snprintf(buffer, sizeof(buffer), "SEND\n%s%s%s%s.\n", sender, receiver, subject, message);
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}
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}
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else if (strcmp(buffer, "LIST") == 0)
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else if (strcmp(buffer, "LIST") == 0)
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{
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{
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char username[BUF];
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char username[BUF];
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printf("Username: ");
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printf("Username: ");
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fgets(username, BUF - 1, stdin);
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fgets(username, BUF - 1, stdin);
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snprintf(buffer, sizeof(buffer), "LIST\n%s", username);
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snprintf(buffer, sizeof(buffer), "LIST\n%s", username);
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}
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}
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else if (strcmp(buffer, "READ") == 0)
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else if (strcmp(buffer, "READ") == 0)
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{
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{
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char username[BUF], msgNum[10];
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char username[BUF], msgNum[10];
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printf("Username: ");
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printf("Username: ");
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fgets(username, BUF - 1, stdin);
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fgets(username, BUF - 1, stdin);
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printf("Message Number: ");
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printf("Message Number: ");
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fgets(msgNum, 9, stdin);
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fgets(msgNum, 9, stdin);
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snprintf(buffer, sizeof(buffer), "READ\n%s%s", username, msgNum);
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snprintf(buffer, sizeof(buffer), "READ\n%s%s", username, msgNum);
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}
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}
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else if (strcmp(buffer, "DEL") == 0)
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else if (strcmp(buffer, "DEL") == 0)
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{
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{
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char username[BUF], msgNum[10];
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char username[BUF], msgNum[10];
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printf("Username: ");
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printf("Username: ");
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fgets(username, BUF - 1, stdin);
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fgets(username, BUF - 1, stdin);
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printf("Message Number: ");
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printf("Message Number: ");
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fgets(msgNum, 9, stdin);
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fgets(msgNum, 9, stdin);
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snprintf(buffer, sizeof(buffer), "DEL\n%s%s", username, msgNum);
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snprintf(buffer, sizeof(buffer), "DEL\n%s%s", username, msgNum);
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}
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}
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//////////////////////////////////////////////////////////////////////
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//////////////////////////////////////////////////////////////////////
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// SEND DATA
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// SEND DATA
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// https://man7.org/linux/man-pages/man2/send.2.html
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// https://man7.org/linux/man-pages/man2/send.2.html
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// send will fail if connection is closed, but does not set
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// send will fail if connection is closed, but does not set
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// the error of send, but still the count of bytes sent
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// the error of send, but still the count of bytes sent
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int size = strlen(buffer);
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int size = strlen(buffer);
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if ((send(create_socket, buffer, size + 1, 0)) == -1)
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if ((send(create_socket, buffer, size + 1, 0)) == -1)
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{
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{
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// in case the server is gone offline we will still not enter
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// in case the server is gone offline we will still not enter
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// this part of code: see docs: https://linux.die.net/man/3/send
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// this part of code: see docs: https://linux.die.net/man/3/send
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// >> Successful completion of a call to send() does not guarantee
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// >> Successful completion of a call to send() does not guarantee
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// >> delivery of the message. A return value of -1 indicates only
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// >> delivery of the message. A return value of -1 indicates only
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// >> locally-detected errors.
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// >> locally-detected errors.
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// ... but
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// ... but
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// to check the connection before send is sense-less because
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// to check the connection before send is sense-less because
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// after checking the communication can fail (so we would need
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// after checking the communication can fail (so we would need
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// to have 1 atomic operation to check...)
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// to have 1 atomic operation to check...)
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perror("send error");
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perror("send error");
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break;
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break;
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}
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}
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//////////////////////////////////////////////////////////////////////
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//////////////////////////////////////////////////////////////////////
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// RECEIVE FEEDBACK
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// RECEIVE FEEDBACK
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// consider: reconnect handling might be appropriate in somes cases
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// consider: reconnect handling might be appropriate in somes cases
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// How can we determine that the command sent was received
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// How can we determine that the command sent was received
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// or not?
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// or not?
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// - Resend, might change state too often.
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// - Resend, might change state too often.
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// - Else a command might have been lost.
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// - Else a command might have been lost.
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//
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//
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// solution 1: adding meta-data (unique command id) and check on the
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// solution 1: adding meta-data (unique command id) and check on the
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// server if already processed.
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// server if already processed.
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// solution 2: add an infrastructure component for messaging (broker)
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// solution 2: add an infrastructure component for messaging (broker)
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//
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//
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size = recv(create_socket, buffer, BUF - 1, 0);
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size = recv(create_socket, buffer, BUF - 1, 0);
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if (size == -1)
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if (size == -1)
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{
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{
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perror("recv error");
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perror("recv error");
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break;
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break;
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}
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}
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else if (size == 0)
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else if (size == 0)
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{
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{
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printf("Server closed remote socket\n"); // ignore error
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printf("Server closed remote socket\n"); // ignore error
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break;
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break;
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}
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}
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else
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else
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{
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{
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buffer[size] = '\0';
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buffer[size] = '\0';
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printf("<< %s\n", buffer); // ignore error
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printf("<< %s\n", buffer); // ignore error
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if (strcmp("OK", buffer) != 0)
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/*if (strcmp("OK", buffer) != 0) // needs proper verification, since responses vary between commands
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{
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{
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fprintf(stderr, "<< Server error occured, abort\n");
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fprintf(stderr, "<< Server error occured, abort\n");
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break;
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break;
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}
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}*/
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}
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}
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}
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}
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} while (!isQuit);
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} while (!isQuit);
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////////////////////////////////////////////////////////////////////////////
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////////////////////////////////////////////////////////////////////////////
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// CLOSES THE DESCRIPTOR
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// CLOSES THE DESCRIPTOR
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if (create_socket != -1)
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if (create_socket != -1)
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{
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{
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if (shutdown(create_socket, SHUT_RDWR) == -1)
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if (shutdown(create_socket, SHUT_RDWR) == -1)
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{
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{
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// invalid in case the server is gone already
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// invalid in case the server is gone already
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perror("shutdown create_socket");
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perror("shutdown create_socket");
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}
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}
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if (close(create_socket) == -1)
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if (close(create_socket) == -1)
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{
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{
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perror("close create_socket");
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perror("close create_socket");
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}
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}
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create_socket = -1;
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create_socket = -1;
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}
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}
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return EXIT_SUCCESS;
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return EXIT_SUCCESS;
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}
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}
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