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Anton Yarkov
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Examples of sync and multiplexed async tcp server and client which implements training algorithm/protocol - getting and posting Astrological forecasts.
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‎networking/02 Astro-tcp-server - Simple blocked/client.c

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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <strings.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <fcntl.h>
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#include <netdb.h>
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#include <unistd.h>
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#define PORTNUM 1500 // Port > 1024 because program will not work not as root.
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// Task:
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// Create a test TCP-client which sends commands to TCP-server:
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// HOROSCOPE - get astrological forecasts from server.
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// STARS SAY - send forecast to server.
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// Function read number of bytes and return it. It is necessary to use such a function for read,
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// because system call recv may return not full response and it will be necessary to read in loop.
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ssize_t receive_all(int fd, char *buf, size_t len)
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{
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size_t pos = 0;
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while (pos < len)
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{
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// Buffer returned by system call recv - is not the string, so we can't use string functions with it.
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ssize_t received = recv(fd, buf + pos, len - pos, MSG_NOSIGNAL); // Receive byte by byte.
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if (received == -1) return -1;
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else if (received == 0) return pos;
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else if (received > 0) pos += received;
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}
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return pos;
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}
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void main(int argc, char **argv)
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{
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struct hostent *hp;
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if ((hp = gethostbyname(argv[1])) == 0)
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{
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perror("Error of calling gethostbyname"); /* or strerror */
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exit(1);
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}
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struct sockaddr_in serv_addr;
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memset(&serv_addr, '\0', sizeof(serv_addr));
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bcopy(hp->h_addr_list[0], &serv_addr.sin_addr, hp->h_length);
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serv_addr.sin_family = hp->h_addrtype;
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serv_addr.sin_port = htons(PORTNUM);
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int sockfd = -1;
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if ((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
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{
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perror("Error of calling socket");
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exit(1);
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}
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fprintf(stderr, "Server address: %s\n", inet_ntoa(serv_addr.sin_addr));
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if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1)
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{
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perror("Error of calling connect");
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exit(1);
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}
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int testStep = (*argv[2]) - '0';
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printf("testStep: %d\n", testStep);
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if (testStep == 1)
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{
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// TEST1. Set some HOROSCOPE.
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char setzodiak[] = "STARS SAY Aries ";
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int sent = send(sockfd, setzodiak, strlen(setzodiak) + 1, MSG_NOSIGNAL);
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printf("Sent to server: %s, %d bytes\n", setzodiak, sent);
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char desc[] = "Some of my descriptions here. ";
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sent = send(sockfd, desc, strlen(desc) + 1, MSG_NOSIGNAL);
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printf("Sent to server: %s, %d bytes\n", desc, sent);
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char thanks[10];
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memset(thanks, '\0', 10);
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int received = receive_all(sockfd, thanks, 10);
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printf("Received from server: %d bytes\n", received);
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if (received > 0)
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{
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printf("Received from server: %s\n", thanks);
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}
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}
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else if (testStep == 2)
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{
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// TEST2. Get HOROSCOPE which was set.
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char getzodiak[] = "HOROSCOPE Aries ";
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int sent = send(sockfd, getzodiak, strlen(getzodiak) + 1, MSG_NOSIGNAL);
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printf("Sent to server: %s, %d bytes\n", getzodiak, sent);
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char horoscope[80];
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memset(horoscope, '\0', 80);
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int received = receive_all(sockfd, horoscope, 80);
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printf("Received from server: %d bytes\n", received);
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if (received > 0)
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{
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printf("Received from server: %s\n", horoscope);
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}
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}
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else if (testStep == 3)
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{
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// TEST3. Good COMMAND, Bad attributes.
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char getzodiak[] = "HOROSCOPE Abracadabra";
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int sent = send(sockfd, getzodiak, strlen(getzodiak) + 1, MSG_NOSIGNAL);
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printf("Sent to server: %s, %d bytes\n", getzodiak, sent);
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char denied[10];
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memset(denied, '\0', 10);
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int received = receive_all(sockfd, denied, 10);
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printf("Received from server: %d bytes\n", received);
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if (received > 0)
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{
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printf("Received from server: %s\n", denied);
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}
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}
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else if (testStep == 4)
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{
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// TEST4. Wrong COMMAND.
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char wrongCommand[] = "ABRA CADABRA BOOM BOOM";
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int sent = send(sockfd, wrongCommand, strlen(wrongCommand) + 1, MSG_NOSIGNAL);
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printf("Sent to server: %s, %d bytes\n", wrongCommand, sent);
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char denied[10];
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memset(denied, '\0', 10);
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int received = receive_all(sockfd, denied, 10);
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printf("Received from server: %d bytes\n", received);
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}
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close(sockfd);
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printf("Client off!\n\n"); \
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}

‎networking/02 Astro-tcp-server - Simple blocked/server.c

Lines changed: 198 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include <fcntl.h>
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#include <netdb.h>
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#include <unistd.h>
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#define PORTNUM 1500 // Port > 1024 because program will not work not as root.
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// Task:
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// Create a TCP-server which returns astrological forecasts as a response to client command HOROSCOPE.
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// It should remember forecast on a STARS SAY command from client. Server should handle possible errors.
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// Function read number of bytes and return it. It is necessary to use such a function for read,
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// because system call recv may return not full response and it will be necessary to read in loop.
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ssize_t receive_all(int fd, char *buf, size_t len)
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{
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size_t pos = 0;
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while (pos < len)
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{
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// Buffer returned by system call recv - is not the string, so we can't use string functions with it.
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ssize_t received = recv(fd, buf + pos, len - pos, MSG_NOSIGNAL); // Receive byte by byte.
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if (received == -1) return -1;
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else if (received == 0) return pos;
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else if (received > 0) pos += received;
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}
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return pos;
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}
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void main()
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{
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printf("ASTRO Server PID -- %d.\n", getpid());
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// Create socket
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int sockfd = -1;
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if ((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
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{
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perror("Error of calling socket"); /* or strerror */
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exit(1);
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}
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// For UDP SO_REUSEADDR may mean some problems...
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int optval = 1;
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if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(int)) == -1)
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{
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perror("Error of calling setsockopt");
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exit(1);
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}
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// Set address
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struct sockaddr_in serv_addr;
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memset(&serv_addr, '\0', sizeof(serv_addr));
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serv_addr.sin_family = AF_INET;
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serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); // 0.0.0.0 (INADDR_LOOPBACK - 127.0.0.1)
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// Change bytes order to network'
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int nport = htons((int)PORTNUM);
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serv_addr.sin_port = nport;
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// Link socket with address
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if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)) == -1)
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{
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perror("Error of calling bind");
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exit(1);
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}
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fprintf(stderr, "Server is ready: %s\n", inet_ntoa(serv_addr.sin_addr));
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// Server is ready to get SOMAXCONN connection requests (128).
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// This is *SHOULD* be enought to call accept and create child process.
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if (listen(sockfd, SOMAXCONN) == -1)
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{
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perror("Error of calling listen");
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exit(1);
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}
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struct sockaddr_in clnt_addr;
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socklen_t addrlen = sizeof(clnt_addr);
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memset(&clnt_addr, '\0', sizeof(clnt_addr));
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int newsocket = -1;
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char zodiaks[12][12] = { "Aries ", "Taurus ", "Gemini ", "Cancer ",
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"Leo ", "Virgo ", "Libra ", "Scorpio ", "Sagittarius",
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"Capricorn ", "Aquarius ", "Pisces " };
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char descriptions[12][80] = { "", "", "", "", "", "", "", "", "", "", "", "" };
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char thanks[] = "THANKS!";
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char denied[] = "DENIED!";
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char sorry[] = "SORRY!";
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while (1)
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{
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if ((newsocket = accept(sockfd, (struct sockaddr *)&clnt_addr, &addrlen)) == -1)
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{
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perror("Error of calling accept");
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exit(1);
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}
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printf("Client = %s \n", inet_ntoa(clnt_addr.sin_addr));
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char command[22];
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memset(command, '\0', 22);
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int received = receive_all(newsocket, command, 22);
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printf("Received from client: %s, %d bytes\n", command, received);
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if (received == 22)// && command[21] == '\n')
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{
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// Get znak zodiak
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char zodiak[11];
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for (int i = 10; i < 21; i++)
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{
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zodiak[i - 10] = command[i];
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}
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printf("Received from client: zodiak %s\n", zodiak);
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// Find it in array.
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int desc_index = -1;
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for (int i = 0; i < 12; i++)
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{
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if (strncmp(zodiaks[i], zodiak, 12) == 0)
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{
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desc_index = i;
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break;
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}
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}
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printf("Position in array of zodiaks: %d\n", desc_index);
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if (strncmp(command, "STARS SAY ", 10) == 0)
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{
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// If found, get description.
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if (desc_index > -1)
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{
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// Receive 80 bytes of description.
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char desc[80];
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memset(desc, '\0', 80);
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int received_dest = receive_all(newsocket, desc, 80);
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if (received_dest > 0)
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{
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memcpy(descriptions[desc_index], desc, received_dest);
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}
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printf("Received from client: %s, %d bytes\n", desc, received_dest);
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// Send thanks
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int sent = send(newsocket, thanks, strlen(thanks) + 1, MSG_NOSIGNAL);
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printf("Sent to client: %s, %d bytes\n", thanks, sent);
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}
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else
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{
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int sent = send(newsocket, denied, strlen(denied) + 1, MSG_NOSIGNAL);
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printf("Sent to client: %s, %d bytes\n", denied, sent);
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}
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}
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else if (strncmp(command, "HOROSCOPE ", 10) == 0)
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{
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// Send 80 bytes description
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if (desc_index > -1)
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{
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if (strlen(descriptions[desc_index]) > 1)
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{
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int sent = send(newsocket, descriptions[desc_index], sizeof(descriptions[desc_index]), MSG_NOSIGNAL);
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printf("Sent to client: %s, %d bytes\n", descriptions[desc_index], sent);
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}
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else
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{
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int sent = send(newsocket, sorry, strlen(sorry) + 1, MSG_NOSIGNAL);
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printf("Sent to client: %s, %d bytes\n", sorry, sent);
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}
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}
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else
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{
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int sent = send(newsocket, denied, strlen(denied) + 1, MSG_NOSIGNAL);
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printf("Sent to client: %s, %d bytes\n", denied, sent);
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}
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}
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}
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printf("Connection to client closed!");
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close(newsocket);
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}
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printf("Server stopped!");
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close(sockfd);
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exit(0);
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}

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