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Commit 8a17484

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author
Anton Yarkov
committed
Examples of multiprocess tcp servers working in Prefork or Process-per-request modes.
1 parent 92b5f73 commit 8a17484

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4 files changed

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lines changed

4 files changed

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Lines changed: 61 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <strings.h>
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#include <sys/types.h> /*для совместимости */
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#include <sys/socket.h>
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#include <arpa/inet.h> // Для преобразования htonl, htons, ntohl, ntohs
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#include <netinet/in.h> // для sockaddr_in
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#include <fcntl.h>
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#include <netdb.h>
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#include <unistd.h> // Для close()
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//#include <errno> - не используем, иногда может содержать ошибку другого процесса
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#define EXIT_FAILURE 1
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#define PORTNUM 1500 // Port > 1024 because program will not work not as root.
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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"); /* или strerror */
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exit(EXIT_FAILURE);
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}
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struct sockaddr_in serv_addr;
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bzero(&serv_addr, sizeof(serv_addr)); // устаревшая, TODO use memset
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bcopy(hp->h_addr_list[0], &serv_addr.sin_addr, hp->h_length); // устаревшая, TODO use memcpy, memmove
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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(EXIT_FAILURE);
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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(EXIT_FAILURE);
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}
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char buf[80] = "Hello, world!";
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send(sockfd, buf, sizeof(buf), MSG_NOSIGNAL);
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if (recv(sockfd, buf, sizeof(buf), MSG_NOSIGNAL) < 0)
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{
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perror("Error of calling recv");
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exit(EXIT_FAILURE);
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}
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printf("Received from server: %s\n", buf);
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// Если был вызыван fork, то дескриптор будет доступен и в процессе родителя и child-процессе.
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// Соединение разрывается только когда закрыты все дескрипторы, связанные с сокетом.
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close(sockfd);
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printf("Client off!\n\n");
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}
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#include <stdio.h>
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#include <stdlib.h>
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#include <strings.h>
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#include <sys/types.h> // для совместимости
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#include <sys/socket.h>
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#include <arpa/inet.h> // Для преобразования htonl, htons, ntohl, ntohs
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#include <fcntl.h>
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#include <netdb.h>
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#include <unistd.h> // Для close()
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//#include <errno> - не используем, иногда может содержать ошибку другого процесса
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#define EXIT_FAILURE 1
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#define PORTNUM 1500 // Port > 1024 because program will not work not as root.
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void main()
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{
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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"); /* или strerror */
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exit(EXIT_FAILURE);
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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(EXIT_FAILURE);
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}
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// Set address
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struct sockaddr_in serv_addr;
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bzero(&serv_addr, sizeof(serv_addr)); // устаревшая, TODO use memset
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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
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// Change bytes order to network'
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serv_addr.sin_port = htons((int)PORTNUM);
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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(EXIT_FAILURE);
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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(EXIT_FAILURE);
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}
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struct sockaddr_in clnt_addr;
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int ns, pid;
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while (1)
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{
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socklen_t addrlen;
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bzero(&clnt_addr, sizeof(clnt_addr)); // устаревшая, TODO use memset
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addrlen = sizeof(clnt_addr);
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if ((ns = 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(EXIT_FAILURE);
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}
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fprintf(stderr, "Client = %s \n", inet_ntoa(clnt_addr.sin_addr));
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if ((pid = fork()) == -1)
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{
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perror("Error of calling fork");
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exit(EXIT_FAILURE);
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}
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if (pid == 0)
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{
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int nbytes;
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int fout;
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close(sockfd);
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char buf[80];
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while ((nbytes = recv(ns, buf, sizeof(buf), MSG_NOSIGNAL)) != 0)
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{
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send(ns, buf, sizeof(buf), 0);
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}
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close(ns);
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exit(0);
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}
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// Если был вызыван fork, то дескриптор будет доступен и в процессе родителя и child-процессе.
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// Соединение разрывается только когда закрыты все дескрипторы, связанные с сокетом.
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close(ns);
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printf("Server off! To change this behavior, look in code!\n\n");
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// To change this behavior just comment eixt(0) below:
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exit(0);
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}
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}
Lines changed: 141 additions & 0 deletions
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#include <stdio.h>
2+
#include <stdlib.h>
3+
#include <strings.h>
4+
#include <sys/types.h> // For compatibility
5+
#include <sys/socket.h>
6+
#include <arpa/inet.h> // For convertions htonl, htons, ntohl, ntohs
7+
#include <fcntl.h>
8+
#include <netdb.h>
9+
#include <unistd.h> // For close()
10+
#include <sys/wait.h> // For wait, waitpid
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//#include <errno> - don't use it because sometimes it may contains an error from another process
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// Task:
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// Create a prefork TCP server which sends «Hi there!\n» to client 5 times with 1 second time shift
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// Client: $> nc 127.0.0.1 1500
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#define EXIT_FAILURE 1
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#define PORTNUM 1500 // Port > 1024 because program will not work not as root.
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#define NUMBER_OF_PROCESSES 2
20+
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void main()
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{
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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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{
27+
perror("Error of calling socket"); /* или strerror */
28+
exit(EXIT_FAILURE);
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}
30+
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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");
35+
exit(EXIT_FAILURE);
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}
37+
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// Set address
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struct sockaddr_in serv_addr;
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bzero(&serv_addr, sizeof(serv_addr));
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serv_addr.sin_family = AF_INET;
42+
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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serv_addr.sin_port = htons((int)PORTNUM);
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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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{
50+
perror("Error of calling bind");
51+
exit(EXIT_FAILURE);
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}
53+
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fprintf(stderr, "Server is ready: %s\n", inet_ntoa(serv_addr.sin_addr));
55+
56+
// Server is ready to get SOMAXCONN connection requests (128).
57+
// This is *SHOULD* be enought to call accept and create child process.
58+
if (listen(sockfd, SOMAXCONN) == -1)
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{
60+
perror("Error of calling listen");
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exit(EXIT_FAILURE);
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}
63+
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pid_t childs[NUMBER_OF_PROCESSES];
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struct sockaddr_in clnt_addr;
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int ns;
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// Create and handle child processes.
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for (int i = 0; i < NUMBER_OF_PROCESSES; i++)
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{
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pid_t pid;
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int status;
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switch (pid = fork())
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{
75+
case -1:
76+
perror("Error of calling fork"); /* произошла ошибка */
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exit(EXIT_FAILURE); /*выход из родительского процесса*/
78+
case 0:
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{
80+
int cpid = getpid();
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printf("NEW CHILD: PID -- %d, Parent PID -- %d\n", cpid, getppid());
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socklen_t addrlen;
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bzero(&clnt_addr, sizeof(clnt_addr));
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addrlen = sizeof(clnt_addr);
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printf("CHILD %d: Waiting to accept connection...\n", cpid);
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if ((ns = accept(sockfd, (struct sockaddr *)&clnt_addr, &addrlen)) == -1)
90+
{
91+
perror("Error of calling accept");
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exit(EXIT_FAILURE);
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}
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fprintf(stderr, "CHILD %d: Client = %s \n", cpid, inet_ntoa(clnt_addr.sin_addr));
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int counter = 0;
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char buf[11] = "Hi there!\n";
99+
while (counter != 5)
100+
{
101+
send(ns, buf, sizeof(buf), MSG_NOSIGNAL);
102+
++counter;
103+
sleep(1);
104+
}
105+
106+
// Если был вызыван fork, то дескриптор будет доступен и в процессе родителя и child-процессе.
107+
// Соединение разрывается только когда закрыты все дескрипторы, связанные с сокетом.
108+
close(ns);
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printf("CHILD %d: Exit!\n", cpid);
110+
exit(0);
111+
}
112+
default:
113+
printf("PARENT: PID -- %d, remember NEW CHILD -- %d\n", getpid(), pid);
114+
childs[i] = pid;
115+
break;
116+
}
117+
}
118+
119+
// Wait for ending child processes.
120+
for (int i = 0; i < NUMBER_OF_PROCESSES; i++)
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{
122+
int status;
123+
printf("PARENT: Waiting while CHILD %d calls exit()...\n", childs[i]);
124+
while (-1 == waitpid(childs[i], &status, 0));
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printf("PARENT: Exit code of CHILD %d is: %d\n", childs[i], WEXITSTATUS(status));
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// If the child process fails to exit normally with a status of 0, then it didn't complete its work.
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// If the child processes are supposed to be killed by signals, or different exit codes are used, need to change this check accordingly.
129+
short isNormalTermination = WIFEXITED(status);
130+
if (!isNormalTermination ||
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// WEXITSTATUS should be used only if normal termination = true.
132+
(isNormalTermination && WEXITSTATUS(status) != 0))
133+
{
134+
printf("PARENT: CHILD %d failed...\n", childs[i]);
135+
exit(0);
136+
}
137+
}
138+
139+
close(sockfd);
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exit(0);
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}

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