first commit

Author: Roman Loskutov

.gitignore

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+client
+server
+*~
+*.swp
+*.swo
+

README.md

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+```
+chmod a+x c.sh
+chmod a+x s.sh
+./c.sh
+./s.sh
+./server
+```
+
+Then in new terminal:
+
+```
+./client
+```
+

c.sh

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+gcc client.c erproc.c -W -Wall -Werror -o client

client.c

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+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "erproc.h"
+
+int main() {
+    int fd = Socket(AF_INET, SOCK_STREAM, 0);
+    struct sockaddr_in adr = {0};
+    adr.sin_family = AF_INET;
+    adr.sin_port = htons(34543);
+    Inet_pton(AF_INET, "127.0.0.1", &adr.sin_addr);
+    Connect(fd, (struct sockaddr *) &adr, sizeof adr);
+    write(fd, "Hello\n", 6);
+    char buf[256];
+    ssize_t nread;
+    nread = read(fd, buf, 256);
+    if (nread == -1) {
+        perror("read failed");
+        exit(EXIT_FAILURE);
+    }
+    if (nread == 0) {
+        printf("EOF occured\n");
+    }
+    write(STDOUT_FILENO, buf, nread);
+    sleep(10);
+    close(fd);
+    return 0;
+}

erproc.c

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+#include "erproc.h"
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+
+int Socket(int domain, int type, int protocol) {
+    int res = socket(domain, type, protocol);
+    if (res == -1) {
+        perror("socket failed");
+        exit(EXIT_FAILURE);
+    }
+    return res;
+}
+
+void Bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
+    int res = bind(sockfd, addr, addrlen);
+    if (res == -1) {
+        perror("bind failed");
+        exit(EXIT_FAILURE);
+    }
+}
+
+void Listen(int sockfd, int backlog) {
+    int res = listen(sockfd, backlog);
+    if (res == -1) {
+        perror("listen failed");
+        exit(EXIT_FAILURE);
+    }
+}
+
+int Accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen) {
+    int res = accept(sockfd, addr, addrlen);
+    if (res == -1) {
+        perror("accept failed");
+        exit(EXIT_FAILURE);
+    }
+    return res;
+}
+
+void Connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
+    int res = connect(sockfd, addr, addrlen);
+    if (res == -1) {
+        perror("connect failed");
+        exit(EXIT_FAILURE);
+    }
+}
+
+void Inet_pton(int af, const char *src, void *dst) {
+    int res = inet_pton(af, src, dst);
+    if (res == 0) {
+        printf("inet_pton failed: src does not contain a character"
+            " string representing a valid network address in the specified"
+            " address family\n");
+        exit(EXIT_FAILURE);
+    }
+    if (res == -1) {
+        perror("inet_pton failed");
+        exit(EXIT_FAILURE);
+    }
+}
+
+

erproc.h

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+#ifndef ERPROC_H
+#define ERPROC_H
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+int Socket(int domain, int type, int protocol);
+
+void Bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
+
+void Listen(int sockfd, int backlog);
+
+int Accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);
+
+void Connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
+
+void Inet_pton(int af, const char *src, void *dst);
+
+#endif
+

s.sh

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+gcc server.c erproc.c -W -Wall -Werror -o server

server.c

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+#include <sys/types.h>
+#include <sys/socket.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include "erproc.h"
+
+int main() {
+    int server = Socket(AF_INET, SOCK_STREAM, 0);
+    struct sockaddr_in adr = {0};
+    adr.sin_family = AF_INET;
+    adr.sin_port = htons(34543);
+    Bind(server, (struct sockaddr *) &adr, sizeof adr);
+    Listen(server, 5);
+    socklen_t adrlen = sizeof adr;
+    int fd = Accept(server, (struct sockaddr *) &adr, &adrlen);
+    ssize_t nread;
+    char buf[256];
+    nread = read(fd, buf, 256);
+    if (nread == -1) {
+        perror("read failed");
+        exit(EXIT_FAILURE);
+    }
+    if (nread == 0) {
+        printf("END OF FILE occured\n");
+    }
+    write(STDOUT_FILENO, buf, nread);
+    write(fd, buf, nread);
+
+    sleep(15);
+
+    close(fd);
+    close(server);
+    return 0;
+}