UDP echo example

c/echo_server-udp/echo-client.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <unistd.h>		/* для вызова close() для сокета */
+
+int main(void)
+{
+	int sock;
+	struct sockaddr_in sa;
+	int bytes_sent;
+	const char *buffer = "Привет!";
+	int buffer_length;
+
+	buffer_length = strlen(buffer) + 1;
+
+	sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
+
+	if (sock == -1) {
+		printf("Ошибка создания сокета");
+		return 0;
+	}
+
+	sa.sin_family = PF_INET;
+	sa.sin_addr.s_addr = htonl(0x7F000001);
+	sa.sin_port = htons(7654);
+
+	bytes_sent = sendto(sock, buffer, strlen(buffer) + 1, 0, (struct sockaddr *)&sa, sizeof(struct sockaddr_in));
+
+	if (bytes_sent < 0)
+		printf("Ошибка отправки пакета: %s\n", strerror(errno));
+
+	close(sock);
+	return 0;
+}

c/echo_server-udp/echo-server.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <string.h>
+#include <stdio.h>
+
+int main()
+{
+	int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
+
+	struct sockaddr_in sa;
+	int bound;
+	ssize_t recsize;
+	socklen_t *address_len = NULL;
+
+	sa.sin_addr.s_addr = INADDR_ANY;
+	sa.sin_port = htons(7654);
+
+	bound = bind(sock, (struct sockaddr *)&sa, sizeof(struct sockaddr));
+
+	if (bound < 0)
+		fprintf(stderr, "bind(): ошибка %s\n", strerror(errno));
+
+	char Hz[1024];
+
+	while (1) {
+		printf("recv test....\n");
+		recsize = recvfrom(sock, (void *)Hz, 100, 0, (struct sockaddr *)&sa, address_len);
+
+		if (recsize < 0)
+			perror("Ошибка:");
+
+		printf("recsize: %d\n ", (int)recsize);
+		//sleep(1);
+		printf("datagram: %s\n", Hz);
+	}
+}

c/echo_server-udp/int2ip.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <netdb.h>
+
+static const char *int2ip(unsigned int ip)
+{
+	static char s[16];
+	sprintf(s, "%d.%d.%d.%d", ip >> 24, ip << 8 >> 24, ip << 16 >> 24, ip << 24 >> 24);
+	return s;
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 2) {
+		perror("need hex ip address");
+		exit(1);
+	}
+
+	unsigned int ip = 0;
+	sscanf(argv[1], "%X", &ip);
+
+	printf("%s\n", int2ip(ip));
+
+	return 0;
+}

c/echo_server-udp/ip2int.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <netdb.h>
+
+unsigned int ip2int(const char *s)
+{
+	int ip[4];
+	sscanf(s, "%d.%d.%d.%d", ip, ip + 1, ip + 2, ip + 3);
+	return ip[0] << 24 | ip[1] << 16 | ip[2] << 8 | ip[3];
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 2) {
+		perror("need ip address string");
+		exit(1);
+	}
+
+	printf("%X\n", ip2int(argv[1]));
+
+	return 0;
+}

c/echo_server-udp/sock1.c

@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+//~ domain = AF_UNIX, AF_INET, AF_INET6, AF_IPX
+//~ type = SOCK_STREAM, SOCK_DGRAM, SOCK_RAW
+//~ int socket(int domain, int type, int protocol);
+
+//~ struct sockaddr {
+    //~ unsigned short    sa_family;    // Семейство адресов, AF_xxx
+    //~ char              sa_data[14];  // 14 байтов для хранения адреса
+//~ };
+//~ struct sockaddr_in {
+    //~ short int          sin_family;  // Семейство адресов
+    //~ unsigned short int sin_port;    // Номер порта
+    //~ struct in_addr     sin_addr;    // IP-адрес
+    //~ unsigned char      sin_zero[8]; // "Дополнение" до размера структуры sockaddr
+//~ };
+//~ struct in_addr {
+    //~ unsigned long s_addr;
+//~ };
+//~ htons, htonl, ntohs, ntohl
+//~ int bind(int sockfd, struct sockaddr *addr, int addrlen);
+
+//~ int listen(int sockfd, int backlog);
+//~ int accept(int sockfd, void *addr, int *addrlen);
+
+// клиент
+//~ int connect(int sockfd, struct sockaddr *serv_addr, int addrlen);
+
+//~ int send(int sockfd, const void *msg, int len, int flags);
+
+// отправка буфера целиком
+//~ int sendall(int s, char *buf, int len, int flags)
+//~ {
+    //~ int total = 0;
+    //~ int n;
+//~
+    //~ while(total < len)
+    //~ {
+	//~ n = send(s, buf+total, len-total, flags);
+	//~ if(n == -1) { break; }
+	//~ total += n;
+    //~ }
+//~
+    //~ return (n==-1 ? -1 : total);
+//~ }
+
+//~ int recv(int sockfd, void *buf, int len, int flags);
+
+// закрытие соединения
+//~ int close(int fd);
+
+// запрет передачи 0 - чтения, 1 - записи, 2 - и того, и др.
+//~ int shutdown(int sockfd, int how);
+
+int main(int argc, char *argv[])
+{
+	struct a {
+		char aaa[256];
+	};
+
+	printf("%lu\n", sizeof(struct a));
+	return 0;
+}

c/echo_server-udp/tmp1.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+void f()
+{
+	int c = 0;
+	printf("c=%lu\n", (unsigned long)&c);
+}
+
+int main(int argc, char *argv[])
+{
+	//~ printf("%lu\n", sizeof(long));
+
+	int a = 0;
+
+	int pid = fork();
+	printf("pid=%d\n", pid);
+	printf("a=%lu\n", (unsigned long)&a);
+
+	int b = 0;
+	printf("b=%lu\n", (unsigned long)&b);
+
+	f();
+
+	return 0;
+}