距離詳解Linux下的UDP方式通訊

2020-01-26 14:50:21

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UDP方式點對點通訊

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;struct sockaddr_in c_addr;int sock;socklen_t addr_len;int len;char buff[128];/* 創建 socket , 關鍵在于這個 SOCK_DGRAM */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");memset(&s_addr, 0, sizeof(struct sockaddr_in));/* 設置地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);elses_addr.sin_addr.s_addr = INADDR_ANY;/* 綁定地址和端口信息 */if ((bind(sock, (struct sockaddr *) &s_addr, sizeof(s_addr))) == -1) {perror("bind");exit(errno);} elseprintf("bind address to socket./n/r");/* 循環接收數據 */addr_len = sizeof(c_addr);while (1) {len = recvfrom(sock, buff, sizeof(buff) - 1, 0,(struct sockaddr *) &c_addr, &addr_len);if (len < 0) {perror("recvfrom");exit(errno);}buff[len] = '/0';printf("收到來自%s:%d的消息:%s/n/r",inet_ntoa(c_addr.sin_addr), ntohs(c_addr.sin_port), buff);}return 0;}

客戶端源代碼如下：

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;int sock;int addr_len;int len;char buff[128];/* 創建 socket , 關鍵在于這個 SOCK_DGRAM */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");/* 設置對方地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);else {printf("消息必須有一個接收者！/n");exit(0);}/* 發送UDP消息 */addr_len = sizeof(s_addr);strcpy(buff, "hello i'm here");len = sendto(sock, buff, strlen(buff), 0,(struct sockaddr *) &s_addr, addr_len);if (len < 0) {printf("/n/rsend error./n/r");return 3;}printf("send success./n/r");return 0;}

編譯程序用下列命令：

gcc -Wall simple-udpserver.c -o servergcc -Wall simple-udpclient.c -o client

運行程序用下列命令：

./server 127.0.0.1 7838./client 127.0.0.1 7838

UDP方式廣播通訊
源代碼變成下面的：

#include <stdio.h>#include <string.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <errno.h>#include <stdlib.h>#include <arpa/inet.h>int main(int argc, char **argv){struct sockaddr_in s_addr;int sock;int addr_len;int len;char buff[128];int yes;/* 創建 socket */if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {perror("socket");exit(errno);} elseprintf("create socket./n/r");/* 設置通訊方式對廣播，即本程序發送的一個消息，網絡上所有主機均可以收到 */yes = 1;setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &yes, sizeof(yes));/* 唯一變化就是這一點了 *//* 設置對方地址和端口信息 */s_addr.sin_family = AF_INET;if (argv[2])s_addr.sin_port = htons(atoi(argv[2]));elses_addr.sin_port = htons(7838);if (argv[1])s_addr.sin_addr.s_addr = inet_addr(argv[1]);else {printf("消息必須有一個接收者！/n");exit(0);}/* 發送UDP消息 */addr_len = sizeof(s_addr);strcpy(buff, "hello i'm here");len = sendto(sock, buff, strlen(buff), 0,(struct sockaddr *) &s_addr, addr_len);if (len < 0) {printf("/n/rsend error./n/r");return 3;}printf("send success./n/r");return 0;}

編譯這個程序用下列命令：