9.2网络-socket2_UDP通信 2015/8/7

---

UDP

recvfrom

阻塞等待客户端数去请求
接收客户端发送来的数据，和地址端口信息
#include

sendto

给客户端地址端口addr发送数据应答
#include

#include <stdio.h>#include <string.h>#include <ctype.h>#include <sys/socket.h>#include <unistd.h>#include <sys/types.h>#include <arpa/inet.h>#define SERV_PORT 8000int main(void){    int sockfd;    struct sockaddr_in servaddr, cliaddr;    int n, i;    char buf[256];    char str[256];    socklen_t cliaddrlen;    sockfd = socket(AF_INET, SOCK_DGRAM, 0);     bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(SERV_PORT);    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));    printf("Receiving ...\n");    while (1) {        cliaddrlen = sizeof(cliaddr);        n = recvfrom(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&cliaddr, &cliaddrlen);  //接收        printf("Rece: %s, PORT:%d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, str, cliaddrlen), ntohs(cliaddr.sin_port));        for (i = 0; i < n; i++)            buf[i]  = toupper(buf[i]);        sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&cliaddr, cliaddrlen);    //发送        bzero(buf, sizeof(buf));    }    close(sockfd);    return 0;}

client.c

#include <stdio.h>#include <unistd.h>#include <sys/socket.h>#include <sys/types.h>#include <arpa/inet.h>#include <string.h>#include <strings.h>#define SERV_PORT 8000int main(void){    int sockfd;    struct sockaddr_in servaddr;    char buf[256];    socklen_t servaddlen;    int n;    sockfd = socket(AF_INET, SOCK_DGRAM, 0);     bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(SERV_PORT);    inet_pton(AF_INET, "192.168.188.133",  &servaddr.sin_addr);    while (fgets(buf, sizeof(buf), stdin) != NULL) {        servaddlen = sizeof(servaddr);        sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&servaddr, servaddlen);          n = recvfrom(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&servaddr, &servaddlen);        write(STDOUT_FILENO, buf, n);    }    close(sockfd);    return 0;}