linux下UDP的socket编程

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自己实现了一下，主要是使用了sendto函数和recvfrom函数；

另外recvfrom和recv最主要的区别是可以得到发送端的地址。

下次接着准备实现一下ftp:

发送端：

#include <stdio.h>#include <sys/socket.h>#include <sys/types.h>#include <string.h>#include <netinet/in.h>#define PORT 6789#define Buflen 100#define Maxiter 20int main(){struct sockaddr_in send_addr;int sockfd, i;char content[Buflen], server_ip[Buflen];ssize_t send_size;sockfd = socket(AF_INET, SOCK_DGRAM, 0);if(sockfd < 0){printf("socket create error\n");return -1;}send_addr.sin_port = htons(PORT);send_addr.sin_family = AF_INET;send_addr.sin_addr.s_addr = htonl(INADDR_ANY);printf("please input dest ip:\n");read(0, server_ip, Buflen);send_addr.sin_addr.s_addr = inet_addr(server_ip);for(i = 0; i < Maxiter; i ++){printf("please input the send message(not more than 100bytes):\n");read(0, content, Buflen);send_size = sendto(sockfd, content, Buflen, 0, (struct sockaddr *)&send_addr, sizeof(struct sockaddr));if(send_size < 0){printf("error! %d iters\n", i);return -1;} }send_size = sendto(sockfd, "stop", 5, 0, (struct sockaddr *)&send_addr,sizeof(struct sockaddr));if(send_size < 0){printf("error!\n");return -1;}close(sockfd);return 0;}

接收端：

#include <stdio.h>#include <sys/socket.h>#include <sys/types.h>#include <string.h>#include <netinet/in.h>#include <stdlib.h>#define PORT 6789#define Buflen 100int main(){struct sockaddr_in send_addr, recv_addr;int sockfd, bind_err;ssize_t recv_size;char content[Buflen];sockfd = socket(AF_INET, SOCK_DGRAM, 0);if(sockfd < 0){printf("socket create error!\n");return -1;}recv_addr.sin_port = htons(PORT);recv_addr.sin_family = AF_INET;recv_addr.sin_addr.s_addr = htonl(INADDR_ANY);bind_err = bind(sockfd, (struct sockaddr *)&recv_addr, sizeof(struct sockaddr));if(bind_err < 0){printf("bind error!\n");return;}while(1){memset(&send_addr, 0, sizeof(send_addr));socklen_t buflen = sizeof(struct sockaddr);recv_size = recvfrom(sockfd, content, Buflen, 0, (struct sockaddr *)&send_addr, &buflen);if(recv_size < 0){printf("recvfrom error!\n");return -1;}if(strncmp(content, "stop", 4) == 0) break;printf("recv : %s\n", content);}close(sockfd);return 0;}

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