21、网络IPC：套接字(2)

1、数据传输

//发送数据,成功返回发送的字节数//发送成功只能表示数据已经无错误的发送到网络驱动程序上ssize_t send(int sockfd, const void *buf, size_t nbytes, int flags);//sendto可以为无连接的套接字指定一个目标地址//面向连接的套接字连接中隐含目标地址ssize_t sendto(int sockfd, const void *buf, size_t nbytes, int flags, const struct sockaddr *destaddr, socklen_t destlen);//指定多重缓冲区传输数据ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);struct msghdr{    void *msg_name;    socklen_t msg_namelen;    struct iovec *msg_iov;    int msg_iov_len;    .....};//接收数据ssize_t recv(int sockfd, void *buf, size_t nbytes, int flags);ssize_t recvfrom(int sockfd, void *restrict buf, size_t len, int flags, struct sockaddr *restrict addr, socklen_t *restrict addrlen);ssize_t recvmsg(int sockfd, struct msghdr *msg, int flags);

2、通信程序-服务器端

#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <sys/socket.h>#include <sys/types.h>#include <string.h>#include <arpa/inet.h>int main(int argc, char *argv[]){    struct sockaddr_in clientaddr, serveraddr;    int sockfd;    int connfd;    int addrlen;    sockfd = socket(AF_INET, SOCK_STREAM, 0);    bzero(&serveraddr, sizeof(serveraddr));    serveraddr.sin_family = AF_INET;    serveraddr.sin_port = htons(atoi(argv[2]));    inet_pton(AF_INET, argv[1], &serveraddr.sin_addr);    bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));    listen(sockfd,128);    while(1){        addrlen = sizeof(clientaddr);        connfd = accept(sockfd, (struct sockaddr *)&clientaddr, &addrlen);         int ret;        do{            char buf[1024];            memset(buf, '\0',sizeof(buf));            ret = recv(connfd,buf, sizeof(buf), 0);            write(STDOUT_FILENO, buf, strlen(buf));            char dst[128];            printf("from ip:%s\tport:%d\n",inet_ntop(AF_INET, &clientaddr.sin_addr, dst, sizeof(dst)), ntohs(clientaddr.sin_port));            printf("*------------------------*\n");            memset(buf, '\0',sizeof(buf));            read(STDOUT_FILENO, buf, strlen(buf));            send(connfd,buf,sizeof(buf), 0);            printf("msg is sent\n");            printf("*------------------------*\n");        }while(ret);        close(connfd);          }    close(sockfd);    return 0;}

2、通信程序-客户端

#include <stdio.h>#include <sys/socket.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <arpa/inet.h>#include <sys/types.h>int main(int argc, char *argv[]){    struct sockaddr_in serveraddr;    int sockfd;    sockfd = socket(AF_INET, SOCK_STREAM, 0);    bzero(&serveraddr, sizeof(serveraddr));    serveraddr.sin_family = AF_INET;    serveraddr.sin_port = htons(atoi(argv[2]));    inet_pton(AF_INET, argv[1], &serveraddr.sin_addr);    connect(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));    while(1){        char buf[1024] = { 0 };        read(STDOUT_FILENO, buf, sizeof(buf));        send(sockfd, buf, strlen(buf), 0);        printf("msg is sent\n");        printf("*------------------------*\n");        memset(buf, '\0',sizeof(buf));        recv(sockfd,buf, sizeof(buf), 0);        write(STDOUT_FILENO, buf, strlen(buf));        char dst[128];        printf("from ip:%s\tport:%d\n",inet_ntop(AF_INET, &serveraddr.sin_addr, dst, sizeof(dst)), ntohs(serveraddr.sin_port));        printf("*------------------------*\n");    }    close(sockfd);    return 0;}

3、

//设置套接字选项int setsockopt(int sockfd, int level, int option, const void *val, socklen_t len);//查看选项的当前值int getsockopt(int socket, int level, int option, void *restrict val, socklen_t *restrict lenp);

4、带外数据：允许更高优先级的数据传输，TCP支持带外数据（称为紧急数据）仅支持一个字节的紧急数据，UDP不支持。TCP支持紧急标记：在普通数据流中紧急数据所在的位置。