第8章 基本UDP套接字编程

客户端：

#include "../Gnet.h"void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len){    char buf[MAX_LINE];    int nread;    while(fgets(buf, MAX_LINE, stdin) != NULL)    {        sendto(udpfd, buf, strlen(buf), 0, pserver_addr, server_addr_len);        nread = recvfrom(udpfd, buf, MAX_LINE, 0, NULL, NULL);        fputs(buf, stdout);    }}int main(int argc, const char* argv[]){    int udpfd;    struct sockaddr_in server_addr;    if(argc < 2)        perr_exit("usage : client <IPaddress>");    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_port = htons(SERVER_PORT);    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));    return 0;}

#include "../Gnet.h"void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len){    char buf[MAX_LINE];    char reply_ip[INET_ADDRSTRLEN];    int nread;    struct sockaddr_in reply_addr;    socklen_t reply_addr_len;    reply_addr_len = server_addr_len;    while(fgets(buf, MAX_LINE, stdin) != NULL)    {        sendto(udpfd, buf, strlen(buf), 0, pserver_addr, server_addr_len);        nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&reply_addr, &reply_addr_len);        if(reply_addr_len != server_addr_len ||           memcmp(&reply_addr, pserver_addr, reply_addr_len) != 0)        {            inet_ntop(AF_INET, &reply_addr, reply_ip, INET_ADDRSTRLEN);            printf("reply from %s (ignored)\n", reply_ip);            continue;        }        fputs(buf, stdout);    }}int main(int argc, const char* argv[]){    int udpfd;    struct sockaddr_in server_addr;    if(argc < 2)        perr_exit("usage : client <IPaddress>");    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_port = htons(SERVER_PORT);    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));    return 0;}

#include "../Gnet.h"void do_client(int udpfd, struct sockaddr* pserver_addr, socklen_t server_addr_len){    char buf[MAX_LINE];    int nread;    Connect(udpfd, pserver_addr, server_addr_len);    while(fgets(buf, MAX_LINE, stdin) != NULL)    {        Write(udpfd, buf, strlen(buf));        nread = Read(udpfd, buf, MAX_LINE);                fputs(buf, stdout);    }}int main(int argc, const char* argv[]){    int udpfd;    struct sockaddr_in server_addr;    if(argc < 2)        perr_exit("usage : client <IPaddress>");    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_port = htons(SERVER_PORT);    inet_pton(AF_INET, argv[1], &server_addr.sin_addr);    do_client(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));    return 0;}

服务器：

#include "../Gnet.h"void do_server(int udpfd){    ssize_t nread;    char buf[MAX_LINE];    struct sockaddr_in client_addr;    socklen_t client_addr_len;    while(1)    {        client_addr_len = sizeof(client_addr);        nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&client_addr, &client_addr_len);        sendto(udpfd, buf, nread, 0, (struct sockaddr*)&client_addr, client_addr_len);    }}int main(int argc, const char* argv[]){    int udpfd;    struct sockaddr_in server_addr;    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);    server_addr.sin_port = htons(SERVER_PORT);    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);    Bind(udpfd, (const struct sockaddr*)&server_addr, sizeof(server_addr));    printf("waiting for connecting.\n");    do_server(udpfd);    return 0;}

服务器（select模型+tcp+udp）：

#include "../Gnet.h"void do_server(int connfd){    ssize_t nread;    char buf[MAX_LINE];    while((nread = Read(connfd, buf, MAX_LINE)) > 0)        Write(connfd, buf, nread);}void sig_child(int signo){    pid_t pid;    int stat;    printf("in sig_child.\n");    while((pid = waitpid(-1,&stat, WNOHANG)) > 0)        printf("child %d terminated\n", pid);    printf("out sig_child.\n");}int main(int argc, const char* argv[]){    int lfd, connfd;    int udpfd;    struct sockaddr_in server_addr, client_addr;    socklen_t client_addr_len;    pid_t child_id;    const int on = 1;    fd_set rset;    int maxfd;    int nready;    int nread;    char buf[MAX_LINE];    struct sigaction sigaction_set, sigaction_get;    sigaction_set.sa_handler = sig_child;    sigemptyset(&sigaction_set.sa_mask);    sigaction_set.sa_flags = 0;    if(sigaction(SIGCHLD, &sigaction_set, &sigaction_get) <0)        printf("sigaction(SIGCHLD) error!\n");    memset(&server_addr, 0, sizeof(server_addr));    server_addr.sin_family = AF_INET;    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);    server_addr.sin_port = htons(SERVER_PORT);    lfd = Socket(AF_INET, SOCK_STREAM, 0);    setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));//端口复用    Bind(lfd, (const struct sockaddr*)&server_addr, sizeof(server_addr));    Listen(lfd, LISTENQ);    udpfd = Socket(AF_INET, SOCK_DGRAM, 0);    Bind(udpfd, (struct sockaddr*)&server_addr, sizeof(server_addr));    printf("waiting for connecting.\n");    maxfd = lfd > udpfd ? lfd : udpfd;    FD_ZERO(&rset);    while(1)    {        FD_SET(lfd, &rset);        FD_SET(udpfd, &rset);        if((nready = select(maxfd+1, &rset, NULL, NULL, NULL)) < 0)        {            if(errno == EINTR)                continue;            else                perr_exit("select error");        }        if(FD_ISSET(lfd, &rset))        {            client_addr_len = sizeof(client_addr);            connfd = Accept(lfd, (struct sockaddr*)&client_addr, &client_addr_len);            if((child_id = fork()) == 0)//子进程            {                Close(lfd);                do_server(connfd);                Close(connfd);                exit(0);            }            else//父进程            {                printf("child %d connected\n", child_id);                Close(connfd);            }        }        if(FD_ISSET(udpfd, &rset))        {            client_addr_len = sizeof(client_addr);            nread = recvfrom(udpfd, buf, MAX_LINE, 0, (struct sockaddr*)&client_addr, &client_addr_len);            sendto(udpfd, buf, nread, 0, (struct sockaddr*)&client_addr, client_addr_len);        }    }    return 0;}

connect：绑定对端地址

bind：绑定本端地址

github：https://github.com/gongluck/CodeBase/tree/master/notes/unpv13-notes