C中的UDP服务器和2个UDP客户端
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我阅读了Beej的指南，并创建了UDP服务器和客户端。我首先运行服务器，然后运行2个客户端。服务器应该“ 0”个客户端，“ 1”个其他客户端。当客户端1发送东西时，客户端0接收它。当客户端0发送某些内容时，客户端1不会收到它。谁能看到代码有什么问题吗？我已经阅读了有关UDP，C，服务器，聊天的所有问题，但找不到任何可以帮助我的东西。我正在OSX上编译此代码。任何帮助表示赞赏。以下是服务器代码：
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#define BUFLEN 512
#define PORT 7777
void err(char *str)
{
perror(str);
exit(1);
}
int main(void)
{
struct sockaddr_in my_addr, cli_addr[2],cli_temp;
int sockfd;
socklen_t slen[2],slen_temp;
slen[1]=sizeof(cli_addr[1]);
slen[2]=sizeof(cli_addr[2]);
slen_temp = sizeof(cli_temp);
char buf[BUFLEN];
int clients = 0;
int client_port[2];
if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1)
{
printf(\"test\\n\");
err(\"socket\");
}else{
printf(\"Server : Socket() successful\\n\");
}
bzero(&my_addr, sizeof(my_addr));
my_addr.sin_family = AF_INET;
my_addr.sin_port = htons(PORT);
my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(sockfd, (struct sockaddr* ) &my_addr, sizeof(my_addr))==-1)
{
err(\"bind\");
}else{
printf(\"Server : bind() successful\\n\");
}
while(1)
{
//receive
printf(\"Receiving...\\n\");
if (recvfrom(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_temp, &slen_temp)==-1)
err(\"recvfrom()\");
if (clients==0) {
//first connection
//store the temp connection details to the array
cli_addr[0] = cli_temp;
//get client 0 port
client_port[0] = ntohs(cli_addr[0].sin_port);
clients++;
printf(\"Client 0 connected. Port: %d\\n\",client_port[0]);
sendto(sockfd, \"You are the only client.\", 24, 0, (struct sockaddr*)&cli_temp, slen_temp);
}else if (clients==1) {
//new or existing
if (client_port[0]==ntohs(cli_temp.sin_port)) {
//send back to client 0 that nobody else connected yet
sendto(sockfd, \"You are the only client.\", 24, 0, (struct sockaddr*)&cli_addr[0], slen[0]);
printf(\"Only client\\n\");
}else{
//new connection
cli_addr[1] = cli_temp;
client_port[1] = ntohs(cli_addr[1].sin_port);
clients++;
printf(\"GOt second client\\n\");
sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[0], slen[0]);
}
}else{
//there are 2 clients connected here. If we get an error from the sendto then we decrement clients
if (client_port[0]==ntohs(cli_temp.sin_port)) {
//client 0 talking send to client 1
printf(\"Sedning message to client 1\\n\");
if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[1], slen[1])==-1)
{
clients--;
err(\"sendto()\");
}
}else {
//client 1 talking send to client 0
printf(\"Sending message to client 0\\n\");
if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[1], slen[1])==-1)
{
clients--;
err(\"sendto()\");
}
}
}
//printf(\"Received packet from %s:%d\\nData: %s\\n\",
// inet_ntoa(cli_addr[clients].sin_addr), ntohs(cli_addr[clients].sin_port), buf);
}
close(sockfd);
return 0;
}
#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <signal.h>
#define BUFLEN 512
#define PORT 7777
void err(char *s)
{
perror(s);
exit(1);
}
sig_atomic_t child_exit_status;
void clean_up_child_process (int signal_number)
{
/* Clean up the child process. */
int status;
wait (&status);
/* Store its exit status in a global variable. */
child_exit_status = status;
}
int main(int argc, char** argv)
{
struct sockaddr_in serv_addr;
int sockfd, slen=sizeof(serv_addr);
char buf[BUFLEN];
struct sigaction sigchld_action;
memset (&sigchld_action, 0, sizeof (sigchld_action));
sigchld_action.sa_handler = &clean_up_child_process;
sigaction (SIGCHLD, &sigchld_action, NULL);
int pid,ppid;
if(argc != 2)
{
printf(\"Usage : %s <Server-IP>\\n\",argv[0]);
exit(0);
}
if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1)
err(\"socket\");
bzero(&serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(PORT);
if (inet_aton(argv[1], &serv_addr.sin_addr)==0)
{
fprintf(stderr, \"inet_aton() failed\\n\");
exit(1);
}
pid = fork();
if (pid<0) {
err(\"Fork Error\");
}else if (pid==0) {
//child process will receive from server
while (1) {
bzero(buf,BUFLEN);
printf(\"Attempting to READ to socket %d: \",sockfd);
fflush(stdout);
//recvfrom here
if (recvfrom(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&serv_addr, &slen)==-1)
err(\"recvfrom()\");
printf(\"The message from the server is: %s \\n\",buf);
if (strcmp(buf,\"bye\\n\") == 0) {
ppid = getppid();
kill(ppid, SIGUSR2);
break;
}
}
}else {
//parent will send to server
while(1){
printf(\"Please enter the message to send: \");
bzero(buf,BUFLEN);
fgets(buf,BUFLEN,stdin);
printf(\"Attempting to write to socket %d: \",sockfd);
fflush(stdout);
//send to here
if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&serv_addr, slen)==-1)
{
err(\"sendto()\");
}
}
}
close(sockfd);
return 0;
}
没有找到相关结果
已邀请:
2 个回复
扇献隙
// there are 2 clients connected here. If we get an error from the sendto // then we decrement clients if (client_port[0]==ntohs(cli_temp.sin_port)) { //client 0 talking send to client 1 printf(\"Sedning message to client 1\\n\"); if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[1], slen[1])==-1) { clients--; err(\"sendto()\"); } }else { //client 1 talking send to client 0 printf(\"Sending message to client 0\\n\"); if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[1], slen[1])==-1) { clients--; err(\"sendto()\"); } }。对我来说似乎是个虫子。垫歌蝎降凤
这应该更改为：我浏览了其余代码，没有看到其他错误。我不确定这是否可以解决您的问题，但这绝对是错误的。 （您可能知道这一点，但是）这是错误的，因为数组的第一个元素是，而不是，因此，如果您有一个包含2个元素的数组，则将不存在。 更新资料 更改else { //client 1 talking send to client 0 printf(\"Sending message to client 0\\n\"); if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[1], slen[1])==-1) { clients--; err(\"sendto()\"); } }else { //client 1 talking send to client 0 printf(\"Sending message to client 0\\n\"); if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr[0], slen[1])==-1) { clients--; err(\"sendto()\"); } }