我正在尝试编写一个简单的聊天程序，一个用户可以连接到主机。两人应该能够互相交谈（他们可能会互相打断，但没关系）。我遇到了困难select()。这是代码：
客户端.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define MAXDATASIZE 1024 // max number of bytes we can get at once
// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa) {
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*) sa)->sin_addr);
}
return &(((struct sockaddr_in6*) sa)->sin6_addr);
}
int main(int argc, char *argv[]) {
int sockfd, numbytes;
char buf[MAXDATASIZE];
char buffer[1024];
char *buff;
struct addrinfo hints, *servinfo, *p;
int rv;
char s[INET6_ADDRSTRLEN];
char *port;
int num;
struct timeval tv;
//select data
fd_set rfds;
fd_set wfds;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
if (argc != 2) {
fprintf(stderr, "usage: client port\n");
exit(1);
}
port = argv[1];
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if ((rv = getaddrinfo("localhost", port, &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and connect to the first we can
for (p = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("client: socket");
continue;
}
if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("client: connect");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "client: failed to connect\n");
return 2;
}
inet_ntop(p->ai_family, get_in_addr((struct sockaddr *) p->ai_addr),
s, sizeof s);
printf("client: connecting to %s\n", s);
freeaddrinfo(servinfo); // all done with this structure
FD_SET(sockfd, &rfds);
FD_SET(sockfd, &wfds);
if (select(sockfd + 1, &rfds, &wfds, NULL, &tv) < 0) {
perror("select");
return -1;
}
if (FD_ISSET(sockfd, &wfds)) {
while (1) {
fgets(buffer, MAXDATASIZE - 1, stdin);
if ((send(sockfd, buffer, strlen(buffer), 0)) == -1) {
fprintf(stderr, "Failure Sending Message\n");
close(sockfd);
exit(1);
} else {
printf("Message being sent: %s\n", buffer);
break;
}
}
}
if (FD_ISSET(sockfd, &rfds)) {
while (1) {
if ((num = recv(sockfd, buffer, 10240, 0)) == -1) {
//fprintf(stderr,"Error in receiving message!!\n");
perror("recv");
exit(1);
} else if (num == 0) {
printf("Connection closed\n");
return 0;
}
// num = recv(client_fd, buffer, sizeof(buffer),0);
buffer[num] = '\0';
printf("Message received: %s\n", buffer);
break;
}
}
close(sockfd);
return 0;
}
服务器.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#define BACKLOG 10 // how many pending connections queue will hold
#define MAXDATASIZE 100 // max number of bytes we can get at once
void sigchld_handler(int s) {
while (waitpid(-1, NULL, WNOHANG) > 0);
}
// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa) {
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*) sa)->sin_addr);
}
return &(((struct sockaddr_in6*) sa)->sin6_addr);
}
int main(int argc, char *argv[]) {
int sockfd; // set up socket
int new_sockfd; // new socket after connection
struct addrinfo hints, *results, *p;
struct sockaddr_storage their_addr; // connector's address information
socklen_t sin_size;
struct sigaction sa;
int yes = 1;
char s[INET6_ADDRSTRLEN];
int rv;
int i;
struct timeval tv;
int num;
char buffer[10241];
int nsock;
char buf[MAXDATASIZE];
int numbytes;
char *port;
//select data
fd_set rfds;
fd_set wfds;
FD_ZERO(&rfds);
FD_ZERO(&wfds);
/* validate command-line arguments */
if (argc != 2) {
fprintf(stderr, "Usage: %s port\n", argv[0]);
exit(1);
}
tv.tv_sec = 100;
tv.tv_usec = 0;
/* only argument to port number (./sc [port])*/
port = argv[1];
bzero(&hints, sizeof (struct addrinfo));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE; // any IP
if ((rv = getaddrinfo(NULL, port, &hints, &results)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and bind to the first we can
for (p = results; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("1: socket");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
sizeof (int)) == -1) {
perror("setsockopt");
exit(1);
}
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("server: bind");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "server: failed to bind\n");
return 2;
}
freeaddrinfo(results); // all done with this structure
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(1);
}
sa.sa_handler = sigchld_handler; // reap all dead processes
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
perror("sigaction");
exit(1);
}
printf("server: waiting for connections...\n");
while (1) { // main accept() loop
sin_size = sizeof their_addr;
new_sockfd = accept(sockfd, (struct sockaddr *) &their_addr, &sin_size);
if (new_sockfd == -1) {
perror("accept");
continue;
}
//get the clients info
inet_ntop(their_addr.ss_family,
get_in_addr((struct sockaddr *) &their_addr),
s, sizeof s);
printf("server: got connection from %s\n", s);
FD_SET(new_sockfd, &rfds);
FD_SET(new_sockfd, &wfds);
if (select(new_sockfd + 1, &rfds, &wfds, NULL, &tv) < 0) {
perror("select");
return -1;
}
if (FD_ISSET(new_sockfd, &rfds))
while (1) {
if ((num = recv(new_sockfd, buffer, 10240, 0)) == -1) {
//fprintf(stderr,"Error in receiving message!!\n");
perror("recv");
exit(1);
} else if (num == 0) {
printf("Connection closed\n");
return 0;
}
// num = recv(client_fd, buffer, sizeof(buffer),0);
buffer[num] = '\0';
printf("Message received: %s\n", buffer);
break;
}
if (FD_ISSET(new_sockfd, &wfds))
while (1) {
fgets(buffer, MAXDATASIZE - 1, stdin);
if ((send(new_sockfd, buffer, strlen(buffer), 0)) == -1) {
fprintf(stderr, "Failure Sending Message\n");
close(new_sockfd);
exit(1);
} else {
printf("Message being sent: %s\n", buffer);
break;
}
}
} //Outer While
close(new_sockfd); // parent doesn't need this
return 0;
}
主机和客户端无法通信。谁能告诉我问题出在哪里？