我认为这可能是一个简单的解决方案，我只是想多了。我正在编写一个非常基本的聊天程序，客户端和服务器轮流发送消息。现在我有它，它只来回发送一次消息，客户端关闭套接字。该程序不必同时打开套接字，只要它可以像秋千一样来回切换，而不是一个真正的聊天程序，它可以同时从双方接受多个输入。
客户端中的 while 循环是否会使其保持打开状态，while 循环的条件是什么？
我尝试了几种不同的条件，但都没有奏效……它只是让它挂起。我也试过注释掉close()服务器代码中的一些函数，但这也不起作用。
我也有一个收到的输入打印乱码的小问题，但我认为这是因为它正在打印字符串数组的内存地址，而其中没有任何内容......我只是不记得如何缩短它。哈哈。
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 PORT "3490" // The port users will be connecting to
#define BACKLOG 10 // How many pending connections queue will hold
char input[20];
char *pointer;
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(void)
{
int sockfd, new_fd; // Listen on sock_fd, new connection on new_fd
struct addrinfo hints, *servinfo, *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;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE; // use my IP
if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 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 = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("server: 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(servinfo); // 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");
sin_size = sizeof their_addr;
while((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) > 0) { // Main accept() loop
if (new_fd == -1) {
perror("accept");
continue;
}
inet_ntop(their_addr.ss_family,
get_in_addr((struct sockaddr *)&their_addr),
s, sizeof s);
printf("server: got connection from %s\n", s);
if (!fork()) { // this is the child process
close(sockfd); // child doesn't need the listener
char input[20];
char *pointer;
printf("Type in an server's input: ");
scanf("%s", input);
pointer = input; //Will need to clean this up to be more effcient... later
if (send(new_fd, pointer, strlen(input), 0) == -1) //Need to change the length to
//the actual length of the
//input... later.
perror("send");
close(new_fd);
exit(0);
}
char Cinput[20];
if ((recv(new_fd, Cinput, strlen(Cinput), 0)) == 0) { //NEW LINE ADDED HERE
printf("No more messages");
}
if ((recv(new_fd, Cinput, strlen(Cinput), 0)) == -1) {
perror("recv");
exit(1);
}
printf("Server: received '%s'\n",Cinput);
close(new_fd); // Parent doesn't need this
}
return 0;
}
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 PORT "3490" // The port client will be connecting to
#define MAXDATASIZE 100 // 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];
struct addrinfo hints, *servinfo, *p;
/*
This is what is in the struct
struct addrinfo {
int ai_flags; // AI_PASSIVE, AI_CANONNAME, etc.
int ai_family; // AF_INET, AF_INET6, AF_UNSPEC
int ai_socktype; // SOCK_STREAM, SOCK_DGRAM
int ai_protocol; // Use 0 for "any"
size_t ai_addrlen; // Size of ai_addr in bytes
struct sockaddr *ai_addr; // struct sockaddr_in or _in6
char *ai_canonname; // Full canonical hostname
struct addrinfo *ai_next; // Linked list, next node
};
getaddrinfo() will return a pointer to this
*/
int rv;
char s[INET6_ADDRSTRLEN];
if (argc != 2) {
fprintf(stderr,"usage: client hostname\n");
exit(1);
}
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if ((rv = getaddrinfo(argv[1], 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
while(1)//NEW LINE ADDEDthis is getting the client to repeat asking for the input, but doesn't send it.
{
if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == 0) { //NEW LINE ADDED
printf("Shutdown");
}
if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
perror("recv");
exit(1);
}
buf[numbytes] = '\0';
printf("client: received '%s'\n",buf);
char Cinput[20];
char *pointer;
printf("Type in an client's input: ");
scanf("%s", Cinput);
pointer = Cinput;
if (send(sockfd, pointer, strlen(Cinput), 0) == -1)
{
perror("send");
close(sockfd);
exit(0);
}
}
close(sockfd); //As soon as the client receives a message, it closes the socket.
//We probably need a while loop in here in order to keep the socket open,
//but what are the parameters for the while loop?
return 0;
}