麻烦在C和Linux套接字连接 [英] Trouble with socket connection in C and Linux
问题描述
我工作的一个简单的项目,因为我想了解更多关于Linux下的socket编程。我创建了一个非常简单的服务器,将接受连接,并用一个语句回应。不过,我添加了一个while循环来保持连接活着,所以我可以保持没有它断开发送命令。然而,有一次,我发的第一个命令,该服务器将连接回应。第一个响应后,它只是处于闲置状态,并退出响应。正如你可以从code诉说,我试过接受系统调用内部和外部while循环,因为我不知道,如果调用accept不止一次在同一客户端上会导致它挂起。有一次,我感动了while循环外的接受呼叫,功能仍然挂起,所以我不知道在哪里从这里走。
的#includeserver.h
#包括LT&; netinet / in.h中>
#包括LT&; SYS / socket.h中>
#包括LT&;&stdlib.h中GT;
#包括LT&;&stdio.h中GT;
#包括LT&;&string.h中GT;结构服务器{
INT的sockfd;
INT client_socket; //使用的插座,用于与所述客户端
INT积压; //最大挂起的连接
结构SOCKADDR_IN * serv_addr;
结构SOCKADDR_IN * client_addr; //客户信息时,它连接
};INT server_init(服务器** SERV,诠释了max_connections)
{
* SERV =(服务器*)malloc的(的sizeof(服务器));
如果(* SERV){
(* SERV) - GT;积压= max_connections的;
(* SERV) - GT;的sockfd =插座(AF_INET,SOCK_STREAM,IPPROTO_TCP); (* SERV) - GT; serv_addr =(结构SOCKADDR_IN *)malloc的(的sizeof(结构SOCKADDR_IN));
如果((* SERV) - GT; serv_addr)
memset的((* SERV) - GT; serv_addr->的sin_zero,0,sizeof的((* SERV) - GT; serv_addr->的sin_zero));
其他{
免费(* SERV);
返回-1;
} (* SERV) - GT; serv_addr-> sin_family = AF_INET;
(* SERV) - GT; serv_addr-> sin_addr.s_addr = INADDR_ANY; }其他{
返回-1;
} 返回0;
}/ *
*绑定服务器的端口并开始听
* /
INT server_bind(服务器* SERV,诠释端口)
{
INT结果为0; serv-> serv_addr-> sin_port = htons(端口);
如果(绑定(serv->的sockfd,(结构sockaddr *)&serv- GT; serv_addr,(socklen_t的)的sizeof(*(serv-> serv_addr)))小于0)
返回-1; //如果绑定调用失败,我不想继续尝试监听电话 如果(听(serv->的sockfd,serv->积压)℃下)
结果= -1; 返回结果;
}INT server_unbind(服务器* SERV)
{
INT结果为0; 如果(接近(serv-> client_socket)℃的)
结果= -1; 如果(接近(serv->的sockfd)℃的)
结果= -1; 返回结果;
}诠释server_accept_connections(服务器* SERV,INT(* process_data)(字符*缓冲区,ssize_t供长度,INT client_scoket))
{
INT结果为0;
字符*缓冲=(字符*)malloc的(的sizeof(char)的* 250); 如果(缓冲液){
INT长度= sizeof的((SERV) - GT; client_addr); //可以做一些与此有关的每一次计算它保持
serv-> client_socket =接受(serv->的sockfd,(结构sockaddr *)(SERV) - GT; client_addr,&安培;长度); 而(结果== 0){
// INT长度= sizeof的((SERV) - GT; client_addr);
// serv-> client_socket =接受(serv->的sockfd,(结构sockaddr *)(SERV) - GT; client_addr,&安培;长度);
ssize_t供数据长度=的recv(serv-> client_socket,缓冲器,的sizeof(缓冲液),0);
结果=(* process_data)(缓冲,数据长度,serv-> client_socket);
}
结果= 0;
}
其他
结果= -1; 免费(缓冲);
返回结果;
}无效server_destroy(服务器* SERV)
{
如果(SERV){
免费(serv-> serv_addr);
免费(SERV);
}
}
的#include<&stdio.h中GT;
#包括server.h
#包括LT&;&string.h中GT;
#包括LT&;&stdlib.h中GT;INT process_netdata(字符*缓冲区,ssize_t供长度,INT socket_desc)
{
的printf(%S,缓冲区);
如果(STRCMP(缓冲,跳槽)!= 0){
字符*海峡=我收到你的信息;
INT str_length = strlen的(STR);
写(socket_desc,STR,str_length);
返回0;
}
其他{
字符*海峡=跳槽获得了;
INT str_length = strlen的(STR);
写(socket_desc,STR,str_length);
返回-1;
}
}INT主(INT ARGC,字符** argv的)
{
服务器*服务器;
int值= 0; 值= server_init(安培;服务器,10);
的printf(server_init:%I \\ N,值); 值= server_bind(服务器,2021);
的printf(server_bind:%I \\ N,值); 值= server_accept_connections(服务器,和放大器; process_netdata);
的printf(server_accept:%I \\ N,值); 值= server_unbind(服务器);
的printf(server_unbind:%I \\ N,值); 值= server_destroy(服务器);
的printf(server_destroy:%I \\ N,值); 返回0;
}
您丢失到餐桌,使家长继续听(接受)新的连接,而孩子建立的连接上运行。
I am working on a simple project because I wanted to learn more about socket programming under Linux. I created a very simple server that will accept connections and respond with a single statement. However, I added a while loop to keep the connection alive, so I could keep sending commands without it disconnecting. However, Once I send the first command, the server will respond to the connection. After the first response, it just sits idle and quits responding. As you can tell from the code, I tried the accept system call inside and outside of the while loop because I was not sure if calling accept more than once on the same client would cause it to hang. Once I moved the accept call outside of the while loop, the function still hangs, so I am not sure where to go from here.
#include "server.h"
#include <netinet/in.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
struct server {
int sockfd;
int client_socket; //the socket used for communication with the client
int backlog; //maximum pending connections
struct sockaddr_in *serv_addr;
struct sockaddr_in *client_addr; //the clients information when it connects
};
int server_init(server **serv, int max_connections)
{
*serv = (server *)malloc(sizeof(server));
if (*serv) {
(*serv)->backlog = max_connections;
(*serv)->sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
(*serv)->serv_addr = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in));
if ((*serv)->serv_addr)
memset((*serv)->serv_addr->sin_zero, 0, sizeof((*serv)->serv_addr->sin_zero));
else {
free(*serv);
return -1;
}
(*serv)->serv_addr->sin_family = AF_INET;
(*serv)->serv_addr->sin_addr.s_addr = INADDR_ANY;
} else {
return -1;
}
return 0;
}
/*
* Bind the server to a port and start listening
*/
int server_bind(server *serv, int port)
{
int result = 0;
serv->serv_addr->sin_port = htons(port);
if (bind(serv->sockfd, (struct sockaddr *)serv->serv_addr, (socklen_t)sizeof(*(serv->serv_addr))) < 0)
return -1; //if the bind call fails, I dont want to continue to try the listen call
if (listen(serv->sockfd, serv->backlog) < 0)
result = -1;
return result;
}
int server_unbind(server *serv)
{
int result = 0;
if (close(serv->client_socket) < 0)
result = -1;
if (close(serv->sockfd) < 0)
result = -1;
return result;
}
int server_accept_connections(server *serv, int (*process_data)(char *buffer, ssize_t length, int client_scoket))
{
int result = 0;
char *buffer = (char *) malloc(sizeof(char) * 250);
if (buffer) {
int length = sizeof((serv)->client_addr); //may do something with this to keep from calculating it every time
serv->client_socket = accept(serv->sockfd, (struct sockaddr *)(serv)->client_addr, &length);
while (result == 0) {
//int length = sizeof((serv)->client_addr);
//serv->client_socket = accept(serv->sockfd, (struct sockaddr *)(serv)->client_addr, &length);
ssize_t data_length = recv(serv->client_socket, buffer, sizeof(buffer), 0);
result = (* process_data)(buffer, data_length, serv->client_socket);
}
result = 0;
}
else
result = -1;
free(buffer);
return result;
}
void server_destroy(server *serv)
{
if (serv) {
free(serv->serv_addr);
free(serv);
}
}
#include <stdio.h>
#include "server.h"
#include <string.h>
#include <stdlib.h>
int process_netdata(char *buffer, ssize_t length, int socket_desc)
{
printf("%s",buffer);
if(strcmp(buffer, "quit") != 0) {
char *str = "I got your message";
int str_length = strlen(str);
write(socket_desc, str, str_length);
return 0;
}
else {
char *str = "quit received";
int str_length = strlen(str);
write(socket_desc, str, str_length);
return -1;
}
}
int main(int argc, char **argv)
{
server *server;
int value = 0;
value = server_init(&server, 10);
printf("server_init: %i\n", value);
value = server_bind(server, 2021);
printf("server_bind: %i\n", value);
value = server_accept_connections(server, &process_netdata);
printf("server_accept: %i\n", value);
value = server_unbind(server);
printf("server_unbind: %i\n", value);
value = server_destroy(server);
printf("server_destroy: %i\n", value);
return 0;
}
You are missing to fork so that the parent continues to listen(accept) for new connections , while the child operates on the established connection.
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