C++ Linux 多线程套接字问题

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这是 friend 发给我的客户代码。我对套接字编程知之甚少。它有点像聊天客户端；将文本发送到服务器，服务器将其发送给所有客户端。我编辑了它，其中在执行时显示彩色文本，并带有聊天命令的说明。问题是/ls 命令将被识别，并且暂时不会按预期发送到服务器，但它不会执行 中指示的任何操作。否则如果 陈述。其次，在使用命令或向服务器发送文本后，它不会再让我使用命令或发送文本。我可以打字，但没有任何东西通过服务器，我没有收到典型的例如“已接收字节 12”消息；除非我使用/dis 命令断开与服务器的连接，但我当然会说“收到的字节数 -1”。有什么想法或建议吗？提前致谢。

我还在底部提供了服务器源，以防有人认为那里有问题。

客户来源




#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <netinet/in.h>
#include <resolv.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string>
#include <sstream>
#define ANSI_COLOR_RED "\x1b[31m"
#define ANSI_COLOR_GREEN "\x1b[32m"
#define ANSI_COLOR_YELLOW "\x1b[33m"
#define ANSI_COLOR_BLUE "\x1b[34m"
#define ANSI_COLOR_MAGENTA "\x1b[35m"
#define ANSI_COLOR_CYAN "\x1b[36m"

#define ANSI_COLOR_BRIGHT "\x1b[1m"
#define ANSI_COLOR_RESET "\x1b[0m"

using namespace std;

int main(int argv, char** argc){

 string olr = "Global" ANSI_COLOR_RESET;
 string help = ANSI_COLOR_CYAN "\n\n/help for a list of commands e.g help\n/ls to list online chat rooms e.g. /ls\n/j namehere to join a chat room. e.g. /j Global\n/p namehere -e codehere to private chat. e flag for encryption;\n\tnot required. e.g. /p Sunny got the dox?\n/tp to toggle receiving private messages or not e.g /tp\n/l codehere to listen for encrypted private messages. Seperate \n\tmultiple codes with a comma (,). e.g. /l 123,1234\n/st to stop listening for any encrypted messages e.g /st\n/c namehere to create a chat room. e.g. /c Journalism\n/clr to clear the screen e.g. /clr\n/dis to disconnect from the server e.g. /dis\n/con to connect to the server e.g. /con\n" ANSI_COLOR_RESET;
 int host_port= 1604;
 char* host_name="127.0.0.1";

 struct sockaddr_in my_addr;

 char buffer[1024];
 int bytecount;
 int buffer_len=0;

 int hsock;
 int * p_int;
 int err;

 hsock = socket(AF_INET, SOCK_STREAM, 0);
 if(hsock == -1){
 printf("Error initializing socket %d\n",errno);
 }

 p_int = (int*)malloc(sizeof(int));
 *p_int = 1;

 if( (setsockopt(hsock, SOL_SOCKET, SO_REUSEADDR, (char*)p_int, sizeof(int)) == -1 )||
 (setsockopt(hsock, SOL_SOCKET, SO_KEEPALIVE, (char*)p_int, sizeof(int)) == -1 ) ){
 printf("Error setting options %d\n",errno);
 free(p_int);
 }
 free(p_int);

 my_addr.sin_family = AF_INET ;
 my_addr.sin_port = htons(host_port);

 memset(&(my_addr.sin_zero), 0, 8);
 my_addr.sin_addr.s_addr = inet_addr(host_name);

 if( connect( hsock, (struct sockaddr*)&my_addr, sizeof(my_addr)) == -1 ){
 if((err = errno) != EINPROGRESS){
 fprintf(stderr, "Error connecting socket %d\n", errno);

 }
 }
 printf(ANSI_COLOR_MAGENTA "\nOnline Rooms: ");
 printf(olr.c_str());
 printf(help.c_str());
 //Now lets do the client related stuff
 while (true){
 buffer_len = 1024;
 string pokemon;
 pokemon = "/dis";
 memset(buffer, '\0', buffer_len);
 fgets(buffer, 1024, stdin);
 buffer[strlen(buffer)-1]='\0';
 stringstream ss;
 string bufferstr;
 ss << buffer;
 ss >> bufferstr;
 if (bufferstr == pokemon){
 close(hsock);
 }

 else if (bufferstr == "/help"){
 printf(help.c_str());
 }

 else if (bufferstr == "/ls"){
 printf("Online Rooms: " );
 printf(olr.c_str());
 }

 else if((bytecount=send(hsock, buffer, strlen(buffer),0))== -1){
 fprintf(stderr, "Error sending data %d\n", errno);
 }

 //what happens after sent
 //printf("Sent bytes %d\n", bytecount);

 if((bytecount = recv(hsock, buffer, buffer_len, 0))== -1){
 fprintf(stderr, "Error receiving data %d\n", errno);
 }
 printf("Recieved bytes %d\nReceived string \"%s\"\n", bytecount, buffer);
 }
 //close(hsock);

}

服务器源

#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <netinet/in.h>
#include <resolv.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>

void* SocketHandler(void*);

int main(int argv, char** argc){

    int host_port= 1604;

    struct sockaddr_in my_addr;

    int hsock;
    int * p_int ;
    int err;

    socklen_t addr_size = 0;
    int* csock;
    sockaddr_in sadr;
    pthread_t thread_id=0;


    hsock = socket(AF_INET, SOCK_STREAM, 0);
    if(hsock == -1){
        printf("Error initializing socket %d\n", errno);
      //  goto FINISH;
    }

    p_int = (int*)malloc(sizeof(int));
    *p_int = 1;

    if( (setsockopt(hsock, SOL_SOCKET, SO_REUSEADDR, (char*)p_int, sizeof(int)) == -1 )||
        (setsockopt(hsock, SOL_SOCKET, SO_KEEPALIVE, (char*)p_int, sizeof(int)) == -1 ) ){
        printf("Error setting options %d\n", errno);
        free(p_int);
      //  goto FINISH;
    }
    free(p_int);

    my_addr.sin_family = AF_INET ;
    my_addr.sin_port = htons(host_port);

    memset(&(my_addr.sin_zero), 0, 8);
    my_addr.sin_addr.s_addr = INADDR_ANY ;

    if( bind( hsock, (sockaddr*)&my_addr, sizeof(my_addr)) == -1 ){
        fprintf(stderr,"Error binding to socket, make sure nothing else is listening on this port %d\n",errno);
     //   goto FINISH;
    }
    if(listen( hsock, 10) == -1 ){
        fprintf(stderr, "Error listening %d\n",errno);
//        goto FINISH;
    }

    //Now lets do the server stuff

    addr_size = sizeof(sockaddr_in);

    while(true){
        printf("waiting for a connection\n");
        csock = (int*)malloc(sizeof(int));
        if((*csock = accept( hsock, (sockaddr*)&sadr, &addr_size))!= -1){
            printf("---------------------\nReceived connection from %s\n",inet_ntoa(sadr.sin_addr));
            pthread_create(&thread_id,0,&SocketHandler, (void*)csock );
            pthread_detach(thread_id);
        }
        else{
            fprintf(stderr, "Error accepting %d\n", errno);
        }
    }

FINISH:
;
}

void* SocketHandler(void* lp){
    int *csock = (int*)lp;

    char buffer[1024];
    char pokemon[3];
    int buffer_len = 1024;
    int bytecount;

    int ignore;
    pokemon[0] = '/';

    if (buffer[0] == pokemon[0]){
        ignore = 1;
    } else {ignore = 0;}

    memset(buffer, 0, buffer_len);
    if((bytecount = recv(*csock, buffer, buffer_len, 0))== -1){
        fprintf(stderr, "Error receiving data %d\n", errno);
        //goto FINISH;
    }
    printf("Received bytes %d\nReceived string \"%s\"\n", bytecount, buffer);
    strcat(buffer, " SERVER ECHO");

    if (ignore==0) {
        if((bytecount = send(*csock, buffer, strlen(buffer), 0))== -1){
            fprintf(stderr, "Error sending data %d\n", errno);
            //  goto FINISH;
        }
    }

    printf("Sent bytes %d\n", bytecount);

//FINISH:
  //  free(csock);
    //return 0;
}

Answer 1

我从你的代码中猜测你只是阻止了这个调用:
bytecount = recv(hsock, buffer, buffer_len, 0))== -1

阻塞调用(或同步)是对函数的调用，除非完成，否则不会返回，因为您说的是“嘿，在此套接字上收到 1024 个字节”，除非找到 1024 个字节或“eom”，否则该函数不会返回，如果那个套接字是空的，你将永远在那里等待。

有关 recv(...) 的更多信息以及如何使其非阻塞，请参阅:http://pubs.opengroup.org/onlinepubs/009695399/functions/recv.html

希望这会有所帮助，我没有运行代码，只是那个调用看起来很可疑。

发布服务器代码后，有一个大错误:SocketHandler是你的线程的入口点(它就像你的主进程的“主”)，但它没有循环，你的线程在一次接收发送后退出，然后没有人在服务器端监听那个套接字。您需要向服务器处理程序添加一个类似于客户端中的 while 循环。

此外，为了将来引用，尽量不要将您的变量命名为“pokemon”，这确实会让人分心，并且让其他人更难猜测该变量应该做什么。