c - C ソケットの書き込み回数が多すぎます

Question

ユーザーがデータを入力した後、それが意味をなす場合、データが入力される前に入力されたデータの一部を書き出しますか? スニペットのみを含めましたが、複数回返信する理由を誰かが見ることができますか?

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h> // write

#include<pthread.h> // For Threading

#include<wiringPi.h>
void *connection_handler(void *);
void lightLED(int pin,int status);
int maxConnections = 1;
int totalConnections = 0;
int main(int argc , char *argv[])
{
    int socket_desc , new_socket , c, *new_sock;
    struct sockaddr_in server , client;
    char *message;     
    //Create socket
    socket_desc = socket(AF_INET , SOCK_STREAM , 0);
    if (socket_desc == -1)
    {
        printf("Could not create socket");
    }

    //Prepare the sockaddr_in structure
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons( 8888 );

    //Bind
    if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)
    {
        puts("bind failed");
    }
    puts("bind done");

    //Listen
    listen(socket_desc , 3);

    //Accept and incoming connection
    puts("Waiting for incoming connections...");
    c = sizeof(struct sockaddr_in);
    while( (new_socket = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)) )
    {
     if(new_socket > 0)
     {
      if(totalConnections < maxConnections){
      totalConnections++;
     }
      else
      {
       message = "Sorry Maximum Users Reached\n";
       write(new_socket,message,strlen(message));
       puts("Too many Users");
       close(new_socket);
       continue;
      }
    }
     puts("Connection Accepted");
    char *client_ip = inet_ntoa(client.sin_addr);
    int client_port = ntohs(client.sin_port);
    printf("ClientIP:%s\n",client_ip);
     message = "Hello you have been accepted!\n";
     write(new_socket, message , strlen(message));

    pthread_t sniffer_thread;
    new_sock = malloc(1);
    *new_sock = new_socket;

    if(pthread_create( &sniffer_thread, NULL , connection_handler , (void*) new_sock) <0)
    {
     perror("Could not create thread");
    return 1;
    }
    puts("Handler Assigned");
    }

    if (new_socket<0)
    {
        perror("accept failed");
    return 1;
    }
    return 0;
}

void *connection_handler(void *socket_desc)
{
    int sock = *(int*)socket_desc;
    int read_size;
    char *message , client_message[2000];

    message = "Greeting! I am your Connection Handler\n";
    write(sock , message,strlen(message));

    message =  "What do you want to do\n";
    write(sock,message,strlen(message));

    while( (read_size = recv(sock , client_message , 2000 , 0)) > 0)
    {
     write(sock , client_message , strlen(client_message));
     printf("User Entered:%s\n",client_message);
     int pin = client_message[0]-'0';
     int status = client_message[1]-'0';
     lightLED(pin,status);
    }
    if(read_size == 0)
    {
    puts("Client Disconnected\n");
    fflush(stdout);
    totalConnections--;
    }else if(read_size == -1)
    {
     perror("recv Failed");
    }

    free(socket_desc);
    return 0;
}

void lightLED(int pin,int status)
{
    char message;
    if(wiringPiSetup() == -1){
    puts("wiringPi Error");
        exit(1);
    }

    //pinMode(pin,OUTPUT);
    printf("Changing LED Pin- %d Status- %d\n",pin,status);
    //digitalWrite(pin,status);
}

score 2 · Accepted Answer

最初のパス

どのような問題が発生しているのかわかりません。私はあなたのコード（かなり良い形でした - よくできていました;私は多くの悪い問題を含む多くのコードを見てきました）を取り、それをコンパイルして実行しました。

$ nc localhost 8888
Connection Accepted
ClientIP:127.0.0.1
Handler Assigned
Hello you have been accepted!
Greeting! I am your Connection Handler
What do you want to do
01
User Entered:01

Changing LED Pin- 0 Status- 1
01
21
User Entered:21

Changing LED Pin- 2 Status- 1
21
31
User Entered:31

Changing LED Pin- 3 Status- 1
31
we wish you a merry Christmas
User Entered:we wish you a merry Christmas

Changing LED Pin- 71 Status- 53
we wish you a merry Christmas
Client Disconnected

$

実行されたコードは次のとおりです。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>
//#include <wiringPi.h>

void *connection_handler(void *);
void lightLED(int pin, int status);

int maxConnections = 1;
int totalConnections = 0;

int main(void)
{
    int socket_desc, new_socket, c, *new_sock;
    struct sockaddr_in server, client;
    char *message;

    socket_desc = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_desc == -1)
    {
        printf("Could not create socket");
        return 1;
    }

    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons(8888);

    if ( bind(socket_desc, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        puts("bind failed");
        return 1;
    }
    puts("bind done");

    if (listen(socket_desc, 3) != 0)
    {
        perror("listen() failed");
        return 1;
    }

    puts("Waiting for incoming connections...");
    c = sizeof(struct sockaddr_in);
    while ((new_socket = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)))
    {
        if (new_socket > 0)
        {
            if (totalConnections < maxConnections)
                totalConnections++;
            else
            {
                message = "Sorry Maximum Users Reached\n";
                write(new_socket, message, strlen(message));
                puts("Too many Users");
                close(new_socket);
                continue;
            }
        }
        puts("Connection Accepted");
        char *client_ip = inet_ntoa(client.sin_addr);
        //int client_port = ntohs(client.sin_port);

        printf("ClientIP:%s\n", client_ip);
        message = "Hello you have been accepted!\n";
        write(new_socket, message, strlen(message));

        pthread_t sniffer_thread;
        new_sock = malloc(1 * sizeof(int));       // Oops!
        if (new_sock == 0) { perror("out of memory"); return 1; }
        *new_sock = new_socket;

        if (pthread_create( &sniffer_thread, NULL, connection_handler, (void*) new_sock) <0)
        {
            perror("Could not create thread");
            return 1;
        }
        puts("Handler Assigned");
    }

    if (new_socket<0)
    {
        perror("accept failed");
        return 1;
    }
    return 0;
}

void *connection_handler(void *socket_desc)
{
    int sock = *(int*)socket_desc;
    int read_size;
    char *message, client_message[2000];

    message = "Greeting! I am your Connection Handler\n";
    write(sock, message, strlen(message));

    message =  "What do you want to do\n";
    write(sock, message, strlen(message));

    while ((read_size = recv(sock, client_message, 2000, 0)) > 0)
    {
        write(sock, client_message, strlen(client_message));
        printf("User Entered:%s\n", client_message);
        int pin = client_message[0]-'0';
        int status = client_message[1]-'0';
        lightLED(pin, status);
    }
    if (read_size == 0)
    {
        puts("Client Disconnected\n");
        fflush(stdout);
        totalConnections--;
    }
    else if (read_size == -1)
    {
        perror("recv Failed");
    }

    free(socket_desc);
    return 0;
}

void lightLED(int pin, int status)
{
//    if (wiringPiSetup() == -1)
//    {
//        puts("wiringPi Error");
//        exit(1);
//    }

    printf("Changing LED Pin- %d Status- %d\n", pin, status);
}

それでも問題が解決しない場合は、クライアントコードに問題がある可能性があります。ご覧のとおり、クライアントの代理としてnetcat( ) を使用しました。ncピンが 73 でステータスが 53 であったにもかかわらず、'we wish you a merry Christmas' が有効なコマンドとして受け入れられたことに注意してください。これは、実際の LED では機能しない可能性があります。

のエラーチェックを追加しmalloc()、より正確な量のスペースを割り当てたことに注意してください ( sizeof(int)1 バイトだけではありません)。また、エラーが発生しなかったかのように続行するのではなく、報告されたエラー状態の後に多かれ少なかれ適切なエラーが返されるようにしました。

また、コメントで強調表示されている問題のいくつかを修正していwrite()ません。null 終了を確認して依存しないなどです。これらは引き続き対処する必要があります。

私のテストは、GCC 4.7.1 を搭載した Mac OS X 10.7.5 で行われました。

gcc -O3 -g -std=c99 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Wold-style-definition server.c -o server

セカンドパス

別のテスト実行 — null で終了していない入力の問題を示します。

$ nc localhost 8888
Connection Accepted
ClientIP:127.0.0.1
Hello you have been accepted!
Handler Assigned
Greeting! I am your Connection Handler
What do you want to do
this is a long string - what will you do with it?
User Entered:this is a long string - what will you do with it?

Changing LED Pin- 68 Status- 56
this is a long string - what will you do with it?
01
User Entered:01
s is a long string - what will you do with it?

Changing LED Pin- 0 Status- 1
01
s is a long string - what will you do with it?
Client Disconnected

$

telnetの代わりに実行するとnc、あなたが見たような誤動作が発生したと思います:

$ telnet localhost 8888
Trying 127.0.0.1...
Connection Accepted
ClientIP:127.0.0.1
Handler Assigned
Connected to localhost.
Escape character is '^]'.
Hello you have been accepted!
Greeting! I am your Connection Handler
What do you want to do
Would you like a biscuit?
User Entered:Would you like a biscuit?

Changing LED Pin- 39 Status- 63
Would you like a biscuit?
93
User Entered:93
d you like a biscuit?

Changing LED Pin- 9 Status- 3
93
d you like a biscuit?
Intriguing
User Entered:Intriguing
ke a biscuit?

Changing LED Pin- 25 Status- 62
Intriguing
ke a biscuit?
Bye
User Entered:Bye
guing
ke a biscuit?

Changing LED Pin- 18 Status- 73
Bye
guing
ke a biscuit?
User Entered:ye
guing
ke a biscuit?

Changing LED Pin- -44 Status- 73
ye
guing
ke a biscuit?
^CUser Entered:????guing
ke a biscuit?

Changing LED Pin- -49 Status- -60
User Entered:???guing
ke a biscuit?

Changing LED Pin- -49 Status- -53
?guing
ke a biscuit?
User Entered:??guing
ke a biscuit?

...continued attempts with control-C (interrupt)...
...and control-D (EOF) not producing anything useful...

^]
telnet> qConnection closed.
Client Disconnected

$

そのため、telnet誤解を招いている可能性があります...サーバーに何も問題がなく、クライアント ( telnet) が期待どおりに動作していないだけです。

更新されたコード

更新されたサーバーコードとの会話:

$ nc localhost 8888
Connection Accepted
ClientIP: 127.0.0.1
Handler Assigned
Hello you have been accepted!
Greetings! I am your Connection Handler
What do you want to do
13
User Entered:13

Changing LED Pin 1 status 3
13
21
User Entered:21

Changing LED Pin 2 status 1
21
elephants?
User Entered:elephants?

Changing LED Pin 53 status 60
elephants?
21
User Entered:21

Changing LED Pin 2 status 1
21
quit 
User Entered:quit

Changing LED Pin 65 status 69
quit
Client Disconnected

$

更新されたサーバーコード

このバージョンは長さに注意を払い、文字列が null で終了するようにします。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>
//#include <wiringPi.h>

void *connection_handler(void *);
void lightLED(int pin, int status);
static void write_sock(int sock, const char *msg);

int maxConnections = 1;
int totalConnections = 0;

int main(void)
{
    int socket_desc, new_socket, c, *new_sock;
    struct sockaddr_in server, client;

    socket_desc = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_desc == -1)
    {
        printf("Could not create socket");
        return 1;
    }

    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons(8888);

    if (bind(socket_desc, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        puts("bind failed");
        return 1;
    }
    puts("bind done");

    if (listen(socket_desc, 3) != 0)
    {
        perror("listen() failed");
        return 1;
    }

    puts("Waiting for incoming connections...");
    c = sizeof(struct sockaddr_in);
    while ((new_socket = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)))
    {
        if (new_socket > 0)
        {
            if (totalConnections < maxConnections)
                totalConnections++;
            else
            {
                write_sock(new_socket, "Sorry Maximum Users Reached\n");
                puts("Too many Users");
                close(new_socket);
                continue;
            }
        }

        puts("Connection Accepted");
        char *client_ip = inet_ntoa(client.sin_addr);
        //int client_port = ntohs(client.sin_port);

        printf("ClientIP: %s\n", client_ip);
        write_sock(new_socket, "Hello you have been accepted!\n");

        pthread_t sniffer_thread;
        new_sock = malloc(1 * sizeof(int));       // Oops!
        if (new_sock == 0) { perror("out of memory"); return 1; }
        *new_sock = new_socket;

        if (pthread_create(&sniffer_thread, NULL, connection_handler, (void *)new_sock) < 0)
        {
            perror("Could not create thread");
            return 1;
        }
        puts("Handler Assigned");
    }

    if (new_socket < 0)
    {
        perror("accept failed");
        return 1;
    }
    return 0;
}

// Avoid repetition - use functions!
static void write_sock(int sock, const char *msg)
{
    int len = strlen(msg);
    if (write(sock, msg, len) != len)
    {
        perror("short write on socket");
        exit(1);
    }
}

void *connection_handler(void *socket_desc)
{
    int sock = *(int*)socket_desc;
    int read_size;
    char client_message[2000];

    write_sock(sock, "Greetings! I am your Connection Handler\n");
    write_sock(sock, "What do you want to do\n");

    while ((read_size = recv(sock, client_message, 2000, 0)) > 0)
    {
        client_message[read_size] = '\0';
        write_sock(sock, client_message);
        printf("User Entered:%s\n", client_message);
        int pin = client_message[0]-'0';
        int status = client_message[1]-'0';
        lightLED(pin, status);
    }

    if (read_size == 0)
    {
        puts("Client Disconnected\n");
        fflush(stdout);
        totalConnections--;
    }
    else if (read_size == -1)
    {
        perror("recv Failed");
    }

    free(socket_desc);
    return 0;
}

void lightLED(int pin, int status)
{
//    if (wiringPiSetup() == -1)
//    {
//        puts("wiringPi Error");
//        exit(1);
//    }
    printf("Changing LED Pin %d status %d\n", pin, status);
}

関数を使用して、繰り返されるコードをカプセル化することに注意してくださいwrite_sock()(これには、コードを 1 回記述するだけでよいという副次的な利点があるため、使用するたびに正しいコードにすることができます)。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <pthread.h>
//#include <wiringPi.h>

void *connection_handler(void *);
void lightLED(int pin, int status);
static void write_sock(int sock, const char *msg);

int maxConnections = 1;
int totalConnections = 0;

int main(void)
{
    int socket_desc, new_socket, c, *new_sock;
    struct sockaddr_in server, client;

    socket_desc = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_desc == -1)
    {
        printf("Could not create socket");
        return 1;
    }

    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons(8888);

    if (bind(socket_desc, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        puts("bind failed");
        return 1;
    }
    puts("bind done");

    if (listen(socket_desc, 3) != 0)
    {
        perror("listen() failed");
        return 1;
    }

    puts("Waiting for incoming connections...");
    c = sizeof(struct sockaddr_in);
    while ((new_socket = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)))
    {
        if (new_socket > 0)
        {
            if (totalConnections < maxConnections)
                totalConnections++;
            else
            {
                write_sock(new_socket, "Sorry Maximum Users Reached\n");
                puts("Too many Users");
                close(new_socket);
                continue;
            }
        }

        puts("Connection Accepted");
        char *client_ip = inet_ntoa(client.sin_addr);
        //int client_port = ntohs(client.sin_port);

        printf("ClientIP: %s\n", client_ip);
        write_sock(new_socket, "Hello you have been accepted!\n");

        pthread_t sniffer_thread;
        new_sock = malloc(1 * sizeof(int));       // Oops!
        if (new_sock == 0) { perror("out of memory"); return 1; }
        *new_sock = new_socket;

        if (pthread_create(&sniffer_thread, NULL, connection_handler, (void *)new_sock) < 0)
        {
            perror("Could not create thread");
            return 1;
        }
        puts("Handler Assigned");
    }

    if (new_socket < 0)
    {
        perror("accept failed");
        return 1;
    }
    return 0;
}

// Avoid repetition - use functions!
static void write_sock(int sock, const char *msg)
{
    int len = strlen(msg);
    if (write(sock, msg, len) != len)
    {
        perror("short write on socket");
        exit(1);
    }
}

void *connection_handler(void *socket_desc)
{
    int sock = *(int*)socket_desc;
    int read_size;
    char client_message[2000];

    write_sock(sock, "Greetings! I am your Connection Handler\n");
    write_sock(sock, "What do you want to do\n");

    while ((read_size = recv(sock, client_message, 2000, 0)) > 0)
    {
        client_message[read_size] = '\0';
        write_sock(sock, client_message);
        printf("User Entered:%s\n", client_message);
        int pin = client_message[0]-'0';
        int status = client_message[1]-'0';
        lightLED(pin, status);
    }

    if (read_size == 0)
    {
        puts("Client Disconnected\n");
        fflush(stdout);
        totalConnections--;
    }
    else if (read_size == -1)
    {
        perror("recv Failed");
    }

    free(socket_desc);
    return 0;
}

void lightLED(int pin, int status)
{
//    if (wiringPiSetup() == -1)
//    {
//        puts("wiringPi Error");
//        exit(1);
//    }
    printf("Changing LED Pin %d status %d\n", pin, status);
}

c - C ソケットの書き込み回数が多すぎます

1 に答える 1

最初のパス

セカンドパス

更新されたコード

更新されたサーバー コード

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Reference

更新されたサーバーコード