c - 发送包含多个数字的字符串 客户端/服务器 TCP

Question

我正在使用 C 语言进行 TCP 客户端/服务器通信。客户端必须获取数据的数量(不是 > 6)，获取数据并将它们以单个字符串消息的形式发送到服务器，如下所示:4 11 21 9 11.4为数据个数，11、21、9、11为数据。

然后，服务器必须读取消息，打印它并将接收到的数据数(4)发送给客户端。

我为客户试过这个:

#include <stdio.h>      
#include <sys/types.h>
#include <sys/socket.h>   
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>




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

    int simpleSocket = 0;
    int simplePort = 0;
    int returnStatus= 0;
    char buffsend[256];
    char buffrecv[256];
    int n, i;
    struct sockaddr_in simpleServer;

    if (3 != argc) {

        fprintf(stderr, "Usage: %s <server> <port>\n", argv[0]);
        exit(1);

    }

    /* create a streaming socket      */
    simpleSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (simpleSocket == -1) {

        fprintf(stderr, "Could not create a socket!\n");
        exit(1);

    }
    else {
        fprintf(stderr, "Socket created!\n");
    }

    /* retrieve the port number for connecting */
    simplePort = atoi(argv[2]);

    /* setup the address structure */
    /* use the IP address sent as an argument for the server address  */
    //bzero(&simpleServer, sizeof(simpleServer)); 
    memset(&simpleServer, '\0', sizeof(simpleServer));
    simpleServer.sin_family = AF_INET;
    //inet_addr(argv[2], &simpleServer.sin_addr.s_addr);
    simpleServer.sin_addr.s_addr=inet_addr(argv[1]);
    simpleServer.sin_port = htons(simplePort);

    /*  connect to the address and port with our socket  */
    returnStatus = connect(simpleSocket, (struct sockaddr *)&simpleServer, sizeof(simpleServer));

    if (returnStatus == 0) {
        fprintf(stderr, "Connect successful!\n");
    }
    else {
        fprintf(stderr, "Could not connect to address!\n");
    close(simpleSocket);
    exit(1);
    }





    /* get the message from the server   */



      do {

        printf("get numb of data or terminate(write '0'): ");
        fgets(buffsend,256,stdin);
        n=atoi(buffsend);
        if(n>6) {
          printf("Error\n");

         }
        else {
                for(i=0;i<n;i++) {
                   printf("insert number: ");
                   fgets(buffsend,256,stdin);
                   write(simpleSocket, buffsend, strlen(buffsend)+1);


         }



     } while((n!=0) && (n>0));





    close(simpleSocket);
    return 0;

}

这对于服务器:

#include <stdio.h>      
#include <sys/types.h>
#include <sys/socket.h>   
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> 

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

    int simpleSocket = 0;
    int simplePort = 0;
    int returnStatus = 0;
    char buff[256];
    char message[256];
    int count;

    struct sockaddr_in simpleServer;

    if (2 != argc) {

        fprintf(stderr, "Usage: %s <port>\n", argv[0]);
        exit(1);

    }

    simpleSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if (simpleSocket == -1) {

        fprintf(stderr, "Could not create a socket!\n");
        exit(1);

    }
    else {
        fprintf(stderr, "Socket created!\n");
    }

    /* retrieve the port number for listening */
    simplePort = atoi(argv[1]);

    /* setup the address structure */
    /* use INADDR_ANY to bind to all local addresses  */
    memset(&simpleServer, '\0', sizeof(simpleServer)); 
    simpleServer.sin_family = AF_INET;
    simpleServer.sin_addr.s_addr = htonl(INADDR_ANY);
    simpleServer.sin_port = htons(simplePort);

    /*  bind to the address and port with our socket  */
    returnStatus = bind(simpleSocket,(struct sockaddr *)&simpleServer,sizeof(simpleServer));

    if (returnStatus == 0) {
        fprintf(stderr, "Bind completed!\n");
    }
    else {
        fprintf(stderr, "Could not bind to address!\n");
    close(simpleSocket);
    exit(1);
    }

    /* lets listen on the socket for connections      */
    returnStatus = listen(simpleSocket, 5);

    if (returnStatus == -1) {
        fprintf(stderr, "Cannot listen on socket!\n");
    close(simpleSocket);
        exit(1);
    }

    while (1)

    {

        struct sockaddr_in clientName = { 0 };
    int simpleChildSocket = 0;
    int clientNameLength = sizeof(clientName);

    /* wait here */

        simpleChildSocket = accept(simpleSocket,(struct sockaddr *)&clientName, &clientNameLength);

    if (simpleChildSocket == -1) {

            fprintf(stderr, "Cannot accept connections!\n");
        close(simpleSocket);
        exit(1);

    }

        /* handle the new connection request  */
    /* write out our message to the client */


        while(read(simpleChildSocket, buff, 256))
            cont++;
            printf("%s", buff);
        printf("Data received: %d %s\n", cont, buff);



       close(simpleChildSocket);
    }

    close(simpleSocket);
    return 0;

}

Answer 1

问题在于客户端在每个值之后发送一个字符串终止符 (\0)，因此当服务器打印整个消息时，它在第一个值之后停止打印。

这个特殊问题可以通过在发送时不包括字符串终止符来解决:

      write(simpleSocket, buffsend, strlen(buffsend)); /* Removed the +1 */

接收消息时需要添加字符串结束符:

    int length;
    char buff[256];

    while((length = read(simpleChildSocket, buff, 256-1)) > 0) {
        buff[length] = `\0`;
        cont++;
        printf("Data received: %d %d %s\n", cont, length, buff);
    }

另请注意，您正在使用基于流的套接字。这意味着套接字本身没有消息协议(protocol)的概念。参见 this question获取更多信息。