socket chat

Umiddelbart får jeg en besked tilbage til serveren, når jeg ændre din kode til følgende :

<-- Client -->

#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>

#define PORT 3553 // the port client will be connecting to

#define MAXDATASIZE 100

const char * response = "And handshake from the client!\n";

int main(int argc, char *argv[])
{
  int sockfd, numbytes;
  char buf[MAXDATASIZE];
  struct hostent *he;
  struct sockaddr_in their_addr;

  if (argc != 2) {
    fprintf(stderr,"usage: client hostname\n");
    exit(1);
  }

  if ((he=gethostbyname(argv[1])) == NULL) {  // get the host info
    perror("gethostbyname");
    exit(1);
  }

  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("socket");
    exit(1);
  }

  their_addr.sin_family = AF_INET;    // host byte order
  their_addr.sin_port = htons(PORT);  // short, network byte order
  their_addr.sin_addr = *((struct in_addr *)he->h_addr);
  memset(&(their_addr.sin_zero), '\0', 8);  // zero the rest of the struct

  if (connect(sockfd, (struct sockaddr *)&their_addr,
              sizeof(struct sockaddr)) == -1) {
    perror("connect");
    exit(1);
  }

  if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
    perror("recv");
    exit(1);
  }

  buf[numbytes] = '\0';
  send(sockfd,response,strlen(response),0); /* send to the client welcome message */
  printf("Received: %s",buf);

  close(sockfd);

  return 0;
}

<-- client end -->

<-- server -->

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#define PORT 3553
#define BACKLOG 10
#define MAXDATASIZE 100

const char * greeting = "Welcome to my server\n";

main()
{
  char buf[MAXDATASIZE];
  int fd, fd2, numbytes; /* file descriptors */

  struct sockaddr_in server; /* server's address information */
  struct sockaddr_in client; /* client's address information */

  int sin_size;


  if ((fd=socket(AF_INET, SOCK_STREAM, 0)) == -1 ){  /* calls socket() */
    printf("socket() errorn");
    exit(-1);
  }

  server.sin_family = AF_INET;
  server.sin_port = htons(PORT);  /* Remember htons() from "Conversions" section? =) */
  server.sin_addr.s_addr = INADDR_ANY;  /* INADDR_ANY puts your IP address automatically */
  bzero(&(server.sin_zero),8); /* zero the rest of the structure */


  if(bind(fd,(struct sockaddr*)&server,sizeof(struct sockaddr))==-1) { /* calls bind() */
      printf("bind() errorn");
      exit(-1);
  }

  if(listen(fd,BACKLOG) == -1){  /* calls listen() */
      printf("listen() errorn");
      exit(-1);
  }

  while(1)
  {
    sin_size=sizeof(struct sockaddr_in);
    if ((fd2 = accept(fd,(struct sockaddr *)&client,&sin_size))==-1){ /* calls accept() */
      printf("accept() errorn");
      exit(-1);
    }

    printf("You got a connection from %s \n",inet_ntoa(client.sin_addr) ); /* prints client's IP */

    send(fd2,greeting,strlen(greeting),0); /* send to the client welcome message */
    numbytes = 0;
    while (numbytes==0)
    {
      if ((numbytes=recv(fd2, buf, MAXDATASIZE-1, 0)) == -1) {
        perror("recv");
        exit(1);
      }
    }

    buf[numbytes] = '\0';

    printf("Received: %s",buf);
    printf("close \n");
    close(fd2); /*  close fd2 */
  }
}

<-- server end -->

At blive ved med at læse, indtil du ikke modtager noget : while (numbytes!=0), er stedet hvor kæden hopper af !

Hvis du vil have et komplet handshake mellem server og client :

<-- client begin -->

#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>

#define PORT 3553 // the port client will be connecting to

#define MAXDATASIZE 100

const char * response = "And handshake from the client!\n";

int main(int argc, char *argv[])
{
  int sockfd, numbytes;
  char buf[MAXDATASIZE];
  struct hostent *he;
  struct sockaddr_in their_addr;

  if (argc != 2) {
    fprintf(stderr,"usage: client hostname\n");
    exit(1);
  }

  if ((he=gethostbyname(argv[1])) == NULL) {  // get the host info
    perror("gethostbyname");
    exit(1);
  }

  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("socket");
    exit(1);
  }

  their_addr.sin_family = AF_INET;    // host byte order
  their_addr.sin_port = htons(PORT);  // short, network byte order
  their_addr.sin_addr = *((struct in_addr *)he->h_addr);
  memset(&(their_addr.sin_zero), '\0', 8);  // zero the rest of the struct

  if (connect(sockfd, (struct sockaddr *)&their_addr,
              sizeof(struct sockaddr)) == -1) {
    perror("connect");
    exit(1);
  }

  if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
    perror("recv");
    exit(1);
  }

  buf[numbytes] = '\0';
  printf("Received: %s",buf);

  send(sockfd,response,strlen(response),0); /* send to the client welcome message */

  if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
    perror("recv");
    exit(1);
  }

  buf[numbytes] = '\0';
  printf("Received (2nd time) : %s",buf);

  close(sockfd);

  return 0;
}

<-- client end -->

<-- server begin -->

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#define PORT 3553
#define BACKLOG 10
#define MAXDATASIZE 100

const char * greeting  = "Welcome to my server\n";
const char * greeting2 = "Glad to see live clients\n";

main()
{
  char buf[MAXDATASIZE];
  int fd, fd2, numbytes; /* file descriptors */

  struct sockaddr_in server; /* server's address information */
  struct sockaddr_in client; /* client's address information */

  int sin_size;


  if ((fd=socket(AF_INET, SOCK_STREAM, 0)) == -1 ){  /* calls socket() */
    printf("socket() errorn");
    exit(-1);
  }

  server.sin_family = AF_INET;
  server.sin_port = htons(PORT);  /* Remember htons() from "Conversions" section? =) */
  server.sin_addr.s_addr = INADDR_ANY;  /* INADDR_ANY puts your IP address automatically */
  bzero(&(server.sin_zero),8); /* zero the rest of the structure */


  if(bind(fd,(struct sockaddr*)&server,sizeof(struct sockaddr))==-1) { /* calls bind() */
      printf("bind() errorn");
      exit(-1);
  }

  if(listen(fd,BACKLOG) == -1){  /* calls listen() */
      printf("listen() errorn");
      exit(-1);
  }

  while(1)
  {
    sin_size=sizeof(struct sockaddr_in);
    if ((fd2 = accept(fd,(struct sockaddr *)&client,&sin_size))==-1){ /* calls accept() */
      printf("accept() errorn");
      exit(-1);
    }

    printf("You got a connection from %s \n",inet_ntoa(client.sin_addr) ); /* prints client's IP */

    send(fd2,greeting,strlen(greeting),0); /* send to the client welcome message */
    numbytes = 0;
    while (numbytes==0)
    {
      if ((numbytes=recv(fd2, buf, MAXDATASIZE-1, 0)) == -1) {
        perror("recv");
        exit(1);
      }
    }

    buf[numbytes] = '\0';

    printf("Received: %s",buf);
    printf("Sending second message\n");

    send(fd2,greeting2,strlen(greeting2),0); /* Final part of handshake */

    printf("close \n");
    close(fd2); /*  close fd2 */
  }
}

<-- server end -->

takker