Linux_C socket 服务器与客户端交互程序（输入小写转换为大写）

client.c

/* interactionSocket/client.c
 *                 实现终端与服务器端的交互式输入输出
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h> 
#include <unistd.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#define MAXLINE 80
#define PORTNUM 12345

int main(void) {
  int sock, len;
  struct sockaddr_in saddr;
  struct hostent *hp;
  char buf[MAXLINE];
  char request[MAXLINE];
  char hostname[BUFSIZ];

  sock=socket(AF_INET, SOCK_STREAM, 0);
  if(sock==-1) exit(-1);
  
  bzero((void*)&saddr, sizeof(saddr));
  //inet_pton(AF_INET, "127.0.0.1", (void*)&saddr.sin_addr);
  gethostname(hostname, BUFSIZ);
  hp=gethostbyname(hostname);
  bcopy(hp->h_addr, (void*)&saddr.sin_addr, hp->h_length);
  saddr.sin_port=htons(PORTNUM);
  saddr.sin_family=AF_INET;
  
  connect(sock, (struct sockaddr *)&saddr, sizeof(saddr));
  while( fgets(buf, MAXLINE, stdin)!=NULL) {
    write(sock, buf, strlen(buf));
    len=read(sock, buf, MAXLINE);
    if(len==0)
      printf("the other side has been closed");
    else 
      write(STDOUT_FILENO, buf, len);
  }
  close(sock);
  return 1;
}

server.c

/* interaction/server.c
 */
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netdb.h>

#define MAXLINE 80
#define SERV_PORT 12345
#define BACKLOG 20
int main(void ) {
  int sock, connfd;
  struct sockaddr_in saddr, cliaddr;
  struct hostent *hp;
  socklen_t cliaddr_len;
  char buf[MAXLINE];
  char str[MAXLINE];
  char hostname[BUFSIZ];
  int i, n;
  
  sock=socket(PF_INET, SOCK_STREAM, 0);
  if(sock==-1)
    exit(-1);
  bzero((void*)&saddr, sizeof(saddr));
  //saddr.sin_addr.s_addr=htonl(INADDR_ANY);
  gethostname(hostname, BUFSIZ);
  hp=gethostbyname(hostname);
  bcopy(hp->h_addr, (void*)&saddr.sin_addr, hp->h_length);
  saddr.sin_family=AF_INET;
  saddr.sin_port=htons(SERV_PORT);
  if(bind(sock, (struct sockaddr*)&saddr, sizeof(saddr))==-1)
    exit(-1);
  if(listen(sock, BACKLOG)==-1)
    exit(-1);
  printf("accepting connections...
");
  while(1) {
    cliaddr_len=sizeof(cliaddr);
    connfd=accept(sock, (struct sockaddr*)&cliaddr, &cliaddr_len);
    while(1) {
      n=read(connfd, buf, MAXLINE);
      if(n==0){ 
    printf("the other side has been closed.
");
    break;
      }
      //printf("received from %s at PORT %d
", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port));
      for(i=0; i<n; i++) 
    buf[i]=toupper(buf[i]);
      write(connfd, buf, n);
    }
    close(connfd);
  }
}