How to implement linux chat room program

代码：

#ifndef _i_h
 
#define _i_h
 
#include <math.h>
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <inttypes.h>
#include <time.h>
#include <sys/ioctl.h> 
#include <net/if.h>
#include <signal.h>
#include <ncurses.h>
#include <math.h>
 
#define sevr_ip   "127.0.0.1"
#define sevr_port  8081
#define cntnt_len  150
#define msg_len   sizeof(struct msg)
#define addr_len  sizeof(struct sockaddr)
#define usr_len   sizeof(struct user)
#define prt_len   8
#define hstr_len  sizeof(struct chat_history)
 
/* declare global variables */
int mainfd;/* used as chat histroy file handle*/
int sockfd;/* used as socket local handle */
int count;
struct sockaddr_in server;
 
/* msg is used for communicating message */
struct msg
{
  int flag; /* flag meaning:1,ordinary; 2,log msg; 3,reg msg, other,file*/
  int id_from;
  int id_to;
  char content[cntnt_len];
  char append[10]; 
};
 
/* user is used information list */
struct user
{
  int id;
  char name[10];
  char password[10];
  char *p_chatlog;
  struct sockaddr user_addr; 
};
/* chat_history used for reading chat history */
struct chat_history
{
  char content[cntnt_len];
  char time[25];
  int to;
  int from;
  int count;
};
 
/* i_functions below is funtions needed by both client and sever */
extern int i_saveto_chat(struct msg *pmsg);
 
int i_clean_stdin ()
{
  while (&#39;\n&#39; == getchar())
  {
    continue;
  }
 
  return(0);
}
 
int i_print(char *pmsg, int size)
{
  int i = 1;
 
  for (i; i<= size; i++)
  {
    if (*pmsg != &#39;\n&#39;)
    {
      printf("%c", *pmsg);
      pmsg ++;
    }
    else
    {
      return(0);
    }
  }
 
  return(0);
}
int i_input(char *p_input)
{
  char c = &#39;\0&#39;;
  int i; 
 
  for (i = 0; i < cntnt_len; i++)
  {
    p_input[i] = getchar();
    if (p_input[i] ==&#39;\n&#39;)
    {
      return(0);   
    }    
  }
 
  printf("you have input long enough!\n");
  return(0);
}
int i_socket(int domain, int type, int protocol)
{
  int fd; 
 
  if ((fd = socket(domain, type, protocol)) == -1)
  {
    perror("creat socket error:");
    exit(1);
  }
   
  return(fd); 
}
 
int i_bind(int fd, const struct sockaddr *addr, int namelen)
{
  if (-1 == bind(fd, addr, namelen))
  {
    perror("i_bind error:");
    exit(1);
  }
   
  return (0);
}
 
int i_recvfrom(int fd, void *buf, size_t len, int flags, 
    struct sockaddr *addr, int *size)
{  
  if (-1 == recvfrom(fd, buf, len, flags, addr, size))
  {
    perror("i_recvfrom error:");
    exit(1);  
  }
   
  return(0);
}
 
int i_sendto(int fd, void *buf, size_t len, int flags,
    struct sockaddr *addr, int size)
{
  if (-1 == sendto(fd, buf, len, flags, addr, size))
  {
    perror("i_sendto error");
    exit(1);  
  }
   
  return (0);
}
 
int i_open(const char *pathname, int flags)
{
  int fd;
  if ((fd = open(pathname, flags)) == -1)
  {
    perror("open_failed");
    exit(1);
  }
   
  return (fd);
}
int i_read(int fd, void *msg, int len)
{
  if(-1 == read(fd, msg, len))
  {
    perror("i_read error");
    exit(1);
  }
  return(0);
}
int i_write(int fd, void *msg, int len)
{
  if (-1 == write(fd, msg, len))
  {
    perror("i_write error");
    exit(0);
  }
  return(0);
}
 
/* init a socket,file and server addr */
int i_init()
{
  mainfd = i_open("./chat_log", o_rdwr|o_creat);
  sockfd = i_socket(af_inet, sock_dgram, 0);
 
  /* initialize server address */
  bzero(&server, sizeof(server));
  server.sin_family = af_inet;
  inet_pton(af_inet, "127.0.0.1", &server.sin_addr);
  server.sin_port = htons(sevr_port);
 
  perror("init");
   
  return (0);
}
 
char *i_get_time()
{
  time_t time_now;
  time(&time_now);
 
  return(ctime(&time_now));
}
int i_lseek(int fd, off_t size, int position)
{
  if (-1 == lseek(fd, size, position))
  {
    perror("seek error");
    exit(1);
  }
  return(0);
}
int i_saveto_chat(struct msg *pmsg)
{  
  struct chat_history hstr;
 
 
  bzero(&hstr, hstr_len);
  count = count + 1;
  hstr.count =count;
  hstr.from = pmsg->id_from;
  hstr.to = pmsg->id_to;
  strncpy(hstr.content, pmsg->content, cntnt_len);
  strncpy(hstr.time, i_get_time(), 25);
 
  i_lseek(mainfd, 0, seek_end);
 
  i_write(mainfd, &hstr, hstr_len);
 
  return(0);
}
 
int i_print_history(int len, int i)
{
  struct chat_history chat_reader;
  int j;
  int position;
   
  bzero(&chat_reader, hstr_len);
  if (i != 0)
  {
    position = len*i*hstr_len;
    i_lseek(mainfd, position, seek_end);
  }
  else
  {
    position = len*i*hstr_len;
 
    i_lseek(mainfd, hstr_len, seek_set);
  }
     
  for (j = 1; j <= len; j++)
  {
     
    i_read(mainfd, &chat_reader, hstr_len);
    printf("\n#item%d:id%dto id%d \n", j,
      chat_reader.from, chat_reader.to);
    i_print(chat_reader.content, cntnt_len);
    printf("\n time:%s\n", chat_reader.time);
  }
 
  return(0);
}
 
#endif

代码二：

#include "i.h"
 
int user_list_fd;
 
/* start:initialization */
int init()
{
  i_init();
 
  user_list_fd = i_open("./user_list", o_rdwr|o_creat);
 
  struct user usr;
  /* init the user list file's fist user to 0*/
  memset((struct user*)&usr, '\0', sizeof(struct user));
  i_lseek(user_list_fd, 0, seek_set);
  i_write(user_list_fd, (char*)&usr, usr_len);
 
  /* bind the struct sockaddr_in server to the sockfd */
  i_bind(sockfd, (struct sockaddr*)&server, addr_len);  
 
  struct chat_history apple; 
 
  bzero(&apple, hstr_len);
  i_lseek(mainfd, 0, seek_set);
  i_write(mainfd, &apple, hstr_len);
  i_lseek(mainfd, -hstr_len, seek_end);
  i_read(mainfd, &apple, hstr_len);
  count = apple.count;
 
  return(0);
}
/* end:initialization */
 
/* start:message control */
int send_msg(struct msg *msg_recv, struct sockaddr *addr)
{
  int i;
  struct user usr;
 
  /* a common message come */
  printf("a ordinar message come !\n");
   
  i = msg_recv->id_to;
  i_lseek(user_list_fd, i*usr_len, seek_set);
  i_read(user_list_fd, &usr, usr_len);
  strncpy(msg_recv->append, usr.name, 10);
 
  i_sendto(sockfd, msg_recv, msg_len, 0,
    &(usr.user_addr), addr_len);
   
  printf("id%d send a message to id%d sucess!\n", msg_recv->id_from, msg_recv->id_to);
 
  return(0);
}
int check_login(struct msg *msg_recv, struct sockaddr *addr)
{
  int i = msg_recv->id_from;;
  struct user usr;
 
  /* a login requet */
  printf("a login request come!\n");
   
  /* get the id's information */
  i_lseek(user_list_fd, i*usr_len, seek_set);
  i_read(user_list_fd, &usr, usr_len);
 
  int n;
  n = strcmp(usr.password, msg_recv->content);
  /* 如果验证成功，则发送成功信息 */
  if (n == 0)
  {
    /* save user new address */
    i_lseek(user_list_fd, -usr_len, seek_cur);
    usr.user_addr = *addr;
    i_write(user_list_fd, &usr, usr_len);
    /* tell user pass */
    i_sendto(sockfd, (struct msg*)msg_recv, sizeof(struct msg), 0,
      &(usr.user_addr), addr_len);
     
  }
  else
  {
    /* 出错的话的respond */
    if (0 != n)
    {
      printf("id %d login error.\n", i);
      bzero(msg_recv->content, cntnt_len);     
      msg_recv->flag = -1;
      i_sendto(sockfd, (struct msg*)msg_recv, sizeof(struct msg), 0,
        &(usr.user_addr), addr_len);
     
    }
    return(1);
  }
  printf("id %d login sucess!\n", i); 
   
  return(0);
}
int reg_user(struct msg *msg_recv, struct sockaddr *addr)
{
  struct user usr;
   
  printf("a regit requet come:\n");
 
  /* find the last user and hava the please to add a new user */
  int n;
  i_lseek(user_list_fd, -usr_len, seek_end);
  i_read(user_list_fd, &usr, usr_len);
  /* 把新用户的信息赋值到usr然后填入到user list file中 */
  const char *name;
  const char *password;
 
  name = &(msg_recv->content[0]);
  password = &(msg_recv->content[10]);
  strcpy((usr.name), name);
  strcpy(usr.password, password);
  memcpy(&(usr.user_addr),addr, addr_len);
 
  usr.id = (usr.id + 1);
  i_lseek(user_list_fd, 0, seek_end);
  i_write(user_list_fd, &usr, usr_len);
 
  msg_recv->id_from = usr.id;
  /* regist to the user list then tell the user reg success */
  i_sendto(sockfd, (struct msg*)msg_recv, sizeof(struct msg), 0,
    addr, addr_len); 
 
  printf("id %d regist sucess!\n", usr.id);
 
  return(0);
   
}
int msg_cntl()
{
  struct msg msg_recv;
  struct sockaddr addr_recv;
 
  printf("begin listen input...\n");
  int size = addr_len;
 
  for (;;)
  {
    bzero(&msg_recv, msg_len);
    i_recvfrom(sockfd, &msg_recv, sizeof(struct msg), 0,
      &addr_recv, &size);
    printf("message received...\n");
 
    i_saveto_chat(&msg_recv);
 
    switch (msg_recv.flag)
    {
      case 1 :
        send_msg(&msg_recv,(struct sockaddr*)&addr_recv);/* send ordinary chat */
        break;
      case 2 :
        check_login(&msg_recv, (struct sockaddr*)&addr_recv);
        break;     
      case 3 :
        reg_user(&msg_recv, (struct sockaddr*)&addr_recv);
        break;
      default :
        break;
    }
  }
  return(0);
}
/* end:message control*/
/* start:exit_sys()*/
int exit_sys()
{
  close(sockfd);
  close(mainfd);
  close(user_list_fd);
  printf("exit system");
  kill(0, sigabrt);
 
  exit(0);
}
/* end:exit_sys()*/
 
/* start:chat_history*/
int get_page_size()
{
  struct chat_history page_size_reader;
   
  i_lseek(mainfd, -hstr_len, seek_end);
  i_read(mainfd, &page_size_reader, hstr_len);
 
  return(page_size_reader.count);
}
 
int read_chat_history()
{
  printf("****char*history***");
  printf("(n-nextpage; p-prepage; q-quit)\n");
 
  int page_num;/* */
  int remains;
  int berry = get_page_size();
 
 
  page_num = berry / 8;
  remains = berry % 8;
 
  if (remains != 0)
    page_num ++;
  else
    page_num = page_num;
     
  printf("there are %d page total %d items", 
    page_num, berry);
 
  int i = -1;
 
  while (1)
  {  
    char flag; 
 
    if ((berry + i*8) >= 0)
    {
      printf("(%d~%d)\n", (berry + i*8), (berry + (i+1)*8));
 
      i_print_history(prt_len, i);
 
      printf("@@@\n");
      while ('\n' == (flag = getchar()))
      {
      }
 
      switch (flag)
      {
        case 'p' :
          i--;
          break;
        case 'n' :
          i++;
          break;
        case 'q' :
          return(0);
        default :
          break;
      }  
      if (i >= 0)
      {
        printf("have at the end!\n");
        printf("return to menu!\n");
      }    
    }
    else
    {
      printf("(1~%d)\n", remains);      
     
      i_print_history(remains, 0);
       
      printf("#########over##############\n");
 
      return(0);
    }  
  }
     
  return(0);
}
/* end:chat_history*/
/* start:menu*/
int menu()
{
  sleep(1);
 
  printf("----------help----menu---------\n");
  printf("\t r--report to user\n");
  printf("\t c--chat history\n");
  printf("\t h--help menu\n");
  printf("\t e--exit the system\n");
  printf("----------help_menu---------\n");
 
  int command = 0;
 
  printf("input command>");
  command = getchar();
  switch(command)
  {
 
    case 'c':
      read_chat_history();
      break;
    case 'e':
      exit_sys();
      break;
    case 'r':
      //report();
      //break;
    default :
      menu();
      break;
  }
  getchar();
   
  return(0);
}
/* end:menu*/
int main()
{
  init();
  pid_t pid;
  switch (pid = fork())
  {
    case -1 :
      perror("fork error\n");
      exit(1);
      break;
    case 0 :
      msg_cntl();
      break;
    default :
      menu();
      break;
  }
 
  return(0);
}

代码三：

#include "i.h"
 
#define start_port 8089
 
struct sockaddr_in my_addr;
int my_id;
 
int my_log();/* declare funtion*/
 
/* */
int i_send_msg()
{    
  int id;
  struct msg the_msg;
  char end = '@';
 
  printf("input recver id:");
  scanf("%d", &id);
  getchar();
  printf("\ninput content:");
  i_input(the_msg.content);  
 
  char flag = 'y';
     
  if (1)
  {
    the_msg.flag = 1;
    the_msg.id_from = my_id;
    the_msg.id_to = id;
     
    i_sendto(sockfd, &the_msg, sizeof(struct msg), 0,
      (struct sockaddr*)&server, sizeof(struct sockaddr));
     
    i_saveto_chat(&the_msg); /* save to history */
 
    printf("send to id:%d success.\n", my_id);
    return(0);
  }
  else
    return(1);
 
  return(0);
}
 
int reply()
{
  return(0);
}
int send_file()
{
  return(0);
}
/**/
/* start:initialize */
int init()
{  
  struct ifreq req;
  struct sockaddr_in *host;
  int port;
 
  i_init();
  /* init user addr */
  bzero(&my_addr, sizeof(struct sockaddr));
  my_addr.sin_family = af_inet;
  strcpy(req.ifr_name, "lo");
  if ( ioctl(sockfd, siocgifaddr, &req) < 0 ) /* get local ip address */
  {
    perror("get local ip error");
    exit(1);
    } 
 
  host = (struct sockaddr_in*)&(req.ifr_addr);
  printf("ip: %s\n", inet_ntoa(host->sin_addr));
 
  memcpy(&my_addr, (struct sockaddr_in*)&(req.ifr_addr),
     sizeof(struct sockaddr_in));
 
  port = start_port;
 
  do
  {
    port++;
    my_addr.sin_port = htons(port);
    bind(sockfd, (struct sockaddr*)&my_addr,
       sizeof(struct sockaddr));   
  } 
  while (errno == eaddrinuse);
 
  struct chat_history apple; 
   
  memset(&apple, &#39;b&#39;, hstr_len);
  i_lseek(mainfd, 0, seek_set);
  apple.count = 0;
  i_write(mainfd, &apple, hstr_len);
  i_lseek(mainfd, -hstr_len, seek_end);
  i_read(mainfd, &apple, hstr_len);
  count = apple.count;
 
  
  printf("port:%d\n", port); 
  printf("init successful!!!\n"); 
 
  return(0);
 
}
/* end:initialize */
/* start:chat_history*/
int get_page_size()
{
  struct chat_history page_size_reader;
   
  i_lseek(mainfd, -hstr_len, seek_end);
  i_read(mainfd, &page_size_reader, hstr_len);
 
  return(page_size_reader.count);
}
 
int read_chat_history()
{
  printf("****char*history***");
  printf("(n-nextpage; p-prepage; q-quit)\n");
 
  int page_num;/* */
  int remains;
  int berry = get_page_size();
 
 
  page_num = berry / 8;
  remains = berry % 8;
 
  if (remains != 0)
    page_num ++;
  else
    page_num = page_num;
     
  printf("there are %d page total %d items", 
    page_num, berry);
 
  int i = -1;
 
  while (1)
  {  
    char flag; 
 
    if ((berry + i*8) >= 0)
    {
      printf("(%d~%d)\n", (berry + i*8), (berry + (i+1)*8));
 
      i_print_history(prt_len, i);
 
      printf("@@@\n");
      while (&#39;\n&#39; == (flag = getchar()))
      {
      }
 
      switch (flag)
      {
        case &#39;p&#39; :
          i--;
          break;
        case &#39;n&#39; :
          i++;
          break;
        case &#39;q&#39; :
          return(0);
        default :
          break;
      }  
      if (i >= 0)
      {
        printf("have at the end!\n");
        printf("return to menu!\n");
      }    
    }
    else
    {
      printf("(1~%d)\n", remains);      
     
      i_print_history(remains, 0);
       
      printf("#########over##############\n");
 
      return(0);
    }  
  }
     
  return(0);
}
/* end:chat_history*/
/* start:exit_sys*/
void exit_sys()
{
  close(sockfd);
  close(mainfd);
  kill(0, sigabrt);
 
  exit(0);
}
/* end:exit_sys*/
 
/* start:menu*/
int print_menu()
{
  printf("\n--------------help--menu----------------\n");
  printf("\t h--help munu\n");
  printf("\t s--send message\n");
  printf("\t r--reply to\n");
  printf("\t c--chat history\n");
  printf("\t f--send files\n");
  printf("\t e--exit the system\n");
  printf("----------------help--menu----------------\n");
}
int get_input(char *command)
{  
  printf(">");
  scanf("%c", command);
 
  return(1);
}
int menu()
{
  /* to avoid the output at mixed with the sub process */
  sleep(1);
 
  print_menu();
   
  char command;
 
  while (1 == get_input(&command))
  {  
    switch(command)
    {
      case &#39;h&#39;:
        print_menu();
        break;   
      case &#39;s&#39;:
        i_send_msg();
        break;
      case &#39;r&#39;:
        reply();
        break;
      case &#39;f&#39;:
        send_file();
        break;
      case &#39;c&#39;:
        read_chat_history();
        break;
      case &#39;e&#39;:
        exit_sys();
        break;
      default :
        printf(">");
        break;
    }
  }
  return(0);
}
/* end:menu*/
/* start:message contol :send_msg and recv_msg */
int ordnary_msg_recv(struct msg *pmsg)
{
  char time_info[25];
  char end_symble;
  end_symble = &#39;&&#39;;
 
  /* handle the msg */
  printf("message:from %s(id%d) to u:\n", pmsg->append, pmsg->id_from);
  i_print(pmsg->content, msg_len);
  printf("\n\t%s", i_get_time());
 
  return(0);
}
int file_msg_recv(struct msg *pmsg)
{
}
int handle_msg(struct msg *pmsg)
{  
  if (pmsg->flag == 1)
  {
    ordnary_msg_recv(pmsg);
    return(0);
  }
  else if (pmsg->flag >= 4)
  {
    file_msg_recv(pmsg);
    return(0);
  }  
  return(0);
}
int listen_msg()
{
  struct msg msg_recv;
  struct sockaddr addr_recv;
  int len = addr_len;
 
  printf("begin listen...\n");
 
  for ( ; ; )
  {  
    i_recvfrom(sockfd, &msg_recv, msg_len, 0, 
       &addr_recv, &len);
 
    i_saveto_chat(&msg_recv); /* save to history */
     
     ordnary_msg_recv(&msg_recv);
  }
}
 
/* end:message contol*/
 
/* start:log process :login and regist */
int login()
{
  /* input id:*/
  printf("*****login>>\n");
  printf("id:");
  scanf("%d", &my_id);
  /* input password*/
  char password[15];
  printf("\npassword(*less 15 char):");
  scanf("%s", password);
  getchar();
   
  /* send login information */
  struct msg log_msg;
 
  bzero(&log_msg, msg_len);
  log_msg.flag = 2;
  log_msg.id_from = my_id;
  log_msg.id_to = 0;
  strncpy(log_msg.content, password, 15);
 
  i_saveto_chat(&log_msg); /* save to history */
   
  i_sendto(sockfd, (struct msg*)&log_msg, msg_len, 0, 
    (struct sockaddr*)&server, sizeof(struct sockaddr));
//printf("log_msg : %d\n", log_msg.id_from);
//printf("password: %s\n", log_msg.content);
  /* after input msg ,wait for server respond*/
  struct sockaddr in_addr;
  int len = addr_len;
  i_recvfrom(sockfd, (struct msg*)&log_msg, msg_len,0,
    &in_addr, &len);
  if (2 == log_msg.flag)
  {
    printf("login success\n");
    return(0);
  }  
  else
  {
    printf("login error:%s\n", log_msg.content);
    printf("please relog..\n");
    menu();
  }
   
  return (0);
}
int regist()
{
  printf("*****regist>>\n");
  /* input chat name */
  char name[10];
 
  bzero(name, 10);
  printf("input your chat name(less 8 char):");
  scanf("%s", name);
 
  //name[9] = &#39;;&#39;;     /* add a ; symbol in the end of name */
  /* input password */
  char password[15];
 
  bzero(password, 15);
  printf("\ninput your password(less 14 char):");
  scanf("%s", password);
 
  /* send regist information*/
  struct msg reg_msg;
 
  bzero(&reg_msg, msg_len);
  reg_msg.flag = 3;
  reg_msg.id_from = 0;
  reg_msg.id_to = 0;
  bzero(reg_msg.content, cntnt_len);
  strncpy(reg_msg.content, name, 10);
  strncpy(&(reg_msg.content[10]), password, 15);
  reg_msg.content[25] = &#39;\n&#39;;
 
  i_saveto_chat(&reg_msg); /* save to history */
 
  /* send regist informatin to server */
  i_sendto(sockfd, (struct msg*)&reg_msg, sizeof(struct msg), 0, 
    (struct sockaddr*)&server, addr_len);
  /* after input msg ,wait for server respond*/
  printf("wating for server reply...\n");
 
  struct sockaddr in_addr;
  struct msg msg_back;
  int len = addr_len;
   
  bzero(&in_addr, addr_len);
  bzero(&msg_back, msg_len);
  i_recvfrom(sockfd,(struct msg*)&msg_back, msg_len,0,
    &in_addr, &len);
 
  /* check whether pass */
  if (3 != msg_back.flag)
  {
    printf("error: %s \n", msg_back.content);
    exit(1);
  }
  else
    my_id = msg_back.id_to;
    printf("congratulate! you have regist"
      "id %s(id %d) success\n", msg_back.content, msg_back.id_to);
 
    login();
 
  return(0); 
}
 
int my_log()
{
  /* choose login or regist*/
  char flag;
  printf("are you want login or regist(l/r)\n");
  scanf("%c", &flag);
  getchar();
  switch (flag){
    case &#39;l&#39; :
      login();
      break;
    case &#39;r&#39; :
      regist();
      break;
    default :
      printf("error input\n");
      my_log();
      break;
  }
  return (0);
}
/* end:log */
 
int main()
{
  init();
  printf("\n************welcome!************\n");
  my_log();
 
  pid_t pid;
 
  switch (pid = fork())
  {
    case -1 :
      perror("fork error!\n");
      exit(1);
      break;
    case 0 :
      listen_msg();
      break;
    default :
      menu();
      break;
  }
}

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