tcp server in c

最新推荐文章于 2024-07-30 21:58:59 发布

原创最新推荐文章于 2024-07-30 21:58:59 发布 · 1.5k 阅读

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CC 4.0 BY-SA版权

文章标签：

#server #tcp #socket #buffer #function #struct

此博客展示了一个TCP服务器程序的代码。代码包含创建套接字、绑定端口、监听连接等操作，还定义了读取数据的函数。通过循环不断接收客户端连接和数据，利用自定义的read_line函数从套接字读取数据，实现了基本的TCP服务器功能。

/* fpont 1/00 */
/* pont.net */
/* tcpServer.c */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h> /* close */

#define SUCCESS 0
#define ERROR 1

#define END_LINE 0x0
#define SERVER_PORT 1500
#define MAX_MSG 100

/* function readline */
int read_line();

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

int sd, newSd, cliLen;

struct sockaddr_in cliAddr, servAddr;
char line[MAX_MSG];

/* create socket */
sd = socket(AF_INET, SOCK_STREAM, 0);
   if(sd<0) {
    perror("cannot open socket ");
    return ERROR;
}

/* bind server port */
servAddr.sin_family = AF_INET;
servAddr.sin_addr.s_addr = htonl(INADDR_ANY);
servAddr.sin_port = htons(SERVER_PORT);

if(bind(sd, (struct sockaddr *) &servAddr, sizeof(servAddr))<0) {
    perror("cannot bind port ");
    return ERROR;
}

listen(sd,5);

while(1) {

printf("%s: waiting for data on port TCP %u/n",argv[0],SERVER_PORT);

    cliLen = sizeof(cliAddr);
    newSd = accept(sd, (struct sockaddr *) &cliAddr, &cliLen);
    if(newSd<0) {
      perror("cannot accept connection ");
      return ERROR;
    }

    /* init line */
    memset(line,0x0,MAX_MSG);

    /* receive segments */
    while(read_line(newSd,line)!=ERROR) {

      printf("%s: received from %s:TCP%d : %s/n", argv[0],
      inet_ntoa(cliAddr.sin_addr),
      ntohs(cliAddr.sin_port), line);
      /* init line */
      memset(line,0x0,MAX_MSG);

    } /* while(read_line) */

} /* while (1) */

}

/* WARNING WARNING WARNING WARNING WARNING WARNING WARNING       */
/* this function is experimental.. I don't know yet if it works */
/* correctly or not. Use Steven's readline() function to have    */
/* something robust.                                             */
/* WARNING WARNING WARNING WARNING WARNING WARNING WARNING       */

/* rcv_line is my function readline(). Data is read from the socket when */
/* needed, but not byte after bytes. All the received data is read.      */
/* This means only one call to recv(), instead of one call for           */
/* each received byte.                                                   */
/* You can set END_CHAR to whatever means endofline for you. (0x0A is /n)*/
/* read_lin returns the number of bytes returned in line_to_return       */
int read_line(int newSd, char *line_to_return) {

static int rcv_ptr=0;
static char rcv_msg[MAX_MSG];
static int n;
int offset;

offset=0;

while(1) {
    if(rcv_ptr==0) {
      /* read data from socket */
      memset(rcv_msg,0x0,MAX_MSG); /* init buffer */
      n = recv(newSd, rcv_msg, MAX_MSG, 0); /* wait for data */
      if (n<0) {
perror(" cannot receive data ");
return ERROR;
      } else if (n==0) {
printf(" connection closed by client/n");
close(newSd);
return ERROR;
      }
    }

    /* if new data read on socket */
    /* OR */
    /* if another line is still in buffer */

    /* copy line into 'line_to_return' */
    while(*(rcv_msg+rcv_ptr)!=END_LINE && rcv_ptr<n) {
      memcpy(line_to_return+offset,rcv_msg+rcv_ptr,1);
      offset++;
      rcv_ptr++;
    }

    /* end of line + end of buffer => return line */
    if(rcv_ptr==n-1) {
      /* set last byte to END_LINE */
      *(line_to_return+offset)=END_LINE;
      rcv_ptr=0;
      return ++offset;
    }

    /* end of line but still some data in buffer => return line */
    if(rcv_ptr <n-1) {
      /* set last byte to END_LINE */
      *(line_to_return+offset)=END_LINE;
      rcv_ptr++;
      return ++offset;
    }

    /* end of buffer but line is not ended => */
    /* wait for more data to arrive on socket */
    if(rcv_ptr == n) {
      rcv_ptr = 0;
    }

} /* while */
}