Linux網絡編程9——對TCP與UDP的簡易封裝2.0，網絡編程udp

Linux網絡編程9——對TCP與UDP的簡易封裝2.0，網絡編程udp

具體生成動態庫的操作及使用該動態庫的操作請參見上篇博文。以下僅僅列出改進版本的代碼。

代碼

my_socket.h

#ifndef __MY_SOCKET_H__
#define __MY_SOCKET_H__

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define IN
#define OUT
#define IN_OUT
#define MY_TCP 1
#define MY_UDP 2
typedef struct sockaddr* pSA ;
typedef struct sockaddr_in SA ;
#define MY_ASSERT(flag,msg) ( (flag) ? NULL : ( fprintf(stdout,msg), exit(EXIT_FAILURE) ) )   // NULL代表什麼也不做

void my_socket(OUT int *local_sfd, int protocal, char *local_ip, int local_port);
void my_listen(int local_sfd, int backlog);
void my_accept(OUT int *peer_sfd, int local_sfd, OUT pSA peer_addr, IN_OUT int *addr_len );
void my_connect(int local_sfd, char *peer_ip, int peer_port);
void my_recv(OUT int *recv_len, int peer_sfd, IN_OUT void *base, int len);
void my_send(OUT int *send_len, int peer_sfd, void *base, int len);
void my_recvfrom(OUT int *recvfrom_len, int peer_sfd, IN_OUT void *base, int len, OUT char* peer_ip, OUT int *peer_port);
void my_sendto(OUT int *sendto_len, int peer_sfd, OUT void *base, int len,  char *peer_ip, int peer_port);
void my_close(int sfd);


#endif

my_socket.c

/*************************************************************************
    > File Name: my_socket.c
    > Author: KrisChou
    > Mail:[email protected] 
    > Created Time: Mon 01 Sep 2014 06:54:48 PM CST
 ************************************************************************/

/* 本代碼用於在一台主機上模擬socket通信。因此IP地址對於server和client而言是一樣的。
 * 為了簡化代碼，此處即使是客戶端，也提前分配好端口號。事實上，主動方的端口號可以由系統分配，不用提前綁定
 * --> 無論server或者client，都會預先綁定本地socket */

/* 本代碼local_sfd代表本地socket描述符。
 * 對於服務器而言，就是用於監聽的socket; 對於客戶端而言就是用於通信的socket
 * peer_sfd，代表與對方通信的socket描述符。
 * 對於服務器而言，由accept以傳出參數形式返回；對於客戶端而言，就是本地socket */

#include "my_socket.h"

void my_socket(OUT int *local_sfd, int protocal, char *local_ip, int local_port)
{
    MY_ASSERT(protocal == MY_TCP || protocal == MY_UDP, "wrong arg! protocal is MY_TCP or MY_UDP! \n");
    /* 創建本地socket */
    if(protocal == MY_TCP)
    {
        MY_ASSERT(-1 != (*local_sfd = socket(AF_INET, SOCK_STREAM, 0)), "tcp_socket init falure!\n");
        int reuse = 1;
        setsockopt(*local_sfd, SOL_SOCKET, SO_REUSEADDR, (void*)&reuse, sizeof(reuse));
    }else if(protocal == MY_UDP)
    {
        MY_ASSERT(-1 != (*local_sfd = socket(AF_INET, SOCK_DGRAM, 0)),  "udp_socket init failure!\n");
    }
    /* 將本地聯系方式bind到本地socket */
    SA local_addr;
    memset(&local_addr, 0, sizeof(SA));
    local_addr.sin_family      = AF_INET;
    local_addr.sin_port        = htons(local_port);
    local_addr.sin_addr.s_addr = inet_addr(local_ip);
    MY_ASSERT( 0 == bind(*local_sfd, (pSA)&local_addr, sizeof(SA)), "bind failure!\n");
}

/*----------------------------- 以下針對TCP ----------------------------------------------------- */

/* server: listen + accept */
void my_listen(int local_sfd, int backlog)
{
    MY_ASSERT( 0 == listen(local_sfd, backlog), "listen failure!\n");
}

void my_accept(OUT int *peer_sfd, int local_sfd, OUT pSA peer_addr, IN_OUT int *addr_len )
{
    MY_ASSERT(-1 != (*peer_sfd = accept(local_sfd, peer_addr, addr_len)), "accept failure!\n");
}

/* client: connect */
void my_connect(int local_sfd, char *peer_ip, int peer_port )
{
    int cnt = 0;
    SA peer_addr;
    memset(&peer_addr, 0, sizeof(SA));
    peer_addr.sin_family      = AF_INET;
    peer_addr.sin_port        = htons(peer_port);
    peer_addr.sin_addr.s_addr = inet_addr(peer_ip);
    // 10次連不上就退出程序
    while(-1 == connect(local_sfd, (pSA)&peer_addr, sizeof(SA)))
    {
        cnt++;
        if(cnt == 10)
        {
            printf("connect failure!\n");
            exit(EXIT_FAILURE);
        }
        sleep(1);
    }
}

/* recv and send */
void my_recv(OUT int *recv_len, int peer_sfd, IN_OUT void *base, int len)
{
    int recvn;
    int recv_sum = 0;
    while(recv_sum < len)
    {
        MY_ASSERT(-1 != (recvn = recv(peer_sfd, base + recv_sum, len - recv_sum, 0)), "recv error! \n");
        recv_sum += recvn;
    }
    if(recv_len != NULL)
    {
        *recv_len = recv_sum;
    }
}

void my_send(OUT int *send_len, int peer_sfd, void *base, int len)
{
    int sendn;
    int send_sum = 0;
    while(send_sum < len)
    {
        MY_ASSERT(-1 != (sendn = send(peer_sfd, base + send_sum, len - send_sum, 0)), "send error! \n");
        send_sum += sendn;
    }
    if(send_len != NULL)
    {
        *send_len = send_sum;
    }
}

/*---------------------------- 以下針對UDP--------------------------------------------------------*/

void my_recvfrom(OUT int *recvfrom_len, int peer_sfd, IN_OUT void *base, int len, OUT char* peer_ip, OUT int *peer_port)
{
    int recvn;
    SA peer_addr;
    int addr_len = sizeof(SA);
    MY_ASSERT(-1 != (recvn = recvfrom(peer_sfd, base, len, 0, (pSA)&peer_addr, &addr_len)), "recvfrom failure!\n");
    if(recvfrom_len != NULL)
    {
        *recvfrom_len = recvn;
    }
    if(peer_ip != NULL)
    {
        char *p = inet_ntoa(peer_addr.sin_addr);
        MY_ASSERT(strlen(peer_ip) >= strlen(p) + 1, "buf for ip is too short! \n");
        strcpy(peer_ip, p);
    }
    if(peer_port != NULL)
    {
        *peer_port = ntohs(peer_addr.sin_port);
    }
}


void my_sendto(OUT int *sendto_len, int peer_sfd, OUT void *base, int len,  char *peer_ip, int peer_port)
{
    int sendn;
    SA peer_addr;
    memset(&peer_addr, 0, sizeof(SA));
    peer_addr.sin_family      = AF_INET;
    peer_addr.sin_port        = htons(peer_port);
    peer_addr.sin_addr.s_addr = inet_addr(peer_ip);
    MY_ASSERT(-1 != (sendn = sendto(peer_sfd, base, len, 0, (pSA)&peer_addr, sizeof(SA))), "sendto failure!\n");
    if(sendto_len != NULL)
    {
        *sendto_len = sendn;
    }
}



/* close */
void my_close(int sfd)
{
    MY_ASSERT(0 == close(sfd), "close failure!\n");
}

測試代碼

server.c

#include "my_socket.h"
#define IP "192.168.153.128"
#define PORT 8888
int main(int argc, char *argv[])
{
    int fd_server, fd_client;
    int val;  //用4個字節的地址空間來傳數據
    int len;
    my_socket(&fd_server, MY_TCP, IP, PORT);
    my_listen(fd_server,5);
    my_accept(&fd_client, fd_server, NULL, NULL);
    printf("accept success!\n");
    while(1)
    {
        //my_accept(&fd_client, fd_server, NULL, NULL);
        //printf("accept success!\n");
        my_recv(&len, fd_client, (void*)&val, sizeof(val));
        printf("recv data: %d\n", val);
        my_send(&len, fd_client, (void*)&val, sizeof(val));
        printf("%d has sent!\n\n", val);
    }
    my_close(fd_client);
    my_close(fd_server);
    return 0;
}

client.c

#include "my_socket.h"
#define IP "192.168.153.128"
#define MY_PORT 6666
#define SERVER_PORT 8888

int main(int argc, char *argv[])
{
    /* socket */
    int fd_client;
    my_socket(&fd_client, MY_TCP, IP, MY_PORT);
    
    /* connect */
    my_connect(fd_client, IP, SERVER_PORT);
    printf("connect success!\n");
    
    /* 發送一個數據，並從服務器端返回這個數據 */
    int val_in,val_out,len;
    while(scanf("%d", &val_in) == 1)
    {
        my_send(NULL,fd_client,(void*)&val_in,sizeof(int));
        my_recv(NULL,fd_client,(void*)&val_out,sizeof(int));
        printf("recv fron server: %d\n", val_out);
    }
    
    my_close(fd_client);
    return 0;
    
}

網絡編程中，TCP與UDP有什不同

tcp能確保你的包正確的發送到了指定地址，而udp只負責發送，不管是否送達及送達的包是否正確。
 

tcp報文與udp報文都是封裝在IP包中的?

是的，從TCP/IP四層模型可以看出。TCP和UDP是在第三層傳輸層。而IP在第二層網際層。數據從上層封裝到下層。所以TCP和UDP被封裝在IP包裡。另外：TCP和UDP是不同的傳輸方式。不能同時出現！