TCP之簡單回傳（二）

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鑒於TCP之簡單回傳（一）   中所出現的問題，本博文所要採取的一種方法是：

用戶端：先向伺服器傳送一個 int32_t 大小的資料，表示隨後所要發送資料的真實長度； 伺服器：先接收一個int32_t 大小的資料，再接收真實的資料；

本程式中所用到的函數都可以在 TCP之函數封裝 中找到；

server伺服器端具體實現： 

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/stat.h>#include <errno.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#define ERR_EXIT(m)     do {         perror(m);        exit(EXIT_FAILURE);    }while(0)void do_server(int fd);int main(int argc, const char *argv[]){//socket        int listenfd = socket(AF_INET, SOCK_STREAM, 0 );    if( -1 == listenfd)        ERR_EXIT("socket");//地址複用    int on = 1;    if(setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on) < 0)        ERR_EXIT("setsockopt");//bind    struct sockaddr_in addr;    memset(&addr, 0, sizeof(addr));    addr.sin_family = AF_INET;    addr.sin_port = htons(8888); //主機位元組序轉化為網路位元組序    addr.sin_addr.s_addr = inet_addr("127.0.0.1");//點分十進位轉化成網路位元組序    if( -1 == bind( listenfd, (struct sockaddr*)&addr, sizeof(addr)))        ERR_EXIT("bind");//listen    if( -1 == listen(listenfd,SOMAXCONN ))        ERR_EXIT("listen");    //accept        int peerfd = accept(listenfd, NULL, NULL);//對方的IP&PORT//read&write        do_server(peerfd);//close    close(peerfd);    close(listenfd);    return 0;}void do_server(int  fd){    char recvbuf[1024100] = {0};    int cnt =0;    while(1)    {        int32_t len = recv_int32(fd);//先接收一個表示真是長度的int型資料            int nread = readn(fd, recvbuf, len);//讀取資料        if(nread == -1)//err        {            if(errno == EINTR)                continue;            ERR_EXIT("read");        }else if (nread == 0 || nread < len )//write close        {            printf("close...\n");            exit(EXIT_FAILURE);        }                // ok         printf("count = %d recv size = %d\n",++cnt, nread);        memset(recvbuf, 0, sizeof(recvbuf));    }}

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client用戶端具體實現：

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <errno.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#define ERR_EXIT(m)     do {         perror(m);        exit(EXIT_FAILURE);    }while(0)void do_server(int fd);int main(int argc, const char *argv[]){//socket    int peerfd = socket(AF_INET, SOCK_STREAM,0);    if( -1 == peerfd)        ERR_EXIT("socket");//connect    struct sockaddr_in addr;    addr.sin_family = AF_INET;    addr.sin_port = htons(8888);    addr.sin_addr.s_addr = inet_addr("127.0.0.1");        if( -1 == connect(peerfd,(struct sockaddr*)&addr, sizeof(addr) ))        ERR_EXIT("connect");//read&write    do_server(peerfd);    return 0;}void do_server(int fd){    #define SIZE 1024    char sendbuf[SIZE +1]= {0};    int i ;    for (i = 0; i < SIZE; i++)     {        sendbuf[i]= ‘a‘;        }    int cnt =0;    while(1)    {        int i;        for (i = 0; i < 10; i++)         {            send_int32(fd, SIZE);//先發送一個表示真實長度的int型資料            int nwrite =writen(fd, sendbuf, SIZE);//寫資料            if( nwrite != SIZE)//err                ERR_EXIT("writen");            printf("cout = %d,write %d bytes\n",++cnt, SIZE);        }        nano_sleep(4.5);    }}

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測試結果：

./servercount = 1 recv size = 1024count = 2 recv size = 1024count = 3 recv size = 1024count = 4 recv size = 1024count = 5 recv size = 1024count = 6 recv size = 1024count = 7 recv size = 1024count = 8 recv size = 1024count = 9 recv size = 1024count = 10 recv size = 1024count = 11 recv size = 1024count = 12 recv size = 1024count = 13 recv size = 1024count = 14 recv size = 1024count = 15 recv size = 1024count = 16 recv size = 1024count = 17 recv size = 1024count = 18 recv size = 1024count = 19 recv size = 1024count = 20 recv size = 1024

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./clientcout = 1,write 1024 bytescout = 2,write 1024 bytescout = 3,write 1024 bytescout = 4,write 1024 bytescout = 5,write 1024 bytescout = 6,write 1024 bytescout = 7,write 1024 bytescout = 8,write 1024 bytescout = 9,write 1024 bytescout = 10,write 1024 bytescout = 11,write 1024 bytescout = 12,write 1024 bytescout = 13,write 1024 bytescout = 14,write 1024 bytescout = 15,write 1024 bytescout = 16,write 1024 bytescout = 17,write 1024 bytescout = 18,write 1024 bytescout = 19,write 1024 bytescout = 20,write 1024 bytes

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TCP之簡單回傳（二）