下面程式碼實現的功能:

客戶c程式碼

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<unistd.h>
#include<stdlib.h>
#include<errno.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<string.h>
 
 
#define ERR_EXIT(m) \
    do { \
        perror(m); \
        exit(EXIT_FAILURE); \
    } while (0)
 
 
 
 
int main(void)
{
    int sock;
    if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
        //  listenfd = socket(AF_INET, SOCK_STREAM, 0)
        ERR_EXIT("socket error");
 
 
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5188);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    /* inet_aton("127.0.0.1", &servaddr.sin_addr); */
 
    if (connect(sock, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
        ERR_EXIT("connect error");
    struct sockaddr_in localaddr;
	char cli_ip[20];
	socklen_t local_len = sizeof(localaddr);
	memset(&localaddr, 0, sizeof(localaddr));
	if( getsockname(sock,(struct sockaddr *)&localaddr,&local_len) != 0 )
	    ERR_EXIT("getsockname error");
	inet_ntop(AF_INET, &localaddr.sin_addr, cli_ip, sizeof(cli_ip));
	printf("host %s:%d\n", cli_ip, ntohs(localaddr.sin_port)); 
 
    char sendbuf[1024] = {0};
    char recvbuf[1024] = {0};
    while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)
    {
 
        write(sock, sendbuf, strlen(sendbuf));
        read(sock, recvbuf, sizeof(recvbuf));
 
 
        fputs(recvbuf, stdout);
 
        memset(sendbuf, 0, sizeof(sendbuf));
        memset(recvbuf, 0, sizeof(recvbuf));
    }
 
 
    close(sock);
 
 
    return 0;
}
 

伺服器 c程式碼 

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<unistd.h>
#include<stdlib.h>
#include<errno.h>
#include<arpa/inet.h>
#include<netinet/in.h>
#include<string.h>
 
#define ERR_EXIT(m) \
    do { \
        perror(m); \
        exit(EXIT_FAILURE); \
    } while (0)
 
 
int main(void)
{
    int listenfd; //被動套接字(檔案描述符），即只可以accept
    if ((listenfd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
        //  listenfd = socket(AF_INET, SOCK_STREAM, 0)
        ERR_EXIT("socket error");
 
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(5188);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    /* servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); */
    /* inet_aton("127.0.0.1", &servaddr.sin_addr); */
 
    int on = 1;
    if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)
        ERR_EXIT("setsockopt error");
 
    if (bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
        ERR_EXIT("bind error");
 
    if (listen(listenfd, SOMAXCONN) < 0) //listen應在socket和bind之後，而在accept之前
        ERR_EXIT("listen error");
 
    struct sockaddr_in peeraddr; //傳出引數
    socklen_t peerlen = sizeof(peeraddr); //傳入傳出引數，必須有初始值
    int conn; // 已連線套接字(變為主動套接字，即可以主動connect)
    if ((conn = accept(listenfd, (struct sockaddr *)&peeraddr, &peerlen)) < 0)
        ERR_EXIT("accept error");
    printf("recv connect ip=%s port=%d\n", inet_ntoa(peeraddr.sin_addr),ntohs(peeraddr.sin_port));
	struct sockaddr_in localaddr;
	char serv_ip[20];
	socklen_t local_len = sizeof(localaddr);
	memset(&localaddr, 0, sizeof(localaddr));
	if( getsockname(conn,(struct sockaddr *)&localaddr,&local_len) != 0 )
	    ERR_EXIT("getsockname error");
	inet_ntop(AF_INET, &localaddr.sin_addr, serv_ip, sizeof(serv_ip));
	printf("host %s:%d\n", serv_ip, ntohs(localaddr.sin_port)); 
 
    char recvbuf[1024];
    while (1)
    {
        memset(recvbuf, 0, sizeof(recvbuf));
        int ret = read(conn, recvbuf, sizeof(recvbuf));
        fputs(recvbuf, stdout);
        write(conn, recvbuf, ret);
    }
 
    close(conn);
    close(listenfd);
 
    return 0;
}
 

makefile 

.PHONY:clean all
CC=gcc
CFLAGS=-Wall -g  
#這個名字必須和.c檔案的名字一一對應起來，才能利用makefile相關的預設規則輸出連結的可執行檔案
BIN=client serve
all:$(BIN)
%.o:%.c
	$(CC) $(CFLAGS) -c $< -o [email protected]
clean:
	rm -f *.o $(BIN)