UNIX网络编程1.1概述 1.2时间获取客户函数 1.4错误处理包裹函数

逻辑上socket处于应用层与传输层之间。

ip,端口，协议，一起决定了网络的一个端点。

#include <iostream>

#include "unp.h"

int main(int argc, char** argv)
{
    int sockfd;
    int n;
    char recvline[MAXLINE + 1];
    struct sockaddr_in servaddr;

    if (argc != 2)
    {
        err_quit("usage: a.out <IPaddress>");
    }

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        err_sys("socket error");
    }

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port   = htons(13); // daytime server
    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
    {
        err_quit("inet_pton error for %s", argv[1]);
    }

    if (connect(sockfd, (SA*)&servaddr, sizeof(servaddr)) < 0)
    {
        err_sys("connect error");
    }

    while ( (n = read(sockfd, recvline, MAXLINE)) > 0)
    {
        recvline[n] = 0; // null terminate
        if (fputs(recvline, stdout) == EOF)
        {
            err_sys("fputs error");
        }
    }
    if (n < 0)
    {
        err_sys("read error");
    }

    exit(0);
}

ALL = daytimetcpcli daytimetcpsrv client server byteorder
CFLAGS = -Wall -g

all: ${ALL}

daytimetcpcli.o: daytimetcpcli.cpp
	g++ ${CFLAGS} -c daytimetcpcli.cpp -I ../lib -o daytimetcpcli.o
daytimetcpcli: daytimetcpcli.o
	g++ ${CFLAGS} daytimetcpcli.o ../libunp.a -I ../lib -o daytimetcpcli

daytimetcpsrv.o: daytimetcpsrv.cpp
	g++ ${CFLAGS} -c daytimetcpsrv.cpp -I ../lib -o daytimetcpsrv.o
daytimetcpsrv: daytimetcpsrv.o
	g++ ${CFLAGS} daytimetcpsrv.o ../libunp.a -I ../lib -o daytimetcpsrv

client.o: client.cpp
	g++ ${CFLAGS} -c client.cpp -o client.o
client: client.o
	g++ ${CFLAGS} client.o -o client

server.o: server.cpp
	g++ ${CFLAGS} -c server.cpp -o server.o
server: server.o
	g++ ${CFLAGS} server.o -o server

byteorder.o: byteorder.cpp
	g++ ${CFLAGS} -c byteorder.cpp -I ../lib -o byteorder.o
byteorder: byteorder.o
	g++ ${CFLAGS} byteorder.o -I ../lib -o byteorder

clean:
	rm *.o ${ALL}