unp.h的安装以及第一个程序的运行

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unp.h的安装以及第一个程序的运行

  1. 源代码下载以及编译

    点击此处下载源代码

    解压到本地文件夹，如果访问不了GitHub的话就用我搬到gitee的仓库吧

    git clone https://gitee.com/Find-ing/unpv13e.git

    直接这样就不用解压了

    这里可以看看README

    按照README上的顺序

    首先执行./configure

    然后

    cd lib
make
cd ../libfree
make
cd ../libroute
make

    如果出现了错误，就再来一次

    cd ../lib
make
cd ../libfree
make
cd ../libroute
make

    第二遍做完之后，如果出现了如下错误：

    [root@docker libfree]# cd ../libroute
[root@docker libroute]# make
gcc -I../lib -g -O2 -D_REENTRANT -Wall   -c -o get_rtaddrs.o get_rtaddrs.c
In file included from get_rtaddrs.c:1:
unproute.h:3:10: fatal error: net/if_dl.h: No such file or directory
 #include <net/if_dl.h>  /* sockaddr_sdl */
          ^~~~~~~~~~~~~
compilation terminated.
make: *** [<builtin>: get_rtaddrs.o] Error 1

    哈哈哈，看了半天教程，改了好久也没搞好，仔细看看README，我真是

​ 好，仔细看看README怎么说的

>     cd ../libroute # only if your system supports 4.4BSD style routing sockets
>     make           # only if your system supports 4.4BSD style routing sockets

<font color=\'red\'>only if your system supports 4.4BSD style routing sockets</font>

okok，下一步

​ 可以看到内容已经被编译到unpv13e/libunp.a里面去了

  1. 拷贝

    sudo cp libunp.a /usr/lib
sudo cp libunp.a /usr/lib64
# 有的系统可能没有这个文件夹，那就不用拷贝这个了，反正我的有

    在.\\lib\\unp.h中将#include "../config.h"改为#include "config.h"

    然后

    sudo cp config.h /usr/include
sudo cp lib/unp.h /usr/include

  2. 现在是第三阶段，因为我们在运行代码时会报一个错

    /tmp/ccM5DNZP.o: In function `main\':
test.c:(.text+0x2c): undefined reference to `err_quit\'
test.c:(.text+0x58): undefined reference to `err_sys\'
test.c:(.text+0xd2): undefined reference to `err_quit\'
test.c:(.text+0xfe): undefined reference to `err_sys\'
test.c:(.text+0x13a): undefined reference to `err_sys\'
test.c:(.text+0x171): undefined reference to `err_sys\'
collect2: error: ld returned 1 exit status

    原因是err_quit,err_sys等这些函数都是作者自己定义的函数真正的函数在http://www.apuebook.com/code3e.html下载。

    把error.c的文件名改为myerr.c

    在apue.h文件最后一行#endif /* _APUE_H */前加入#include "myerr.c"

    在unp.h中加入#include "apue.h"

    将apue.h和myerr.c文件都拷贝到/usr/include中去

    上面这些改改找找的操作各位要是想做就可以做一遍，如果是在不想做，就按照下面的操作

    打开/usr/include

    然后删除unp.h里面所有内容，然后复制这一段粘进去

    /* include unph */
/* Our own header.  Tabs are set for 4 spaces, not 8 */

#ifndef	__unp_h
#define	__unp_h
#include "apue.h"
#include	"config.h"	/* configuration options for current OS */
							/* "../config.h" is generated by configure */
#define MAX_LINE 2048
/* If anything changes in the following list of #includes, must change
   acsite.m4 also, for configure\'s tests. */

#include	<sys/types.h>	/* basic system data types */
#include	<sys/socket.h>	/* basic socket definitions */
#if TIME_WITH_SYS_TIME
#include	<sys/time.h>	/* timeval for select() */
#include	<time.h>		/* timespec for pselect() */
#else
#if HAVE_SYS_TIME_H
#include	<sys/time.h>	/* includes <time.h> unsafely */
#else
#include	<time.h>		/* old system? */
#endif
#endif
#include	<netinet/in.h>	/* sockaddr_in and other Internet defns */
#include	<arpa/inet.h>	/* inet(3) functions */
#include	<errno.h>
#include	<fcntl.h>		/* for nonblocking */
#include	<netdb.h>
#include	<signal.h>
#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>
#include	<sys/stat.h>	/* for S_xxx file mode constants */
#include	<sys/uio.h>		/* for iovec and readv/writev */
#include	<unistd.h>
#include	<sys/wait.h>
#include	<sys/un.h>		/* for Unix domain sockets */

#ifdef	HAVE_SYS_SELECT_H
# include	<sys/select.h>	/* for convenience */
#endif

#ifdef	HAVE_SYS_SYSCTL_H
#ifdef	HAVE_SYS_PARAM_H
# include	<sys/param.h>	/* OpenBSD prereq for sysctl.h */
#endif
# include	<sys/sysctl.h>
#endif

#ifdef	HAVE_POLL_H
# include	<poll.h>		/* for convenience */
#endif

#ifdef	HAVE_SYS_EVENT_H
# include	<sys/event.h>	/* for kqueue */
#endif

#ifdef	HAVE_STRINGS_H
# include	<strings.h>		/* for convenience */
#endif

/* Three headers are normally needed for socket/file ioctl\'s:
 * <sys/ioctl.h>, <sys/filio.h>, and <sys/sockio.h>.
 */
#ifdef	HAVE_SYS_IOCTL_H
# include	<sys/ioctl.h>
#endif
#ifdef	HAVE_SYS_FILIO_H
# include	<sys/filio.h>
#endif
#ifdef	HAVE_SYS_SOCKIO_H
# include	<sys/sockio.h>
#endif

#ifdef	HAVE_PTHREAD_H
# include	<pthread.h>
#endif

#ifdef HAVE_NET_IF_DL_H
# include	<net/if_dl.h>
#endif

#ifdef HAVE_NETINET_SCTP_H
#include	<netinet/sctp.h>
#endif

/* OSF/1 actually disables recv() and send() in <sys/socket.h> */
#ifdef	__osf__
#undef	recv
#undef	send
#define	recv(a,b,c,d)	recvfrom(a,b,c,d,0,0)
#define	send(a,b,c,d)	sendto(a,b,c,d,0,0)
#endif

#ifndef	INADDR_NONE
/* $$.Ic INADDR_NONE$$ */
#define	INADDR_NONE	0xffffffff	/* should have been in <netinet/in.h> */
#endif

#ifndef	SHUT_RD				/* these three POSIX names are new */
#define	SHUT_RD		0	/* shutdown for reading */
#define	SHUT_WR		1	/* shutdown for writing */
#define	SHUT_RDWR	2	/* shutdown for reading and writing */
/* $$.Ic SHUT_RD$$ */
/* $$.Ic SHUT_WR$$ */
/* $$.Ic SHUT_RDWR$$ */
#endif

/* *INDENT-OFF* */
#ifndef INET_ADDRSTRLEN
/* $$.Ic INET_ADDRSTRLEN$$ */
#define	INET_ADDRSTRLEN		16	/* "ddd.ddd.ddd.ddd\\0"
								    1234567890123456 */
#endif

/* Define following even if IPv6 not supported, so we can always allocate
   an adequately sized buffer without #ifdefs in the code. */
#ifndef INET6_ADDRSTRLEN
/* $$.Ic INET6_ADDRSTRLEN$$ */
#define	INET6_ADDRSTRLEN	46	/* max size of IPv6 address string:
				   "xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx" or
				   "xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:ddd.ddd.ddd.ddd\\0"
				    1234567890123456789012345678901234567890123456 */
#endif
/* *INDENT-ON* */

/* Define bzero() as a macro if it\'s not in standard C library. */
#ifndef	HAVE_BZERO
#define	bzero(ptr,n)		memset(ptr, 0, n)
/* $$.If bzero$$ */
/* $$.If memset$$ */
#endif

/* Older resolvers do not have gethostbyname2() */
#ifndef	HAVE_GETHOSTBYNAME2
#define	gethostbyname2(host,family)		gethostbyname((host))
#endif

/* The structure returned by recvfrom_flags() */
struct unp_in_pktinfo 
  struct in_addr	ipi_addr;	/* dst IPv4 address */
  int				ipi_ifindex;/* received interface index */
;
/* $$.It unp_in_pktinfo$$ */
/* $$.Ib ipi_addr$$ */
/* $$.Ib ipi_ifindex$$ */

/* We need the newer CMSG_LEN() and CMSG_SPACE() macros, but few
   implementations support them today.  These two macros really need
    an ALIGN() macro, but each implementation does this differently. */
#ifndef	CMSG_LEN
/* $$.Im CMSG_LEN$$ */
#define	CMSG_LEN(size)		(sizeof(struct cmsghdr) + (size))
#endif
#ifndef	CMSG_SPACE
/* $$.Im CMSG_SPACE$$ */
#define	CMSG_SPACE(size)	(sizeof(struct cmsghdr) + (size))
#endif

/* POSIX requires the SUN_LEN() macro, but not all implementations DefinE
   it (yet).  Note that this 4.4BSD macro works regardless whether there is
   a length field or not. */
#ifndef	SUN_LEN
/* $$.Im SUN_LEN$$ */
# define	SUN_LEN(su) \\
	(sizeof(*(su)) - sizeof((su)->sun_path) + strlen((su)->sun_path))
#endif

/* POSIX renames "Unix domain" as "local IPC."
   Not all systems DefinE AF_LOCAL and PF_LOCAL (yet). */
#ifndef	AF_LOCAL
#define AF_LOCAL	AF_UNIX
#endif
#ifndef	PF_LOCAL
#define PF_LOCAL	PF_UNIX
#endif

/* POSIX requires that an #include of <poll.h> DefinE INFTIM, but many
   systems still DefinE it in <sys/stropts.h>.  We don\'t want to include
   all the STREAMS stuff if it\'s not needed, so we just DefinE INFTIM here.
   This is the standard value, but there\'s no guarantee it is -1. */
#ifndef INFTIM
#define INFTIM          (-1)    /* infinite poll timeout */
/* $$.Ic INFTIM$$ */
#ifdef	HAVE_POLL_H
#define	INFTIM_UNPH				/* tell unpxti.h we defined it */
#endif
#endif

/* Following could be derived from SOMAXCONN in <sys/socket.h>, but many
   kernels still #define it as 5, while actually supporting many more */
#define	LISTENQ		1024	/* 2nd argument to listen() */

/* Miscellaneous constants */
#define	MAXLINE		4096	/* max text line length */
#define	BUFFSIZE	8192	/* buffer size for reads and writes */

/* Define some port number that can be used for our examples */
#define	SERV_PORT		 9877			/* TCP and UDP */
#define	SERV_PORT_STR	"9877"			/* TCP and UDP */
#define	UNIXSTR_PATH	"/tmp/unix.str"	/* Unix domain stream */
#define	UNIXDG_PATH		"/tmp/unix.dg"	/* Unix domain datagram */
/* $$.ix [LISTENQ]~constant,~definition~of$$ */
/* $$.ix [MAXLINE]~constant,~definition~of$$ */
/* $$.ix [BUFFSIZE]~constant,~definition~of$$ */
/* $$.ix [SERV_PORT]~constant,~definition~of$$ */
/* $$.ix [UNIXSTR_PATH]~constant,~definition~of$$ */
/* $$.ix [UNIXDG_PATH]~constant,~definition~of$$ */

/* Following shortens all the typecasts of pointer arguments: */
#define	SA	struct sockaddr

#ifndef HAVE_STRUCT_SOCKADDR_STORAGE
/*
 * RFC 3493: protocol-independent placeholder for socket addresses
 */
#define	__SS_MAXSIZE	128
#define	__SS_ALIGNSIZE	(sizeof(int64_t))
#ifdef HAVE_SOCKADDR_SA_LEN
#define	__SS_PAD1SIZE	(__SS_ALIGNSIZE - sizeof(u_char) - sizeof(sa_family_t))
#else
#define	__SS_PAD1SIZE	(__SS_ALIGNSIZE - sizeof(sa_family_t))
#endif
#define	__SS_PAD2SIZE	(__SS_MAXSIZE - 2*__SS_ALIGNSIZE)

struct sockaddr_storage 
#ifdef HAVE_SOCKADDR_SA_LEN
	u_char		ss_len;
#endif
	sa_family_t	ss_family;
	char		__ss_pad1[__SS_PAD1SIZE];
	int64_t		__ss_align;
	char		__ss_pad2[__SS_PAD2SIZE];
;
#endif

#define	FILE_MODE	(S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
					/* default file access permissions for new files */
#define	DIR_MODE	(FILE_MODE | S_IXUSR | S_IXGRP | S_IXOTH)
					/* default permissions for new directories */

typedef	void	Sigfunc(int);	/* for signal handlers */

#define	min(a,b)	((a) < (b) ? (a) : (b))
#define	max(a,b)	((a) > (b) ? (a) : (b))

#ifndef	HAVE_ADDRINFO_STRUCT
# include	"../lib/addrinfo.h"
#endif

#ifndef	HAVE_IF_NAMEINDEX_STRUCT
struct if_nameindex 
  unsigned int   if_index;  /* 1, 2, ... */
  char          *if_name;   /* null-terminated name: "le0", ... */
;
/* $$.It if_nameindex$$ */
/* $$.Ib if_index$$ */
/* $$.Ib if_name$$ */
#endif

#ifndef	HAVE_TIMESPEC_STRUCT
struct timespec 
  time_t	tv_sec;		/* seconds */
  long		tv_nsec;	/* and nanoseconds */
;
/* $$.It timespec$$ */
/* $$.Ib tv_sec$$ */
/* $$.Ib tv_nsec$$ */
#endif
/* end unph */

			/* prototypes for our own library functions */
int		 connect_nonb(int, const SA *, socklen_t, int);
int		 connect_timeo(int, const SA *, socklen_t, int);
int	 daemon_init(const char *, int);
void	 daemon_inetd(const char *, int);
void	 dg_cli(FILE *, int, const SA *, socklen_t);
void	 dg_echo(int, SA *, socklen_t);
int		 family_to_level(int);
char	*gf_time(void);
void	 heartbeat_cli(int, int, int);
void	 heartbeat_serv(int, int, int);
struct addrinfo *host_serv(const char *, const char *, int, int);
int		 inet_srcrt_add(char *);
u_char  *inet_srcrt_init(int);
void	 inet_srcrt_print(u_char *, int);
void	 inet6_srcrt_print(void *);
char   **my_addrs(int *);
int		 readable_timeo(int, int);
ssize_t	 readline(int, void *, size_t);
ssize_t	 readn(int, void *, size_t);
ssize_t	 read_fd(int, void *, size_t, int *);
ssize_t	 recvfrom_flags(int, void *, size_t, int *, SA *, socklen_t *,
		 struct unp_in_pktinfo *);
Sigfunc *signal_intr(int, Sigfunc *);
int		 sock_bind_wild(int, int);
int		 sock_cmp_addr(const SA *, const SA *, socklen_t);
int		 sock_cmp_port(const SA *, const SA *, socklen_t);
int		 sock_get_port(const SA *, socklen_t);
void	 sock_set_addr(SA *, socklen_t, const void *);
void	 sock_set_port(SA *, socklen_t, int);
void	 sock_set_wild(SA *, socklen_t);
char	*sock_ntop(const SA *, socklen_t);
char	*sock_ntop_host(const SA *, socklen_t);
int		 sockfd_to_family(int);
void	 str_echo(int);
void	 str_cli(FILE *, int);
int		 tcp_connect(const char *, const char *);
int		 tcp_listen(const char *, const char *, socklen_t *);
void	 tv_sub(struct timeval *, struct timeval *);
int		 udp_client(const char *, const char *, SA **, socklen_t *);
int		 udp_connect(const char *, const char *);
int		 udp_server(const char *, const char *, socklen_t *);
int		 writable_timeo(int, int);
ssize_t	 writen(int, const void *, size_t);
ssize_t	 write_fd(int, void *, size_t, int);

#ifdef	MCAST
int		 mcast_leave(int, const SA *, socklen_t);
int		 mcast_join(int, const SA *, socklen_t, const char *, u_int);
int		 mcast_leave_source_group(int sockfd, const SA *src, socklen_t srclen,
								  const SA *grp, socklen_t grplen);
int		 mcast_join_source_group(int sockfd, const SA *src, socklen_t srclen,
								 const SA *grp, socklen_t grplen,
								 const char *ifname, u_int ifindex);
int		 mcast_block_source(int sockfd, const SA *src, socklen_t srclen,
							const SA *grp, socklen_t grplen);
int		 mcast_unblock_source(int sockfd, const SA *src, socklen_t srclen,
							  const SA *grp, socklen_t grplen);
int		 mcast_get_if(int);
int		 mcast_get_loop(int);
int		 mcast_get_ttl(int);
int		 mcast_set_if(int, const char *, u_int);
int		 mcast_set_loop(int, int);
int		 mcast_set_ttl(int, int);

void	 Mcast_leave(int, const SA *, socklen_t);
void	 Mcast_join(int, const SA *, socklen_t, const char *, u_int);
void	 Mcast_leave_source_group(int sockfd, const SA *src, socklen_t srclen,
								  const SA *grp, socklen_t grplen);
void	 Mcast_join_source_group(int sockfd, const SA *src, socklen_t srclen,
								 const SA *grp, socklen_t grplen,
								 const char *ifname, u_int ifindex);
void	 Mcast_block_source(int sockfd, const SA *src, socklen_t srclen,
							const SA *grp, socklen_t grplen);
void	 Mcast_unblock_source(int sockfd, const SA *src, socklen_t srclen,
							  const SA *grp, socklen_t grplen);
int		 Mcast_get_if(int);
int		 Mcast_get_loop(int);
int		 Mcast_get_ttl(int);
void	 Mcast_set_if(int, const char *, u_int);
void	 Mcast_set_loop(int, int);
void	 Mcast_set_ttl(int, int);
#endif

uint16_t	in_cksum(uint16_t *, int);

#ifndef	HAVE_GETADDRINFO_PROTO
int		 getaddrinfo(const char *, const char *, const struct addrinfo *,
					 struct addrinfo **);
void	 freeaddrinfo(struct addrinfo *);
char	*gai_strerror(int);
#endif

#ifndef	HAVE_GETNAMEINFO_PROTO
int		 getnameinfo(const SA *, socklen_t, char *, size_t, char *, size_t, int);
#endif

#ifndef	HAVE_GETHOSTNAME_PROTO
int		 gethostname(char *, int);
#endif

#ifndef	HAVE_HSTRERROR_PROTO
const char	*hstrerror(int);
#endif

#ifndef	HAVE_IF_NAMETOINDEX_PROTO
unsigned int	 if_nametoindex(const char *);
char			*if_indextoname(unsigned int, char *);
void			 if_freenameindex(struct if_nameindex *);
struct if_nameindex *if_nameindex(void);
#endif

#ifndef	HAVE_INET_PTON_PROTO
int			 inet_pton(int, const char *, void *);
const char	*inet_ntop(int, const void *, char *, size_t);
#endif

#ifndef	HAVE_INET_ATON_PROTO
int		 inet_aton(const char *, struct in_addr *);
#endif

#ifndef	HAVE_PSELECT_PROTO
int		 pselect(int, fd_set *, fd_set *, fd_set *,
				 const struct timespec *, const sigset_t *);
#endif

#ifndef	HAVE_SOCKATMARK_PROTO
int		 sockatmark(int);
#endif

#ifndef	HAVE_SNPRINTF_PROTO
int		 snprintf(char *, size_t, const char *, ...);
#endif

			/* prototypes for our own library wrapper functions */
void	 Connect_timeo(int, const SA *, socklen_t, int);
int		 Family_to_level(int);
struct addrinfo *Host_serv(const char *, const char *, int, int);
const char		*Inet_ntop(int, const void *, char *, size_t);
void			 Inet_pton(int, const char *, void *);
char			*If_indextoname(unsigned int, char *);
unsigned int		 If_nametoindex(const char *);
struct if_nameindex	*If_nameindex(void);
char   **My_addrs(int *);
ssize_t	 Read_fd(int, void *, size_t, int *);
int		 Readable_timeo(int, int);
ssize_t	 Recvfrom_flags(int, void *, size_t, int *, SA *, socklen_t *,
		 struct unp_in_pktinfo *);
Sigfunc *Signal(int, Sigfunc *);
Sigfunc *Signal_intr(int, Sigfunc *);
int		 Sock_bind_wild(int, int);
char	*Sock_ntop(const SA *, socklen_t);
char	*Sock_ntop_host(const SA *, socklen_t);
int		 Sockfd_to_family(int);
int		 Tcp_connect(const char *, const char *);
int		 Tcp_listen(const char *, const char *, socklen_t *);
int		 Udp_client(const char *, const char *, SA **, socklen_t *);
int		 Udp_connect(const char *, const char *);
int		 Udp_server(const char *, const char *, socklen_t *);
ssize_t	 Write_fd(int, void *, size_t, int);
int		 Writable_timeo(int, int);

			/* prototypes for our Unix wrapper functions: see Sec errors */
void	*Calloc(size_t, size_t);
void	 Close(int);
void	 Dup2(int, int);
int		 Fcntl(int, int, int);
void	 Gettimeofday(struct timeval *, void *);
int		 Ioctl(int, int, void *);
pid_t	 Fork(void);
void	*Malloc(size_t);
int	 Mkstemp(char *);
void	*Mmap(void *, size_t, int, int, int, off_t);
int		 Open(const char *, int, mode_t);
void	 Pipe(int *fds);
ssize_t	 Read(int, void *, size_t);
void	 Sigaddset(sigset_t *, int);
void	 Sigdelset(sigset_t *, int);
void	 Sigemptyset(sigset_t *);
void	 Sigfillset(sigset_t *);
int		 Sigismember(const sigset_t *, int);
void	 Sigpending(sigset_t *);
void	 Sigprocmask(int, const sigset_t *, sigset_t *);
char	*Strdup(const char *);
long	 Sysconf(int);
void	 Sysctl(int *, u_int, void *, size_t *, void *, size_t);
void	 Unlink(const char *);
pid_t	 Wait(int *);
pid_t	 Waitpid(pid_t, int *, int);
void	 Write(int, void *, size_t);

			/* prototypes for our stdio wrapper functions: see Sec errors */
void	 Fclose(FILE *);
FILE	*Fdopen(int, const char *);
char	*Fgets(char *, int, FILE *);
FILE	*Fopen(const char *, const char *);
void	 Fputs(const char *, FILE *);

			/* prototypes for our socket wrapper functions: see Sec errors */
int		 Accept(int, SA *, socklen_t *);
void	 Bind(int, const SA *, socklen_t);
void	 Connect(int, const SA *, socklen_t);
void	 Getpeername(int, SA *, socklen_t *);
void	 Getsockname(int, SA *, socklen_t *);
void	 Getsockopt(int, int, int, void *, socklen_t *);
#ifdef	HAVE_INET6_RTH_INIT
int		 Inet6_rth_space(int, int);
void	*Inet6_rth_init(void *, socklen_t, int, int);
void	 Inet6_rth_add(void *, const struct in6_addr *);
void	 Inet6_rth_reverse(const void *, void *);
int		 Inet6_rth_segments(const void *);
struct in6_addr *Inet6_rth_getaddr(const void *, int);
#endif
#ifdef	HAVE_KQUEUE
int		 Kqueue(void);
int		 Kevent(int, const struct kevent *, int,
				struct kevent *, int, const struct timespec *);
#endif
void	 Listen(int, int);
#ifdef	HAVE_POLL
int		 Poll(struct pollfd *, unsigned long, int);
#endif
ssize_t	 Readline(int, void *, size_t);
ssize_t	 Readn(int, void *, size_t);
ssize_t	 Recv(int, void *, size_t, int);
ssize_t	 Recvfrom(int, void *, size_t, int, SA *, socklen_t *);
ssize_t	 Recvmsg(int, struct msghdr *, int);
int		 Select(int, fd_set *, fd_set *, fd_set *, struct timeval *);
void	 Send(int, const void *, size_t, int);
void	 Sendto(int, const void *, size_t, int, const SA *, socklen_t);
void	 Sendmsg(int, const struct msghdr *, int);
void	 Setsockopt(int, int, int, const void *, socklen_t);
void	 Shutdown(int, int);
int		 Sockatmark(int);
int		 Socket(int, int, int);
void	 Socketpair(int, int, int, int *);
void	 Writen(int, void *, size_t);

void	 err_dump(const char *, ...);
void	 err_msg(const char *, ...);
void	 err_quit(const char *, ...);
void	 err_ret(const char *, ...);
void	 err_sys(const char *, ...);

#endif	/* __unp_h */

    新建一个apue.h，把下面这段粘贴进去

    /*
 * Our own header, to be included before all standard system headers.
 */
#ifndef	_APUE_H
#define	_APUE_H

#define _POSIX_C_SOURCE 200809L

#if defined(SOLARIS)		/* Solaris 10 */
#define _XOPEN_SOURCE 600
#else
#define _XOPEN_SOURCE 700
#endif

#include <sys/types.h>		/* some systems still require this */
#include <sys/stat.h>
#include <sys/termios.h>	/* for winsize */
#if defined(MACOS) || !defined(TIOCGWINSZ)
#include <sys/ioctl.h>
#endif

#include <stdio.h>		/* for convenience */
#include <stdlib.h>		/* for convenience */
#include <stddef.h>		/* for offsetof */
#include <string.h>		/* for convenience */
#include <unistd.h>		/* for convenience */
#include <signal.h>		/* for SIG_ERR */

#define	MAXLINE	4096			/* max line length */

/*
 * Default file access permissions for new files.
 */
#define	FILE_MODE	(S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)

/*
 * Default permissions for new directories.
 */
#define	DIR_MODE	(FILE_MODE | S_IXUSR | S_IXGRP | S_IXOTH)

typedef	void	Sigfunc(int);	/* for signal handlers */

#define	min(a,b)	((a) < (b) ? (a) : (b))
#define	max(a,b)	((a) > (b) ? (a) : (b))

/*
 * Prototypes for our own functions.
 */
char	*path_alloc(size_t *);				/* Prog pathalloc */
long	 open_max(void);					/* Prog openmax */

int		 set_cloexec(int);					/* Prog setfd */
void	 clr_fl(int, int);
void	 set_fl(int, int);					/* Prog setfl */

void	 pr_exit(int);						/* Prog prexit */

void	 pr_mask(const char *);				/* Prog prmask */
Sigfunc	*signal_intr(int, Sigfunc *);		/* Prog signal_intr_function */

void	 daemonize(const char *);			/* Prog daemoninit */

void	 sleep_us(unsigned int);			/* Ex sleepus */
ssize_t	 readn(int, void *, size_t);		/* Prog readn_writen */
ssize_t	 writen(int, const void *, size_t);	/* Prog readn_writen */

int		 fd_pipe(int *);					/* Prog sock_fdpipe */
int		 recv_fd(int, ssize_t (*func)(int,
		         const void *, size_t));	/* Prog recvfd_sockets */
int		 send_fd(int, int);					/* Prog sendfd_sockets */
int		 send_err(int, int,
		          const char *);			/* Prog senderr */
int		 serv_listen(const char *);			/* Prog servlisten_sockets */
int		 serv_accept(int, uid_t *);			/* Prog servaccept_sockets */
int		 cli_conn(const char *);			/* Prog cliconn_sockets */
int		 buf_args(char *, int (*func)(int,
		          char **));				/* Prog bufargs */

int		 tty_cbreak(int);					/* Prog raw */
int		 tty_raw(int);						/* Prog raw */
int		 tty_reset(int);					/* Prog raw */
void	 tty_atexit(void);					/* Prog raw */
struct termios	*tty_termios(void);			/* Prog raw */

int		 ptym_open(char *, int);			/* Prog ptyopen */
int		 ptys_open(char *);					/* Prog ptyopen */
#ifdef	TIOCGWINSZ
pid_t	 pty_fork(int *, char *, int, const struct termios *,
		          const struct winsize *);	/* Prog ptyfork */
#endif

int		lock_reg(int, int, int, off_t, int, off_t); /* Prog lockreg */

#define	read_lock(fd, offset, whence, len) \\
			lock_reg((fd), F_SETLK, F_RDLCK, (offset), (whence), (len))
#define	readw_lock(fd, offset, whence, len) \\
			lock_reg((fd), F_SETLKW, F_RDLCK, (offset), (whence), (len))
#define	write_lock(fd, offset, whence, len) \\
			lock_reg((fd), F_SETLK, F_WRLCK, (offset), (whence), (len))
#define	writew_lock(fd, offset, whence, len) \\
			lock_reg((fd), F_SETLKW, F_WRLCK, (offset), (whence), (len))
#define	un_lock(fd, offset, whence, len) \\
			lock_reg((fd), F_SETLK, F_UNLCK, (offset), (whence), (len))

pid_t	lock_test(int, int, off_t, int, off_t);		/* Prog locktest */

#define	is_read_lockable(fd, offset, whence, len) \\
			(lock_test((fd), F_RDLCK, (offset), (whence), (len)) == 0)
#define	is_write_lockable(fd, offset, whence, len) \\
			(lock_test((fd), F_WRLCK, (offset), (whence), (len)) == 0)

void	err_msg(const char *, ...);			/* App misc_source */
void	err_dump(const char *, ...) __attribute__((noreturn));
void	err_quit(const char *, ...) __attribute__((noreturn));
void	err_cont(int, const char *, ...);
void	err_exit(int, const char *, ...) __attribute__((noreturn));
void	err_ret(const char *, ...);
void	err_sys(const char *, ...) __attribute__((noreturn));

void	log_msg(const char *, ...);			/* App misc_source */
void	log_open(const char *, int, int);
void	log_quit(const char *, ...) __attribute__((noreturn));
void	log_ret(const char *, ...);
void	log_sys(const char *, ...) __attribute__((noreturn));
void	log_exit(int, const char *, ...) __attribute__((noreturn));

void	TELL_WAIT(void);		/* parent/child from Sec race_conditions */
void	TELL_PARENT(pid_t);
void	TELL_CHILD(pid_t);
void	WAIT_PARENT(void);
void	WAIT_CHILD(void);
#include "myerr.c"
#endif	/* _APUE_H */

    再新建一个myerr.c，把下面内容填充进去

    #include "apue.h"
#include <errno.h>		/* for definition of errno */
#include <stdarg.h>		/* ISO C variable aruments */

static void	err_doit(int, int, const char *, va_list);

/*
 * Nonfatal error related to a system call.
 * Print a message and return.
 */
void
err_ret(const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);


/*
 * Fatal error related to a system call.
 * Print a message and terminate.
 */
void
err_sys(const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	exit(1);


/*
 * Nonfatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and return.
 */
void
err_cont(int error, const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, error, fmt, ap);
	va_end(ap);


/*
 * Fatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and terminate.
 */
void
err_exit(int error, const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, error, fmt, ap);
	va_end(ap);
	exit(1);


/*
 * Fatal error related to a system call.
 * Print a message, dump core, and terminate.
 */
void
err_dump(const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	abort();		/* dump core and terminate */
	exit(1);		/* shouldn\'t get here */


/*
 * Nonfatal error unrelated to a system call.
 * Print a message and return.
 */
void
err_msg(const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);


/*
 * Fatal error unrelated to a system call.
 * Print a message and terminate.
 */
void
err_quit(const char *fmt, ...)

	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);
	exit(1);


/*
 * Print a message and return to caller.
 * Caller specifies "errnoflag".
 */
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)

	char	buf[MAXLINE];

	vsnprintf(buf, MAXLINE-1, fmt, ap);
	if (errnoflag)
		snprintf(buf+strlen(buf), MAXLINE-strlen(buf)-1, ": %s",
		  strerror(error));
	strcat(buf, "\\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(NULL);		/* flushes all stdio output streams */

然后编译就成功了

然后运行就失败了

解决方案：

sudo apt-get install xinetd
# sudo yum install xinetd
vi /etc/xinetd.d/daytime

把disable = yes改成disable = no

service daytime

    disable         = no
    type            = INTERNA:L
    id              = daytime-stream
    socket_type     = stream
    protocol        = tcp
    user            = root
    wait            = no

接下来：

sudo service xinetd reload
netstat -a -t | grep daytime # 确认服务正在运行

如果不行，报错了，就看看这篇照着做肯定行https://www.cnblogs.com/yewandemty/p/5396391.html（一般centOS可能会报错，Ubuntu一般不会报错）

照着做完之后代码运行成功：

我运行的代码：

#include    "unp.h"  
  
int  
main(int argc, char **argv)  
  
    int                 sockfd, 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);

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