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Unix网络编程代码第8章基本UDP套接字编程

2013年10月08日 ⁄ 综合 ⁄ 共 27690字 ⁄ 字号小中大 ⁄ 评论关闭

文章目录

8.13.1 写固定数目的数据报的客户端
8.13.2 对接收数目进行计数的服务器端
8.13.3 增大套接字接收队列大小

第8章基本UDP套接字编程

8.3 UDP回射服务器程序

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<string.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<errno.h>
#include	<stdarg.h>	/* ANSI C header file */
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (bind(fd, sa, salen) < 0)
		err_sys("bind error");
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr *sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

void dg_echo(int sockfd, SA * pcliaddr, socklen_t clilen)
{
	int n;
	socklen_t len;
	char mesg[MAXLINE];

	for (;;) {
		len = clilen;
		n = Recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);

		Sendto(sockfd, mesg, n, 0, pcliaddr, len);
	}
}

int main()
{
	int sockfd;
	struct sockaddr_in servaddr, cliaddr;

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);

	Bind(sockfd, (SA *) & servaddr, sizeof(servaddr));

	dg_echo(sockfd, (SA *) & cliaddr, sizeof(cliaddr));
}

8.5 UDP回射客户程序

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<stdarg.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<string.h>
#include	<errno.h>
#include	<arpa/inet.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

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

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Inet_pton(int family, const char *strptr, void *addrptr)
{
	int n;

	if ((n = inet_pton(family, strptr, addrptr)) < 0)
		err_sys("inet_pton error for %s", strptr);	/* errno set */
	else if (n == 0)
		err_quit("inet_pton error for %s", strptr);	/* errno not set */

	/* nothing to return */
}

char *Fgets(char *ptr, int n, FILE * stream)
{
	char *rptr;

	if ((rptr = fgets(ptr, n, stream)) == NULL && ferror(stream))
		err_sys("fgets error");

	return (rptr);
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr * sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

void Fputs(const char *ptr, FILE * stream)
{
	if (fputs(ptr, stream) == EOF)
		err_sys("fputs error");
}

void dg_cli(FILE * fp, int sockfd, const SA * pservaddr, socklen_t servlen)
{
	int n;
	char sendline[MAXLINE], recvline[MAXLINE + 1];

	while (Fgets(sendline, MAXLINE, fp) != NULL) {

		Sendto(sockfd, sendline, strlen(sendline), 0, pservaddr,
		       servlen);

		n = Recvfrom(sockfd, recvline, MAXLINE, 0, NULL, NULL);

		recvline[n] = 0;	/* null terminate */
		Fputs(recvline, stdout);
	}
}

int main(int argc, char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;

	if (argc != 2)
		err_quit("usage: udpcli <IPaddress>");

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT);
	Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	dg_cli(stdin, sockfd, (SA *) & servaddr, sizeof(servaddr));

	exit(0);
}

8.8 验证接收到的响应

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<sys/un.h>
#include	<stdarg.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<string.h>
#include	<errno.h>
#include	<arpa/inet.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

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

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Inet_pton(int family, const char *strptr, void *addrptr)
{
	int n;

	if ((n = inet_pton(family, strptr, addrptr)) < 0)
		err_sys("inet_pton error for %s", strptr);	/* errno set */
	else if (n == 0)
		err_quit("inet_pton error for %s", strptr);	/* errno not set */

	/* nothing to return */
}

char *Fgets(char *ptr, int n, FILE * stream)
{
	char *rptr;

	if ((rptr = fgets(ptr, n, stream)) == NULL && ferror(stream))
		err_sys("fgets error");

	return (rptr);
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr * sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

void Fputs(const char *ptr, FILE * stream)
{
	if (fputs(ptr, stream) == EOF)
		err_sys("fputs error");
}

void *Malloc(size_t size)
{
	void *ptr;

	if ((ptr = malloc(size)) == NULL)
		err_sys("malloc error");
	return (ptr);
}

char *sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char portstr[8];
	static char str[128];	/* Unix domain is largest */

	switch (sa->sa_family) {
	case AF_INET:{
			struct sockaddr_in *sin = (struct sockaddr_in *)sa;

			if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str))
			    == NULL)
				return (NULL);
			if (ntohs(sin->sin_port) != 0) {
				snprintf(portstr, sizeof(portstr), ":%d",
					 ntohs(sin->sin_port));
				strcat(str, portstr);
			}
			return (str);
		}
		/* end sock_ntop */

#ifdef	IPV6
	case AF_INET6:{
			struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;

			str[0] = '[';
			if (inet_ntop
			    (AF_INET6, &sin6->sin6_addr, str + 1,
			     sizeof(str) - 1) == NULL)
				return (NULL);
			if (ntohs(sin6->sin6_port) != 0) {
				snprintf(portstr, sizeof(portstr), "]:%d",
					 ntohs(sin6->sin6_port));
				strcat(str, portstr);
				return (str);
			}
			return (str + 1);
		}
#endif

#ifdef	AF_UNIX
	case AF_UNIX:{
			struct sockaddr_un *unp = (struct sockaddr_un *)sa;

			/* OK to have no pathname bound to the socket: happens on
			   every connect() unless client calls bind() first. */
			if (unp->sun_path[0] == 0)
				strcpy(str, "(no pathname bound)");
			else
				snprintf(str, sizeof(str), "%s", unp->sun_path);
			return (str);
		}
#endif

#ifdef	HAVE_SOCKADDR_DL_STRUCT
	case AF_LINK:{
			struct sockaddr_dl *sdl = (struct sockaddr_dl *)sa;

			if (sdl->sdl_nlen > 0)
				snprintf(str, sizeof(str), "%*s (index %d)",
					 sdl->sdl_nlen, &sdl->sdl_data[0],
					 sdl->sdl_index);
			else
				snprintf(str, sizeof(str), "AF_LINK, index=%d",
					 sdl->sdl_index);
			return (str);
		}
#endif
	default:
		snprintf(str, sizeof(str),
			 "sock_ntop: unknown AF_xxx: %d, len %d", sa->sa_family,
			 salen);
		return (str);
	}
	return (NULL);
}

char *Sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char *ptr;

	if ((ptr = sock_ntop(sa, salen)) == NULL)
		err_sys("sock_ntop error");	/* inet_ntop() sets errno */
	return (ptr);
}

void dg_cli(FILE * fp, int sockfd, const SA * pservaddr, socklen_t servlen)
{
	int n;
	char sendline[MAXLINE], recvline[MAXLINE + 1];
	socklen_t len;
	struct sockaddr *preply_addr;

	preply_addr = (struct sockaddr *)Malloc(servlen);

	while (Fgets(sendline, MAXLINE, fp) != NULL) {

		Sendto(sockfd, sendline, strlen(sendline), 0, pservaddr,
		       servlen);

		len = servlen;
		n = Recvfrom(sockfd, recvline, MAXLINE, 0, preply_addr, &len);
		if (len != servlen || memcmp(pservaddr, preply_addr, len) != 0) {
			printf("reply from %s (ignored)\n",
			       Sock_ntop(preply_addr, len));
			continue;
		}

		recvline[n] = 0;	/* null terminate */
		Fputs(recvline, stdout);
	}
}

int main(int argc, char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;

	if (argc != 2)
		err_quit("usage: udpcli <IPaddress>");

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT);
	Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	dg_cli(stdin, sockfd, (SA *) & servaddr, sizeof(servaddr));

	exit(0);
}

8.12 dg_cli函数（修订版）

//调用connect版本
//运行结果跟书上不符：向一个不可达的主机发起连接，没有返回连接拒绝的错误，read永远阻塞
#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<stdarg.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<string.h>
#include	<errno.h>
#include	<arpa/inet.h>
#include	<unistd.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

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

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Inet_pton(int family, const char *strptr, void *addrptr)
{
	int n;

	if ((n = inet_pton(family, strptr, addrptr)) < 0)
		err_sys("inet_pton error for %s", strptr);	/* errno set */
	else if (n == 0)
		err_quit("inet_pton error for %s", strptr);	/* errno not set */

	/* nothing to return */
}

char *Fgets(char *ptr, int n, FILE * stream)
{
	char *rptr;

	if ((rptr = fgets(ptr, n, stream)) == NULL && ferror(stream))
		err_sys("fgets error");

	return (rptr);
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr * sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

void Fputs(const char *ptr, FILE * stream)
{
	if (fputs(ptr, stream) == EOF)
		err_sys("fputs error");
}

void Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (connect(fd, sa, salen) < 0)
		err_sys("connect error");
}

void Write(int fd, void *ptr, int nbytes)
{
	if (write(fd, ptr, nbytes) != nbytes)
		err_sys("write error");
}

ssize_t Read(int fd, void *ptr, size_t nbytes)
{
	ssize_t n;

	if ((n = read(fd, ptr, nbytes)) == -1)
		err_sys("read error");
	return (n);
}

void dg_cli(FILE * fp, int sockfd, const SA * pservaddr, socklen_t servlen)
{
	int n;
	char sendline[MAXLINE], recvline[MAXLINE + 1];

	Connect(sockfd, (SA *) pservaddr, servlen);

	while (Fgets(sendline, MAXLINE, fp) != NULL) {

		Write(sockfd, sendline, strlen(sendline));

		n = Read(sockfd, recvline, MAXLINE);

		recvline[n] = 0;	/* null terminate */
		Fputs(recvline, stdout);
	}
}

int main(int argc, char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;

	if (argc != 2)
		err_quit("usage: udpcli <IPaddress>");

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT);
	Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	dg_cli(stdin, sockfd, (SA *) & servaddr, sizeof(servaddr));

	exit(0);
}

8.13 UDP缺乏流量控制

8.13.1 写固定数目的数据报的客户端

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<stdarg.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<string.h>
#include	<errno.h>
#include	<arpa/inet.h>
#include	<unistd.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

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

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Inet_pton(int family, const char *strptr, void *addrptr)
{
	int n;

	if ((n = inet_pton(family, strptr, addrptr)) < 0)
		err_sys("inet_pton error for %s", strptr);	/* errno set */
	else if (n == 0)
		err_quit("inet_pton error for %s", strptr);	/* errno not set */

	/* nothing to return */
}

char *Fgets(char *ptr, int n, FILE * stream)
{
	char *rptr;

	if ((rptr = fgets(ptr, n, stream)) == NULL && ferror(stream))
		err_sys("fgets error");

	return (rptr);
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr * sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

#define	NDG		2000	/* datagrams to send */
#define	DGLEN	1400		/* length of each datagram */
void dg_cli(FILE * fp, int sockfd, const SA * pservaddr, socklen_t servlen)
{
	int i;
	char sendline[DGLEN];

	for (i = 0; i < NDG; i++) {
		Sendto(sockfd, sendline, DGLEN, 0, pservaddr, servlen);
	}
}

int main(int argc, char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;

	if (argc != 2)
		err_quit("usage: udpcli <IPaddress>");

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT);
	Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	dg_cli(stdin, sockfd, (SA *) & servaddr, sizeof(servaddr));

	exit(0);
}

8.13.2 对接收数目进行计数的服务器端

#define _POSIX_SOURCE
#include	<strings.h>
#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<string.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<errno.h>
#include	<stdarg.h>	/* ANSI C header file */
#include	<signal.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
typedef void Sigfunc(int);	/* for signal handlers */
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (bind(fd, sa, salen) < 0)
		err_sys("bind error");
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr *sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

static int count;
void recvfrom_int(int signo)
{
	printf("\nreceived %d datagrams\n", count);
	exit(0);
}

Sigfunc *signal(int signo, Sigfunc * func)
{
	struct sigaction act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	if (signo == SIGALRM) {
#ifdef	SA_INTERRUPT
		act.sa_flags |= SA_INTERRUPT;	/* SunOS 4.x */
#endif
	} else {
#ifdef	SA_RESTART
		act.sa_flags |= SA_RESTART;	/* SVR4, 44BSD */
#endif
	}
	if (sigaction(signo, &act, &oact) < 0)
		return (SIG_ERR);
	return (oact.sa_handler);
}

Sigfunc *Signal(int signo, Sigfunc * func)
{				/* for our signal() function */
	Sigfunc *sigfunc;

	if ((sigfunc = signal(signo, func)) == SIG_ERR)
		err_sys("signal error");
	return (sigfunc);
}

void dg_echo(int sockfd, SA * pcliaddr, socklen_t clilen)
{
	socklen_t len;
	char mesg[MAXLINE];

	Signal(SIGINT, recvfrom_int);

	for (;;) {
		len = clilen;
		Recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);

		count++;
	}
}

int main()
{
	int sockfd;
	struct sockaddr_in servaddr, cliaddr;

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);

	Bind(sockfd, (SA *) & servaddr, sizeof(servaddr));

	dg_echo(sockfd, (SA *) & cliaddr, sizeof(cliaddr));
}

8.13.3 增大套接字接收队列大小

#define _POSIX_SOURCE
#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<string.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<errno.h>
#include	<stdarg.h>	/* ANSI C header file */
#include	<signal.h>
#include	<strings.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
typedef void Sigfunc(int);	/* for signal handlers */
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (bind(fd, sa, salen) < 0)
		err_sys("bind error");
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr *sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

static int count;
void recvfrom_int(int signo)
{
	printf("\nreceived %d datagrams\n", count);
	exit(0);
}

Sigfunc *signal(int signo, Sigfunc * func)
{
	struct sigaction act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	if (signo == SIGALRM) {
#ifdef	SA_INTERRUPT
		act.sa_flags |= SA_INTERRUPT;	/* SunOS 4.x */
#endif
	} else {
#ifdef	SA_RESTART
		act.sa_flags |= SA_RESTART;	/* SVR4, 44BSD */
#endif
	}
	if (sigaction(signo, &act, &oact) < 0)
		return (SIG_ERR);
	return (oact.sa_handler);
}

Sigfunc *Signal(int signo, Sigfunc * func)
{				/* for our signal() function */
	Sigfunc *sigfunc;

	if ((sigfunc = signal(signo, func)) == SIG_ERR)
		err_sys("signal error");
	return (sigfunc);
}

void Setsockopt(int fd, int level, int optname, const void *optval,
		socklen_t optlen)
{
	if (setsockopt(fd, level, optname, optval, optlen) < 0)
		err_sys("setsockopt error");
}

void dg_echo(int sockfd, SA * pcliaddr, socklen_t clilen)
{
	int n;
	socklen_t len;
	char mesg[MAXLINE];

	Signal(SIGINT, recvfrom_int);

	n = 220 * 1024;
	Setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n));

	for (;;) {
		len = clilen;
		Recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);

		count++;
	}
}

int main()
{
	int sockfd;
	struct sockaddr_in servaddr, cliaddr;

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);

	Bind(sockfd, (SA *) & servaddr, sizeof(servaddr));

	dg_echo(sockfd, (SA *) & cliaddr, sizeof(cliaddr));
}

8.14 UDP中的外出接口的确定

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<stdarg.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<string.h>
#include	<errno.h>
#include	<arpa/inet.h>
#include	<unistd.h>
#include	<sys/un.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	SA	struct sockaddr
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_quit(const char *fmt, ...)
{
	va_list ap;

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

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Inet_pton(int family, const char *strptr, void *addrptr)
{
	int n;

	if ((n = inet_pton(family, strptr, addrptr)) < 0)
		err_sys("inet_pton error for %s", strptr);	/* errno set */
	else if (n == 0)
		err_quit("inet_pton error for %s", strptr);	/* errno not set */

	/* nothing to return */
}

char *Fgets(char *ptr, int n, FILE * stream)
{
	char *rptr;

	if ((rptr = fgets(ptr, n, stream)) == NULL && ferror(stream))
		err_sys("fgets error");

	return (rptr);
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr * sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

void Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (connect(fd, sa, salen) < 0)
		err_sys("connect error");
}

void Getsockname(int fd, struct sockaddr *sa, socklen_t * salenptr)
{
	if (getsockname(fd, sa, salenptr) < 0)
		err_sys("getsockname error");
}

char *sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char portstr[8];
	static char str[128];	/* Unix domain is largest */

	switch (sa->sa_family) {
	case AF_INET:{
			struct sockaddr_in *sin = (struct sockaddr_in *)sa;

			if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str))
			    == NULL)
				return (NULL);
			if (ntohs(sin->sin_port) != 0) {
				snprintf(portstr, sizeof(portstr), ":%d",
					 ntohs(sin->sin_port));
				strcat(str, portstr);
			}
			return (str);
		}
		/* end sock_ntop */

#ifdef	IPV6
	case AF_INET6:{
			struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;

			str[0] = '[';
			if (inet_ntop
			    (AF_INET6, &sin6->sin6_addr, str + 1,
			     sizeof(str) - 1) == NULL)
				return (NULL);
			if (ntohs(sin6->sin6_port) != 0) {
				snprintf(portstr, sizeof(portstr), "]:%d",
					 ntohs(sin6->sin6_port));
				strcat(str, portstr);
				return (str);
			}
			return (str + 1);
		}
#endif

#ifdef	AF_UNIX
	case AF_UNIX:{
			struct sockaddr_un *unp = (struct sockaddr_un *)sa;

			/* OK to have no pathname bound to the socket: happens on
			   every connect() unless client calls bind() first. */
			if (unp->sun_path[0] == 0)
				strcpy(str, "(no pathname bound)");
			else
				snprintf(str, sizeof(str), "%s", unp->sun_path);
			return (str);
		}
#endif

#ifdef	HAVE_SOCKADDR_DL_STRUCT
	case AF_LINK:{
			struct sockaddr_dl *sdl = (struct sockaddr_dl *)sa;

			if (sdl->sdl_nlen > 0)
				snprintf(str, sizeof(str), "%*s (index %d)",
					 sdl->sdl_nlen, &sdl->sdl_data[0],
					 sdl->sdl_index);
			else
				snprintf(str, sizeof(str), "AF_LINK, index=%d",
					 sdl->sdl_index);
			return (str);
		}
#endif
	default:
		snprintf(str, sizeof(str),
			 "sock_ntop: unknown AF_xxx: %d, len %d", sa->sa_family,
			 salen);
		return (str);
	}
	return (NULL);
}

char *Sock_ntop(const struct sockaddr *sa, socklen_t salen)
{
	char *ptr;

	if ((ptr = sock_ntop(sa, salen)) == NULL)
		err_sys("sock_ntop error");	/* inet_ntop() sets errno */
	return (ptr);
}

int main(int argc, char **argv)
{
	int sockfd;
	socklen_t len;
	struct sockaddr_in cliaddr, servaddr;

	if (argc != 2)
		err_quit("usage: udpcli <IPaddress>");

	sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(SERV_PORT);
	Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

	Connect(sockfd, (SA *) & servaddr, sizeof(servaddr));

	len = sizeof(cliaddr);
	Getsockname(sockfd, (SA *) & cliaddr, &len);
	printf("local address %s\n", Sock_ntop((SA *) & cliaddr, len));

	exit(0);
}

8.15 使用select函数的TCP和UDP回射服务器程序

#include	<netinet/in.h>	/* sockaddr_in{} and other Internet defns */
#include	<strings.h>
#include	<sys/select.h>
#include	<string.h>
#include	<stdlib.h>
#include	<stdio.h>
#include	<errno.h>
#include	<stdarg.h>	/* ANSI C header file */
#include	<signal.h>
#include	<unistd.h>
#include	<sys/wait.h>
#define	MAXLINE		4096	/* max text line length */
#define	SERV_PORT		 9877	/* TCP and UDP */
#define	LISTENQ		1024	/* 2nd argument to listen() */
#define	max(a,b)	((a) > (b) ? (a) : (b))
#define	SA	struct sockaddr
typedef void Sigfunc(int);	/* for signal handlers */
void err_doit(int errnoflag, const char *fmt, va_list ap)
{
	int errno_save;
	char buf[MAXLINE];

	errno_save = errno;	/* value caller might want printed */
	vsprintf(buf, fmt, ap);
	if (errnoflag)
		sprintf(buf + strlen(buf), ": %s", strerror(errno_save));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(stderr);		/* SunOS 4.1.* doesn't grok NULL argument */
	return;
}

void err_sys(const char *fmt, ...)
{
	va_list ap;

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

int Socket(int family, int type, int protocol)
{
	int n;

	if ((n = socket(family, type, protocol)) < 0)
		err_sys("socket error");
	return (n);
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
	if (bind(fd, sa, salen) < 0)
		err_sys("bind error");
}

ssize_t Recvfrom(int fd, void *ptr, size_t nbytes, int flags,
		 struct sockaddr *sa, socklen_t * salenptr)
{
	ssize_t n;

	if ((n = recvfrom(fd, ptr, nbytes, flags, sa, salenptr)) < 0)
		err_sys("recvfrom error");
	return (n);
}

void Sendto(int fd, const void *ptr, size_t nbytes, int flags,
	    const struct sockaddr *sa, socklen_t salen)
{
	if (sendto(fd, ptr, nbytes, flags, sa, salen) != (ssize_t) nbytes)
		err_sys("sendto error");
}

Sigfunc *Signal(int signo, Sigfunc * func)
{				/* for our signal() function */
	Sigfunc *sigfunc;

	if ((sigfunc = signal(signo, func)) == SIG_ERR)
		err_sys("signal error");
	return (sigfunc);
}

void Setsockopt(int fd, int level, int optname, const void *optval,
		socklen_t optlen)
{
	if (setsockopt(fd, level, optname, optval, optlen) < 0)
		err_sys("setsockopt error");
}

void Listen(int fd, int backlog)
{
	char *ptr;

	/*4can override 2nd argument with environment variable */
	if ((ptr = getenv("LISTENQ")) != NULL)
		backlog = atoi(ptr);

	if (listen(fd, backlog) < 0)
		err_sys("listen error");
}

int Accept(int fd, struct sockaddr *sa, socklen_t * salenptr)
{
	int n;

 again:
	if ((n = accept(fd, sa, salenptr)) < 0) {
#ifdef	EPROTO
		if (errno == EPROTO || errno == ECONNABORTED)
#else
		if (errno == ECONNABORTED)
#endif
			goto again;
		else
			err_sys("accept error");
	}
	return (n);
}

pid_t Fork(void)
{
	pid_t pid;

	if ((pid = fork()) == -1)
		err_sys("fork error");
	return (pid);
}

void Close(int fd)
{
	if (close(fd) == -1)
		err_sys("close error");
}

ssize_t writen(int fd, const void *vptr, size_t n)
{
	size_t nleft;
	ssize_t nwritten;
	const char *ptr;

	ptr = (const char *)vptr;
	nleft = n;
	while (nleft > 0) {
		if ((nwritten = write(fd, ptr, nleft)) <= 0) {
			if (nwritten < 0 && errno == EINTR)
				nwritten = 0;	/* and call write() again */
			else
				return (-1);	/* error */
		}

		nleft -= nwritten;
		ptr += nwritten;
	}
	return (n);
}

void Writen(int fd, void *ptr, int nbytes)
{
	if (writen(fd, ptr, nbytes) != nbytes)
		err_sys("writen error");
}

void str_echo(int sockfd)
{
	ssize_t n;
	char buf[MAXLINE];

 again:
	while ((n = read(sockfd, buf, MAXLINE)) > 0)
		Writen(sockfd, buf, n);

	if (n < 0 && errno == EINTR)
		goto again;
	else if (n < 0)
		err_sys("str_echo: read error");
}

void sig_chld(int signo)
{
	pid_t pid;
	int stat;

	while ((pid = waitpid(-1, &stat, WNOHANG)) > 0)
		printf("child %d terminated\n", pid);
	return;
}

int main()
{
	int listenfd, connfd, udpfd, nready, maxfdp1;
	char mesg[MAXLINE];
	pid_t childpid;
	fd_set rset;
	ssize_t n;
	socklen_t len;
	const int on = 1;
	struct sockaddr_in cliaddr, servaddr;

	/* 4create listening TCP socket */
	listenfd = Socket(AF_INET, SOCK_STREAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);

	Setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
	Bind(listenfd, (SA *) & servaddr, sizeof(servaddr));

	Listen(listenfd, LISTENQ);

	/* 4create UDP socket */
	udpfd = Socket(AF_INET, SOCK_DGRAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);

	Bind(udpfd, (SA *) & servaddr, sizeof(servaddr));
	/* end udpservselect01 */

	/* include udpservselect02 */
	Signal(SIGCHLD, sig_chld);	/* must call waitpid() */

	FD_ZERO(&rset);
	maxfdp1 = max(listenfd, udpfd) + 1;
	for (;;) {
		FD_SET(listenfd, &rset);
		FD_SET(udpfd, &rset);
		if ((nready = select(maxfdp1, &rset, NULL, NULL, NULL)) < 0) {
			if (errno == EINTR)
				continue;	/* back to for() */
			else
				err_sys("select error");
		}

		if (FD_ISSET(listenfd, &rset)) {
			len = sizeof(cliaddr);
			connfd = Accept(listenfd, (SA *) & cliaddr, &len);

			if ((childpid = Fork()) == 0) {	/* child process */
				Close(listenfd);	/* close listening socket */
				str_echo(connfd);	/* process the request */
				exit(0);
			}
			Close(connfd);	/* parent closes connected socket */
		}

		if (FD_ISSET(udpfd, &rset)) {
			len = sizeof(cliaddr);
			n = Recvfrom(udpfd, mesg, MAXLINE, 0, (SA *) & cliaddr,
				     &len);

			Sendto(udpfd, mesg, n, 0, (SA *) & cliaddr, len);
		}
	}
}

【上篇】关于C++的几个预处理命令
【下篇】[tamarin系列之3] ASC编译器命令行基础

作者: bluebird4

该日志由 bluebird4 于11年前发表在综合分类下，最后更新于 2013年10月08日.
转载请注明: Unix网络编程代码第8章基本UDP套接字编程 | 学步园 +复制链接

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学步园

Unix网络编程代码第8章基本UDP套接字编程

第8章基本UDP套接字编程

8.3 UDP回射服务器程序

8.5 UDP回射客户程序

8.8 验证接收到的响应

8.12 dg_cli函数（修订版）

8.13 UDP缺乏流量控制

8.13.1 写固定数目的数据报的客户端

8.13.2 对接收数目进行计数的服务器端

8.13.3 增大套接字接收队列大小

8.14 UDP中的外出接口的确定

8.15 使用select函数的TCP和UDP回射服务器程序

作者: bluebird4

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学步园

Unix网络编程代码 第8章 基本UDP套接字编程

第8章 基本UDP套接字编程

8.3 UDP回射服务器程序

8.5 UDP回射客户程序

8.8 验证接收到的响应

8.12 dg_cli函数（修订版）

8.13 UDP缺乏流量控制

8.13.1 写固定数目的数据报的客户端

8.13.2 对接收数目进行计数的服务器端

8.13.3 增大套接字接收队列大小

8.14 UDP中的外出接口的确定

8.15 使用select函数的TCP和UDP回射服务器程序

作者: bluebird4

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Unix网络编程代码第8章基本UDP套接字编程

第8章基本UDP套接字编程