由于前面已有介绍，关于函数就不介绍了

/*server.c_非阻塞式*/

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define SIZE 512

int sock_bind(int lisfd, int port)

{

struct sockaddr_in myaddr;

memset((char *)&myaddr, 0, sizeof(struct sockaddr_in));//清零

myaddr.sin_family = AF_INET;//IPV4

myaddr.sin_port = htons(port);//端口

myaddr.sin_addr.s_addr = htonl(INADDR_ANY);//允许连接到所有本地地址上

if (bind(lisfd, (struct sockaddr *)&myaddr, sizeof(struct sockaddr))==-1)

{

perror("sock_bind failed!\n");

exit(1);

}

return 0;

}

int main(int argc, char **argv)

{

if (argc != 2)

{

printf("Usage: %s \n", argv[0]);

exit(1);

}

int lisfd;

int i;

int flag;

int nbytes;

socklen_t len;

char msg[SIZE];

struct sockaddr_in cliaddr;

bzero(msg, SIZE);

len = sizeof(cliaddr);

bzero(&cliaddr, sizeof(cliaddr));

lisfd = socket(AF_INET, SOCK_DGRAM, 0);

if (lisfd == -1)

{

perror("socket failed.\n");

exit(1);

}

sock_bind(lisfd, atoi(argv[1]));

flag = fcntl(lisfd, F_GETFL, 0);

if (flag < 0)

{

perror("fcntl failed.\n");

exit(1);

}

flag |= O_NONBLOCK;

if (fcntl(lisfd, F_SETFL, flag) < 0)

{

perror("fcntl failed.\n");

exit(1);

}

while(1)

{

nbytes = recvfrom(lisfd, msg, SIZE, 0, (struct sockaddr *)&cliaddr, &len);

if (nbytes == -1 && errno != EAGAIN)

{

perror("recv failed.\n");

exit(1);

}else if (nbytes == 0 || (nbytes==-1 && errno==EAGAIN))

{

continue;

}else

{

printf("recv: %s\n", msg);

}

for (i=0; i

{

msg[i] = toupper(msg[i]);

}

nbytes = sendto(lisfd, msg, sizeof(msg), 0, (struct sockaddr *)&cliaddr, len);//udp发送要指定IP和端口

if (nbytes == -1 && errno != EAGAIN)

{

perror("recv failed.\n");

exit(1);

}

}

close(lisfd);

return 0;

}

/*server.c_阻塞式*/

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define SIZE 512

int sock_bind(int lisfd, int port)

{

struct sockaddr_in myaddr;

memset((char *)&myaddr, 0, sizeof(struct sockaddr_in));//清零

myaddr.sin_family = AF_INET;//IPV4

myaddr.sin_port = htons(port);//端口

myaddr.sin_addr.s_addr = htonl(INADDR_ANY);//允许连接到所有本地地址上

if (bind(lisfd, (struct sockaddr *)&myaddr, sizeof(struct sockaddr))==-1)

{

perror("sock_bind failed!\n");

exit(1);

}

return 0;

}

int main(int argc, char **argv)

{

if (argc != 2)

{

printf("Usage: %s \n", argv[0]);

exit(1);

}

int lisfd;

int i;

socklen_t len;

char msg[SIZE];

struct sockaddr_in cliaddr;

bzero(msg, SIZE);

len = sizeof(cliaddr);

bzero(&cliaddr, sizeof(cliaddr));

lisfd = socket(AF_INET, SOCK_DGRAM, 0);

if (lisfd == -1)

{

perror("socket failed.\n");

exit(1);

}

sock_bind(lisfd, atoi(argv[1]));

while(1)

{

recvfrom(lisfd, msg, SIZE, 0, (struct sockaddr *)&cliaddr, &len);

printf("recv: %s\n", msg);

for (i=0; i

{

msg[i] = toupper(msg[i]);

}

sendto(lisfd, msg, sizeof(msg), 0, (struct sockaddr *)&cliaddr, len);//udp发送要指定IP和端口

}

close(lisfd);

return 0;

}

/*client.c*/

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define SIZE 512

int main(int argc, char **argv)

{

struct sockaddr_in remoaddr;

struct sockaddr_in localaddr;

if (argc != 3)

{

printf("Usage: %s \n", argv[0]);

exit(1);

}

int sockfd;

char msg[SIZE];

socklen_t len;

bzero(msg, SIZE);

sockfd = socket(AF_INET, SOCK_DGRAM, 0);

len = sizeof(localaddr);

remoaddr.sin_family = AF_INET;

remoaddr.sin_port = htons(atoi(argv[2]));

if (inet_pton(AF_INET, argv[1], &remoaddr.sin_addr)<0)

{

perror("inet_pton failed.\n");

exit(1);

}

while(fgets(msg, SIZE, stdin) != NULL)

{

sendto(sockfd, msg, SIZE, 0, (struct sockaddr *)&remoaddr, len);//udp发送要指定IP和端口

recvfrom(sockfd, msg, SIZE, 0, (struct sockaddr *)&localaddr, &len);

printf("recv: %s\n", msg);

}

close(sockfd);

return 0;

}

#makefile

CFLAGS = -Wall -g

CC = gcc

TARGET1 = server

TARGET2 = client

all:$(TARGET1) $(TARGET2)

$(TARGET1):$(TARGET1).o

$(CC) $(CFLAGS) -o $@ $^

$(TARGET2):$(TARGET2).o

$(CC) $(CFLAGS) -o $@ $^

%.o:%.c %.h

$(CC) -c $(CFLAGS) -o $@ $<

clean:

rm -f $(TARGET1) $(TARGET2) *.o