Linux 网络编程六（socket通信UDP版）

//udp接收消息
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int arg, char * args[])
{
    if (arg < 3)
    {
        printf("please print two param!\n");
        return -1;
    }
    int port = atoi(args[2]);
    //create socket
    int st = socket(AF_INET, SOCK_DGRAM, 0);
    if (st == -1)
    {
        printf("create socket failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    //UDP广播必须设置socket属性
    /*
    int on = 1;
    if (setsockopt(st, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) == -1)
    {
        printf("setsockopt failed ! error message :%s\n", strerror(errno));
        return -1;
    }
    */
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    //设置结构sockaddr_in类型是TCP/IP
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = inet_addr(args[1]);
    char buf[1024] = { 0 };
    while (1)
    {
        //read
        read(STDIN_FILENO, buf, sizeof(buf));
        if (sendto(st, buf, strlen(buf), 0, (struct sockaddr *) &addr,
                sizeof(addr)) == -1)
        {
            printf("sendto failed ! error message :%s\n", strerror(errno));
            break;
        }
        memset(buf,0,sizeof(buf));
    }
    close(st);
    return 0;
}

//udp接收消息
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(int arg, char * args[])
{
    if(arg<2)
    {
        printf("please print one param !\n");
        return -1;
    }
    int st=socket(AF_INET,SOCK_DGRAM,0);
    if(st==-1)
    {
        printf("open socket failed ! error message : %s\n",strerror(errno));
        return -1;
    }
    int port=atoi(args[1]);
    //defien ip address strcut
    struct sockaddr_in addr;
    //define addr type
    addr.sin_family=AF_INET;
    addr.sin_port=htons(port);
    addr.sin_addr.s_addr=htonl(INADDR_ANY);
    //bind port
    if(bind(st,(struct sockaddr *)&addr,sizeof(addr))==-1)
    {
        printf("bind IP failed ! error message : %s\n",strerror(errno));
        goto END;
    }
    char buf[1024]={0};
    struct sockaddr_in client_addr;
    socklen_t addrlen=sizeof(client_addr);
    while(1)
    {
        memset(&client_addr,0,sizeof(client_addr));
        if(recvfrom(st,buf,sizeof(buf),0,(struct sockaddr *)&client_addr,&addrlen)==-1)
        {
            printf("recvfrom failed ! error message : %s\n",strerror(errno));
            goto END;
        }else
        {
            printf("from %s:%s",inet_ntoa(client_addr.sin_addr),buf);
        }
        memset(buf,0,sizeof(buf));
    }
    END:close(st);
    return 0;
}

.SUFFIXES:.c .o
CC=gcc
SRCS1=udpsend.c
SRCS2=udprecv.c
OBJS1=$(SRCS1:.c=.o)
OBJS2=$(SRCS2:.c=.o)
EXEC1=msend
EXEC2=mrecv

start:$(OBJS1) $(OBJS2)
    $(CC) -o $(EXEC1) $(OBJS1)
    $(CC) -o $(EXEC2) $(OBJS2)
    @echo "-------ok-----------"
.c.o:
    $(CC) -Wall -g -o $@ -c $<
clean:
    rm -f $(OBJS1)
    rm -f $(EXEC1)
    rm -f $(OBJS2)
    rm -f $(EXEC2)