socketclientudp.c

基于嵌入式linux下

#include <stdio.h>      /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket(), connect(), sendto(), and recvfrom() */
#include <arpa/inet.h>  /* for sockaddr_in and inet_addr() */
#include <stdlib.h>     /* for atoi() and exit() */
#include <string.h>     /* for memset() */
#include <unistd.h>     /* for close() */

#define ECHOMAX 255     /* Longest string to echo */

//void DieWithError(char "message can't b sent");  /* External error handling function */

int main(int argc, char *argv[])
{
    int sock;                        /* Socket descriptor */
    struct sockaddr_in echoServAddr; /* Echo server address */
    struct sockaddr_in fromAddr;     /* Source address of echo */
    unsigned short echoServPort;     /* Echo server port */
    unsigned int fromSize;           /* In-out of address size for recvfrom() */
    char *servIP;                    /* IP address of server */
    char *echoString;                /* String to send to echo server */
    char echoBuffer[ECHOMAX+1];      /* Buffer for receiving echoed string */
    int echoStringLen;               /* Length of string to echo */
    int respStringLen;               /* Length of received response */
    
    

    if ((argc < 3) || (argc > 4))    /* Test for correct number of arguments */
    {
        fprintf(stderr,"Usage: %s <Server IP> <Echo Word> [<Echo Port>]\n", argv[0]);
        //exit(1);
    }

	
	servIP="192.168.0.138";
	echoString="你好！啊";
	
	printf("servIP:%s\r\n",servIP);
    printf("echoString:%s\r\n",echoString);
    
    //servIP = argv[1];           /* First arg: server IP address (dotted quad) */
    //echoString = argv[2];       /* Second arg: string to echo */

    if ((echoStringLen = strlen(echoString)) > ECHOMAX)  /* Check input length */
        printf("word too length!\r\n");

    echoServPort = 8000;  /* 7 is the well-known port for the echo service */

    /* Create a datagram/UDP socket */
    if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
        printf("socket fail!\r\n");

    /* Construct the server address structure */
    memset(&echoServAddr, 0, sizeof(echoServAddr));    /* Zero out structure */
    echoServAddr.sin_family = AF_INET;                 /* Internet addr family */
    echoServAddr.sin_addr.s_addr = inet_addr(servIP);  /* Server IP address */
    echoServAddr.sin_port   = htons(echoServPort);     /* Server port */

    /* Send the string to the server */
    if (sendto(sock, echoString, echoStringLen, 0, (struct sockaddr *)
               &echoServAddr, sizeof(echoServAddr)) != echoStringLen)
        printf("sendto fail!\r\n");
  
    /* Recv a response */
    fromSize = sizeof(fromAddr);
    if ((respStringLen = recvfrom(sock, echoBuffer, ECHOMAX, 0, 
         (struct sockaddr *) &fromAddr, &fromSize)) != echoStringLen)
        printf("recv fail!\r\n");

    if (echoServAddr.sin_addr.s_addr != fromAddr.sin_addr.s_addr)
    {
        fprintf(stderr,"Error: received a packet from unknown source.\n");
        exit(1);
    }

    /* null-terminate the received data */
    echoBuffer[respStringLen] = '\0';
    printf("respStringLen:%d\n\r",respStringLen);
    printf("Received: %s\n", echoBuffer);    /* Print the echoed arg */
    
    close(sock);
    exit(0);
    
 /*   
    struct timeval val;

    
    fcntl(sock, F_SETFL, O_NONBLOCK);

while (1) {
FD_ZERO(&fdset);
FD_SET(sock, &fdset);
val.tv_sec = 1;
val.tv_usec = 0;

if (select(sock + 1, &fdset, NULL, NULL, &val) < 0) {
printf("select error: ");
continue;
}
if (FD_ISSET(sock, &fdset)) {
fromSize = sizeof(fromAddr);
respStringLen = recvfrom (sock, echoBuffer, sizeof(echoBuffer), 0,
(struct sockaddr *)&fromAddr, &fromSize);
if (respStringLen <= 0) {
p_error("socket closed by remote client"); 
close(sock);
exit(0);
}
*/
}