UDP 客户端分段错误

Question

请帮忙！这是几个小时后到期的，我在网上搜索时没有运气

代码：

/* 描述： 客户端应首先向 LocationServer 发送数据报。 LocationServer 将监听主机 c-lnx001.engr.uiowa.edu 的端口号 23510。 此数据报中包含的消息应该是指定的 UserID（没有空字符、空格、换行符或其他无关字符）。 LocationServer 将使用包含以下信息的数据报进行响应： [WeatherServer 主机名] [WeatherServer 端口#] */

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>  /* for fprintf */
#include <string.h> /* for memcpy */
#include <strings.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdlib.h>

#define SIZE 2048

int main(){

struct hostent *hp;     /* host information */
struct sockaddr_in servaddr;    /* server address */
char *my_message = "laura\0";/*USERID as message to server*/
char *buf_addr;
char *host = "c-lnx001.engr.uiowa.edu\0";
int port = 23510;
int fd;

/* fill in the server's address and data */
//memset((char*)&servaddr, 0, sizeof(servaddr)); ?
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(23510);

/* look up the address of the server given its name */
hp = gethostbyname("c-lnx001.engr.uiowa.edu");
if (!hp) {
    fprintf(stderr, "could not obtain address of %s\n", host);
    return 0;
}



/* put the host's address into the server address structure */
// DOESN't WORK: memcpy((void *)&servaddr.sin_addr, hp->h_addr_list[0], hp->h_length);

bcopy(hp->h_addr,(char*)&servaddr.sin_addr,hp->h_length);

if((fd = socket(AF_INET,SOCK_DGRAM, 0))<0)
{
    exit(2);

}

/* send a message to the server */
if (sendto(fd, my_message, strlen(my_message), 0, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0) 
{
    perror("sendto failed");
    return 0;
}
int addrlen = sizeof(servaddr);

recvfrom(fd,buf_addr,SIZE,0,(struct sockaddr*)&servaddr,&addrlen);
printf("%s\n", buf_addr);

}

Answer 1

我认为您的问题是您没有重置 serveraddr
这是一份工作副本

#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define IP_ADDRESS "127.0.0.1"
#define SERVER_PORT 5060

int main (int argc, char *argv[])
{
    int recBytes, clientSocket=socket(AF_INET, SOCK_DGRAM, 0);
    char buf[80], msg[]="greeting to server";
    const int msgLen = sizeof(msg);
    struct sockaddr_in serverAddr;
    socklen_t reSize;

    memset(&serverAddr, sizeof(struct sockaddr_in), 0);

    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(SERVER_PORT);
    inet_aton(IP_ADDRESS, &serverAddr.sin_addr);

    if(sendto(clientSocket, msg, sizeof(msg), 0, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) != (sizeof(msg)))
    {
        perror("sendto");
        return -1;
    }

    reSize = sizeof(struct sockaddr);
    if((recBytes = recvfrom(clientSocket, buf, sizeof(buf)-1, 0, (struct sockaddr*)&serverAddr, &reSize)) == -1)
    {
        perror("recvfrom");
        return -1;
    }
    buf[recBytes]='\0';
    printf("%s\n", buf);

    return 0;
}