recvfrom的:错误地址,SENDTO:地址协议不支持 [英] recvfrom: Bad address, sendto: Address family not supported by protocol
问题描述
我试图实现在C小UDP的服务器/客户端应用程序,并获得对服务器端两个错误: recvfrom的:错误地址&放大器;&安培; SENDTO:地址家族不受协议的支持。我搜索了这个错误,并用Google搜索答案,但遗憾的是,他们并没有真正有益......也许我是铸造参数,以错误的方式,并没有得到它。我希望你能给我一个提示:。)
的#include<&unistd.h中GT;
#包括LT&;&文件ctype.h GT;
#包括LT&; SYS / socket.h中>
#包括LT&; SYS / types.h中>
#包括LT&; ARPA / inet.h>
#包括LT&;&errno.h中GT;#定义BUFFSIZE 256
#定义IP127.0.0.1
#定义端口7755诠释主要(无效){ INT socket_fd =插座(AF_INET,SOCK_DGRAM,0);
炭缓冲[1] =S; 结构SOCKADDR_IN SRC_ADDR;
结构SOCKADDR_IN dest_addr; src_addr.sin_family = AF_INET;
src_addr.sin_port = htons(PORT);
src_addr.sin_addr.s_addr = inet_addr(IP); 如果(socket_fd == - 1)
PERROR(插座); 如果(绑定(socket_fd,(结构sockaddr *)及SRC_ADDR,sizeof的(SRC_ADDR))== - 1)
PERROR(绑定); 如果(recvfrom的(socket_fd,缓冲,2,0,(结构sockaddr *)及dest_addr,(无符号整数*)的sizeof(结构SOCKADDR_IN))== - 1)
PERROR(recvfrom的); 如果(SENDTO(socket_fd,缓冲液,2,0,(结构sockaddr *)及dest_addr,sizeof的(dest_addr))== - 1)
PERROR(SENDTO); 如果(接近(socket_fd)== - 1)
PERROR(亲密); 返回0;}
您需要通过有效的指针给recvfrom。 (无符号整数*)的sizeof(结构SOCKADDR_IN)
不是一个有效的指针。
修改
如果(recvfrom的(socket_fd,缓冲,2,0,(结构sockaddr *)及dest_addr,
(无符号整数*)的sizeof(结构SOCKADDR_IN)== -1)
要如
socklen_t的LEN = sizeof的dest_addr;
如果(recvfrom的(socket_fd,缓冲液,2,0,
(结构sockaddr *)及dest_addr,和放大器; LEN)== -1)
您还构建您发送一个无效的数组,你阵列具有1的长度,但你告诉的sendto / recvfrom的,它有2的长度,以便更改
字符缓冲区[1] =S;
到
字符缓冲区[] =S;
(字符串s是字符's'和一个0字节,所以缓冲
将具有长度2在后一种情况下)。
i'm trying to implement a little UDP-Server/Client Application in C and got two errors on Server-side: recvfrom: Bad address && sendto: Address family not supported by protocol. I searched for the mistake and googled for answers but, unfortunately, they wasn't really helpfully... maybe i'm casting a parameter in a wrong way and don't get it. I hope you can give me a hint :).
#include <unistd.h>
#include <ctype.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <errno.h>
#define BUFFSIZE 256
#define IP "127.0.0.1"
#define PORT 7755
int main(void){
int socket_fd = socket(AF_INET, SOCK_DGRAM, 0);
char buffer[1] = "s";
struct sockaddr_in src_addr;
struct sockaddr_in dest_addr;
src_addr.sin_family = AF_INET;
src_addr.sin_port = htons(PORT);
src_addr.sin_addr.s_addr = inet_addr(IP);
if(socket_fd==-1)
perror("socket");
if(bind(socket_fd, (struct sockaddr*)&src_addr, sizeof(src_addr))==-1)
perror("bind");
if(recvfrom(socket_fd, buffer, 2, 0, (struct sockaddr*)&dest_addr, (unsigned int *)sizeof(struct sockaddr_in))==-1)
perror("recvfrom");
if(sendto(socket_fd, buffer, 2, 0,(struct sockaddr*)&dest_addr, sizeof(dest_addr))==-1)
perror("sendto");
if(close(socket_fd)==-1)
perror("close");
return 0;
}
You need to pass a valid pointer to recvfrom. (unsigned int *)sizeof(struct sockaddr_in)
is not a valid pointer.
Change
if(recvfrom(socket_fd, buffer, 2, 0, (struct sockaddr*)&dest_addr,
(unsigned int *)sizeof(struct sockaddr_in) == -1)
to e.g.
socklen_t len = sizeof dest_addr;
if(recvfrom(socket_fd, buffer, 2, 0,
(struct sockaddr*)&dest_addr, &len) == -1)
You are also constructing an invalid array that you send, Your array has a length of 1, but you tell sendto/recvfrom that it has a length of 2. So change
char buffer[1] = "s";
to
char buffer[] = "s";
(The string "s" is the character 's' and a 0 byte, so buffer
will have length 2 in the latter case.)
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