我在main中调用udpclient,其中我传递"这是一个测试"作为参数消息。
#define MAX_BUFFER 128
void udpclient(char *message, char *target_ip, int target_port){
///* address of server we trying to reach */
struct sockaddr_in targetaddress;
/* buffer to receive echo */
char buffer[MAX_BUFFER];
/* create socket */
int socketfd;
socketfd = socket(AF_INET, SOCK_DGRAM, 0);
if(socketfd == -1)
socketerror();
/* target server informations */
memset(&targetaddress, 0, sizeof(targetaddress));
targetaddress.sin_family = AF_INET;
targetaddress.sin_port = htons(target_port);
targetaddress.sin_addr.s_addr = inet_addr(target_ip);
在我向服务器发送消息后,服务器必须回复"echo:这是一个测试",但由于某种原因,recvfrom((返回n=8,所以当我写(1,buffer,n(时,它会截断缓冲区。
/* send message to targetaddress */
ssize_t n;
n = sendto(socketfd, message, sizeof(message), 0, (const struct sockaddr *) &targetaddress, sizeof(targetaddress));
if(n == -1)
udpsenderror();
printf("%in", n);
socklen_t addrlen;
addrlen = sizeof(targetaddress);
/* receive echo from targetaddress */
n = recvfrom(socketfd, buffer, MAX_BUFFER, 0, (struct sockaddr *) &targetaddress, &addrlen);
if(n == -1)
udpechoerror();
printf("%in", n);
write(1, "echo: ", 6);
write(1, buffer, n);
return;
}
Recvfrom((应该返回消息的长度,如果我没有错的话,我不知道我做错了什么!帮助
n = sendto(socketfd, message, sizeof(message), 0, (const struct sockaddr *) &targetaddress, sizeof(targetaddress));
由于message
是char *
,sizeof(message)
给出了char *
在您的平台上占用的字节数。显然,这是8个字节,所以您发送了一条8字节的消息。