[英]htons and ntohs not working? C UNIX networking
我是C語言網絡編程的新手,我首先嘗試將從鍵盤讀取的數組發送到服務器。 問題是,每當我從鍵盤上讀取數組的長度時,它將增加2/3,而不再執行任何操作。 例如:
我給出的長度或數組:2客戶端將從鍵盤讀取4或5個元素,如果以后嘗試打印它們,它們將沒有我賦予它們的值。 他們得到一些完全不同的數字。
這是我的客戶的樣子:
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
int main(int argc, char* argv[]) {
int sockfd;
struct sockaddr_in server;
/*char msg[1000], serv_reply[2000];*/
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("Error in creating the stupid sock client ");
exit(errno);
}
puts("Socket created in client ");
memset(&server, 0, sizeof(server));
server.sin_addr.s_addr = inet_addr("127.0.0.1");
server.sin_family = AF_INET;
server.sin_port = htons(9255);
if ( connect(sockfd, (struct sockaddr*)&server, sizeof(server)) < 0) {
perror("Connection failed ");
exit(errno);
}
puts("Yey! Connected");
printf("Let's try \n" );
printf("Nr of elem = ");
**int a;
scanf("%d", &a);
a = htons(a);
if ( send(sockfd, &a, sizeof(a), 0 ) < 0 ) {
perror("CLient sent error");
exit(errno);
}
int i, elem;
for( i =0; i<a; i++) {
printf("Enter a number: ");
scanf("%d", &elem);
elem = htons(elem);
printf("%d", elem);
if ( send(sockfd, &elem, sizeof(elem), 0) < 0) {
perror("Couldn't send the damn element ");
exit(errno);
}
}**
int somth;
recv(sockfd, &somth, sizeof(somth), 0);
somth = ntohs(somth);
printf("WE GOT IT %d ", somth);
close(sockfd);
}
這是我的服務器:
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MY_PORT 9999
#define MAXBUF 1024
int main (int argc, char* argv[]) {
int sockfd;
struct sockaddr_in server, client;
int c, l;
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("Error creating the stupid socket ");
exit(errno);
}
memset(&server, 0, sizeof(server));
server.sin_port = htons(9255);
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
if ( bind(sockfd, (struct sockaddr *) &server, sizeof(server)) < 0) {
perror("Error in socket binding ");
exit(errno);
}
if ( listen (sockfd, 20) < 0) {
perror("Erro listening to the dumb sock ");
exit(errno);
}
printf("WE'RE ON!! " );
l = sizeof(client);
memset(&client, 0, l);
while(1) {
int a;
c = accept(sockfd, (struct sockaddr *) &client, &l);
if (c == -1) {
perror("Error accepting connection");
continue;
} else {
printf("Cool, we have a new client! \n");
}
if (recv( c, &a, sizeof(a), MSG_WAITALL) < 0) {
perror("Error reading in server ");
exit(errno);
}
a = ntohs(a);
int i, elem,sum;
for ( i = 0; i<a; i++) {
if ( recv(c, &elem, sizeof(elem), MSG_WAITALL)< 0) {
perror("Error reading elems ");
exit(errno);
}
elem = ntohs(elem);
sum = sum + elem;
}
sum= ntohs(sum);
if ( send(c, &sum, sizeof(sum), 0) < 0) {
perror("Error sending to client ");
exit(errno);
}
close(c);
}
}
我試圖將htons切換為ntohs,反之亦然。 知道有什么問題嗎?
一個主要的問題是,你失去原來的a
,你在客戶端輸入,所以當你在后面的循環條件使用它,它可能不是你所期望的。
另一個主要問題是,例如htons
中的s
表示short
,而在現代PC系統上, short
通常為16位,而int
為32位。
嘗試改用htonl
和ntohl
!
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