我还有一个问题 :) 我有一个简单的 C 中的 UDP 服务器，它读取一些字节，对这些字节应用一些解码，当它具有 ###@####@###@# 形式的字符串时## 他通过 UDP 将它发送到 C 中的另一台服务器。这是我的 C 服务器的代码，称为 preprocesamiento.c 我发布整个事情因为它更容易，但也许这与我的问题无关。
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <stdint.h>
#include <string.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>
#define MAXBUF 512
#define SENDING 0x52
#define RESIVING 0xB4
#define TYPE 0xA3F0
int createSocket();
char *unbase64(unsigned char *input, int length);
/* This function recives bytes(ASCII numbers) and returns the char */
void cambiarAChars(char* bytes, char* result)
{
unsigned int ch;
char a[4];
char buff[50];
strcpy(result,"");
int i=0;
while(i<strlen(bytes))
{
if(bytes[i]=='1')
{
a[0]=bytes[i];
a[1]=bytes[i+1];
a[2]=bytes[i+2];
a[3]='\0';
i=i+3;
}
else
{
a[0]=bytes[i];
a[1]=bytes[i+1];
a[2]='\0';
i=i+2;
}
ch = atoi(a);
sprintf(buff,"%c",ch);
strcat(result,buff);
}
}
/*this is the message that is going to be sent to the other server*/
char msg[MAXBUF];
/*this is the bytes recived*/
char bytes[MAXBUF];
void loadConfig(struct sockaddr_in *udpServer,struct sockaddr_in *thisServer,unsigned char *file);
int sendDataToServerXX(struct sockaddr_in *udpServer, int udpSocket);
int *useStdrr;
int *maxRequests;
int returnStatus;
int main(int argc, char* argv[])
{
if (argc < 2)
{
fprintf(stderr, "Usage: %s <file.config adress>\n", argv[0]);
exit(1);
}
useStdrr=malloc(sizeof(int));
maxRequests=malloc(sizeof(int));
struct sockaddr_in udpServer,thisServer,udpClient;
loadConfig(&udpServer,&thisServer, argv[1]);
int thisServerSocket = createSocket();
int udpSocket=createSocket();
int addrlen;
printf("Listening on.. %d \n",thisServer.sin_port);
thisServer.sin_family = AF_INET;
returnStatus = bind(thisServerSocket, (struct sockaddr*)&thisServer, sizeof(thisServer));
if (returnStatus == 0) {
fprintf(stderr, "Bind completed!\n");
}
else {
fprintf(stderr, "Could not bind to address \n" );
close(thisServerSocket);
exit(1);
}
/*En este while infinito estamos esperando los datos de las tramas*/
while (1)
{
addrlen = sizeof(udpClient);
/* How to resive a struct? */
returnStatus = recvfrom(thisServerSocket,(char*)&bytes, sizeof(bytes), 0,
(struct sockaddr*)&udpClient, &addrlen);
if (returnStatus == -1) {
fprintf(stderr, "Could not receive message!\n");
}
else {
printf("Lo que llego: %s \n",bytes);
/*Primero quitamos el 0 y 1 y guardamos el nuevo arreglo en p*/
bytes[strlen(bytes)-1]='\0';
char p[strlen(bytes)];
int i=0;
while(bytes[i+1]!='\0'){
p[i]=bytes[i+1];
i++;
}
/*esto simula la cambiada a base10 de base64*/
char *result=malloc(512);
char *p2=malloc(sizeof(p)+1);
strcpy(p2,p);
cambiarAChars(p2,result);
strcat(result,"\n\0");
printf("TAMANO: %d \n",strlen(result));
char *output = unbase64(result, strlen(result));
printf("Unbase64: %s\n", output);
msg[0]='%';
strcat(msg,output);
int f=strlen(msg);
msg[f]='%';
msg[f+1]='\0';
printf("Voy a mandar: %s \n",msg);
sendDataToServerXX(&udpServer,udpSocket);
free(output);
}
}
close(thisServerSocket);
close(udpSocket);
}
int createSocket()
{
/* create a socket */
int Socket;
Socket = socket(AF_INET, SOCK_DGRAM, 0);
if (Socket == -1)
{
if(*useStdrr)
{
fprintf(stderr, "Could not create a socket!\n");
}
exit(1);
}
else {
printf("Socket created.\n");
}
return Socket;
}
void loadConfig(struct sockaddr_in *udpServer,struct sockaddr_in *thisServer, unsigned char *file)
{
char line[256];
int linenum=0;
FILE* f = fopen(file, "r");
while(fgets(line, 256, f) != NULL)
{
char atribute[256], value[256];
linenum++;
if(line[0] == '#'||line[0] == ' ') {
continue;
}
else{
if(sscanf(line, "%s %s", atribute, value) != 2)
{
fprintf(stderr, "Syntax error, line %d\n", linenum);
continue;
}
if(!strcmp(atribute,"server_address" ))
{
if(!strcmp(value,""))
{
udpServer->sin_addr.s_addr = htonl(INADDR_ANY);
}
else{
udpServer->sin_addr.s_addr = inet_addr(value);
}
}
else if(!strcmp(atribute,"server_port"))
{
udpServer->sin_port = htons(atoi(value));
}
else if(!strcmp(atribute,"print_message_details"))
{
if(!strcmp(value,"ON"))
{
*useStdrr=1;
}
else
{
*useStdrr=0;
}
}
else if(!strcmp(atribute,"request_count"))
{
*maxRequests=5;
}
else if(!strcmp(atribute,"valor_que_viene_del_cohete_simulado"))
{
}
else if(!strcmp(atribute,"this_server_address"))
{
if(!strcmp(value,""))
{
thisServer->sin_addr.s_addr = htonl(INADDR_ANY);
}
else{
thisServer->sin_addr.s_addr = inet_addr(value);
}
}
else if(!strcmp(atribute,"this_server_port"))
{
thisServer->sin_port = htons(atoi(value));
}
}
}
}
int sendDataToServerXX(struct sockaddr_in *udpServer, int udpSocket)
{
udpServer->sin_family = AF_INET;
int in=0;
int boolv=0;
while(in<*maxRequests)
{
in++;
returnStatus = sendto(udpSocket,(char*) &msg, sizeof(msg), 0,
(struct sockaddr*)udpServer, sizeof(*udpServer));
if (returnStatus == -1) {
if(*useStdrr)
{
fprintf(stderr, "Could not send message!\n");
}
}
else {
printf("Datos enviados al servidor xx.\n");
memset(msg, 0, strlen(msg));
in=*maxRequests;
boolv=1;
}
}
if(!boolv)
{
if(*useStdrr)
{
fprintf(stderr, "fixed number of requests finished.. no reply.\n");
}
}
return 0;
}
char *unbase64(unsigned char *input, int length)
{
BIO *b64, *bmem;
char *buffer = (char *)malloc(length);
memset(buffer, 0, length);
b64 = BIO_new(BIO_f_base64());
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
bmem = BIO_new_mem_buf(input, length);
bmem = BIO_push(b64, bmem);
BIO_read(bmem, buffer, length);
BIO_free_all(bmem);
return buffer;
}
好的，所以我制作了一个向该服务器发送数据的模拟器...基本上是一个 UDP 客户端，可以按我的需要发送字节。而且连接和整个事情都非常好:)。现在我正在尝试连接到真正的测试仪，这是一个 java jar，它通过 UDP 按照我的服务器需要发送数据。唯一的问题是我没有 java 源代码，因为它不是我的...但是程序似乎运行顺利(java jar)但是当我检查我的服务器时没有收到连接。是的，我在正确的端口等待，C 和 Java 程序都在同一台机器 (UBUNTU) 上运行。
我发布了我用 C 编写的客户端模拟器，它非常适合这个服务器。
抱歉，它有点长，因为我从配置文件加载:
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define MAXBUF 1024
#define SENDING 0x52
#define RESIVING 0xB4
#define TYPE 0xA3F0
int createSocket();
char msg[MAXBUF];
void loadConfig(struct sockaddr_in *udpServer, char *file);
int *useStdrr;
int *maxRequests;
int *timeOut;
int main(int argc, char* argv[])
{
int returnStatus;
int addrlen;
struct sockaddr_in udpClient, udpServer;
char buf[MAXBUF];
useStdrr=malloc(sizeof(int));
maxRequests=malloc(sizeof(int));
timeOut=malloc(sizeof(int));
/*ms.timezone="AES";*/
if (argc < 2)
{
fprintf(stderr, "Usage: %s <file.config adress>\n", argv[0]);
exit(1);
}
int udpSocket=createSocket();
udpServer.sin_family = AF_INET;
loadConfig(&udpServer, argv[1]);
/*how to send a struct here?*/
int in=0;
int boolv=0;
printf("Request number %i\n",*maxRequests);
while(in<*maxRequests)
{
in++;
printf("Request number %i\n",in);
printf("Adresss::: %d\n",udpServer.sin_addr.s_addr);
printf("PORT:::: %i\n",udpServer.sin_port);
returnStatus = sendto(udpSocket,(char*) &msg, sizeof(msg), 0,
(struct sockaddr*)&udpServer, sizeof(udpServer));
if (returnStatus == -1) {
if(*useStdrr)
{
fprintf(stderr, "Could not send message!\n");
}
}
else {
printf("Message sent.\n");
/* message sent: look for confirmation */
/*
addrlen = sizeof(udpServer);
returnStatus = recvfrom(udpSocket, (char*) &msg, sizeof(msg), 0,
(struct sockaddr*)&udpServer, &addrlen);
if (returnStatus == -1) {
if(*useStdrr)
{
fprintf(stderr, "Did not receive confirmation!\n");
}
}
else {
printf("Second: %s\n", msg);
*/
in=*maxRequests;
boolv=1;
/*
}*/
}
}
if(!boolv)
{
if(*useStdrr)
{
fprintf(stderr, "fixed number of requests finished.. no reply.\n");
}
}
close(udpSocket);
return 0;
}
int createSocket()
{
/* create a socket */
int Socket;
Socket = socket(AF_INET, SOCK_DGRAM, 0);
if (Socket == -1)
{
if(*useStdrr)
{
fprintf(stderr, "Could not create a socket!\n");
}
exit(1);
}
else {
printf("Socket created.\n");
}
return Socket;
}
void loadConfig(struct sockaddr_in *udpServer, char *file)
{
char line[256];
int linenum=0;
FILE* f = fopen(file, "r");
while(fgets(line, 256, f) != NULL)
{
char atribute[256], value[256];
linenum++;
if(line[0] == '#'||line[0] == ' ') {
continue;
}
else{
if(sscanf(line, "%s %s", atribute, value) != 2)
{
fprintf(stderr, "Syntax error, line %d\n", linenum);
continue;
}
printf("Atribute: %s\n",atribute);
printf("Value: %s\n",value);
if(!strcmp(atribute,"server_address" ))
{
if(!strcmp(value,""))
{
udpServer->sin_addr.s_addr = htonl(INADDR_ANY);
}
else{
udpServer->sin_addr.s_addr = inet_addr(value);
}
}
else if(!strcmp(atribute,"server_port"))
{
udpServer->sin_port = htons(atoi(value));
}
else if(!strcmp(atribute,"print_message_details"))
{
if(!strcmp(value,"ON"))
{
*useStdrr=1;
}
else
{
*useStdrr=0;
}
}
else if(!strcmp(atribute,"request_count"))
{
*maxRequests=atoi(value);
}
else if(!strcmp(atribute,"request_*timeOut"))
{
*timeOut=atoi(value);
}
}
}
}
现在真正的问题是:从 Java 客户端连接到 C 服务器上的 C 是否需要做一些与连接到另一个 C 客户端不同的事情？如果答案是否定的，那么问题出在 java 项目中？他们告诉我它工作正常，但我认为他们已经用 JAVA 服务器对其进行了测试。有什么区别吗？如果问题出在 java 项目中，我应该告诉他们进行哪些更改才能使其与我的 C 服务器一起工作？
非常感谢!!!
亚历杭德罗·卡萨斯
最佳答案
不存在 UDP 连接这样的东西。在 UDP 中，程序只是在给定 IP 的给定端口 throw 数据包。如果该 IP/端口没有任何监听，或者接收程序决定忽略 UDP 数据包，它就会被丢弃。如果您想要一个实际的连接，您可以使用 TCP。
另外，一些ISP默认会屏蔽某些类型的UDP数据包
在 Java 中，TCP 套接字称为 Socket，UDP 套接字称为 DatagramSocket。确保您从 Java 客户端上的 DatagramSocket 发送。
虽然我还没有用 C 编写套接字编程。
最后，如果您发布了一些 Java 代码，将会有所帮助。
关于java - C服务器和Java客户端之间的UDP连接，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9673072/