Here is my code for a node.js TCP server hosted on both Heroku and AppFog. My client was written in C and it simply sends a message to the server and get the response. When I host the server on local, they work fine. But when I try to connect to the online server, the client fails("ERROR connecting: Operation timed out"). Any idea what happened?
Server(node.js):
var net = require('net');
var server = net.createServer(function (socket) {
socket.on("data", function(data){
socket.write(data.toString());
});
});
var port = process.env.VCAP_APP_PORT || 8081;
console.log(port);
server.listen(port);
Client(C, from http://www.linuxhowtos.org/C_C++/socket.htm):
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
void error(const char *msg)
{
perror(msg);
exit(0);
}
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
if (argc < 3) {
fprintf(stderr,"usage %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
server = gethostbyname(argv[1]);
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
while (1){
printf("Please enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));
if (n < 0)
error("ERROR writing to socket");
bzero(buffer,256);
n = read(sockfd,buffer,255);
if (n < 0)
error("ERROR reading from socket");
printf("%s\n",buffer);
}
close(sockfd);
return 0;
}
The client must always connect on port 80 regardless of what process.env.VCAP_APP_PORT is set to. AppFog proxies requests from port 80 to the port your app is running on.
Related
i am setting up a web server in c++. I need to return from server a feature vector in the form of vector. I see that the socket doesn't allow such object to pass through directly, but need to serialize it. I am trying to serialize it by converting my vector result to a char* a. but when i do curl request, it still get back nothing.
Would anyone let me know the trick here?
/* A simple server in the internet domain using TCP
The port number is passed as an argument */
// server.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <vector>
#include <iostream>
void error(const char *msg)
{
perror(msg);
exit(1);
}
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno;
socklen_t clilen;
char buffer[256];
struct sockaddr_in serv_addr, cli_addr;
int n;
if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
if (bind(sockfd, (struct sockaddr *) &serv_addr,
sizeof(serv_addr)) < 0)
error("ERROR on binding");
listen(sockfd,5);
while (1 == 1) {
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,
(struct sockaddr *) &cli_addr,
&clilen);
if (newsockfd < 0)
error("ERROR on accept");
bzero(buffer,256);
n = read(newsockfd,buffer,255);
if (n < 0) error("ERROR reading from socket");
printf("before result: %s\n",buffer);
std::vector<float> fv;
fv.push_back(7);
fv.push_back(8);
char* result = reinterpret_cast<char*>(&fv);
send(newsockfd, result, sizeof(result), 0);
//n = write(newsockfd,"I got your message",18);
//if (n < 0) error("ERROR writing to socket");
printf("message sent. \n");
close(newsockfd);
//close(sockfd);
}
return 0;
}
To compile the code:
g++ -o server server.cpp
And run:
./server 8080
For curl request:
curl http://localhost:8080
And i get:
alliey:socket alliey$ curl http://localhost:8080
`N�.
How should i interpret the response?
i figure it out, by simply send raw data:
send(newsockfd, result.data(), sizeof(result[0])*result.size(), 0);
On the client side, i used python struck.unpack to receive the result. It works pretty well.
But still thanks for all the tips above!
I'm a beginner in programming in c++ with a bit of experience in java.
My goal is transfer files (in local host) between a server and a client (in two different folders).
I have found this code online that works well for me, it opens sockets and makes a connection between the server and the client and you can send a message typed in the terminal.
I have tried a lot of different codes on the INTERNET and either it doesn't compile or it isn't what I need.
Here is a code that I found that works to transmit a message.
server.cpp file
enter code here
/* A simple server in the internet domain using TCP
The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
void error(const char *msg)
{
perror(msg);
exit(1);
}
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno;
socklen_t clilen;
char buffer[256];
struct sockaddr_in serv_addr, cli_addr;
int n;
if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
error("ERROR opening socket");
exit(1);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) {
error("ERROR on binding");
}
listen(sockfd,1);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,
(struct sockaddr *) &cli_addr,
&clilen);
if (newsockfd < 0)
error("ERROR on accept");
bzero(buffer,256);
n = read(newsockfd,buffer,255);
if (n < 0) error("ERROR reading from socket");
printf("Here is the message: %s\n",buffer);
n = write(newsockfd,"I got your message",18);
if (n < 0) error("ERROR writing to socket");
close(newsockfd);
close(sockfd);
return 0;
}
client.cpp file
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
void error(const char *msg)
{
perror(msg);
exit(0);
}
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
if (argc < 3) {
fprintf(stderr,"usage %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
server = gethostbyname(argv[1]);
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
printf("Please enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));
if (n < 0)
error("ERROR writing to socket");
bzero(buffer,256);
n = read(sockfd,buffer,255);
if (n < 0)
error("ERROR reading from socket");
printf("%s\n",buffer);
close(sockfd);
return 0;
}
I'm compiling with g++ in ubuntu.
I'd love if you could help me to at least be able to send a txt file from the client or download a file from the server, as soon as i try to add functionalities in this code nothing works anymore, maybe I'm starting with a bad example?
you should try this example, it works good for me
receive:
size_t datasize;
FILE* fd = fopen(filename, "wb");
while (!received)
{
datasize = recv(connection, text, sizeof(text), 0);
fwrite(&text, 1, datasize, fd);
}
fclose(fd);
send:
FILE *fd = fopen(filename, "rb");
size_t rret, wret;
int bytes_read;
while (!feof(fd)) {
if ((bytes_read = fread(&buffer, 1, BUFFER_SIZE, fd)) > 0)
send(sock, buffer, bytes_read, 0);
else
break;
}
fclose(fd);
Good luck:)
Below is the basic client and server code .
While iam trying to start an appliaction(which has to keep running in the machine once we send a msg to server) during connect call.
using system(/bin/myApplication) in the client code (This basically is a simple c executable with an infinite loop,assuming my application has to be running);
Once iam starting the application the server is in CLOSED_WAIT State and its coming back to listen only if i stop this application .
The issue is with the server socket in CLOSED_WAIT state, Is there a way that this application keep running as a seperate process and server would be in listen state again.
Client Code: There is a system command after read.and it starts an application(basically is an c executable with an infinite while loop)
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
int sockfd = 0, n = 0;
char recvBuff[1024];
struct sockaddr_in serv_addr;
if(argc != 2)
{
printf("\n Usage: %s <ip of server> \n",argv[0]);
return 1;
}
memset(recvBuff, '0',sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Error : Could not create socket \n");
return 1;
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(5000);
if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0)
{
printf("\n inet_pton error occured\n");
return 1;
}
if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\n Error : Connect Failed \n");
return 1;
}
while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
{
recvBuff[n] = 0;
if(fputs(recvBuff, stdout) == EOF)
{
printf("\n Error : Fputs error\n");
}
}
system(/bin/myApplication);
if(n < 0)
{
printf("\n Read error \n");
}
return 0;
Server Code:
int main(int argc, char *argv[])
{
int listenfd = 0, connfd = 0;
struct sockaddr_in serv_addr;
char sendBuff[1025];
time_t ticks;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_addr.sin_port = htons(5000);
bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
listen(listenfd, 10);
while(1)
{
connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
ticks = time(NULL);
snprintf(sendBuff, sizeof(sendBuff), "%.24s\r\n", ctime(&ticks));
write(connfd, sendBuff, strlen(sendBuff));
close(connfd);
sleep(1);
}
}
My Sample C File , which iam trying to execute using system command in client
code. with
gcc Sample.c -o myApplication
int main(int argc, char *argv[])
{
while(1)
{
}
}
I have tried using fork , but still the socket is in same state , is there anyway that this application runs seperately and doesnt effect the socket nor does it depend on the parent process(Server here).
Your client app never closes the socket, and since the sample app you spawn loops forever, the client never exits. This leaves the TCP connection state hanging on both sides.
In the client, try closing the socket before spawning the sample app.
Also, I think you're confused about the TCP states. A server endpont in the LISTEN state does not transition to CLOSE_WAIT and back. The LISTEN endpoint (the socket you called listen() on) will stay in that state until closed. The connected endpoint (the socket returned by accept()) will transition through various states during its lifetime.
If you're using the netstat command to see the states, be sure to use the -a flag to display the listening endpoints as well.
I added the below line before the system command
fcntl(sockfd, F_SETFD, fcntl(sockfd, F_GETFD) | FD_CLOEXEC);
And Changed my client code to
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <fcntl.h>
int main(int argc, char *argv[])
{
int sockfd = 0, n = 0;
char recvBuff[1024];
struct sockaddr_in serv_addr;
if(argc != 2)
{
printf("\n Usage: %s <ip of server> \n",argv[0]);
return 1;
}
memset(recvBuff, '0',sizeof(recvBuff));
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
printf("\n Error : Could not create socket \n");
return 1;
}
memset(&serv_addr, '0', sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(5000);
if(inet_pton(AF_INET, argv[1], &serv_addr.sin_addr)<=0)
{
printf("\n inet_pton error occured\n");
return 1;
}
if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
{
printf("\n Error : Connect Failed \n");
return 1;
}
while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
{
recvBuff[n] = 0;
if(fputs(recvBuff, stdout) == EOF)
printf("\n Error : Fputs error\n");
}
}
fcntl(sockfd, F_SETFD, fcntl(sockfd, F_GETFD) | FD_CLOEXEC);
system("/software/itcsm/itcsm/refasset/bin/start_script.sh 1");
if(n < 0)
{
printf("\n Read error \n");
}
printf("\n after system \n");
return 0;
}
By default whenever we fork a process (which system command does), the child inherits all the parent's file descriptors. If the child doesn't need those descriptors, it SHOULD close them voluntarily on file descriptor using fcntl(sockfd, F_SETFD, fcntl(sockfd, F_GETFD) | FD_CLOEXEC);
I am sorry if the title is misleading. I cannot really think of a better one. Here is some simple socket program that I have:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/poll.h>
#include <iostream>
#define BACKLOG 10
void error(const char *msg)
{
perror(msg);
exit(1);
}
int main(int argc, char *argv[])
{
if (argc < 2) {
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
struct sockaddr_in serv_addr;
bzero((char *) &serv_addr, sizeof(serv_addr));
int portno = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
auto bindsuccess = bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
if (bindsuccess < 0)
error("ERROR on binding");
struct pollfd newPollFD[1];
newPollFD[0].fd = sockfd;
newPollFD[0].events = POLLIN;
char buffer[256];
bzero(buffer,256);
listen(sockfd, BACKLOG);
struct sockaddr_in cli_addr;
socklen_t clilen = sizeof(cli_addr);
int newsockfd;
int rv = poll(newPollFD, 1, -1);
if (rv == -1) {
error("Error occured in Poll");
}
else {
if (newPollFD[0].revents & POLLIN){
newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
if (newsockfd < 0)
error("ERROR on accept");
int rwsuccess;
rwsuccess = read(newsockfd,buffer,255);
if (rwsuccess < 0)
error("ERROR reading from socket");
printf("Here is the message: %s\n",buffer);
rwsuccess = write(newsockfd,"I got your message \n",18);
if (rwsuccess < 0)
error("ERROR writing to socket");
}
}
close(newsockfd);
close(sockfd);
return 0;
}
If I execute this code with a port number, and then telnet to that port number, the server listens in, but as soon as I send my first message, the connection terminates. I want the sever to keep on listening and sending acknowledgement back as many times as I send message from telnet. How do I accomplish that?
Thanks in advance!
The continue is curiously extraneous, and causes the compilation to break. (It is now corrected in your edit.) But, you are missing a for loop. And, you should add a check if the read returns 0.
for (;;) {
int rwsuccess;
rwsuccess = read(newsockfd,buffer,255);
if (rwsuccess < 0)
error("ERROR reading from socket");
if (rwsuccess == 0) break;
printf("Here is the message: %s\n",buffer);
rwsuccess = write(newsockfd,"I got your message \n",18);
if (rwsuccess < 0)
error("ERROR writing to socket");
}
I have two versions of this code. In one version if the user inputs the phrase "GET /index.html" the server responds properly. In the second version, the "GET /index.html" phrase is built in without prompting the user. The second version hangs when reading a response from the server, any idea why?
First Version - Prompts user for phrase
#include <stdio.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
void error(char *msg)
{
perror(msg);
exit(0);
}
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[10000];
portno = atoi("85");
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error((char *)"ERROR opening socket");
server = gethostbyname("vilive.us");
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
memset((char *) &serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
memcpy((char *)&serv_addr.sin_addr.s_addr, (char *)server->h_addr, server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error((char *)"ERROR connecting");
printf("Please enter the message: ");
memset(buffer,0,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));
if (n < 0)
error((char *)"ERROR writing to socket");
memset(buffer,0,256);
n = read(sockfd,buffer,500);
if (n < 0)
error((char *)"ERROR reading from socket");
printf("%s\n",buffer);
return 0;
}
Second Version - Automatically sends "GET /index.html" - This one hangs
#include <stdio.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
void error(char *msg)
{
perror(msg);
exit(0);
}
int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[10000];
//TEST
char getI[16];
getI[0]='G';
getI[1]='E';
getI[2]='T';
getI[3]=' ';
getI[4]='/';
getI[5]='i';
getI[6]='n';
getI[7]='d';
getI[8]='e';
getI[9]='x';
getI[10]='.';
getI[11]='h';
getI[12]='t';
getI[13]='m';
getI[14]='l';
getI[15]='\0';
portno = atoi("85");
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error((char *)"ERROR opening socket");
server = gethostbyname("vilive.us");
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
memset((char *) &serv_addr, 0, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
memcpy((char *)&serv_addr.sin_addr.s_addr, (char *)server->h_addr, server->h_length);
serv_addr.sin_port = htons(portno);
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error((char *)"ERROR connecting");
/*printf("Please enter the message: ");
memset(buffer,0,256);
fgets(buffer,255,stdin);*/
n = write(sockfd,getI,strlen(getI));
if (n < 0)
error((char *)"ERROR writing to socket");
memset(buffer,0,256);
n = read(sockfd,buffer,500);
if (n < 0)
error((char *)"ERROR reading from socket");
printf("%s\n",buffer);
return 0;
}
The request must be terminated with 2 carriage return and line feed pairs, this is missing in your second example.
char charI[] = "GET /index.html\r\n\r\n";
Please, switch to a modern version of HTTP. I find it amazing that your server agrees to reply, as the request isn't remotely valid HTTP.
This would be a suitable HTTP/1.1 request in your situation
char charI[] = "GET /index.html HTTP/1.1\r\nHost: vilive.us\r\nConnection: close\r\n\r\n";
note the Host header, that allow you to talk with sites that do virtual hosting, like ... stackoverflow.com and superuser.com that points to the same ip address. they only rely on the Host header to figure out if the user want to access stackoverflow.com or superuser.com.
Also, your should close the socket descriptor when you are done using the socket.