I have written a client server sctp program in c. on sctp client side I create two client threads and each thread binds with local port 8888 and 9999 port respectively. However, when I connect client to server and see the client ports on sever by stripping client tcp header. i receive completly different port and both client ports seems to be same in server log. I want to connect two different ports from sctp client to the same sctp server port. Is it possible ? it server side multiplexing is possible in scpt? Is many to one connection from client to server is possible in sctp?
client code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>
#include <pthread.h>
static void die(const char *s) {
perror(s);
exit(1);
}
void* client_thread(void* arg)
{
int clientSocket;
struct sockaddr_in clientAddress;
struct sockaddr_in serverAddress;
const char *msg = "Hello, Server!";
int ret;
int clientPort = *((int*)arg);
// Create the client socket
clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP);
if (clientSocket == -1) {
perror("Failed to create socket");
exit(EXIT_FAILURE);
}
// Set up the client address and port
clientAddress.sin_family = AF_INET;
clientAddress.sin_port = htons(clientPort); // Specify the source port number here
clientAddress.sin_addr.s_addr = INADDR_ANY;
// Bind the client socket to the local address and port
if (bind(clientSocket, (struct sockaddr *)&clientAddress, sizeof(clientAddress)) < 0) {
perror("Failed to bind socket");
exit(EXIT_FAILURE);
}
// Set up the server address and port
serverAddress.sin_family = AF_INET;
serverAddress.sin_port = htons(62325); // Specify the destination port number here
serverAddress.sin_addr.s_addr = inet_addr("127.0.0.1"); // Specify the server IP address here
// Connect to the server
if (connect(clientSocket, (struct sockaddr *)&serverAddress, sizeof(serverAddress)) < 0) {
perror("Failed to connect to server");
exit(EXIT_FAILURE);
}
char buffer[45];
int length = snprintf(buffer, sizeof(buffer), "Hello, Server! The value of client port %d", clientPort);
ret = sctp_sendmsg(clientSocket, (void *) buffer, length + 1, NULL, 0, 0, 0, 0, 0, 0 );
if (ret < 0)
die("sctp_sendmsg");
close(clientSocket);
return NULL;
}
int main(int argc, char **argv)
{
pthread_t thread1, thread2;
int client_port1 = 8888;
int client_port2 = 9999;
// Create thread 1
if (pthread_create(&thread1, NULL, client_thread, &client_port1) != 0) {
perror("Failed to create thread 1");
exit(EXIT_FAILURE);
}
// Create thread 2
if (pthread_create(&thread2, NULL, client_thread, &client_port2) != 0) {
perror("Failed to create thread 2");
exit(EXIT_FAILURE);
}
// Wait for threads to finish
if (pthread_join(thread1, NULL) != 0) {
perror("Failed to join thread 1");
exit(EXIT_FAILURE);
}
if (pthread_join(thread2, NULL) != 0) {
perror("Failed to join thread 2");
exit(EXIT_FAILURE);
}
return 0;
}
server code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/sctp.h>
#include <arpa/inet.h>
#define MY_PORT_NUM 62325
static void die(const char *s) {
perror(s);
exit(1);
}
static void server(void) {
int listen_fd, conn_fd, flags, ret, in;
struct sctp_rcvinfo rcvinfo;
struct sockaddr_in servaddr = {
.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY),
.sin_port = htons(MY_PORT_NUM),
};
struct sctp_initmsg initmsg = {
.sinit_num_ostreams = 5,
.sinit_max_instreams = 5,
.sinit_max_attempts = 4,
};
listen_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP);
if (listen_fd < 0)
die("socket");
ret = bind(listen_fd, (struct sockaddr *) &servaddr, sizeof(servaddr));
if (ret < 0)
die("bind");
ret = setsockopt(listen_fd, IPPROTO_SCTP, SCTP_INITMSG, &initmsg, sizeof(initmsg));
if (ret < 0)
die("setsockopt");
ret = listen(listen_fd, initmsg.sinit_max_instreams);
if (ret < 0)
die("listen");
for (;;) {
char buffer[1024];
printf("Waiting for connection\n");
fflush(stdout);
conn_fd = accept(listen_fd, (struct sockaddr *) NULL, NULL);
if(conn_fd < 0)
die("accept()");
printf("New client connected\n");
fflush(stdout);
in = sctp_recvmsg(conn_fd, buffer, sizeof(buffer), NULL, 0, &rcvinfo, &flags);
if (in > 0) {
printf("Received data: %s\n", buffer);
// Extract the source port from the SCTP header
uint16_t sourcePort = ntohs(rcvinfo.rcv_sid);
printf("Source port: %u\n", sourcePort);
fflush(stdout);
}
close(conn_fd);
}
}
int main(int argc, char **argv)
{
server();
return 0;
}
output
New client connected
Received data: Hello, Server! The value of client port 9999
Source port: 61608 ------------------------------------> using 9999 client port but shows 61608
Waiting for connection
New client connected
Received data: Hello, Server! The value of client port 8888
Source port: 61608 ------------------------------------> using 8888 client port but shows 61608
Waiting for connection
