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Hi,

I've made use of what I understood from the echo-client codes that Thomas had corrected and tried to implement my knowledge on the echo-server program instead.

It's now able to receive, but the moment it tries to echo back to the client, it gives an "input/output error". Can someone advise on what could be wrong? I've attached the client and server codes as attachments so that all of you can have a look. Thank you!!!


Cheers,
Oon, Heok Kee



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/* Echo Client Example */

/* SCTP client */

/* Compile this file with "gcc -o sctp_client sctp_client.c -Wall -lsctpsocket -lsctp -lglib -lstdc++ -lpthread". */

#include <stdio.h> /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket(), connect(), send(), and recv() */
#include <arpa/inet.h> /* for sockaddr_in and inet_addr() */
#include <stdlib.h> /* for atoi() */
#include <string.h> /* for memset() */
#include <unistd.h> /* for close() */
#include <sys/types.h>
#include <sys/time.h>
#include <ext_socket.h>
#include <net/route.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sctp.h>

#define RCVBUFSIZE 1024 /* Size of receive buffer */
#define OUTSTREAM 3 /* Number of out-bound streams */
#define INSTREAM 2 /* Number of in-bound streams */


void DieWithError(char *errorMessage)
{
perror(errorMessage);
exit(1);
}


int main(int argc, char *argv[])
{
int sock; /* Socket descriptor */
struct sockaddr_in echoServAddr;/* Echo server address */
unsigned short echoServPort; /* Echo server port */
char *servIP; /* Server IP address (dotted quad) */
char *echoString; /* String to send to echo server */
char echoBuffer[RCVBUFSIZE]; /* Buffer for echo string */
unsigned int echoStringLen; /* Length of string to echo */
int bytesRcvd, totalBytesRcvd; /* Bytes read in single recv() and total bytes read */
struct sctp_initmsg sim;
struct sctp_sndrcvinfo *sinfo;
struct msghdr msg[1];
struct cmsghdr *cmsg;
struct iovec iov[1];
char cbuf[sizeof(*cmsg) + sizeof(*sinfo) + sizeof(*echoString)];
struct sctp_event_subscribe events;

/* Test for correct number of arguments */
if ((argc < 3) || (argc > 4)) {
fprintf(stderr, "Usage: %s <Server IP> <Echo Word> [<Echo Port>]\n",argv[0]);
exit(1);
}

servIP = argv[1]; /* First arg: server IP address (dotted quad) */

echoString = argv[2]; /* Second arg: string to echo */

if (argc == 4)
echoServPort = atoi(argv[3]); /* Use given port, if any */
else
/* 7 is the well-known port for the echo service */
echoServPort = 7;

printf("\nCreating socket... ");
/* Create a reliable, stream socket using TCP */
if ((sock = ext_socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP)) < 0)
{
DieWithError("socket() failed");
}
printf("Socket created.\n\n");

(&sim)->sinit_num_ostreams = OUTSTREAM;
(&sim)->sinit_max_instreams = INSTREAM;
(&sim)->sinit_max_attempts = 3;
(&sim)->sinit_max_init_timeo = 30;

/* Setting socket options */
if (ext_setsockopt(sock, IPPROTO_SCTP, SCTP_INITMSG, &sim, sizeof(sim)) < 0)
{
DieWithError("setsockopt() failed");
}

memset((char*)&events,0,sizeof(events));
events.sctp_data_io_event = 1;
if (ext_setsockopt(sock, IPPROTO_SCTP, SCTP_SET_EVENTS, &events, sizeof(events)) < 0) {
DieWithError("setsockopt() failed");
}

memset(msg, 0, sizeof(*msg));
msg->msg_control = cbuf;
msg->msg_controllen = sizeof(struct cmsghdr) + sizeof(struct sctp_sndrcvinfo);
msg->msg_flags = 0;

(&iov[0])->iov_base = echoString;
(&iov[0])->iov_len = strlen(echoString);

msg->msg_iov = (struct iovec*)&iov;
msg->msg_iovlen = 1;

cmsg = (struct cmsghdr *)cbuf;
sinfo = (struct sctp_sndrcvinfo *)(cmsg + 1);

cmsg->cmsg_len = sizeof(struct cmsghdr) + sizeof(struct sctp_sndrcvinfo);
cmsg->cmsg_level = IPPROTO_SCTP;
cmsg->cmsg_type = SCTP_SNDRCV;

sinfo->sinfo_assoc_id = 0;
sinfo->sinfo_stream = 2; /* streamNumber */
sinfo->sinfo_flags = 0;
sinfo->sinfo_ppid = 0x12345678; /* ppid */
sinfo->sinfo_context = (uint32_t)NULL;
sinfo->sinfo_timetolive = (unsigned int)-1;

/* Construct the server address structure */
/* Zero out structure */
memset(&echoServAddr, 0, sizeof(echoServAddr));

echoServAddr.sin_family = AF_INET; /* Internet address family */

/* Server IP address */
echoServAddr.sin_addr.s_addr = inet_addr(servIP);

echoServAddr.sin_port = htons(echoServPort); /* Server port */

printf("Connecting to server at %s:%u ... ", servIP, echoServPort);
/* Establish the connection to the echo server */
if (ext_connect(sock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr)) < 0)
DieWithError("connect() failed");
printf("Connected.\n\n");

echoStringLen = strlen(echoString); /* Determine input length */

printf("Sending message \"%s\" to server... ", echoString);
/* Send the string to the server */
if (ext_sendmsg(sock, msg, 0) < 0)
DieWithError("send() failed!");
printf("Message sent.\n\n");

/* Receive the same string back from the server */
totalBytesRcvd = 0;

(&iov[0])->iov_base = echoBuffer;
(&iov[0])->iov_len = sizeof(echoBuffer);
msg->msg_iov = (struct iovec*)&iov;
msg->msg_iovlen = 1;
msg->msg_control = cbuf;
msg->msg_controllen = sizeof(cbuf);
msg->msg_flags = 0;
msg->msg_name = NULL;
msg->msg_namelen = 0;

printf("Receiving echo from server... ");
printf("Received: "); /* Setup to print the echoed string */

while (totalBytesRcvd < echoStringLen)
{
/* Receive up to the buffer size (minus 1 to leave space for a null terminator) bytes from the sender */
if ((bytesRcvd = ext_recvmsg(sock, msg, 0)) <= 0) /*echoBuffer, RCVBUFSIZE - 1, 0)) <= 0)*/
DieWithError("recv() failed or conn. closed prematurely");
totalBytesRcvd += bytesRcvd; /* Keep tally of total bytes */

echoBuffer[bytesRcvd] = '\0'; /* Terminate the string! */

printf(echoBuffer); /* Print the echo buffer */

if(msg->msg_controllen > 0) {
cmsg = CMSG_FIRSTHDR(msg);
if((cmsg != NULL) && (cmsg->cmsg_level == IPPROTO_SCTP) && (cmsg->cmsg_type == SCTP_SNDRCV)) {
sinfo = (struct sctp_sndrcvinfo*)CMSG_DATA(cmsg);
printf("Stream ID: %d\n",sinfo->sinfo_stream);
printf("Protocol ID: %08x\n",sinfo->sinfo_ppid);
}
}
}

printf("\n\n"); /* Print a final linefeed */

ext_close(sock);

usleep(100000);

exit(0);
}

/**** Echo Server Example ****/

/* SCTP server */

/* Compile this file with "gcc -o sctp_server sctp_server.c -Wall -lsctpsocket -lsctp -lglib -lstdc++ -lpthread". */

#include <stdio.h> /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket(), bind(), and connect() */
#include <arpa/inet.h> /* for sockaddr_in and inet_ntoa() */
#include <stdlib.h> /* for atoi() */
#include <string.h> /* for memset() */
#include <unistd.h> /* for close() */
#include <sys/types.h>
#include <sys/time.h>
#include <ext_socket.h>
#include <net/route.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sctp.h>


#define MAXPENDING 5 /* Maximum outstanding connection requests */
#define RCVBUFSIZE 1024 /* Size of receive buffer */
#define OUTSTREAM 3 /* Number of out-bound streams to initialise */
#define INSTREAM 3 /*Number of in-bound streams to initialise */


void DieWithError(char *errorMessage)
{
perror(errorMessage);
exit(1);
}


void HandleSCTPClient(int clntSocket)
{
char echoBuffer[RCVBUFSIZE];
int recvMsgSize; /* Size of received message */
struct msghdr msg[1];
struct cmsghdr *cmsg;
struct sctp_sndrcvinfo *sri;
struct iovec iov[1];
size_t cmsglen = sizeof(struct cmsghdr) + sizeof(struct sctp_sndrcvinfo) + sizeof(echoBuffer);
char cbuf[cmsglen];

memset(msg, 0, sizeof(*msg));
msg->msg_control = cbuf;
msg->msg_controllen = cmsglen;
msg->msg_flags = 0;

printf("Receiving message from client...\n\n");
(&iov[0])->iov_base = echoBuffer;
(&iov[0])->iov_len = sizeof(echoBuffer);

msg->msg_iov = (struct iovec*)&iov;
msg->msg_iovlen = 1;

cmsg = (struct cmsghdr *)cbuf;
sri = (struct sctp_sndrcvinfo *)(cmsg + 1);

cmsg->cmsg_len = cmsglen;
cmsg->cmsg_level = IPPROTO_SCTP;
cmsg->cmsg_type = SCTP_SNDRCV;

sri->sinfo_assoc_id = 0;
sri->sinfo_stream = 1;
sri->sinfo_flags = 0;
sri->sinfo_ppid = 0x12345678;
sri->sinfo_context = (uint32_t)NULL;
sri->sinfo_timetolive = (unsigned int)-1;

printf("Message received: ");

do{
recvMsgSize = 0;

msg->msg_flags = 0;
msg->msg_control = cbuf;
msg->msg_controllen = cmsglen;
msg->msg_name = NULL;
msg->msg_namelen = 0;

if ((recvMsgSize = ext_recvmsg(clntSocket, msg, 0)) <= 0)
{
DieWithError("recvmsg() failed");
} else {
printf("recvMsgSize = %d\n\n", recvMsgSize);
echoBuffer[recvMsgSize] = '\0';
printf("%s", echoBuffer);
}

(&iov[0])->iov_base = echoBuffer;
(&iov[0])->iov_len = sizeof(echoBuffer);
msg->msg_iov = (struct iovec*)&iov;
msg->msg_iovlen = 1;

msg->msg_flags = 0;
msg->msg_control = cbuf;
msg->msg_controllen = cmsglen - sizeof(echoBuffer);
msg->msg_name = NULL;
msg->msg_namelen = 0;

if (ext_sendmsg(clntSocket, msg, 0) < 0)
DieWithError("send() failed");
} while (recvMsgSize > 0);

printf("\n\nClosing connection... ");
ext_close(clntSocket); /* Close client socket */
printf("Connection closed.\n\n");
}


int main(int argc, char *argv[])
{
int servSock; /* Socket descriptor for server */
int clntSock; /* Socket descriptor for client */
struct sockaddr_in echoServAddr; /* Local address */
struct sockaddr_in echoClntAddr; /* Client address */
unsigned int clntLen; /* Length of client address */
unsigned short echoServPort; /* Server port */
struct sctp_initmsg sim;
struct sctp_event_subscribe events;

if (argc != 2) /* Test for correct number of arguments */
{
fprintf(stderr, "Usage: %s <Server Port>\n", argv[0]);
exit(1);
}

echoServPort = atoi(argv[1]); /* First arg: local port */

printf("\nCreating socket... ");
/* Create socket for incoming connections */
if ((servSock = ext_socket(AF_INET, SOCK_STREAM, IPPROTO_SCTP)) < 0)
DieWithError("socket() failed");
printf("Socket created.\n\n");

/* Construct local address structure */
/* Zero out structure */
memset(&echoServAddr, 0, sizeof(echoServAddr));

echoServAddr.sin_family = AF_INET;/* Internet addr. family */

/* Any incoming interface */
echoServAddr.sin_addr.s_addr = htonl(INADDR_ANY);

echoServAddr.sin_port = htons(echoServPort); /* Local port */

/* To initialise the number of in and out streams needed with the
client */
(&sim)->sinit_num_ostreams = OUTSTREAM;
(&sim)->sinit_max_instreams = INSTREAM;
(&sim)->sinit_max_attempts = 3;
(&sim)->sinit_max_init_timeo = 30;

if (ext_setsockopt(servSock, IPPROTO_SCTP, SCTP_INITMSG, &sim, sizeof(sim)) < 0)
{
DieWithError("setsockopt() failed");
exit(1);
}

memset((char *)&events, 0, sizeof(events));
events.sctp_data_io_event = 1;
if (ext_setsockopt(servSock, IPPROTO_SCTP, SCTP_SET_EVENTS, &events, sizeof(events)) < 0)
DieWithError("setsockopt() failed");

printf("Binding to address... ");
/* Bind to the local address */
if (ext_bind(servSock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr)) < 0)
DieWithError("bind() failed");
printf("Address bounded.\n\n");

/* Mark the socket so it will listen for incoming conn. */
printf("Waiting for connection... ");
if (ext_listen(servSock, MAXPENDING) < 0)
DieWithError("listen() failed");

for (;;) /* Run forever */
{
/* Set the size of the in-out parameter */
clntLen = sizeof(echoClntAddr);

/* Wait for a client to connect */
if ((clntSock = ext_accept(servSock, (struct sockaddr *) &echoClntAddr, &clntLen)) < 0)
DieWithError("accept() failed");
printf("Connected.\n\n");

/* clntSock is connected to a client! */
printf("Handling client %s\n\n",
inet_ntoa(echoClntAddr.sin_addr));

HandleSCTPClient(clntSock);
}
}

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• [SCTP-Discussion] input/output error, Oon Heok Kee, 09/03/2002
  • Re: [SCTP-Discussion] input/output error, Thomas Dreibholz, 09/03/2002

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