In here I am sending file name first then sending the file in chunks, then trying to read the received message but it is just freezing. No respond. But after loop if I shutdown the WR shutdown(connfd,SHUT_WR); It is working fine. Though I should be able to send message again, if I do this I can not do that.
CLIENT.C
write(sockfd, fname,100);
FILE *fp = fopen(fname,"rb");
if(fp==NULL)
{
printf("File opern error");
exit(1);
}
int hi = 0;
while(1)
{
/* First read file in chunks of 256 bytes */
unsigned char buff[1024]={0};
int nread = fread(buff,1,1024,fp);
/* If read was success, send data. */
if(nread > 0)
{
hi++;
//printf("Sending \n");
write(sockfd, buff, nread);
}
if (nread < 1024)
{
if (feof(fp))
{
printf("File transfer completed!\n");
}
if (ferror(fp))
printf("Error reading\n");
break;
}
}
char fname2[100];
// cant read
read(sockfd, fname2, 100);
printf("File Name: %s\n",fname2);
SERVER.C
FILE *fp;
int bytesReceived = 0;
char recvBuff[1024];
char fname[100];
char fname2[100];
read(newsockfd, fname, 100);
//strcat(fname,"AK");
printf("File Name: %s\n",fname);
printf("Receiving file...");
fp = fopen(fname, "ab");
if(NULL == fp)
{
printf("Error opening file");
}
long double sz=1;
/* Receive data in chunks of 256 bytes */
printf("\nCompleted.\n");
int hi = 0;
while((bytesReceived = read(newsockfd, recvBuff, 1024)) > 0)
{
hi++;
sz++;
fwrite(recvBuff, 1,bytesReceived,fp);
}
printf("Not pring this this!");
if(bytesReceived < 0)
{
printf("\n Read Error \n");
}
write(newsockfd, "SayGee",100);
I had to send the size of the file, then check from the other side inside loop. It was in deadlock.I found the solution. So thanks anyway!
Related
I'm sending a file from the client to the server.
Client sends filename
Server receives filename
Client sends file size
Server receives file size
Client sends file contents
Server receives file contents
When I print out the file size that I sent, it is the exact number of bytes as the file I wish to send so that's fine. The issue is that the server (receives) doesn't seem to exit the while loop when writing to the new file. I know this because the final print statement printf("The server has received the requested document\n"); is never reached and it just hangs. What could be causing this?
Client snippet (sends):
else if(strcmp(shortCommand, "put") == 0){
char *tmp = buf + 4;
char filename[MAX_BLOCK_SIZE];
size_t size, bytes_read, bytes_written;
int x;
strcpy(filename, "filename ");
strcat(filename, tmp);
FILE *fp;
printf("File name: %s\n", tmp);
fp = fopen(tmp, "rb");
if(fp == NULL){
printf("ERROR: Requested file does not exist.\n");
}
else{
printf("Client sending filename...\n");
if ((x = write(sd, buf, sizeof(buf))) < 0){ //sending the file name to the client first
printf("Error sending client's filename.\n");
}
printf("Client sending file...\n");
fseek(fp, 0, SEEK_END);
size = ftell(fp);
fseek(fp, 0, SEEK_SET);
printf("Sending file size\n");
if((write(sd, &size, sizeof(size))) < 0){ //sending filesize
printf("error sending file size\n");
}
printf("Sending file\n");
while((bytes_read = fread(buf, 1, sizeof(buf), fp)) > 0){ //sending file contents
if ((bytes_written = write(sd, buf, bytes_read)) < 0){
printf("Error sending client file.\n");
}
}
printf("bytes written: %ld\n", bytes_written);
fclose(fp);
}
}
Server snippet (receives):
if(strcmp(shortCommand, "put") == 0){
char *tmp = buf + 4;
char filename2[MAX_BLOCK_SIZE];
size_t filesize;
size_t total_bytes_read = 0;
ssize_t bytes_read = 0;
size_t error;
FILE *fp;
strcpy(filename2, tmp);
printf("Server receiving file name...\n"); //filename is received on the first read before this IF
fp = fopen(filename2, "wb");
if(fp == NULL){
printf("File could not be opened.\n");
exit(1);
}
printf("Server receiving file size...\n");
if((error = read(sd, &filesize, sizeof(filesize))) < 0){ //receiving file size
perror("Error reading filesize\n");
exit(1);
}
printf("Filesize is: %ld \n", filesize);
while(total_bytes_read < filesize){
while((bytes_read = read(sd, buf, sizeof(buf))) > 0){ //receving file contents and writing to file
fwrite(buf, 1, bytes_read, fp);
total_bytes_read += bytes_read;
if(ferror(fp)){
perror("error");
fclose(fp);
}
}
}
printf("The server has received the requested document.\n");
fflush(stdout);
fclose(fp);
}
After I exit the program by force, I can actually see that the file has been copied. Just doesn't exit that while loop to let me go back to the client.
Time for some basic debugging. I'd suggest changing your read loop to something like this:
while (total_bytes_read < filesize) {
printf("DEBUG A: total=%zu, size=%zu\n", total_bytes_read, filesize);
while ((bytes_read = read(sd, buf, sizeof(buf))) > 0) {
printf("DEBUG B: read=%zd\n", bytes_read);
fwrite(buf, 1, bytes_read, fp);
total_bytes_read += bytes_read;
printf("DEBUG C: total=%zu\n", total_bytes_read);
if (ferror(fp))
printf("DEBUG D\n");
perror("error");
fclose(fp);
}
printf("DEBUG E\n");
}
printf("DEBUG F\n");
}
printf("DEBUG G\n");
Then run it, piping the output through less or some other pager, it should then hopefully become clearer what's actually happening.
Feel free to post the output of this modified code (in a comment, or in the actual question), we'll no doubt be able to help with the analysis.
I'm trying to download a file from my server; both the client and the server are Linux, yet ssh_scp_read() returns an incorrect integer. According to the documentation the function writes up to 65536 bytes, yet is only reading 16384 when the file is 37980, but that's not my main concern; near the end of this 16384 bytes it starts to fill the buffer with NULL garbage, that will then be written to the file.
The creation of recursive directories works fine; the problem is downloading files larger than 16384 bytes. At this point I'll use sftp instead of scp, but I would like to know what I am doing wrong.
This is the function code:
int get(ssh_session gno_ses,ssh_scp scp)
{
int rc;
int size, permissions;
char *buff, *filename, path[PATH_MAX];
while(1)
{
rc = ssh_scp_pull_request(scp);
switch (rc)
{
// cases [...]
case SSH_SCP_REQUEST_NEWFILE:
size = ssh_scp_request_get_size(scp);
printf("Size is %d\n",size);
filename = strdup(ssh_scp_request_get_filename(scp));
permissions = ssh_scp_request_get_permissions(scp);
FILE *file;
file = fopen(filename, "w+");
if (!file)
{
ssh_scp_deny_request(scp,"Unable to open");
fprintf(stderr, " %s: %s\n", filename, strerror(errno));
fclose(file);
break;
}
buff = malloc(size);
printf("Size of buffer is %d\n", size);
if (!buff)
{
fprintf(stderr, "\nBuff memory allocation error.\n");
return SSH_ERROR;
}
if( ssh_scp_accept_request(scp) != SSH_OK)
{
fprintf(stderr, "Error accepting request: %s\n", ssh_get_error(gno_ses));
break;
}
do
{
rc = ssh_scp_read(scp, buff, size);
if (rc == SSH_ERROR)
{
fprintf(stderr, "Error receiving file data: %s\n", ssh_get_error(gno_ses));
break;
}
if (fwrite(buff, 1, size, file) != size)
{
perror("Error at writting to file: ");
break;
}
printf("ssh_scp_read got %d\n",rc);
} while (rc != 0);
fclose(file);
free(filename);
free(buff);
break;
}
}
return SSH_OK;
}
And this is the output:
Size is 37980
Size of buffer is 37980
ssh_scp_read got 16384
ssh_scp_read got 16384
ssh_scp_read got 5212
Error receiving file data: ssh_scp_read called under invalid state
Any input would be appreciated.
The problem was that I was writing size bytes when indeed scp_scp_read() had reported that it had read less than that:
rc = ssh_scp_read(scp, buff, size);
fwrite(buff, 1, size, file)
The fix is to write only rc bytes:
int len_loop = size;
int len;
do
{
rc = ssh_scp_read(scp, buff, size);
if (rc == SSH_ERROR || rc < 0)
{
fprintf(stderr, "Error receiving file data: %s\n", ssh_get_error(gno_ses));
break;
}
else if (!rc)
{
break;
}
len = fwrite(buff, 1, rc, file);
if (len != rc)
{
perror("Error at writting to file: ");
break;
}
printf("ssh_scp_read got %d\n",rc);
len_loop -= rc;
} while(len_loop);
change your inner loop as
int len = size;
do
{
rc = ssh_scp_read(scp, buff, size);
if (rc == SSH_ERROR)
{
fprintf(stderr, "Error receiving file data: %s\n",
ssh_get_error(gno_ses));
break;
}
if (fwrite(buff, 1, rc, file) != size)
{
perror("Error at writting to file: ");
break;
}
printf("ssh_scp_read got %d\n",rc);
len-=rc;
} while (len);
I have written the following code for sending file from a client:
FILE *fp = fopen("video.mp4","rb");
if(fp==NULL)
{
printf("File opern error");
return 1;
}
int bytesToWrite=84440670;
int bytesWritten=0;
while(bytesWritten<bytesToWrite)
{
int m=minimum(256,bytesToWrite-bytesWritten);
/* First read file in chunks of 256 bytes or the remaining bytes*/
unsigned char *buff=malloc(sizeof(char)*m);
bzero(buff, m);
int nread = fread(buff,1,m,fp);
printf("Bytes read %d \n", nread);
bytesWritten+=m;
/* If read was success, send data. */
if(nread > 0)
{
printf("Sending \n");
write(sockfd, buff, nread);
}
/*
* There is something tricky going on with read ..
* Either there was error, or we reached end of file.
*/
if (nread < 256)
{
if (feof(fp))
printf("End of file\n");
if (ferror(fp))
printf("Error reading\n");
break;
}
}
and the following code for receiving by the server :
FILE *fp;
fp = fopen("receive.mp4", "wb");
if(NULL == fp)
{
printf("Error opening file");
return 1;
}
int bytesToRead=84440670;
/* Receive data in chunks of 256 or remaining bytes */
int totalbytesread=0;
while(totalbytesread < bytesToRead)
{
int m = minimum(256,bytesToRead-totalbytesread);
char *recvBuff=malloc(sizeof(char)*m);
bzero(recvBuff,m);
bytesReceived = read(newsocfd, recvBuff,m );
printf("Bytes received %d\n",bytesReceived);
totalbytesread += bytesReceived;
fwrite(recvBuff, 1,bytesReceived,fp);
}
if(bytesReceived < 0)
{
printf("\n Read Error \n");
}
The sending is working correctly for .txt files ,some data is being lost in sending other formats(for e.g some ending seconds of .mp4 files is not being sent).
I am new to socket programming. Any help would be deeply appreciated.
You are missing a fclose(fp); in the server after you have finished receiving. You can also use fflush(fp); to just flush the contents.
Besides, there are several memory leaks and improper error handling.
I'm trying to send files using TCP from a windows client to a Linux server in C.
The size of the buffer I use to send the data is 65535. When the size of the file exceeds this value, I get an error saying 'connection reset by peer' or the error code 10054. When the size of the file is less than 65535 bytes, the server receives only a part of it (usually 2760 bytes).
I just want to send files with a maximum size of 50 MB.
This is the part of the windows client that I use to send data:
char *fileName; // pointer to filename
char buf[65535]; // buffer
int fileSize; // # bytes to send
for(i = 0; i < ARRAYSIZE; i++) {
if(selectList[i] != NULL) {
// select file
fileName= selectList[i]; // get path and filename from selectList
printf("=============================================\nSending: %s\n", fileName);
filefd = fopen(fileName, "rb"); // open file
if(filefd == NULL) {
printf("File %s not found\n", fileName);
exit(1);
}
// read and send file
memset(buf, '\0', 65535);
while((fileSize= fread(buf, sizeof(char), 65535, filefd)) > 0) { // read file
if((numberOfBytes = send(sockfd, buf, fileSize, 0)) < 0) { // send buffer
printf("send: %s (Error: %d)\n", filename, WSAGetLastError());
break;
}
printf("#bytes = %i \n", numberOfBytes);
memset(buf, '\0', 65535);
}
printf("File %s send!\n", filename);
// close file after sending it
if(fclose(filefd) < 0) {
printf("fclose: %i", WSAGetLastError());
}
} else if(selectList[0] == NULL) {
printf("no files selected");
}
}
The selectList contains multiple strings such as: C:\Windows\test.txt
The recieve part of the Linux server:
char* fr_name = "/home/MtFS/UploadedFiles/public/testFile.gif";
FILE *fr = fopen(fr_name, "wb");
if(fr == NULL)
printf("[Open_File]file %s cannot be created\n", fr_name);
else {
bzero(revbuf, LENGTH);
int fr_block_sz = 0;
while((fr_block_sz = recv(nsockfd, revbuf, LENGTH, 0)) > 0) {
int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);
if(write_sz < fr_block_sz) {
error("[Write] error\n");
}
bzero(revbuf, LENGTH);
if (fr_block_sz == 0 || fr_block_sz != 512) {
break;
}
}
if(fr_block_sz < 0) {
if (errno == EAGAIN) {
printf("[Receive] time out\n");
}
else {
printf("[Receive] error\n");
exit(1);
}
}
printf("[Receive] succesfull\n");
fclose(fr);
}
What am I doing wrong?
Your problem are those 3 lines of code. That's not the correct way to know that you're done:
if (fr_block_sz == 0 || fr_block_sz != 512) {
break;
}
Also you check against 512 instead of LENGTH. But only 0 means that you're done (assuming your connection is not NONBLOCKED.)
As a side note: you do not have to clear your buffers (bzero, memset) before using them with a read since the read/recv will overwrite the content of the buffers anyway.
I think the culprit is this line in your server
if (fr_block_sz == 0 || fr_block_sz != 512) {
fr_block_sz cab be anything between 1 to 65535 - the size block that you sent.
In your code, when its not 512 so your server is terminating the connection.
The below code works fine for smaller files where the last packet contains data less than maximum length, the function exit properly by displaying file received.
How ever if the last packet or buffer of file being transmitted contains exact number as the size of receiving buffer array 512 in my case. then th program keeps waiting for next packet.
All files with size multiple of 512 in my case stuck.
Below is the code:
CLIENT code for receiving:
void receiveFile() {
printf("inside receiveFile method\n");
char* fr_name = "final.txt";
int i;
FILE *fr = fopen(fr_name, "a");
int LENGTH = 512;
int fileLength=0;
char revbuf[LENGTH];
if (fr == NULL) {
printf("File %s Cannot be opened.\n", fr_name);
} else {
printf("starting to write the file\n");
bzero(revbuf, LENGTH);
int fr_block_sz = 0;
i=0;
while ((fr_block_sz = recv(4, revbuf, LENGTH, 0)) > 0) {
fileLength+=fr_block_sz;
i++;
printf("Received buffer: %d, %d\n",fr_block_sz,i);
int write_sz = fwrite(revbuf, sizeof(char), fr_block_sz, fr);
if (write_sz < fr_block_sz) {
error("File write failed.\n");
}
bzero(revbuf, LENGTH);
if (fr_block_sz == 0 || fr_block_sz != 512) {
break;
}
}
if (fr_block_sz < 0) {
if (errno == EAGAIN) {
printf("recv() timed out.\n");
} else {
fprintf(stderr, "recv() failed due to errno = %d\n", errno);
}
}
printf("FILE RECEIVED....Total Bytes received:%d \n",fileLength);
}
fclose(fr);
}
Server for Receiving the file:
void sendFile() {
printf("inside sendFile method\n");
char* fs_name = "mb.txt";
int LENGTH = 512;
int sfileLength=0;
char sdbuf[LENGTH];
int i=0;
printf("[Client] Sending %s to the Server... \n", fs_name);
FILE *fs = fopen(fs_name , "r");
if (fs == NULL) {
perror("ERROR: File not found.\n");
exit(1);
}
bzero(sdbuf, LENGTH);
int fs_block_sz;
while ((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs)) > 0) {
i++;
printf("Sent:%d , %d \n", fs_block_sz,i);
sfileLength+=fs_block_sz;
if (send(4, sdbuf, fs_block_sz, 0) < 0) {
fprintf(stderr, "ERROR: Failed to send file %s. (errno = %d)\n",
fs_name, errno);
break;
}
bzero(sdbuf, LENGTH);
}
printf("File sent.... Total Bytes:%d\n", sfileLength);
fclose(fs);
}
if (fr_block_sz == 0 || fr_block_sz != 512) {
break;
}
Remove this code. The first part of the test can never be true due to the 'while' condition, and the second part is unnecessary for the same reason.