C++ send file and text via socket

Question

Im trying to send a image using socket but I have to send the file name as well. Im using a code that i send the file but when I send the file name i receive some strange characters in client.

Client:

#define PORT 20000
#define LENGTH 512 

int main(int argc, char *argv[]){
int sockfd; 
int nsockfd;
char revbuf[LENGTH]; 
struct sockaddr_in remote_addr;

/* Get the Socket file descriptor */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
    fprintf(stderr, "ERROR: Failed to obtain Socket Descriptor! (errno = %d)\n",errno);
    exit(1);
}

/* Fill the socket address struct */
remote_addr.sin_family = AF_INET; 
remote_addr.sin_port = htons(PORT); 
inet_pton(AF_INET, "127.0.0.1", &remote_addr.sin_addr); 
bzero(&(remote_addr.sin_zero), 8);

/* Try to connect the remote */
if (connect(sockfd, (struct sockaddr *)&remote_addr, sizeof(struct sockaddr)) == -1)
{
    fprintf(stderr, "ERROR: Failed to connect to the host! (errno = %d)\n",errno);
    exit(1);
}
else 
    printf("[Client] Connected to server at port %d...ok!\n", PORT);

/* Send File to Server */
//if(!fork())
//{
    char* fs_name = "house.jpg";
    char sdbuf[LENGTH]; 

            char buffer[256];
            int n;
            fgets(buffer,255,stdin);
            bzero(buffer,256);
            n = write(sockfd,buffer, strlen(buffer));
            if(n<0) printf("Error: sending filename");

    printf("[Client] Sending %s to the Server... ", fs_name);
    FILE *fs = fopen(fs_name, "r");
    if(fs == NULL)
    {
        printf("ERROR: File %s not found.\n", fs_name);
        exit(1);
    }

    bzero(sdbuf, LENGTH); 
    int fs_block_sz;
    while((fs_block_sz = fread(sdbuf, sizeof(char), LENGTH, fs)) > 0)
    {
        if(send(sockfd, 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("Ok File %s from Client was Sent!\n", fs_name);
//}


close (sockfd);
printf("[Client] Connection lost.\n");
return (0);
}

Part of client that sends the text:

char buffer[256];
int n;
fgets(buffer,255,stdin);
bzero(buffer,256);
n = write(sockfd,buffer, strlen(buffer));
if(n<0) printf("Error: sending filename");

Server:

#define PORT 20000 
#define BACKLOG 5
#define LENGTH 512 

int main ()
{
int sockfd; 
int nsockfd; 
int num;
int sin_size; 
struct sockaddr_in addr_local; /* client addr */
struct sockaddr_in addr_remote; /* server addr */
char revbuf[LENGTH];

/* Get the Socket file descriptor */
if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 )
{
    fprintf(stderr, "ERROR: Failed to obtain Socket Descriptor. (errno = %d)\n", errno);
    exit(1);
}
else 
    printf("[Server] Obtaining socket descriptor successfully.\n");

/* Fill the client socket address struct */
addr_local.sin_family = AF_INET; // Protocol Family
addr_local.sin_port = htons(PORT); // Port number
addr_local.sin_addr.s_addr = INADDR_ANY; // AutoFill local address
bzero(&(addr_local.sin_zero), 8); // Flush the rest of struct

/* Bind a special Port */
if( bind(sockfd, (struct sockaddr*)&addr_local, sizeof(struct sockaddr)) == -1 )
{
    fprintf(stderr, "ERROR: Failed to bind Port. (errno = %d)\n", errno);
    exit(1);
}
else 
    printf("[Server] Binded tcp port %d in addr 127.0.0.1 sucessfully.\n",PORT);

/* Listen remote connect/calling */
if(listen(sockfd,BACKLOG) == -1)
{
    fprintf(stderr, "ERROR: Failed to listen Port. (errno = %d)\n", errno);
    exit(1);
}
else
    printf ("[Server] Listening the port %d successfully.\n", PORT);

int success = 0;
while(success == 0)
{
    sin_size = sizeof(struct sockaddr_in);

    /* Wait a connection, and obtain a new socket file despriptor for single connection */
    if ((nsockfd = accept(sockfd, (struct sockaddr *)&addr_remote, &sin_size)) == -1) 
    {
        fprintf(stderr, "ERROR: Obtaining new Socket Despcritor. (errno = %d)\n", errno);
        exit(1);
    }
    else 
        printf("[Server] Server has got connected from %s.\n", inet_ntoa(addr_remote.sin_addr));


            char buffer[256];
            bzero(buffer,256);
            int n = 0;
            n = read(nsockfd, buffer, 255);
            if (n < 0) error("ERROR reading from socket");
            printf("msg: %s\n",buffer);

    /*Receive File from Client */
    char* fr_name = "/house.jpg";
    FILE *fr = fopen(fr_name, "a");
    if(fr == NULL)
        printf("File %s Cannot be opened file on server.\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("File write failed on server.\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);
                exit(1);
            }
        }
        printf("Ok received from client!\n");
        fclose(fr); 
    }
}

}

Part of server that receive the text:

char buffer[256];
bzero(buffer,256);
int n = 0;
n = read(nsockfd, buffer, 255);
if (n < 0) error("ERROR reading from socket");
printf("msg: %s\n",buffer);

Need some help with that. Thanks...

Answer 1

In this code in your client:

        char buffer[256];
        int n;
        fgets(buffer,255,stdin);
        bzero(buffer,256);
        n = write(sockfd,buffer, strlen(buffer));

It looks like you are trying to read the file name from the stdin and send it on the sockfd . But. you zero out the buffer before you send it.