Sockets API

[Kazekama]

Greetings,

I am new to the forums and I want to say I have gained a pretty good foundation off of here the last two years or so. I have been accommodating myself with the sockets API and I wanted to try a project. I have a client and server as usual. Below is my server. It is meant to receive STDOUT from a remote client and "puts" it in the entirety to the screen. No matter how much I increase the buffer size, there is a cut off from my puts output. I run wireshark and tested in out on loopback and I can see my execve netstat in the TCP stream altogether as it should be. I am afraid I am not accounting for something.

server:

#include<stdio.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<netinet/in.h>




#define BUFFSIZE 6000


int main( int argc, char *argv[] ) {


if (argc < 2 || argc > 2) {
puts("<port>");
exit(1);
}
//Variables
in_port_t servPort = atoi(argv[1]);
char buffer[BUFFSIZE];






//CREATE SOCKET
int sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);


//STRUCTURES
struct sockaddr_in server;
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_port = htons(servPort);


//Bind


bind(sock, (struct sockaddr *) &server, sizeof(server));


//Listen


listen(sock, 10);


for (;;) {


//CLIENTstruct
struct sockaddr_in client;
socklen_t clientLen = sizeof(client);




//ACCEPT
int cliSock;
cliSock = accept(sock, (struct sockaddr *) &client, &clientLen);


read(cliSock,buffer,BUFFSIZE);
puts(buffer); 
}


return 0;

}

client:

#include<stdio.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>




int main(int argc, char *argv[]) {


if (argc != 3) {
printf("<server><port>\n");
exit(1);
}


//Variables
char *servIP = argv[1];
in_port_t servPort = atoi(argv[2]);


//CREATE SOCKET
int sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);


//STRUCTURES
struct sockaddr_in server;
memset(&server, 0, sizeof(server));
server.sin_family = AF_INET;


//CONVERTADDRESS
inet_pton(AF_INET, servIP, &server.sin_addr.s_addr);
server.sin_port = htons(servPort);








//CONNECT
connect(sock, (struct sockaddr *) &server, sizeof(server));




//DUP2 SEND STDIN AND ERR OVER SOCKET
dup2(sock, STDOUT_FILENO);
dup2(sock, STDERR_FILENO);




//EXECVE LINUX SYSTEM CALL
char *execargv[] = {"/bin/netstat", "-an",  NULL };        //Initialize and fill arrays with exec values
char *environ[] = {NULL};
execve("/bin/netstat", execargv, environ);                 //perform execve


return 0;


}

[Salem]

Well you're ignoring a whole load of return results for one thing.

Also, read doesn't append a \0, like higher level operations such as fgets()

So perhaps

ssize_t r = read(cliSock,buffer,BUFFSIZE-1);  // -1 allows room for the \0
if ( r > 0 ) {
    buffer[r] = '\0';
    puts(buffer);
}

[Kazekama]

I am ignoring the return results just to expedite this, I am going to add them in later. I attempted to add in your suggestions and compile it. I get the same result, of getting a partial netstat.

[Salem]

> I am ignoring the return results just to expedite this
And a fantastic job you're making of it as well.

Look at your loop - you have accept + read + accept + read + accept + read....

    ssize_t r;
    while ( (r=read(cliSock,buffer,BUFFSIZE))>0 ) {
      //!!buffer[r] = 0;
      //!!puts(buffer); // writes a \n as well
      write(STDOUT_FILENO,buffer,r);
    }

[Kazekama]

You are a gentlemen and a scholar. Mr. Salem you have been the first person to assist me on here so thank you very much. I will go back and write this a little neater. I just needed to work that out. I'm just self taught, so taking this upon myself, there are holes in my knowledge and logic that doesn't make sense. I laughed at your last comment and can appreciate your humorous perspective.