vuln.c

#include <stdio.h>
#include <netdb.h>
#include <netinet/in.h>

#define BUFFER_SIZE 1024
#define NAME_SIZE 2048

int handling(int c)
{
	char buffer[BUFFER_SIZE], name[NAME_SIZE];
	int bytes;
	strcpy(buffer, "My name is: ");
	bytes = send(c, buffer, strlen(buffer), 0);
	if (bytes == -1)
		return -1;
	bytes = recv(c, name, sizeof(name), 0);
	if (bytes == -1)
		return -1;
	name[bytes - 1] = '\0';
	sprintf(buffer, "Hey %s, Wellcome\r\n", name);
	bytes = send(c, buffer, strlen(buffer), 0);
	if (bytes == -1)
		return -1;
return 0;
}

int main(int argc, char *argv[])
{
	int s, c, cli_size;
	struct sockaddr_in srv, cli;
	if (argc != 2)
	{
		fprintf(stderr, "usage: %s port\n", argv[0]);
		return 1;
	}
	s = socket(AF_INET, SOCK_STREAM, 0);
	if (s == -1)
	{
		perror("socket() failed");
		return 2;
	}
	srv.sin_addr.s_addr = INADDR_ANY;
	srv.sin_port = htons( (unsigned short int) atol(argv[1]));
	srv.sin_family = AF_INET;
	if (bind(s, &srv, sizeof(srv)) == -1)
	{
		perror("bind() failed");
		return 3;
	}
	if (listen(s, 3) == -1)
	{
		perror("listen() failed");
		return 4;
	}
	for(;;)
		{
		c = accept(s, &cli, &cli_size);
		if (c == -1)
			{
			perror("accept() failed");
			return 5;
		}
		printf("client from %s", inet_ntoa(cli.sin_addr));
		if (handling(c) == -1)
			fprintf(stderr, "%s: handling() failed", argv[0]);
		close(c);
	}
return 0;
}