#include <stdio.h>
#include <sys/socket.h>
#include <dlfcn.h>
#include <netinet/tcp.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdlib.h>

static int silent_mode = 0;
static unsigned send_delay = 0;
static unsigned send_chunk = 1;

char* xgetenv(const char* name, char* def){
	char* rv = getenv(name);
	return rv ? rv : def;
}

__attribute__((constructor)) void slowloris_init(){
	silent_mode = strtoul(xgetenv("SLOWLORIS_SILENT", "0"), NULL, 10);
	send_delay = strtoul(xgetenv("SLOWLORIS_DELAY", "0"), NULL, 10);
	send_chunk = strtoul(xgetenv("SLOWLORIS_CHUNK", "1"), NULL, 10);
	if(!silent_mode){
		printf("preload-slowloris active\nDelay: %d\nChunking: %d\n", send_delay, send_chunk);
	}
}

int socket(int domain, int type, int protocol){
	static int (*real_socket) (int, int, int) = NULL;
	if(!real_socket){
		real_socket = dlsym(RTLD_NEXT, "socket");
	}

	int fd = real_socket(domain, type, protocol);
	int enable = 1;

	if(domain == AF_INET && type == SOCK_STREAM){
		if(setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(enable)) < 0){
			if(!silent_mode){
				perror("setsockopt/tcp_nodelay");
			}
		}
	}
	return fd;
}

ssize_t send(int sockfd, const void* buf, size_t len, int flags){
	static ssize_t (*real_send) (int, void*, size_t, int) = NULL;
	if(!real_send){
		real_send = dlsym(RTLD_NEXT, "send");
	}

	ssize_t rv = 0;

	for(size_t u = 0; u < len; u += send_chunk){
		ssize_t sent = real_send(sockfd, buf + u, (send_chunk < len - u) ? send_chunk : (len - u), flags);
		if(sent < 0){
			return -1;
		}
		rv += sent;
		if(send_delay){
			usleep(send_delay);
		}
	}
	return rv;
}