From 6908e10aab019a59e142c6fd92d969260d9cc054 Mon Sep 17 00:00:00 2001
From: Jack Halford <jack@crans.org>
Date: Fri, 1 Sep 2017 19:29:17 +0200
Subject: [PATCH] packet forging

---
 libft/Makefile                |  4 ++++
 libft/includes/mytime.h       |  5 ++++-
 libft/includes/net.h          | 10 ++++++++++
 libft/srcs/net/forge_ip.c     | 17 +++++++++++++++++
 libft/srcs/net/forge_tcp.c    | 20 ++++++++++++++++++++
 libft/srcs/net/reserve_port.c | 25 +++++++++++++++++++++++++
 libft/srcs/printing/hexdump.c |  2 +-
 libft/srcs/time/epoch.c       | 10 ++++++++++
 8 files changed, 91 insertions(+), 2 deletions(-)
 create mode 100644 libft/srcs/net/forge_ip.c
 create mode 100644 libft/srcs/net/forge_tcp.c
 create mode 100644 libft/srcs/net/reserve_port.c
 create mode 100644 libft/srcs/time/epoch.c

diff --git a/libft/Makefile b/libft/Makefile
index b5abab40..1e31ed7d 100644
--- a/libft/Makefile
+++ b/libft/Makefile
@@ -135,6 +135,9 @@ net/create_client.c\
 net/create_server.c\
 net/net_get.c\
 net/net_send.c\
+net/forge_tcp.c\
+net/forge_ip.c\
+net/reserve_port.c\
 path/ft_path_notdir.c\
 printing/ft_putchar.c\
 printing/ft_putendl.c\
@@ -201,6 +204,7 @@ str/ft_strtrim.c\
 time/ft_mytime_free.c\
 time/ft_mytime_get.c\
 time/ft_time_isrecent.c\
+time/epoch.c\
 sys/open_new.c\
 htb/ft_hash_string.c\
 htb/hashtab_init.c\
diff --git a/libft/includes/mytime.h b/libft/includes/mytime.h
index 61444457..524d2973 100644
--- a/libft/includes/mytime.h
+++ b/libft/includes/mytime.h
@@ -12,6 +12,9 @@
 
 #ifndef MYTIME_H
 # define MYTIME_H
+
+# include <sys/time.h>
+
 # include "libft.h"
 
 struct		s_mytime
@@ -27,8 +30,8 @@ struct		s_mytime
 typedef struct s_mytime		t_mytime;
 
 int			ft_time_isrecent(time_t event);
-
 t_mytime	*ft_mytime_get(time_t epoch);
 void		ft_mytime_free(t_mytime **time);
+size_t		epoch_micro(void);
 
 #endif
diff --git a/libft/includes/net.h b/libft/includes/net.h
index 91698c7f..284db344 100644
--- a/libft/includes/net.h
+++ b/libft/includes/net.h
@@ -8,8 +8,12 @@
 # include <sys/socket.h>
 # include <netdb.h>
 # include <netinet/in.h>
+# include <netinet/ip.h>
+# include <netinet/tcp.h>
 # include <arpa/inet.h>
 
+#include "mytime.h"
+
 int		create_server(int port, int backlog, char *protoname);
 int		create_client(char *addr, int port, char *protoname);
 void	listener(int domain, int sock, int proto, void (*handler)(void *buf, int bytes, struct sockaddr_in *addr));
@@ -20,4 +24,10 @@ int		net_get(int sock, char *msg, int size);
 int		net_get_fd(int sock, int fd, int size);
 int		net_get_large(int sock, int fd);
 
+int		reserve_port(int *port);
+
+void	tcphdr_init(struct tcphdr *header);
+void	iphdr_init(struct iphdr *header);
+
+
 #endif
diff --git a/libft/srcs/net/forge_ip.c b/libft/srcs/net/forge_ip.c
new file mode 100644
index 00000000..40fc91da
--- /dev/null
+++ b/libft/srcs/net/forge_ip.c
@@ -0,0 +1,17 @@
+#include "net.h"
+
+void iphdr_init(struct iphdr *header)
+{
+	memset(header, 0, sizeof(*header));
+	header->version = 4;
+	header->ihl = 5;
+	header->tos = 0;
+	header->tot_len = 0;
+	header->id = ntohl(epoch_micro());
+	header->frag_off = 0;
+	header->ttl = 255;
+	header->protocol = 0;
+	header->daddr = 0;
+	header->saddr = 0;
+	header->check = 0;
+}
diff --git a/libft/srcs/net/forge_tcp.c b/libft/srcs/net/forge_tcp.c
new file mode 100644
index 00000000..e78fea37
--- /dev/null
+++ b/libft/srcs/net/forge_tcp.c
@@ -0,0 +1,20 @@
+#include "net.h"
+
+void	tcphdr_init(struct tcphdr *header)
+{
+	memset(header, 0, sizeof(*header));
+	header->source = htons(0);
+	header->dest = htons(0);
+	header->seq = epoch_micro();
+	header->ack_seq = 0;
+	header->doff = 5;
+	header->fin = 0;
+	header->syn = 0;
+	header->rst = 0;
+	header->psh = 0;
+	header->ack = 0;
+	header->urg = 0;
+	header->window = htons(1024);
+	header->check = 0;
+	header->urg_ptr = 0;
+}
diff --git a/libft/srcs/net/reserve_port.c b/libft/srcs/net/reserve_port.c
new file mode 100644
index 00000000..89e251bd
--- /dev/null
+++ b/libft/srcs/net/reserve_port.c
@@ -0,0 +1,25 @@
+#include "net.h"
+
+int	reserve_port(int *port)
+{
+	struct sockaddr_in sa;
+	int sockfd;
+	unsigned short i;
+
+	if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
+		return (1);
+	sa.sin_family = AF_INET;
+	sa.sin_addr.s_addr = INADDR_ANY;
+	i = 49152;
+	while (i < 65535)
+	{
+		sa.sin_port = htons(i);
+		if (bind(sockfd, (struct sockaddr*)&sa, sizeof(sa)) == 0)
+		{
+			*port = i;
+			return (0);
+		}
+		++i;
+	}
+	return (1);
+}
diff --git a/libft/srcs/printing/hexdump.c b/libft/srcs/printing/hexdump.c
index 924e2004..2a51dc6c 100644
--- a/libft/srcs/printing/hexdump.c
+++ b/libft/srcs/printing/hexdump.c
@@ -36,7 +36,7 @@ void hexdump(void *pAddressIn, long  lSize)
       {
          ucTmp = *pTmp++;
 
-         sprintf(szBuf + lIndex, "%02X ", (unsigned short)ucTmp);
+         sprintf(szBuf + lIndex, "%02x ", (unsigned short)ucTmp);
          if(!isprint(ucTmp))  ucTmp = '.'; // nonprintable char
          szBuf[lIndex2] = ucTmp;
 
diff --git a/libft/srcs/time/epoch.c b/libft/srcs/time/epoch.c
new file mode 100644
index 00000000..eda297db
--- /dev/null
+++ b/libft/srcs/time/epoch.c
@@ -0,0 +1,10 @@
+#include "mytime.h"
+
+size_t	epoch_micro(void)
+{
+	struct timeval tv;
+
+	if (gettimeofday(&tv, NULL))
+		return (0);
+	return (tv.tv_sec * 1000000 + tv.tv_usec);
+}