---

ip.c File Reference

IP (Internet Protocol) layer. More...

#include <const.h>
#include <ctype.h>
#include <errno.h>
#include <arch/mem.h>
#include <kernel/clock.h>
#include <kernel/console.h>
#include <kernel/kmalloc.h>
#include <net/arp.h>
#include <net/eth.h>
#include <net/icmp.h>
#include <net/network.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/ip.h>

Go to the source code of this file.

Functions
uint16_t	ip_checksum (const void *buf, size_t hdr_len)
	Calculate the IP header checksum. Parameters: buf  The IP header content. hdr_len  The IP header length. Returns: The result of the checksum.
void	dump_ip_packet (ip_t *packet)
	Dump an IP packet to the standard output. Parameters: packet  The IP packet.
void	set_host_ip_net (in_addr_t ip, in_addr_t netmask)
	Set the IP and netmask for this host. Parameters: ip  The IP address in network format. netmask  The netmask in network format.
in_addr_t	get_host_ip ()
	Get the IP address of this host. Returns: The IP address expressed in network format.
in_addr_t	get_host_netmask ()
	Get the netmask of this host. Returns: The netmask expressed in network format.
in_addr_t	get_host_bcast ()
	Get the broadcast address of the local network. Returns: The broadcast address of this local network expressed in network format.
int	inet_aton (const char *cp, in_addr_t *inp)
	Converts an internet IP addres from number-and-dot string notation into binary data network byte order. Parameters: cp  The string of the number-and-dot notation IP address. inp  The destination where the binary network byte order address will be put. Returns: Nonzero if the address is valid, zero if not.
void	to_ip_layer (ip_t *packet)
	Process an IP packet received from the ethernet layer. Parameters: packet  The IP packet.
int	send_ip_packet (uint32_t ip_to, const void *data, size_t len, uint8_t ttl, uint8_t proto)
	Send an IP packet to the ethernet layer. Parameters: ip_to  The IP destination address in network format. data  The buffer of data to be sent. len  The size of the buffer to be sent. ttl  TTL (Time To Live). proto  The upper-layer protocol type. Returns: The number of bytes sent in case of success; -EMSGSIZE the packet is too big to be sent; -ENOMEM cannot allocate the packet structure; -ENETUNREACH destination address not found;.
int	recv_ip_packet (ip_t *buf, size_t len)
	Receive an IP packet. Parameters: buf  The buffer where the received packet will be copied. len  The maximum size of the buffer. Returns: The size of the packet received in bytes.
Variables
in_addr_t	host_ip
	This is the IP address of this host (expressed in network format).
in_addr_t	host_netmask
	This is the IP netmask of this host (expressed in network format).

---

Detailed Description

IP (Internet Protocol) layer.

Author:

Andrea Righi <drizzt@inwind.it>

Date:

Last update: 2003-11-09

Note:

Copyright (©) 2003 Andrea Righi

Definition in file ip.c.

---

Function Documentation

void dump_ip_packet (  ip_t *    packet )

Dump an IP packet to the standard output. Parameters: packet  The IP packet. Definition at line 53 of file ip.c. { int i; uint8_t *data = ((void *)packet + (packet->ip_hdr_len * sizeof(uint32_t))); // Dump the IP header // kprintf( "\n\r(ip header)" "\n\rhdr_len:%u dwords, ip_version:%u, ToS:%#04X, tot_len:%u" "\n\rid:%#010x, off:%#010x, TTL:%u, proto:%#04X, ip_chk:%#06X" "\n\rip_src:%u.%u.%u.%u, ip_dst:%u.%u.%u.%u", packet->ip_hdr_len, packet->ip_version, packet->ip_tos, ntohs(packet->ip_len), ntohs(packet->ip_id), ntohs(packet->ip_off), packet->ip_ttl, packet->ip_proto, ntohs(packet->ip_chk), IP_A(ntohl(packet->ip_src)), IP_B(ntohl(packet->ip_src)), IP_C(ntohl(packet->ip_src)), IP_D(ntohl(packet->ip_src)), IP_A(ntohl(packet->ip_dst)), IP_B(ntohl(packet->ip_dst)), IP_C(ntohl(packet->ip_dst)), IP_D(ntohl(packet->ip_dst)) ); // Dump the IP data section // kprintf("\n\r(ip data)\n\r"); for (i=0; i<(ntohs(packet->ip_len) - packet->ip_hdr_len * sizeof(uint32_t)); i++) if ( isprint(data[i]) ) kputchar(data[i]); else kputchar('.'); }

in_addr_t get_host_bcast (    )

Get the broadcast address of the local network. Returns: The broadcast address of this local network expressed in network format. Definition at line 117 of file ip.c. { return( (~host_netmask) | (host_ip & host_netmask) ); }

in_addr_t get_host_ip (    )

Get the IP address of this host. Returns: The IP address expressed in network format. Definition at line 100 of file ip.c. { return( host_ip ); }

in_addr_t get_host_netmask (    )

Get the netmask of this host. Returns: The netmask expressed in network format. Definition at line 108 of file ip.c. { return( host_netmask ); }

int inet_aton (  const char *    cp, in_addr_t *    inp )

Converts an internet IP addres from number-and-dot string notation into binary data network byte order. Parameters: cp  The string of the number-and-dot notation IP address. inp  The destination where the binary network byte order address will be put. Returns: Nonzero if the address is valid, zero if not. Definition at line 131 of file ip.c. { static const in_addr_t max[4] = { 0xFFFFFFFF, 0xFFFFFF, 0xFFFF, 0xFF }; in_addr_t val; char c; union iaddr { uint8_t bytes[4]; uint32_t word; } res; uint8_t *pp = res.bytes; int digit,base; res.word = 0; c = *cp; for (;;) { // Collect number up to '.' // // Values are specified as for C: // // 0x=hex, 0=octal, isdigit=decimal. // if (!isdigit(c)) goto ret_0; val = 0; base = 10; digit = 0; for (;;) { if (isdigit(c)) { val = (val * base) + (c - '0'); c = *++cp; digit = 1; } else { break; } } if (c == '.') { // Internet format: // // a.b.c.d // // a.b.c (with c treated as 16 bits) // // a.b (with b treated as 24 bits) // if (pp > res.bytes + 2 || val > 0xff) { goto ret_0; } *pp++ = val; c = *++cp; } else break; } // Check for trailing characters // if (c != '\0' && (!isascii(c) || !isspace(c))) { goto ret_0; } // Did we get a valid digit? // if (!digit) { goto ret_0; } // Check whether the last part is in its limits depending on // // the number of parts in total. // if (val > max[pp - res.bytes]) { goto ret_0; } if (inp != NULL) { *inp = res.word | htonl (val); } return (1); ret_0: return (0); }

uint16_t ip_checksum (  const void *    buf, size_t    hdr_len )

Calculate the IP header checksum. Parameters: buf  The IP header content. hdr_len  The IP header length. Returns: The result of the checksum. Definition at line 31 of file ip.c. { unsigned long sum = 0; const uint16_t *ip1; ip1 = buf; while (hdr_len > 1) { sum += *ip1++; if (sum & 0x80000000) sum = (sum & 0xFFFF) + (sum >> 16); hdr_len -= 2; } while (sum >> 16) sum = (sum & 0xFFFF) + (sum >> 16); return(~sum); }

int recv_ip_packet (  ip_t *    buf, size_t    len )

Receive an IP packet. Parameters: buf  The buffer where the received packet will be copied. len  The maximum size of the buffer. Returns: The size of the packet received in bytes. Todo: Routine not implemented! For now return protocol not available error. Definition at line 347 of file ip.c. { return( -ENOPROTOOPT ); }

int send_ip_packet (  uint32_t    ip_to, const void *    data, size_t    len, uint8_t    ttl, uint8_t    proto )

Send an IP packet to the ethernet layer. Parameters: ip_to  The IP destination address in network format. data  The buffer of data to be sent. len  The size of the buffer to be sent. ttl  TTL (Time To Live). proto  The upper-layer protocol type. Returns: The number of bytes sent in case of success; -EMSGSIZE the packet is too big to be sent; -ENOMEM cannot allocate the packet structure; -ENETUNREACH destination address not found;. Definition at line 273 of file ip.c. { uint8_t eth_to[ETH_ADDR_LEN]; size_t packet_len = len + sizeof(ip_t); ip_t *packet; int tot_len; if (packet_len > IP_FRAME_LEN) return(-EMSGSIZE); packet = kmalloc(packet_len); if (packet == NULL) return(-ENOMEM); // Create the IP header // packet->ip_version = IP_V4; packet->ip_hdr_len = sizeof(ip_t) / sizeof(dword); packet->ip_tos = 0; packet->ip_len = htons(packet_len); packet->ip_id = htons(0xDEAD); // :-) // packet->ip_off = htons(IP_FLAG_DF | 0); packet->ip_ttl = ttl; packet->ip_proto = proto; packet->ip_chk = 0; packet->ip_dst = ip_to; packet->ip_src = get_host_ip(); packet->ip_chk = ip_checksum(packet, sizeof(ip_t)); // Copy the data into the packet // memcpy(packet + 1, data, len); // Translate the IP address into ethernet address // // using the ARP protocol. // if ( !arp_ip_to_eth(eth_to, ip_to) ) { #ifdef DEBUG kprintf("\n\rARP fails!"); #endif // The ethernet address was not found! // return(-ENETUNREACH); } #ifdef DEBUG kprintf("\n\rsending eth packet to %02x:%02x:%02x:%02x:%02x:%02x...", eth_to[0], eth_to[1], eth_to[2], eth_to[3], eth_to[4], eth_to[5] ); #endif // Go to the ethernet layer... // tot_len = send_eth_packet(eth_to, packet, packet_len, htons(ETH_FRAME_IP)); #ifdef DEBUG kprintf("\n\r%u bytes sent from ethernet layer", tot_len); #endif // Free the memory of the packet // kfree(packet); if ( tot_len < 0 ) // Something wrong from at the ethernet layer // return(tot_len); // Well done! // return(packet_len); }

void set_host_ip_net (  in_addr_t    ip, in_addr_t    netmask )

Set the IP and netmask for this host. Parameters: ip  The IP address in network format. netmask  The netmask in network format. Definition at line 91 of file ip.c. { host_ip = ip; host_netmask = netmask; }

void to_ip_layer (  ip_t *    packet )

Process an IP packet received from the ethernet layer. Parameters: packet  The IP packet. Definition at line 202 of file ip.c. { // Calculate the header checksum // if ( ip_checksum(packet, packet->ip_hdr_len * sizeof(dword)) ) { kprintf("\n\rip header checksum error!!!"); return; } //--------------------------------------------------------------// // Check if we can receive the packet or not // if ( (packet->ip_dst!=get_host_ip()) && (packet->ip_dst!=get_host_bcast()) && (packet->ip_dst!=INADDR_BROADCAST) ) return; //--------------------------------------------------------------// // Identify the right protocol // switch( packet->ip_proto ) { case IPPROTO_ICMP: // ICMP (Internet Control Message Protocol) // to_icmp_layer(packet); break; case IPPROTO_IGMP: // Internet Group Message Protocol) // kprintf("\n\rIGMP protocol not yet implemented!"); dump_ip_packet(packet); break; case IPPROTO_TCP: // TCP (Transmition Control Protocol) // to_tcp_layer( ((void *)packet + (packet->ip_hdr_len * sizeof(uint32_t))), (ntohs(packet->ip_len) - (packet->ip_hdr_len * sizeof(uint32_t))), packet->ip_src, packet->ip_dst ); // dump_ip_packet(packet); break; case IPPROTO_UDP: // UDP (User Datagram Protocol) // to_udp_layer( ((void *)packet + (packet->ip_hdr_len * sizeof(uint32_t))), packet->ip_src, packet->ip_dst ); break; default: kprintf("\n\rUnknown IP protocol!"); dump_ip_packet(packet); break; } }

---

Variable Documentation

in_addr_t host_ip [static]

This is the IP address of this host (expressed in network format). Definition at line 84 of file ip.c.

in_addr_t host_netmask [static]

This is the IP netmask of this host (expressed in network format). Definition at line 86 of file ip.c.

---