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xNBA/contrib/mini-slamd/mini-slamd.c
Michael Brown 1097cf8685 Initial revision
2005-05-17 16:44:57 +00:00

522 lines
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C
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/*
* mini-slamd
* (c) 2002 Eric Biederman
*/
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/ip.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <unistd.h>
#include <arpa/inet.h>
/*
* To specify the default interface for multicast packets use:
* route add -net 224.0.0.0 netmask 240.0.0.0 dev eth1
* This server is stupid and does not override the default.
*/
/* Sever states.
*
* Waiting for clients.
* Sending data to clients.
* Pinging clients for data.
*
*/
#define SLAM_PORT 10000
#define SLAM_MULTICAST_IP ((239<<24)|(255<<16)|(1<<8)|(1<<0))
#define SLAM_MULTICAST_PORT 10000
#define SLAM_MULTICAST_TTL 1
#define SLAM_MULTICAST_LOOPBACK 1
#define SLAM_MAX_CLIENTS 10
#define SLAM_PING_TIMEOUT 100 /* ms */
/*** Packets Formats ***
* Data Packet:
* transaction
* total bytes
* block size
* packet #
* data
*
* Status Request Packet
* transaction
* total bytes
* block packets
*
* Status Packet
* received packets
* requested packets
* received packets
* requested packets
* ...
* received packets
* requested packtes
* 0
*/
#define MAX_HDR (7 + 7 + 7) /* transaction, total size, block size */
#define MIN_HDR (1 + 1 + 1) /* transaction, total size, block size */
#define MAX_DATA_HDR (MAX_HDR + 7) /* header, packet # */
#define MIN_DATA_HDR (MAX_HDR + 1) /* header, packet # */
/* ETH_MAX_MTU 1500 - sizeof(iphdr) 20 - sizeof(udphdr) 8 = 1472 */
#define SLAM_MAX_NACK (1500 - (20 + 8))
/* ETH_MAX_MTU 1500 - sizeof(iphdr) 20 - sizeof(udphdr) 8 - MAX_HDR = 1451 */
#define SLAM_BLOCK_SIZE (1500 - (20 + 8 + MAX_HDR))
/* Define how many debug messages you want
* 1 - sparse but useful
* 2 - everything
*/
#ifndef DEBUG
#define DEBUG 0
#endif
static int slam_encode(
unsigned char **ptr, unsigned char *end, unsigned long value)
{
unsigned char *data = *ptr;
int bytes;
bytes = sizeof(value);
while ((bytes > 0) && ((0xff & (value >> ((bytes -1)<<3))) == 0)) {
bytes--;
}
if (bytes <= 0) {
bytes = 1;
}
if (data + bytes >= end) {
return -1;
}
if ((0xe0 & (value >> ((bytes -1)<<3))) == 0) {
/* packed together */
*data = (bytes << 5) | (value >> ((bytes -1)<<3));
} else {
bytes++;
*data = (bytes << 5);
}
bytes--;
data++;
while(bytes) {
*(data++) = 0xff & (value >> ((bytes -1)<<3));
bytes--;
}
*ptr = data;
return 0;
}
static unsigned long slam_decode(unsigned char **ptr, unsigned char *end, int *err)
{
unsigned long value;
unsigned bytes;
if (*ptr >= end) {
*err = -1;
}
bytes = ((**ptr) >> 5) & 7;
if ((bytes == 0) || (bytes > sizeof(unsigned long))) {
*err = -1;
return 0;
}
if ((*ptr) + bytes >= end) {
*err = -1;
}
value = (**ptr) & 0x1f;
bytes--;
(*ptr)++;
while(bytes) {
value <<= 8;
value |= **ptr;
(*ptr)++;
bytes--;
}
return value;
}
static struct sockaddr_in client[SLAM_MAX_CLIENTS];
static int clients;
void del_client(struct sockaddr_in *old)
{
int i;
for(i = 0; i < clients; i++) {
if ((client[i].sin_family == old->sin_family) &&
(client[i].sin_addr.s_addr == old->sin_addr.s_addr) &&
(client[i].sin_port == old->sin_port)) {
memmove(&client[i], &client[i+1],
(clients - (i+1))*sizeof(client[0]));
clients--;
}
}
}
void add_client(struct sockaddr_in *new)
{
del_client(new);
if (clients >= SLAM_MAX_CLIENTS)
return;
memcpy(&client[clients], new, sizeof(*new));
clients++;
}
void push_client(struct sockaddr_in *new)
{
del_client(new);
if (clients >= SLAM_MAX_CLIENTS) {
clients--;
}
memmove(&client[1], &client[0], clients*sizeof(*new));
memcpy(&client[0], new, sizeof(*new));
clients++;
}
void next_client(struct sockaddr_in *next)
{
/* Find the next client we want to ping next */
if (!clients) {
next->sin_family = AF_UNSPEC;
return;
}
/* Return the first client */
memcpy(next, &client[0], sizeof(*next));
}
int main(int argc, char **argv)
{
char *filename;
uint8_t nack_packet[SLAM_MAX_NACK];
int nack_len;
uint8_t request_packet[MAX_HDR];
int request_len;
uint8_t data_packet[MAX_DATA_HDR + SLAM_BLOCK_SIZE];
int data_len;
uint8_t *ptr, *end;
struct sockaddr_in master_client;
struct sockaddr_in sa_src;
struct sockaddr_in sa_mcast;
uint8_t mcast_ttl;
uint8_t mcast_loop;
int sockfd, filefd;
int result;
struct pollfd fds[1];
int state;
#define STATE_PINGING 1
#define STATE_WAITING 2
#define STATE_RECEIVING 3
#define STATE_TRANSMITTING 4
off_t size;
struct stat st;
uint64_t transaction;
unsigned long packet;
unsigned long packet_count;
unsigned slam_port, slam_multicast_port;
struct in_addr slam_multicast_ip;
slam_port = SLAM_PORT;
slam_multicast_port = SLAM_MULTICAST_PORT;
slam_multicast_ip.s_addr = htonl(SLAM_MULTICAST_IP);
if (argc != 2) {
fprintf(stderr, "Bad argument count\n");
fprintf(stderr, "Usage: mini-slamd filename\n");
exit(EXIT_FAILURE);
}
filename = argv[1];
filefd = -1;
size = 0;
transaction = 0;
/* Setup the udp socket */
sockfd = socket(PF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
fprintf(stderr, "Cannot create socket\n");
exit(EXIT_FAILURE);
}
memset(&sa_src, 0, sizeof(sa_src));
sa_src.sin_family = AF_INET;
sa_src.sin_port = htons(slam_port);
sa_src.sin_addr.s_addr = INADDR_ANY;
result = bind(sockfd, &sa_src, sizeof(sa_src));
if (result < 0) {
fprintf(stderr, "Cannot bind socket to port %d\n",
ntohs(sa_src.sin_port));
exit(EXIT_FAILURE);
}
/* Setup the multicast transmission address */
memset(&sa_mcast, 0, sizeof(sa_mcast));
sa_mcast.sin_family = AF_INET;
sa_mcast.sin_port = htons(slam_multicast_port);
sa_mcast.sin_addr.s_addr = slam_multicast_ip.s_addr;
if (!IN_MULTICAST(ntohl(sa_mcast.sin_addr.s_addr))) {
fprintf(stderr, "Not a multicast ip\n");
exit(EXIT_FAILURE);
}
/* Set the multicast ttl */
mcast_ttl = SLAM_MULTICAST_TTL;
setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL,
&mcast_ttl, sizeof(mcast_ttl));
/* Set the multicast loopback status */
mcast_loop = SLAM_MULTICAST_LOOPBACK;
setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_LOOP, &mcast_loop, sizeof(mcast_loop));
state = STATE_WAITING;
packet = 0;
packet_count = 0;
fds[0].fd = sockfd;
fds[0].events = POLLIN;
fds[0].revents = 0;
for(;;) {
switch(state) {
case STATE_PINGING:
state = STATE_WAITING;
next_client(&master_client);
if (master_client.sin_family == AF_UNSPEC) {
break;
}
#if DEBUG
printf("Pinging %s:%d\n",
inet_ntoa(master_client.sin_addr),
ntohs(master_client.sin_port));
fflush(stdout);
#endif
/* Prepare the request packet, it is all header */
ptr = request_packet;
end = &request_packet[sizeof(request_packet) -1];
slam_encode(&ptr, end, transaction);
slam_encode(&ptr, end, size);
slam_encode(&ptr, end, SLAM_BLOCK_SIZE);
request_len = ptr - request_packet;
result = sendto(sockfd, request_packet, request_len, 0,
&master_client, sizeof(master_client));
/* Forget the client I just asked, when the reply
* comes in we will remember it again.
*/
del_client(&master_client);
break;
case STATE_WAITING:
{
int timeout;
int from_len;
timeout = -1;
if (master_client.sin_family != AF_UNSPEC) {
timeout = SLAM_PING_TIMEOUT;
}
result = poll(fds, sizeof(fds)/sizeof(fds[0]), timeout);
if (result == 0) {
/* On a timeout try the next client */
state = STATE_PINGING;
break;
}
if (result > 0) {
from_len = sizeof(master_client);
result = recvfrom(sockfd,
nack_packet, sizeof(nack_packet), 0,
&master_client, &from_len);
if (result < 0)
break;
nack_len = result;
#if DEBUG
printf("Received Nack from %s:%d\n",
inet_ntoa(master_client.sin_addr),
ntohs(master_client.sin_port));
fflush(stdout);
#endif
#if DEBUG
{
ptr = nack_packet;
end = ptr + result;
packet = 0;
result = 0;
while(ptr < end) {
packet += slam_decode(&ptr, end, &result);
if (result < 0) break;
packet_count = slam_decode(&ptr, end, &result);
if (result < 0) break;
printf("%d-%d ",
packet, packet + packet_count -1);
}
printf("\n");
fflush(stdout);
}
#endif
/* Forget this client temporarily.
* If the packet appears good they will be
* readded.
*/
del_client(&master_client);
ptr = nack_packet;
end = ptr + nack_len;
result = 0;
packet = slam_decode(&ptr, end, &result);
if (result < 0)
break;
packet_count = slam_decode(&ptr, end, &result);
if (result < 0)
break;
/* We appear to have a good packet, keep
* this client.
*/
push_client(&master_client);
/* Reopen the file to transmit */
if (filefd != -1) {
close(filefd);
}
filefd = open(filename, O_RDONLY);
if (filefd < 0) {
fprintf(stderr, "Cannot open %s: %s\n",
filename, strerror(errno));
break;
}
size = lseek(filefd, 0, SEEK_END);
if (size < 0) {
fprintf(stderr, "Seek failed on %s: %s\n",
filename, strerror(errno));
break;
}
result = fstat(filefd, &st);
if (result < 0) {
fprintf(stderr, "Stat failed on %s: %s\n",
filename, strerror(errno));
break;
}
transaction = st.st_mtime;
state = STATE_TRANSMITTING;
break;
}
break;
}
case STATE_RECEIVING:
/* Now clear the queue of received packets */
{
struct sockaddr_in from;
int from_len;
uint8_t dummy_packet[SLAM_MAX_NACK];
state = STATE_TRANSMITTING;
result = poll(fds, sizeof(fds)/sizeof(fds[0]), 0);
if (result < 1)
break;
from_len = sizeof(from);
result = recvfrom(sockfd,
dummy_packet, sizeof(dummy_packet), 0,
&from, &from_len);
if (result <= 0)
break;
#if DEBUG
printf("Received Nack from %s:%d\n",
inet_ntoa(from.sin_addr),
ntohs(from.sin_port));
fflush(stdout);
#endif
/* Receive packets until I don't get any more */
state = STATE_RECEIVING;
/* Process a packet */
if (dummy_packet[0] == '\0') {
/* If the first byte is null it is a disconnect
* packet.
*/
del_client(&from);
}
else {
/* Otherwise attempt to add the client. */
add_client(&from);
}
break;
}
case STATE_TRANSMITTING:
{
off_t off;
off_t offset;
ssize_t bytes;
uint8_t *ptr2, *end2;
/* After I transmit a packet check for packets to receive. */
state = STATE_RECEIVING;
/* Find the packet to transmit */
offset = packet * SLAM_BLOCK_SIZE;
/* Seek to the desired packet */
off = lseek(filefd, offset, SEEK_SET);
if ((off < 0) || (off != offset)) {
fprintf(stderr, "Seek failed on %s:%s\n",
filename, strerror(errno));
break;
}
/* Encode the packet header */
ptr2 = data_packet;
end2 = data_packet + sizeof(data_packet);
slam_encode(&ptr2, end2, transaction);
slam_encode(&ptr2, end2, size);
slam_encode(&ptr2, end2, SLAM_BLOCK_SIZE);
slam_encode(&ptr2, end2, packet);
data_len = ptr2 - data_packet;
/* Read in the data */
bytes = read(filefd, &data_packet[data_len],
SLAM_BLOCK_SIZE);
if (bytes <= 0) {
fprintf(stderr, "Read failed on %s:%s\n",
filename, strerror(errno));
break;
}
data_len += bytes;
/* Write out the data */
result = sendto(sockfd, data_packet, data_len, 0,
&sa_mcast, sizeof(sa_mcast));
if (result != data_len) {
fprintf(stderr, "Send failed %s\n",
strerror(errno));
break;
}
#if DEBUG > 1
printf("Transmitted: %d\n", packet);
fflush(stdout);
#endif
/* Compute the next packet */
packet++;
packet_count--;
if (packet_count == 0) {
packet += slam_decode(&ptr, end, &result);
if (result >= 0)
packet_count = slam_decode(&ptr, end, &result);
if (result < 0) {
/* When a transmission is done close the file,
* so it may be updated. And then ping then start
* pinging clients to get the transmission started
* again.
*/
state = STATE_PINGING;
close(filefd);
filefd = -1;
break;
}
}
break;
}
}
}
return EXIT_SUCCESS;
}
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