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tor_multipath_voip/src/algo_thunder.c

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#include <sys/timerfd.h>
#include "algo_utils.h"
#include "utils.h"
#include "url.h"
#include "proxy.h"
#include "timer.h"
// A Tor cell size is 512 bytes but handle only 498 bytes of data
#define TOR_CELL_SIZE 498
#define MAX_LINKS 64
struct thunder_ctx {
uint16_t recv_id;
uint16_t emit_id;
uint8_t selected_link;
uint8_t total_links;
uint64_t delta_t_per_link[MAX_LINKS];
uint64_t rcv_delta_t_per_link[MAX_LINKS];
uint64_t received_pkts_on_link[MAX_LINKS];
uint64_t blacklisted[MAX_LINKS];
size_t monit_pkt_size;
int64_t allowed_jitter_ms;
struct timespec prev_link_time, prev_rcv_link_time;
};
uint64_t compute_delta(struct timespec* prev_time, uint64_t max) {
struct timespec curr;
int secs, nsecs;
uint64_t mili_sec;
// 1. We compute the time difference
if (clock_gettime(CLOCK_MONOTONIC, &curr) == -1){
perror("clock_gettime error");
exit(EXIT_FAILURE);
}
secs = curr.tv_sec - prev_time->tv_sec;
nsecs = curr.tv_nsec - prev_time->tv_nsec;
*prev_time = curr;
mili_sec = secs * 1000 + nsecs / 1000000;
if (mili_sec > max) mili_sec = max;
return mili_sec;
}
int is_blacklisted(struct thunder_ctx* thunderc, int link_id) {
return thunderc->blacklisted[link_id] >= thunderc->received_pkts_on_link[link_id];
}
void prepare(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
thunderc->emit_id++;
union abstract_packet metadata = {
.fmt.headers.cmd = CMD_UDP_METADATA_THUNDER,
.fmt.headers.size = sizeof(metadata.fmt.headers) + sizeof(metadata.fmt.content.udp_metadata_thunder),
.fmt.headers.flags = 0,
.fmt.content.udp_metadata_thunder.id = thunderc->emit_id,
};
buffer_append_ap (bp, &metadata);
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] UDP metadata added\n");
}
void pad(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
uint64_t ref = 0l + thunderc->emit_id;
dup_buffer_toa (&app_ctx->br, bp, (void *)ref);
// 1. Clean old buffers (we keep only thunderc->total_links buffer, keeping more would be useless)
if (ref > thunderc->total_links && get_app_buffer (&app_ctx->br, (void *)(ref - thunderc->total_links))) {
mv_buffer_atof (&app_ctx->br, (void *)(ref - thunderc->total_links));
}
// 2. Append abstract packets stored in our buffers
uint64_t add_ref = ref;
while(1) {
if (add_ref < 1) break;
add_ref--;
struct buffer_packet *bp_iter = get_app_buffer (&app_ctx->br, (void *)add_ref);
if (bp_iter == NULL) break;
union abstract_packet *ap = buffer_first_ap (bp_iter);
if (ap->fmt.headers.cmd != CMD_UDP_ENCAPSULATED) {
fprintf(stderr, "Invalid buffer payload!\n");
exit(EXIT_FAILURE);
}
union abstract_packet *ap_meta = ap_next (ap);
if (ap_meta->fmt.headers.cmd != CMD_UDP_METADATA_THUNDER) {
fprintf(stderr, "Invalid buffer metadata!\n");
exit(EXIT_FAILURE);
}
if (buffer_full_size (bp) + ap->fmt.headers.size + ap_meta->fmt.headers.size > TOR_CELL_SIZE - thunderc->monit_pkt_size) break;
buffer_append_ap (bp, ap);
buffer_append_ap (bp, ap_meta);
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] Pad packet (now %ld bytes)\n", buffer_full_size (bp));
}
}
int schedule(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
char url[256];
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
struct evt_core_fdinfo *to_fdinfo = NULL;
struct evt_core_cat* cat = evt_core_get_from_cat (ctx, "tcp-write");
uint8_t protect = thunderc->total_links;
do {
// 1. We choose the link
if (cat->socklist->len == 0) {
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] No link available, packet will be dropped\n");
break;
}
to_fdinfo = NULL;
do {
thunderc->selected_link = (thunderc->selected_link + 1) % thunderc->total_links;
sprintf(url, "tcp:write:127.0.0.1:%d", 7500 + thunderc->selected_link);
to_fdinfo = evt_core_get_from_url (ctx, url);
} while (to_fdinfo == NULL);
//printf("URL %s has been retained\n", url);
// 2. We create the packet template
union abstract_packet links = {
.fmt.headers.cmd = CMD_LINK_MONITORING_THUNDER,
.fmt.headers.size = thunderc->monit_pkt_size,
.fmt.headers.flags = 0,
.fmt.content.link_monitoring_thunder.links_status = {}
};
// 3. We append the template to the buffer
struct buffer_packet* bp_dup = dup_buffer_tow (&app_ctx->br, bp, to_fdinfo);
union abstract_packet *new_ap = buffer_append_ap (bp_dup, &links);
// 4. We compute the time difference
uint64_t mili_sec = compute_delta (&thunderc->prev_link_time, UINT16_MAX);
// 5. We create the array
struct link_info *li = &new_ap->fmt.content.link_monitoring_thunder.links_status;
for (int i = 0; i < thunderc->total_links; i++) {
thunderc->delta_t_per_link[i] += mili_sec;
li[i].delta_t = thunderc->delta_t_per_link[i] > UINT16_MAX ? UINT16_MAX : thunderc->delta_t_per_link[i];
}
thunderc->delta_t_per_link[thunderc->selected_link] = 0;
li[thunderc->selected_link].delta_t = 0;
if (ctx->verbose > 1) {
dump_buffer_packet(bp_dup);
fprintf(stderr, " [algo_thunder] Will send this info\n");
}
main_on_tcp_write(ctx, to_fdinfo);
} while (is_blacklisted (thunderc, thunderc->selected_link) && protect-- > 0);
if (protect == 0) {
fprintf(stderr, "all links were blacklisted, resetting\n");
for (int i = 0; i < thunderc->total_links; i++) {
fprintf(stderr, " link=%d, blacklisted=%ld, rcved=%ld\n", i, thunderc->blacklisted[i], thunderc->received_pkts_on_link[i]);
thunderc->received_pkts_on_link[i] = thunderc->blacklisted[i] + 1;
}
}
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] Packets sent\n");
// Release the buffer
mv_buffer_rtof (&app_ctx->br, fdinfo);
return 0;
}
struct block_info {
uint8_t i;
struct algo_ctx* app_ctx;
uint64_t missing;
uint8_t is_timeout;
char reason[1024];
};
void on_block (struct evt_core_ctx* ctx, void* raw) {
struct block_info* bi = raw;
struct thunder_ctx* thunderc = bi->app_ctx->misc;
if (thunderc->received_pkts_on_link[bi->i] >= bi->missing) goto release;
if (thunderc->blacklisted[bi->i] >= bi->missing) goto release;
puts(bi->reason);
thunderc->blacklisted[bi->i] = bi->missing;
release:
if (bi->is_timeout) free(bi);
}
int is_in_order(struct thunder_ctx* thunderc, uint8_t link_id) {
uint64_t ref = thunderc->received_pkts_on_link[link_id];
for (int i = 0; i < thunderc->total_links; i++) {
uint64_t expected = link_id >= i ? ref : ref - 1;
if (thunderc->received_pkts_on_link[i] > expected) {
//printf("link_id=%d, i=%d, pkt_i=%ld, pkt_i_expected=%ld, pkt_link_id=%ld\n", link_id, i, thunderc->received_pkts_on_link[i], expected, ref);
return 0;
}
}
return 1;
}
void classify(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
union abstract_packet* ap = buffer_first_ap (bp);
while (ap != NULL && ap->fmt.headers.cmd != CMD_LINK_MONITORING_THUNDER) ap = ap_next(ap);
if (ap == NULL) {
fprintf(stderr, "Unable to find our packet\n");
exit(EXIT_FAILURE);
}
/*
if (ap->fmt.headers.flags & FLAG_RESET) {
for (int i = 0; i < MAX_LINKS; i++) thunderc->received_pkts_on_link[i] = 1;
}
*/
// 1. Update link info
int link_id = url_get_port_int(fdinfo->url) - 7500;
thunderc->received_pkts_on_link[link_id]++;
//printf("Received %ld packets on link %d\n", thunderc->received_pkts_on_link[link_id], link_id);
struct link_info *li = &ap->fmt.content.link_monitoring_thunder.links_status;
uint64_t mili_sec = compute_delta (&thunderc->prev_rcv_link_time, UINT16_MAX);
for (int i = 0; i < thunderc->total_links; i++) {
thunderc->rcv_delta_t_per_link[i] += mili_sec;
}
thunderc->rcv_delta_t_per_link[link_id] = 0;
// 2. Disable links that have received packets too late
if (is_in_order (thunderc, link_id)) {
/*printf("Local: ");
for (int i = 0; i < thunderc->total_links; i++) {
printf("%ld ", thunderc->rcv_delta_t_per_link[i]);
}
printf("\n");
printf("Packet: ");
for (int i = 0; i < thunderc->total_links; i++) {
printf("%d ", li[i].delta_t);
}
printf("\n");*/
for (int i = 0; i < thunderc->total_links; i++) {
int64_t remote_delta = 0, local_delta = 0, owd_difference = 0;
remote_delta = li[i].delta_t;
local_delta = thunderc->rcv_delta_t_per_link[i];
if (remote_delta > 1000 || local_delta > 10000) continue; // Too many time elapsed for useful comparison
owd_difference = local_delta - remote_delta;
if (owd_difference <= thunderc->allowed_jitter_ms && owd_difference >= -thunderc->allowed_jitter_ms) continue;
struct block_info bi = {0};
bi.is_timeout = 0;
if (owd_difference < -thunderc->allowed_jitter_ms) {
bi.i = i;
bi.app_ctx = app_ctx;
bi.missing = thunderc->received_pkts_on_link[i];
sprintf(bi.reason, " Packet Too Late - Blocked link %d owd_diff=%ld, local_delta=%ld, remote_delta=%ld\n", i, owd_difference, local_delta, remote_delta);
} else if (owd_difference > thunderc->allowed_jitter_ms) {
bi.i = link_id;
bi.app_ctx = app_ctx;
bi.missing = thunderc->received_pkts_on_link[link_id];
sprintf(bi.reason, " Packet Too Late - Blocked link %d owd_diff=%ld, local_delta=%ld, remote_delta=%ld\n", link_id, owd_difference, local_delta, remote_delta);
} else {
fprintf(stderr, "Algorithm is wrong\n");
exit(EXIT_FAILURE);
}
on_block(ctx, &bi);
}
}
// 3. Disable links that miss packets
for (uint8_t i = 0; i < thunderc->total_links; i++) {
uint64_t expected = i <= link_id ? thunderc->received_pkts_on_link[link_id] : thunderc->received_pkts_on_link[link_id] - 1;
if (thunderc->received_pkts_on_link[i] >= expected) continue; // Nothing to do, all packets have been received
int64_t timeout = thunderc->allowed_jitter_ms - li[i].delta_t;
struct block_info *bi = malloc(sizeof(struct block_info));
bi->i = i; bi->app_ctx = app_ctx; bi->missing = expected; bi->is_timeout = 1;
if (timeout <= 0) {
on_block(ctx, bi);
//printf(" Missing Packet - Blocked link %d (expected: %ld, seen: %ld)\n", i, expected, thunderc->received_pkts_on_link[i]);
continue;
}
sprintf(bi->reason, " Missing Packet - Timeout for link %d after %ldms (expected: %ld, seen: %ld)\n", i, timeout, expected, thunderc->received_pkts_on_link[i]);
set_timeout (ctx, timeout, bi, on_block);
if (ctx->verbose > 1) {
fprintf(stderr, " [algo_thunder] Set timeout on link %d of %ld ms (packets expected: %ld, seen: %ld)\n",
i, timeout, expected, thunderc->received_pkts_on_link[i]);
}
}
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] Classify done\n");
printf("Blacklisted links: ");
for (int i = 0; i < thunderc->total_links; i++) {
if (is_blacklisted (thunderc, i)) printf("_");
else printf("U");
}
printf("\n");
}
struct unpad_info {
union abstract_packet *ap_arr_pl[MAX_LINKS], *ap_arr_meta[MAX_LINKS];
uint8_t ap_arr_vals;
};
void unpad(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp, struct unpad_info *ui) {
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
for (union abstract_packet* ap = buffer_first_ap (bp); ap != NULL; ap = ap_next(ap)) {
if (ap->fmt.headers.cmd != CMD_UDP_ENCAPSULATED) continue;
union abstract_packet* ap_meta = ap_next(ap);
if (ap_meta == NULL || ap_meta->fmt.headers.cmd != CMD_UDP_METADATA_THUNDER) {
fprintf(stderr, "Unexpected packet, expecting udp metadata\n");
}
if (ap_meta->fmt.content.udp_metadata_thunder.id > thunderc->recv_id) {
ui->ap_arr_pl[ui->ap_arr_vals] = ap;
ui->ap_arr_meta[ui->ap_arr_vals] = ap_meta;
ui->ap_arr_vals++;
}
}
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] Unpad done\n");
}
void adapt(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp, struct unpad_info *ui) {
struct algo_ctx* app_ctx = fdinfo->cat->app_ctx;
struct thunder_ctx* thunderc = app_ctx->misc;
char url[256];
struct evt_core_fdinfo *to_fdinfo = NULL;
uint64_t delivered = 0;
for (int i = ui->ap_arr_vals-1; i >= 0; i--) {
//fprintf(stderr, "i=%d, ui->ap_arr_vals=%d\n", i, ui->ap_arr_vals);
if (ui->ap_arr_meta[i]->fmt.content.udp_metadata_thunder.id <= thunderc->recv_id) continue;
thunderc->recv_id = ui->ap_arr_meta[i]->fmt.content.udp_metadata_thunder.id;
// Find destination
sprintf(url, "udp:write:127.0.0.1:%d", ui->ap_arr_pl[i]->fmt.content.udp_encapsulated.port);
to_fdinfo = evt_core_get_from_url (ctx, url);
if (to_fdinfo == NULL) {
fprintf(stderr, "No fd for URL %s in tcp-read. Dropping packet :( \n", url);
}
struct buffer_packet *bp_dest = inject_buffer_tow (&app_ctx->br, to_fdinfo);
bp_dest->mode = BP_WRITING;
//dump_buffer_packet (bp_dest);
buffer_append_ap (bp_dest, ui->ap_arr_pl[i]);
main_on_udp_write(ctx, to_fdinfo);
delivered++;
}
if (delivered != 1) {
//printf("[algo_thunder] Delivered %ld packets (now id=%d)\n", delivered, thunderc->recv_id);
}
mv_buffer_rtof (&app_ctx->br, fdinfo);
if (ctx->verbose > 1) fprintf(stderr, " [algo_thunder] Adapt done\n");
}
int algo_thunder_on_stream(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
struct unpad_info ui = {0};
classify(ctx, fdinfo, bp);
unpad(ctx, fdinfo, bp, &ui);
adapt(ctx, fdinfo, bp, &ui);
return 0;
}
int algo_thunder_on_datagram(struct evt_core_ctx* ctx, struct evt_core_fdinfo* fdinfo, struct buffer_packet* bp) {
prepare(ctx, fdinfo, bp);
pad(ctx, fdinfo, bp);
schedule(ctx, fdinfo, bp);
return 0;
}
void algo_thunder_free(void* v) {
struct rr_ctx* rr = v;
free(rr);
}
void algo_thunder_init(struct evt_core_ctx* ctx, struct algo_ctx* app_ctx, struct algo_params* ap) {
app_ctx->misc = malloc(sizeof(struct thunder_ctx));
app_ctx->free_misc = algo_thunder_free;
if (app_ctx->misc == NULL) {
perror("malloc failed in algo thunder init");
exit(EXIT_FAILURE);
}
memset(app_ctx->misc, 0, sizeof(struct thunder_ctx));
struct thunder_ctx* thunderc = app_ctx->misc;
thunderc->recv_id = 1;
thunderc->emit_id = 1;
thunderc->total_links = app_ctx->ap.links;
thunderc->selected_link = thunderc->total_links - 1;
thunderc->allowed_jitter_ms = 200;
for (int i = 0; i < thunderc->total_links; i++) {
thunderc->received_pkts_on_link[i] = 1;
thunderc->rcv_delta_t_per_link[i] = 0;
}
union abstract_packet links = {};
//fprintf(stderr, "Total links %d\n", thunderc->total_links);
thunderc->monit_pkt_size = sizeof(links.fmt.headers) + sizeof(links.fmt.content.link_monitoring_thunder) + sizeof(struct link_info) * (thunderc->total_links - 1);
if (ap->algo_specific_params != NULL) {
sscanf(ap->algo_specific_params, "%ld", &thunderc->allowed_jitter_ms);
}
printf("Allowed jitter set to %ld ms\n", thunderc->allowed_jitter_ms);
init_timer(ctx);
}
int algo_thunder_on_err(struct evt_core_ctx *ctx, struct evt_core_fdinfo *fdinfo) {
if (strstr(fdinfo->cat->name, "udp") != NULL) return 1;
return 0;
}
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