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/*
* Copyright (C) Roman Arutyunyan
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include "ngx_rtmp.h"
#include <openssl/hmac.h>
#include <openssl/sha.h>
static void ngx_rtmp_handshake_send(ngx_event_t *wev);
static void ngx_rtmp_handshake_recv(ngx_event_t *rev);
static void ngx_rtmp_handshake_done(ngx_rtmp_session_t *s);
/* RTMP handshake :
*
* =peer1= =peer2=
* challenge ----> (.....[digest1]......) ----> 1537 bytes
* response <---- (...........[digest2]) <---- 1536 bytes
*
*
* - both packets contain random bytes except for digests
* - digest1 position is calculated on random packet bytes
* - digest2 is always at the end of the packet
*
* digest1: HMAC_SHA256(packet, peer1_partial_key)
* digest2: HMAC_SHA256(packet, HMAC_SHA256(digest1, peer2_full_key))
*/
/* Handshake keys */
static u_char
ngx_rtmp_server_key[] = {
'G', 'e', 'n', 'u', 'i', 'n', 'e', ' ', 'A', 'd', 'o', 'b', 'e', ' ',
'F', 'l', 'a', 's', 'h', ' ', 'M', 'e', 'd', 'i', 'a', ' ',
'S', 'e', 'r', 'v', 'e', 'r', ' ',
'0', '0', '1',
0xF0, 0xEE, 0xC2, 0x4A, 0x80, 0x68, 0xBE, 0xE8, 0x2E, 0x00, 0xD0, 0xD1,
0x02, 0x9E, 0x7E, 0x57, 0x6E, 0xEC, 0x5D, 0x2D, 0x29, 0x80, 0x6F, 0xAB,
0x93, 0xB8, 0xE6, 0x36, 0xCF, 0xEB, 0x31, 0xAE
};
static u_char
ngx_rtmp_client_key[] = {
'G', 'e', 'n', 'u', 'i', 'n', 'e', ' ', 'A', 'd', 'o', 'b', 'e', ' ',
'F', 'l', 'a', 's', 'h', ' ', 'P', 'l', 'a', 'y', 'e', 'r', ' ',
'0', '0', '1',
0xF0, 0xEE, 0xC2, 0x4A, 0x80, 0x68, 0xBE, 0xE8, 0x2E, 0x00, 0xD0, 0xD1,
0x02, 0x9E, 0x7E, 0x57, 0x6E, 0xEC, 0x5D, 0x2D, 0x29, 0x80, 0x6F, 0xAB,
0x93, 0xB8, 0xE6, 0x36, 0xCF, 0xEB, 0x31, 0xAE
};
static const u_char
ngx_rtmp_server_version[4] = {
0x0D, 0x0E, 0x0A, 0x0D
};
static const u_char
ngx_rtmp_client_version[4] = {
0x0C, 0x00, 0x0D, 0x0E
};
#define NGX_RTMP_HANDSHAKE_KEYLEN SHA256_DIGEST_LENGTH
#define NGX_RTMP_HANDSHAKE_BUFSIZE 1537
#define NGX_RTMP_HANDSHAKE_SERVER_RECV_CHALLENGE 1
#define NGX_RTMP_HANDSHAKE_SERVER_SEND_CHALLENGE 2
#define NGX_RTMP_HANDSHAKE_SERVER_SEND_RESPONSE 3
#define NGX_RTMP_HANDSHAKE_SERVER_RECV_RESPONSE 4
#define NGX_RTMP_HANDSHAKE_SERVER_DONE 5
#define NGX_RTMP_HANDSHAKE_CLIENT_SEND_CHALLENGE 6
#define NGX_RTMP_HANDSHAKE_CLIENT_RECV_CHALLENGE 7
#define NGX_RTMP_HANDSHAKE_CLIENT_RECV_RESPONSE 8
#define NGX_RTMP_HANDSHAKE_CLIENT_SEND_RESPONSE 9
#define NGX_RTMP_HANDSHAKE_CLIENT_DONE 10
static ngx_str_t ngx_rtmp_server_full_key
= { sizeof(ngx_rtmp_server_key), ngx_rtmp_server_key };
static ngx_str_t ngx_rtmp_server_partial_key
= { 36, ngx_rtmp_server_key };
static ngx_str_t ngx_rtmp_client_full_key
= { sizeof(ngx_rtmp_client_key), ngx_rtmp_client_key };
static ngx_str_t ngx_rtmp_client_partial_key
= { 30, ngx_rtmp_client_key };
static ngx_int_t
ngx_rtmp_make_digest(ngx_str_t *key, ngx_buf_t *src,
u_char *skip, u_char *dst, ngx_log_t *log)
{
static HMAC_CTX *hmac;
unsigned int len;
if (hmac == NULL) {
#if OPENSSL_VERSION_NUMBER < 0x10100000L
static HMAC_CTX shmac;
hmac = &shmac;
HMAC_CTX_init(hmac);
#else
hmac = HMAC_CTX_new();
if (hmac == NULL) {
return NGX_ERROR;
}
#endif
}
HMAC_Init_ex(hmac, key->data, key->len, EVP_sha256(), NULL);
if (skip && src->pos <= skip && skip <= src->last) {
if (skip != src->pos) {
HMAC_Update(hmac, src->pos, skip - src->pos);
}
if (src->last != skip + NGX_RTMP_HANDSHAKE_KEYLEN) {
HMAC_Update(hmac, skip + NGX_RTMP_HANDSHAKE_KEYLEN,
src->last - skip - NGX_RTMP_HANDSHAKE_KEYLEN);
}
} else {
HMAC_Update(hmac, src->pos, src->last - src->pos);
}
HMAC_Final(hmac, dst, &len);
return NGX_OK;
}
static ngx_int_t
ngx_rtmp_find_digest(ngx_buf_t *b, ngx_str_t *key, size_t base, ngx_log_t *log)
{
size_t n, offs;
u_char digest[NGX_RTMP_HANDSHAKE_KEYLEN];
u_char *p;
offs = 0;
for (n = 0; n < 4; ++n) {
offs += b->pos[base + n];
}
offs = (offs % 728) + base + 4;
p = b->pos + offs;
if (ngx_rtmp_make_digest(key, b, p, digest, log) != NGX_OK) {
return NGX_ERROR;
}
if (ngx_memcmp(digest, p, NGX_RTMP_HANDSHAKE_KEYLEN) == 0) {
return offs;
}
return NGX_ERROR;
}
static ngx_int_t
ngx_rtmp_write_digest(ngx_buf_t *b, ngx_str_t *key, size_t base,
ngx_log_t *log)
{
size_t n, offs;
u_char *p;
offs = 0;
for (n = 8; n < 12; ++n) {
offs += b->pos[base + n];
}
offs = (offs % 728) + base + 12;
p = b->pos + offs;
if (ngx_rtmp_make_digest(key, b, p, p, log) != NGX_OK) {
return NGX_ERROR;
}
return NGX_OK;
}
static void
ngx_rtmp_fill_random_buffer(ngx_buf_t *b)
{
for (; b->last != b->end; ++b->last) {
*b->last = (u_char) rand();
}
}
static ngx_buf_t *
ngx_rtmp_alloc_handshake_buffer(ngx_rtmp_session_t *s)
{
ngx_rtmp_core_srv_conf_t *cscf;
ngx_chain_t *cl;
ngx_buf_t *b;
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: allocating buffer");
cscf = ngx_rtmp_get_module_srv_conf(s, ngx_rtmp_core_module);
if (cscf->free_hs) {
cl = cscf->free_hs;
b = cl->buf;
cscf->free_hs = cl->next;
ngx_free_chain(cscf->pool, cl);
} else {
b = ngx_pcalloc(cscf->pool, sizeof(ngx_buf_t));
if (b == NULL) {
return NULL;
}
b->memory = 1;
b->start = ngx_pcalloc(cscf->pool, NGX_RTMP_HANDSHAKE_BUFSIZE);
if (b->start == NULL) {
return NULL;
}
b->end = b->start + NGX_RTMP_HANDSHAKE_BUFSIZE;
}
b->pos = b->last = b->start;
return b;
}
void
ngx_rtmp_free_handshake_buffers(ngx_rtmp_session_t *s)
{
ngx_rtmp_core_srv_conf_t *cscf;
ngx_chain_t *cl;
if (s->hs_buf == NULL) {
return;
}
cscf = ngx_rtmp_get_module_srv_conf(s, ngx_rtmp_core_module);
cl = ngx_alloc_chain_link(cscf->pool);
if (cl == NULL) {
return;
}
cl->buf = s->hs_buf;
cl->next = cscf->free_hs;
cscf->free_hs = cl;
s->hs_buf = NULL;
}
static ngx_int_t
ngx_rtmp_handshake_create_challenge(ngx_rtmp_session_t *s,
const u_char version[4], ngx_str_t *key)
{
ngx_buf_t *b;
b = s->hs_buf;
b->last = b->pos = b->start;
*b->last++ = '\x03';
b->last = ngx_rtmp_rcpymem(b->last, &s->epoch, 4);
b->last = ngx_cpymem(b->last, version, 4);
ngx_rtmp_fill_random_buffer(b);
++b->pos;
if (ngx_rtmp_write_digest(b, key, 0, s->connection->log) != NGX_OK) {
return NGX_ERROR;
}
--b->pos;
return NGX_OK;
}
static ngx_int_t
ngx_rtmp_handshake_parse_challenge(ngx_rtmp_session_t *s,
ngx_str_t *peer_key, ngx_str_t *key)
{
ngx_buf_t *b;
u_char *p;
ngx_int_t offs;
b = s->hs_buf;
if (*b->pos != '\x03') {
ngx_log_error(NGX_LOG_INFO, s->connection->log, 0,
"handshake: unexpected RTMP version: %i",
(ngx_int_t)*b->pos);
return NGX_ERROR;
}
++b->pos;
s->peer_epoch = 0;
ngx_rtmp_rmemcpy(&s->peer_epoch, b->pos, 4);
p = b->pos + 4;
ngx_log_debug5(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: peer version=%i.%i.%i.%i epoch=%uD",
(ngx_int_t)p[3], (ngx_int_t)p[2],
(ngx_int_t)p[1], (ngx_int_t)p[0],
(uint32_t)s->peer_epoch);
if (*(uint32_t *)p == 0) {
s->hs_old = 1;
return NGX_OK;
}
offs = ngx_rtmp_find_digest(b, peer_key, 772, s->connection->log);
if (offs == NGX_ERROR) {
offs = ngx_rtmp_find_digest(b, peer_key, 8, s->connection->log);
}
if (offs == NGX_ERROR) {
ngx_log_error(NGX_LOG_INFO, s->connection->log, 0,
"handshake: digest not found");
s->hs_old = 1;
return NGX_OK;
}
ngx_log_debug1(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: digest found at pos=%i", offs);
b->pos += offs;
b->last = b->pos + NGX_RTMP_HANDSHAKE_KEYLEN;
s->hs_digest = ngx_palloc(s->connection->pool, NGX_RTMP_HANDSHAKE_KEYLEN);
if (ngx_rtmp_make_digest(key, b, NULL, s->hs_digest, s->connection->log)
!= NGX_OK)
{
return NGX_ERROR;
}
return NGX_OK;
}
static ngx_int_t
ngx_rtmp_handshake_create_response(ngx_rtmp_session_t *s)
{
ngx_buf_t *b;
u_char *p;
ngx_str_t key;
b = s->hs_buf;
b->pos = b->last = b->start + 1;
ngx_rtmp_fill_random_buffer(b);
if (s->hs_digest) {
p = b->last - NGX_RTMP_HANDSHAKE_KEYLEN;
key.data = s->hs_digest;
key.len = NGX_RTMP_HANDSHAKE_KEYLEN;
if (ngx_rtmp_make_digest(&key, b, p, p, s->connection->log) != NGX_OK) {
return NGX_ERROR;
}
}
return NGX_OK;
}
static void
ngx_rtmp_handshake_done(ngx_rtmp_session_t *s)
{
ngx_rtmp_free_handshake_buffers(s);
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: done");
if (ngx_rtmp_fire_event(s, NGX_RTMP_HANDSHAKE_DONE,
NULL, NULL) != NGX_OK)
{
ngx_rtmp_finalize_session(s);
return;
}
ngx_rtmp_cycle(s);
}
static void
ngx_rtmp_handshake_recv(ngx_event_t *rev)
{
ssize_t n;
ngx_connection_t *c;
ngx_rtmp_session_t *s;
ngx_buf_t *b;
c = rev->data;
s = c->data;
if (c->destroyed) {
return;
}
if (rev->timedout) {
ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT,
"handshake: recv: client timed out");
c->timedout = 1;
ngx_rtmp_finalize_session(s);
return;
}
if (rev->timer_set) {
ngx_del_timer(rev);
}
b = s->hs_buf;
while (b->last != b->end) {
n = c->recv(c, b->last, b->end - b->last);
if (n == NGX_ERROR || n == 0) {
ngx_rtmp_finalize_session(s);
return;
}
if (n == NGX_AGAIN) {
ngx_add_timer(rev, s->timeout);
if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
ngx_rtmp_finalize_session(s);
}
return;
}
b->last += n;
}
if (rev->active) {
ngx_del_event(rev, NGX_READ_EVENT, 0);
}
++s->hs_stage;
ngx_log_debug1(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: stage %ui", s->hs_stage);
switch (s->hs_stage) {
case NGX_RTMP_HANDSHAKE_SERVER_SEND_CHALLENGE:
if (ngx_rtmp_handshake_parse_challenge(s,
&ngx_rtmp_client_partial_key,
&ngx_rtmp_server_full_key) != NGX_OK)
{
ngx_log_error(NGX_LOG_INFO, c->log, 0,
"handshake: error parsing challenge");
ngx_rtmp_finalize_session(s);
return;
}
if (s->hs_old) {
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: old-style challenge");
s->hs_buf->pos = s->hs_buf->start;
s->hs_buf->last = s->hs_buf->end;
} else if (ngx_rtmp_handshake_create_challenge(s,
ngx_rtmp_server_version,
&ngx_rtmp_server_partial_key) != NGX_OK)
{
ngx_log_error(NGX_LOG_INFO, c->log, 0,
"handshake: error creating challenge");
ngx_rtmp_finalize_session(s);
return;
}
ngx_rtmp_handshake_send(c->write);
break;
case NGX_RTMP_HANDSHAKE_SERVER_DONE:
ngx_rtmp_handshake_done(s);
break;
case NGX_RTMP_HANDSHAKE_CLIENT_RECV_RESPONSE:
if (ngx_rtmp_handshake_parse_challenge(s,
&ngx_rtmp_server_partial_key,
&ngx_rtmp_client_full_key) != NGX_OK)
{
ngx_log_error(NGX_LOG_INFO, c->log, 0,
"handshake: error parsing challenge");
ngx_rtmp_finalize_session(s);
return;
}
s->hs_buf->pos = s->hs_buf->last = s->hs_buf->start + 1;
ngx_rtmp_handshake_recv(c->read);
break;
case NGX_RTMP_HANDSHAKE_CLIENT_SEND_RESPONSE:
if (ngx_rtmp_handshake_create_response(s) != NGX_OK) {
ngx_log_error(NGX_LOG_INFO, c->log, 0,
"handshake: response error");
ngx_rtmp_finalize_session(s);
return;
}
ngx_rtmp_handshake_send(c->write);
break;
}
}
static void
ngx_rtmp_handshake_send(ngx_event_t *wev)
{
ngx_int_t n;
ngx_connection_t *c;
ngx_rtmp_session_t *s;
ngx_buf_t *b;
c = wev->data;
s = c->data;
if (c->destroyed) {
return;
}
if (wev->timedout) {
ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT,
"handshake: send: client timed out");
c->timedout = 1;
ngx_rtmp_finalize_session(s);
return;
}
if (wev->timer_set) {
ngx_del_timer(wev);
}
b = s->hs_buf;
while(b->pos != b->last) {
n = c->send(c, b->pos, b->last - b->pos);
if (n == NGX_ERROR) {
ngx_rtmp_finalize_session(s);
return;
}
if (n == NGX_AGAIN || n == 0) {
ngx_add_timer(c->write, s->timeout);
if (ngx_handle_write_event(c->write, 0) != NGX_OK) {
ngx_rtmp_finalize_session(s);
}
return;
}
b->pos += n;
}
if (wev->active) {
ngx_del_event(wev, NGX_WRITE_EVENT, 0);
}
++s->hs_stage;
ngx_log_debug1(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: stage %ui", s->hs_stage);
switch (s->hs_stage) {
case NGX_RTMP_HANDSHAKE_SERVER_SEND_RESPONSE:
if (s->hs_old) {
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: old-style response");
s->hs_buf->pos = s->hs_buf->start + 1;
s->hs_buf->last = s->hs_buf->end;
} else if (ngx_rtmp_handshake_create_response(s) != NGX_OK) {
ngx_log_error(NGX_LOG_INFO, c->log, 0,
"handshake: response error");
ngx_rtmp_finalize_session(s);
return;
}
ngx_rtmp_handshake_send(wev);
break;
case NGX_RTMP_HANDSHAKE_SERVER_RECV_RESPONSE:
s->hs_buf->pos = s->hs_buf->last = s->hs_buf->start + 1;
ngx_rtmp_handshake_recv(c->read);
break;
case NGX_RTMP_HANDSHAKE_CLIENT_RECV_CHALLENGE:
s->hs_buf->pos = s->hs_buf->last = s->hs_buf->start;
ngx_rtmp_handshake_recv(c->read);
break;
case NGX_RTMP_HANDSHAKE_CLIENT_DONE:
ngx_rtmp_handshake_done(s);
break;
}
}
void
ngx_rtmp_handshake(ngx_rtmp_session_t *s)
{
ngx_connection_t *c;
c = s->connection;
c->read->handler = ngx_rtmp_handshake_recv;
c->write->handler = ngx_rtmp_handshake_send;
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: start server handshake");
s->hs_buf = ngx_rtmp_alloc_handshake_buffer(s);
s->hs_stage = NGX_RTMP_HANDSHAKE_SERVER_RECV_CHALLENGE;
ngx_rtmp_handshake_recv(c->read);
}
void
ngx_rtmp_client_handshake(ngx_rtmp_session_t *s, unsigned async)
{
ngx_connection_t *c;
c = s->connection;
c->read->handler = ngx_rtmp_handshake_recv;
c->write->handler = ngx_rtmp_handshake_send;
ngx_log_debug0(NGX_LOG_DEBUG_RTMP, s->connection->log, 0,
"handshake: start client handshake");
s->hs_buf = ngx_rtmp_alloc_handshake_buffer(s);
s->hs_stage = NGX_RTMP_HANDSHAKE_CLIENT_SEND_CHALLENGE;
if (ngx_rtmp_handshake_create_challenge(s,
ngx_rtmp_client_version,
&ngx_rtmp_client_partial_key) != NGX_OK)
{
ngx_rtmp_finalize_session(s);
return;
}
if (async) {
ngx_add_timer(c->write, s->timeout);
if (ngx_handle_write_event(c->write, 0) != NGX_OK) {
ngx_rtmp_finalize_session(s);
}
return;
}
ngx_rtmp_handshake_send(c->write);
}
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