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zapret/nfq/protocol.c

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#define _GNU_SOURCE
#include "protocol.h"
#include "helpers.h"
#include "params.h"
#include <string.h>
#include <ctype.h>
#include <arpa/inet.h>
#include <string.h>
// find N level domain
static bool FindNLD(const uint8_t *dom, size_t dlen, int level, const uint8_t **p, size_t *len)
{
int i;
const uint8_t *p1,*p2;
for (i=1,p2=dom+dlen;i<level;i++)
{
for (p2--; p2>dom && *p2!='.'; p2--);
if (p2<=dom) return false;
}
for (p1=p2-1 ; p1>dom && *p1!='.'; p1--);
if (*p1=='.') p1++;
if (p) *p = p1;
if (len) *len = p2-p1;
return true;
}
const char *l7proto_str(t_l7proto l7)
{
switch(l7)
{
case HTTP: return "http";
case TLS: return "tls";
case QUIC: return "quic";
case WIREGUARD: return "wireguard";
case DHT: return "dht";
default: return "unknown";
}
}
bool l7_proto_match(t_l7proto l7proto, uint32_t filter_l7)
{
return (l7proto==UNKNOWN && (filter_l7 & L7_PROTO_UNKNOWN)) ||
(l7proto==HTTP && (filter_l7 & L7_PROTO_HTTP)) ||
(l7proto==TLS && (filter_l7 & L7_PROTO_TLS)) ||
(l7proto==QUIC && (filter_l7 & L7_PROTO_QUIC)) ||
(l7proto==WIREGUARD && (filter_l7 & L7_PROTO_WIREGUARD)) ||
(l7proto==DHT && (filter_l7 & L7_PROTO_DHT));
}
#define PM_ABS 0
#define PM_HOST 1
#define PM_HOST_END 2
#define PM_HOST_SLD 3
#define PM_HOST_MIDSLD 4
#define PM_HOST_ENDSLD 5
#define PM_HTTP_METHOD 6
#define PM_SNI_EXT 7
bool IsHostMarker(uint8_t posmarker)
{
switch(posmarker)
{
case PM_HOST:
case PM_HOST_END:
case PM_HOST_SLD:
case PM_HOST_MIDSLD:
case PM_HOST_ENDSLD:
return true;
default:
return false;
}
}
const char *posmarker_name(uint8_t posmarker)
{
switch(posmarker)
{
case PM_ABS: return "abs";
case PM_HOST: return "host";
case PM_HOST_END: return "endhost";
case PM_HOST_SLD: return "sld";
case PM_HOST_MIDSLD: return "midsld";
case PM_HOST_ENDSLD: return "endsld";
case PM_HTTP_METHOD: return "method";
case PM_SNI_EXT: return "sniext";
default: return "?";
}
}
static size_t CheckPos(size_t sz, ssize_t offset)
{
return (offset>=0 && offset<sz) ? offset : 0;
}
size_t AnyProtoPos(uint8_t posmarker, int16_t pos, const uint8_t *data, size_t sz)
{
ssize_t offset;
switch(posmarker)
{
case PM_ABS:
offset = (pos<0) ? sz+pos : pos;
return CheckPos(sz,offset);
default:
return 0;
}
}
static size_t HostPos(uint8_t posmarker, int16_t pos, const uint8_t *data, size_t sz, size_t offset_host, size_t len_host)
{
ssize_t offset;
const uint8_t *p;
size_t slen;
switch(posmarker)
{
case PM_HOST:
offset = offset_host+pos;
break;
case PM_HOST_END:
offset = offset_host+len_host+pos;
break;
case PM_HOST_SLD:
case PM_HOST_MIDSLD:
case PM_HOST_ENDSLD:
if (((offset_host+len_host)<=sz) && FindNLD(data+offset_host,len_host,2,&p,&slen))
offset = (posmarker==PM_HOST_SLD ? p-data : posmarker==PM_HOST_ENDSLD ? p-data+slen : slen==1 ? p+1-data : p+slen/2-data) + pos;
else
offset = 0;
break;
}
return CheckPos(sz,offset);
}
size_t ResolvePos(const uint8_t *data, size_t sz, t_l7proto l7proto, const struct proto_pos *sp)
{
switch(l7proto)
{
case HTTP:
return HttpPos(sp->marker, sp->pos, data, sz);
case TLS:
return TLSPos(sp->marker, sp->pos, data, sz);
default:
return AnyProtoPos(sp->marker, sp->pos, data, sz);
}
}
void ResolveMultiPos(const uint8_t *data, size_t sz, t_l7proto l7proto, const struct proto_pos *splits, int split_count, size_t *pos, int *pos_count)
{
int i,j;
for(i=j=0;i<split_count;i++)
{
pos[j] = ResolvePos(data,sz,l7proto,splits+i);
if (pos[j]) j++;
}
qsort_size_t(pos, j);
j=unique_size_t(pos, j);
*pos_count=j;
}
const char *http_methods[] = { "GET /","POST /","HEAD /","OPTIONS ","PUT /","DELETE /","CONNECT ","TRACE /",NULL };
const char *HttpMethod(const uint8_t *data, size_t len)
{
const char **method;
size_t method_len;
for (method = http_methods; *method; method++)
{
method_len = strlen(*method);
if (method_len <= len && !memcmp(data, *method, method_len))
return *method;
}
return NULL;
}
bool IsHttp(const uint8_t *data, size_t len)
{
return !!HttpMethod(data,len);
}
static bool IsHostAt(const uint8_t *p)
{
return \
p[0]=='\n' &&
(p[1]=='H' || p[1]=='h') &&
(p[2]=='o' || p[2]=='O') &&
(p[3]=='s' || p[3]=='S') &&
(p[4]=='t' || p[4]=='T') &&
p[5]==':';
}
static uint8_t *FindHostIn(uint8_t *buf, size_t bs)
{
size_t pos;
if (bs<6) return NULL;
bs-=6;
for(pos=0;pos<=bs;pos++)
if (IsHostAt(buf+pos))
return buf+pos;
return NULL;
}
static const uint8_t *FindHostInConst(const uint8_t *buf, size_t bs)
{
size_t pos;
if (bs<6) return NULL;
bs-=6;
for(pos=0;pos<=bs;pos++)
if (IsHostAt(buf+pos))
return buf+pos;
return NULL;
}
// pHost points to "Host: ..."
bool HttpFindHost(uint8_t **pHost,uint8_t *buf,size_t bs)
{
if (!*pHost)
{
*pHost = FindHostIn(buf, bs);
if (*pHost) (*pHost)++;
}
return !!*pHost;
}
bool HttpFindHostConst(const uint8_t **pHost,const uint8_t *buf,size_t bs)
{
if (!*pHost)
{
*pHost = FindHostInConst(buf, bs);
if (*pHost) (*pHost)++;
}
return !!*pHost;
}
bool IsHttpReply(const uint8_t *data, size_t len)
{
// HTTP/1.x 200\r\n
return len>14 && !memcmp(data,"HTTP/1.",7) && (data[7]=='0' || data[7]=='1') && data[8]==' ' &&
data[9]>='0' && data[9]<='9' &&
data[10]>='0' && data[10]<='9' &&
data[11]>='0' && data[11]<='9';
}
int HttpReplyCode(const uint8_t *data, size_t len)
{
return (data[9]-'0')*100 + (data[10]-'0')*10 + (data[11]-'0');
}
bool HttpExtractHeader(const uint8_t *data, size_t len, const char *header, char *buf, size_t len_buf)
{
const uint8_t *p, *s, *e = data + len;
p = (uint8_t*)strncasestr((char*)data, header, len);
if (!p) return false;
p += strlen(header);
while (p < e && (*p == ' ' || *p == '\t')) p++;
s = p;
while (s < e && (*s != '\r' && *s != '\n' && *s != ' ' && *s != '\t')) s++;
if (s > p)
{
size_t slen = s - p;
if (buf && len_buf)
{
if (slen >= len_buf) slen = len_buf - 1;
for (size_t i = 0; i < slen; i++) buf[i] = tolower(p[i]);
buf[slen] = 0;
}
return true;
}
return false;
}
bool HttpExtractHost(const uint8_t *data, size_t len, char *host, size_t len_host)
{
return HttpExtractHeader(data, len, "\nHost:", host, len_host);
}
// DPI redirects are global redirects to another domain
bool HttpReplyLooksLikeDPIRedirect(const uint8_t *data, size_t len, const char *host)
{
char loc[256],*redirect_host, *p;
int code;
if (!host || !*host) return false;
code = HttpReplyCode(data,len);
if ((code!=302 && code!=307) || !HttpExtractHeader(data,len,"\nLocation:",loc,sizeof(loc))) return false;
// something like : https://censor.net/badpage.php?reason=denied&source=RKN
if (!strncmp(loc,"http://",7))
redirect_host=loc+7;
else if (!strncmp(loc,"https://",8))
redirect_host=loc+8;
else
return false;
// somethinkg like : censor.net/badpage.php?reason=denied&source=RKN
for(p=redirect_host; *p && *p!='/' ; p++);
*p=0;
if (!*redirect_host) return false;
// somethinkg like : censor.net
// extract 2nd level domains
const char *dhost, *drhost;
if (!FindNLD((uint8_t*)host,strlen(host),2,(const uint8_t**)&dhost,NULL) || !FindNLD((uint8_t*)redirect_host,strlen(redirect_host),2,(const uint8_t**)&drhost,NULL))
return false;
// compare 2nd level domains
return strcasecmp(dhost, drhost)!=0;
}
size_t HttpPos(uint8_t posmarker, int16_t pos, const uint8_t *data, size_t sz)
{
const uint8_t *method, *host=NULL, *p;
size_t offset_host,len_host;
ssize_t offset;
int i;
switch(posmarker)
{
case PM_HTTP_METHOD:
// recognize some tpws pre-applied hacks
method=data;
if (sz<10) break;
if (*method=='\n' || *method=='\r') method++;
if (*method=='\n' || *method=='\r') method++;
for (p=method,i=0;i<7;i++) if (*p>='A' && *p<='Z') p++;
if (i<3 || *p!=' ') break;
return CheckPos(sz,method-data+pos);
case PM_HOST:
case PM_HOST_END:
case PM_HOST_SLD:
case PM_HOST_MIDSLD:
case PM_HOST_ENDSLD:
if (HttpFindHostConst(&host,data,sz) && (host-data+7)<sz)
{
host+=5;
if (*host==' ' || *host=='\t') host++;
offset_host = host-data;
if (posmarker!=PM_HOST)
for (len_host=0; (offset_host+len_host)<sz && data[offset_host+len_host]!='\r' && data[offset_host+len_host]!='\n'; len_host++);
else
len_host = 0;
return HostPos(posmarker,pos,data,sz,offset_host,len_host);
}
break;
default:
return AnyProtoPos(posmarker,pos,data,sz);
}
return 0;
}
uint16_t TLSRecordDataLen(const uint8_t *data)
{
return pntoh16(data + 3);
}
size_t TLSRecordLen(const uint8_t *data)
{
return TLSRecordDataLen(data) + 5;
}
bool IsTLSRecordFull(const uint8_t *data, size_t len)
{
return TLSRecordLen(data)<=len;
}
bool IsTLSClientHello(const uint8_t *data, size_t len, bool bPartialIsOK)
{
return len >= 6 && data[0] == 0x16 && data[1] == 0x03 && data[2] <= 0x03 && data[5] == 0x01 && (bPartialIsOK || TLSRecordLen(data) <= len);
}
size_t TLSHandshakeLen(const uint8_t *data)
{
return data[1] << 16 | data[2] << 8 | data[3]; // HandshakeProtocol length
}
bool IsTLSHandshakeClientHello(const uint8_t *data, size_t len)
{
return len>=4 && data[0]==0x01 && TLSHandshakeLen(data)>0;
}
bool IsTLSHandshakeFull(const uint8_t *data, size_t len)
{
return (4+TLSHandshakeLen(data))<=len;
}
// bPartialIsOK=true - accept partial packets not containing the whole TLS message
bool TLSFindExtInHandshake(const uint8_t *data, size_t len, uint16_t type, const uint8_t **ext, size_t *len_ext, bool bPartialIsOK)
{
// +0
// u8 HandshakeType: ClientHello
// u24 Length
// u16 Version
// c[32] random
// u8 SessionIDLength
// <SessionID>
// u16 CipherSuitesLength
// <CipherSuites>
// u8 CompressionMethodsLength
// <CompressionMethods>
// u16 ExtensionsLength
size_t l;
if (!bPartialIsOK && !IsTLSHandshakeFull(data,len)) return false;
l = 1 + 3 + 2 + 32;
// SessionIDLength
if (len < (l + 1)) return false;
l += data[l] + 1;
// CipherSuitesLength
if (len < (l + 2)) return false;
l += pntoh16(data + l) + 2;
// CompressionMethodsLength
if (len < (l + 1)) return false;
l += data[l] + 1;
// ExtensionsLength
if (len < (l + 2)) return false;
data += l; len -= l;
l = pntoh16(data);
data += 2; len -= 2;
if (bPartialIsOK)
{
if (len < l) l = len;
}
else
{
if (len < l) return false;
}
while (l >= 4)
{
uint16_t etype = pntoh16(data);
size_t elen = pntoh16(data + 2);
data += 4; l -= 4;
if (l < elen) break;
if (etype == type)
{
if (ext && len_ext)
{
*ext = data;
*len_ext = elen;
}
return true;
}
data += elen; l -= elen;
}
return false;
}
bool TLSFindExt(const uint8_t *data, size_t len, uint16_t type, const uint8_t **ext, size_t *len_ext, bool bPartialIsOK)
{
// +0
// u8 ContentType: Handshake
// u16 Version: TLS1.0
// u16 Length
size_t reclen;
if (!IsTLSClientHello(data, len, bPartialIsOK)) return false;
reclen=TLSRecordLen(data);
if (reclen<len) len=reclen; // correct len if it has more data than the first tls record has
return TLSFindExtInHandshake(data + 5, len - 5, type, ext, len_ext, bPartialIsOK);
}
static bool TLSAdvanceToHostInSNI(const uint8_t **ext, size_t *elen, size_t *slen)
{
// u16 data+0 - name list length
// u8 data+2 - server name type. 0=host_name
// u16 data+3 - server name length
if (*elen < 5 || (*ext)[2] != 0) return false;
*slen = pntoh16(*ext + 3);
*ext += 5; *elen -= 5;
return *slen <= *elen;
}
static bool TLSExtractHostFromExt(const uint8_t *ext, size_t elen, char *host, size_t len_host)
{
// u16 data+0 - name list length
// u8 data+2 - server name type. 0=host_name
// u16 data+3 - server name length
size_t slen;
if (!TLSAdvanceToHostInSNI(&ext,&elen,&slen))
return false;
if (host && len_host)
{
if (slen >= len_host) slen = len_host - 1;
for (size_t i = 0; i < slen; i++) host[i] = tolower(ext[i]);
host[slen] = 0;
}
return true;
}
bool TLSHelloExtractHost(const uint8_t *data, size_t len, char *host, size_t len_host, bool bPartialIsOK)
{
const uint8_t *ext;
size_t elen;
if (!TLSFindExt(data, len, 0, &ext, &elen, bPartialIsOK)) return false;
return TLSExtractHostFromExt(ext, elen, host, len_host);
}
bool TLSHelloExtractHostFromHandshake(const uint8_t *data, size_t len, char *host, size_t len_host, bool bPartialIsOK)
{
const uint8_t *ext;
size_t elen;
if (!TLSFindExtInHandshake(data, len, 0, &ext, &elen, bPartialIsOK)) return false;
return TLSExtractHostFromExt(ext, elen, host, len_host);
}
size_t TLSPos(uint8_t posmarker, int16_t pos, const uint8_t *data, size_t sz)
{
size_t elen;
const uint8_t *ext, *p;
size_t offset_host,len_host;
ssize_t offset;
switch(posmarker)
{
case PM_HOST:
case PM_HOST_END:
case PM_HOST_SLD:
case PM_HOST_MIDSLD:
case PM_HOST_ENDSLD:
case PM_SNI_EXT:
if (TLSFindExt(data,sz,0,&ext,&elen,TLS_PARTIALS_ENABLE))
{
if (posmarker==PM_SNI_EXT)
{
return CheckPos(sz,ext-data+pos);
}
else
{
if (!TLSAdvanceToHostInSNI(&ext,&elen,&len_host))
return 0;
offset_host = ext-data;
return HostPos(posmarker,pos,data,sz,offset_host,len_host);
}
}
return 0;
default:
return AnyProtoPos(posmarker,pos,data,sz);
}
}
static uint8_t tvb_get_varint(const uint8_t *tvb, uint64_t *value)
{
switch (*tvb >> 6)
{
case 0: /* 0b00 => 1 byte length (6 bits Usable) */
if (value) *value = *tvb & 0x3F;
return 1;
case 1: /* 0b01 => 2 bytes length (14 bits Usable) */
if (value) *value = pntoh16(tvb) & 0x3FFF;
return 2;
case 2: /* 0b10 => 4 bytes length (30 bits Usable) */
if (value) *value = pntoh32(tvb) & 0x3FFFFFFF;
return 4;
case 3: /* 0b11 => 8 bytes length (62 bits Usable) */
if (value) *value = pntoh64(tvb) & 0x3FFFFFFFFFFFFFFF;
return 8;
}
// impossible case
if (*value) *value = 0;
return 0;
}
static uint8_t tvb_get_size(uint8_t tvb)
{
return 1 << (tvb >> 6);
}
bool IsQUICCryptoHello(const uint8_t *data, size_t len, size_t *hello_offset, size_t *hello_len)
{
size_t offset = 1;
uint64_t coff, clen;
if (len < 3 || *data != 6) return false;
if ((offset+tvb_get_size(data[offset])) >= len) return false;
offset += tvb_get_varint(data + offset, &coff);
// offset must be 0 if it's a full segment, not just a chunk
if (coff || (offset+tvb_get_size(data[offset])) >= len) return false;
offset += tvb_get_varint(data + offset, &clen);
if ((offset + clen) > len || !IsTLSHandshakeClientHello(data+offset,clen)) return false;
if (hello_offset) *hello_offset = offset;
if (hello_len) *hello_len = (size_t)clen;
return true;
}
/* Returns the QUIC draft version or 0 if not applicable. */
uint8_t QUICDraftVersion(uint32_t version)
{
/* IETF Draft versions */
if ((version >> 8) == 0xff0000) {
return (uint8_t)version;
}
/* Facebook mvfst, based on draft -22. */
if (version == 0xfaceb001) {
return 22;
}
/* Facebook mvfst, based on draft -27. */
if (version == 0xfaceb002 || version == 0xfaceb00e) {
return 27;
}
/* GQUIC Q050, T050 and T051: they are not really based on any drafts,
* but we must return a sensible value */
if (version == 0x51303530 ||
version == 0x54303530 ||
version == 0x54303531) {
return 27;
}
/* https://tools.ietf.org/html/draft-ietf-quic-transport-32#section-15
"Versions that follow the pattern 0x?a?a?a?a are reserved for use in
forcing version negotiation to be exercised"
It is tricky to return a correct draft version: such number is primarily
used to select a proper salt (which depends on the version itself), but
we don't have a real version here! Let's hope that we need to handle
only latest drafts... */
if ((version & 0x0F0F0F0F) == 0x0a0a0a0a) {
return 29;
}
/* QUIC (final?) constants for v1 are defined in draft-33, but draft-34 is the
final draft version */
if (version == 0x00000001) {
return 34;
}
/* QUIC Version 2 */
/* TODO: for the time being use 100 as a number for V2 and let see how v2 drafts evolve */
if (version == 0x709A50C4) {
return 100;
}
return 0;
}
static bool is_quic_draft_max(uint32_t draft_version, uint8_t max_version)
{
return draft_version && draft_version <= max_version;
}
static bool is_quic_v2(uint32_t version)
{
return version == 0x6b3343cf;
}
static bool quic_hkdf_expand_label(const uint8_t *secret, uint8_t secret_len, const char *label, uint8_t *out, size_t out_len)
{
uint8_t hkdflabel[64];
size_t label_size = strlen(label);
if (label_size > 255) return false;
size_t hkdflabel_size = 2 + 1 + label_size + 1;
if (hkdflabel_size > sizeof(hkdflabel)) return false;
phton16(hkdflabel, out_len);
hkdflabel[2] = (uint8_t)label_size;
memcpy(hkdflabel + 3, label, label_size);
hkdflabel[3 + label_size] = 0;
return !hkdfExpand(SHA256, secret, secret_len, hkdflabel, hkdflabel_size, out, out_len);
}
static bool quic_derive_initial_secret(const quic_cid_t *cid, uint8_t *client_initial_secret, uint32_t version)
{
/*
* https://tools.ietf.org/html/draft-ietf-quic-tls-29#section-5.2
*
* initial_salt = 0xafbfec289993d24c9e9786f19c6111e04390a899
* initial_secret = HKDF-Extract(initial_salt, client_dst_connection_id)
*
* client_initial_secret = HKDF-Expand-Label(initial_secret,
* "client in", "", Hash.length)
* server_initial_secret = HKDF-Expand-Label(initial_secret,
* "server in", "", Hash.length)
*
* Hash for handshake packets is SHA-256 (output size 32).
*/
static const uint8_t handshake_salt_draft_22[20] = {
0x7f, 0xbc, 0xdb, 0x0e, 0x7c, 0x66, 0xbb, 0xe9, 0x19, 0x3a,
0x96, 0xcd, 0x21, 0x51, 0x9e, 0xbd, 0x7a, 0x02, 0x64, 0x4a
};
static const uint8_t handshake_salt_draft_23[20] = {
0xc3, 0xee, 0xf7, 0x12, 0xc7, 0x2e, 0xbb, 0x5a, 0x11, 0xa7,
0xd2, 0x43, 0x2b, 0xb4, 0x63, 0x65, 0xbe, 0xf9, 0xf5, 0x02,
};
static const uint8_t handshake_salt_draft_29[20] = {
0xaf, 0xbf, 0xec, 0x28, 0x99, 0x93, 0xd2, 0x4c, 0x9e, 0x97,
0x86, 0xf1, 0x9c, 0x61, 0x11, 0xe0, 0x43, 0x90, 0xa8, 0x99
};
static const uint8_t handshake_salt_v1[20] = {
0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17,
0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a
};
static const uint8_t hanshake_salt_draft_q50[20] = {
0x50, 0x45, 0x74, 0xEF, 0xD0, 0x66, 0xFE, 0x2F, 0x9D, 0x94,
0x5C, 0xFC, 0xDB, 0xD3, 0xA7, 0xF0, 0xD3, 0xB5, 0x6B, 0x45
};
static const uint8_t hanshake_salt_draft_t50[20] = {
0x7f, 0xf5, 0x79, 0xe5, 0xac, 0xd0, 0x72, 0x91, 0x55, 0x80,
0x30, 0x4c, 0x43, 0xa2, 0x36, 0x7c, 0x60, 0x48, 0x83, 0x10
};
static const uint8_t hanshake_salt_draft_t51[20] = {
0x7a, 0x4e, 0xde, 0xf4, 0xe7, 0xcc, 0xee, 0x5f, 0xa4, 0x50,
0x6c, 0x19, 0x12, 0x4f, 0xc8, 0xcc, 0xda, 0x6e, 0x03, 0x3d
};
static const uint8_t handshake_salt_v2[20] = {
0x0d, 0xed, 0xe3, 0xde, 0xf7, 0x00, 0xa6, 0xdb, 0x81, 0x93,
0x81, 0xbe, 0x6e, 0x26, 0x9d, 0xcb, 0xf9, 0xbd, 0x2e, 0xd9
};
int err;
const uint8_t *salt;
uint8_t secret[USHAMaxHashSize];
uint8_t draft_version = QUICDraftVersion(version);
if (version == 0x51303530) {
salt = hanshake_salt_draft_q50;
}
else if (version == 0x54303530) {
salt = hanshake_salt_draft_t50;
}
else if (version == 0x54303531) {
salt = hanshake_salt_draft_t51;
}
else if (is_quic_draft_max(draft_version, 22)) {
salt = handshake_salt_draft_22;
}
else if (is_quic_draft_max(draft_version, 28)) {
salt = handshake_salt_draft_23;
}
else if (is_quic_draft_max(draft_version, 32)) {
salt = handshake_salt_draft_29;
}
else if (is_quic_draft_max(draft_version, 34)) {
salt = handshake_salt_v1;
}
else {
salt = handshake_salt_v2;
}
err = hkdfExtract(SHA256, salt, 20, cid->cid, cid->len, secret);
if (err) return false;
if (client_initial_secret && !quic_hkdf_expand_label(secret, SHA256HashSize, "tls13 client in", client_initial_secret, SHA256HashSize))
return false;
return true;
}
bool QUICIsLongHeader(const uint8_t *data, size_t len)
{
return len>=9 && !!(*data & 0x80);
}
uint32_t QUICExtractVersion(const uint8_t *data, size_t len)
{
// long header, fixed bit, type=initial
return QUICIsLongHeader(data, len) ? ntohl(*(uint32_t*)(data + 1)) : 0;
}
bool QUICExtractDCID(const uint8_t *data, size_t len, quic_cid_t *cid)
{
if (!QUICIsLongHeader(data,len) || !data[5] || data[5] > QUIC_MAX_CID_LENGTH || (6+data[5])>len) return false;
cid->len = data[5];
memcpy(&cid->cid, data + 6, data[5]);
return true;
}
bool QUICDecryptInitial(const uint8_t *data, size_t data_len, uint8_t *clean, size_t *clean_len)
{
uint32_t ver = QUICExtractVersion(data, data_len);
if (!ver) return false;
quic_cid_t dcid;
if (!QUICExtractDCID(data, data_len, &dcid)) return false;
uint8_t client_initial_secret[SHA256HashSize];
if (!quic_derive_initial_secret(&dcid, client_initial_secret, ver)) return false;
uint8_t aeskey[16], aesiv[12], aeshp[16];
bool v1_label = !is_quic_v2(ver);
if (!quic_hkdf_expand_label(client_initial_secret, SHA256HashSize, v1_label ? "tls13 quic key" : "tls13 quicv2 key", aeskey, sizeof(aeskey)) ||
!quic_hkdf_expand_label(client_initial_secret, SHA256HashSize, v1_label ? "tls13 quic iv" : "tls13 quicv2 iv", aesiv, sizeof(aesiv)) ||
!quic_hkdf_expand_label(client_initial_secret, SHA256HashSize, v1_label ? "tls13 quic hp" : "tls13 quicv2 hp", aeshp, sizeof(aeshp)))
{
return false;
}
uint64_t payload_len,token_len;
size_t pn_offset;
pn_offset = 1 + 4 + 1 + data[5];
if (pn_offset >= data_len) return false;
pn_offset += 1 + data[pn_offset];
if ((pn_offset + tvb_get_size(data[pn_offset])) >= data_len) return false;
pn_offset += tvb_get_varint(data + pn_offset, &token_len);
pn_offset += token_len;
if ((pn_offset + tvb_get_size(data[pn_offset])) >= data_len) return false;
pn_offset += tvb_get_varint(data + pn_offset, &payload_len);
if (payload_len<20 || (pn_offset + payload_len)>data_len) return false;
aes_init_keygen_tables();
uint8_t sample_enc[16];
aes_context ctx;
if (aes_setkey(&ctx, 1, aeshp, sizeof(aeshp)) || aes_cipher(&ctx, data + pn_offset + 4, sample_enc)) return false;
uint8_t mask[5];
memcpy(mask, sample_enc, sizeof(mask));
uint8_t packet0 = data[0] ^ (mask[0] & 0x0f);
uint8_t pkn_len = (packet0 & 0x03) + 1;
uint8_t pkn_bytes[4];
memcpy(pkn_bytes, data + pn_offset, pkn_len);
uint32_t pkn = 0;
for (uint8_t i = 0; i < pkn_len; i++) pkn |= (uint32_t)(pkn_bytes[i] ^ mask[1 + i]) << (8 * (pkn_len - 1 - i));
phton64(aesiv + sizeof(aesiv) - 8, pntoh64(aesiv + sizeof(aesiv) - 8) ^ pkn);
size_t cryptlen = payload_len - pkn_len - 16;
if (cryptlen > *clean_len) return false;
*clean_len = cryptlen;
const uint8_t *decrypt_begin = data + pn_offset + pkn_len;
uint8_t atag[16],header[256];
size_t header_len = pn_offset + pkn_len;
if (header_len > sizeof(header)) return false; // not likely header will be so large
memcpy(header, data, header_len);
header[0] = packet0;
for(uint8_t i = 0; i < pkn_len; i++) header[header_len - 1 - i] = (uint8_t)(pkn >> (8 * i));
if (aes_gcm_crypt(AES_DECRYPT, clean, decrypt_begin, cryptlen, aeskey, sizeof(aeskey), aesiv, sizeof(aesiv), header, header_len, atag, sizeof(atag)))
return false;
// check if message was decrypted correctly : good keys , no data corruption
return !memcmp(data + pn_offset + pkn_len + cryptlen, atag, 16);
}
bool QUICDefragCrypto(const uint8_t *clean,size_t clean_len, uint8_t *defrag,size_t *defrag_len)
{
// Crypto frame can be split into multiple chunks
// chromium randomly splits it and pads with zero/one bytes to force support the standard
// mozilla does not split
if (*defrag_len<10) return false;
uint8_t *defrag_data = defrag+10;
size_t defrag_data_len = *defrag_len-10;
uint8_t ft;
uint64_t offset,sz,szmax=0,zeropos=0,pos=0;
bool found=false;
while(pos<clean_len)
{
ft = clean[pos];
pos++;
if (ft>1) // 00 - padding, 01 - ping
{
if (ft!=6) return false; // dont want to know all possible frame type formats
if (pos>=clean_len) return false;
if ((pos+tvb_get_size(clean[pos])>=clean_len)) return false;
pos += tvb_get_varint(clean+pos, &offset);
if ((pos+tvb_get_size(clean[pos])>clean_len)) return false;
pos += tvb_get_varint(clean+pos, &sz);
if ((pos+sz)>clean_len) return false;
if ((offset+sz)>defrag_data_len) return false;
if (zeropos < offset)
// make sure no uninitialized gaps exist in case of not full fragment coverage
memset(defrag_data+zeropos,0,offset-zeropos);
if ((offset+sz) > zeropos)
zeropos=offset+sz;
memcpy(defrag_data+offset,clean+pos,sz);
if ((offset+sz) > szmax) szmax = offset+sz;
found=true;
pos+=sz;
}
}
if (found)
{
defrag[0] = 6;
defrag[1] = 0; // offset
// 2..9 - length 64 bit
// +10 - data start
phton64(defrag+2,szmax);
defrag[2] |= 0xC0; // 64 bit value
*defrag_len = (size_t)(szmax+10);
}
return found;
}
/*
bool QUICExtractHostFromInitial(const uint8_t *data, size_t data_len, char *host, size_t len_host, bool *bDecryptOK, bool *bIsCryptoHello)
{
if (bIsCryptoHello) *bIsCryptoHello=false;
if (bDecryptOK) *bDecryptOK=false;
uint8_t clean[1500];
size_t clean_len = sizeof(clean);
if (!QUICDecryptInitial(data,data_len,clean,&clean_len)) return false;
if (bDecryptOK) *bDecryptOK=true;
uint8_t defrag[1500];
size_t defrag_len = sizeof(defrag);
if (!QUICDefragCrypto(clean,clean_len,defrag,&defrag_len)) return false;
size_t hello_offset, hello_len;
if (!IsQUICCryptoHello(defrag, defrag_len, &hello_offset, &hello_len)) return false;
if (bIsCryptoHello) *bIsCryptoHello=true;
return TLSHelloExtractHostFromHandshake(defrag + hello_offset, hello_len, host, len_host, NULL, true);
}
*/
bool IsQUICInitial(const uint8_t *data, size_t len)
{
// too small packets are not likely to be initials with client hello
// long header, fixed bit
if (len < 256 || (data[0] & 0xC0)!=0xC0) return false;
uint32_t ver = QUICExtractVersion(data,len);
if (QUICDraftVersion(ver) < 11) return false;
// quic v1 : initial packets are 00b
// quic v2 : initial packets are 01b
if ((data[0] & 0x30) != (is_quic_v2(ver) ? 0x10 : 0x00)) return false;
uint64_t offset=5, sz;
// DCID. must be present
if (!data[offset] || data[offset] > QUIC_MAX_CID_LENGTH) return false;
offset += 1 + data[offset];
// SCID
if (data[offset] > QUIC_MAX_CID_LENGTH) return false;
offset += 1 + data[offset];
// token length
offset += tvb_get_varint(data + offset, &sz);
offset += sz;
if (offset >= len) return false;
// payload length
if ((offset + tvb_get_size(data[offset])) > len) return false;
tvb_get_varint(data + offset, &sz);
offset += sz;
if (offset > len) return false;
// client hello cannot be too small. likely ACK
return sz>=96;
}
bool IsWireguardHandshakeInitiation(const uint8_t *data, size_t len)
{
return len==148 && data[0]==1 && data[1]==0 && data[2]==0 && data[3]==0;
}
bool IsDhtD1(const uint8_t *data, size_t len)
{
return len>=7 && data[0]=='d' && data[1]=='1' && data[len-1]=='e';
}
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