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bol-van
347
tpws/protocol.c
Normal file
347
tpws/protocol.c
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@@ -0,0 +1,347 @@
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#define _GNU_SOURCE
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#include "protocol.h"
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#include "helpers.h"
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#include <string.h>
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#include <ctype.h>
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#include <arpa/inet.h>
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#include <string.h>
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const char *http_methods[] = { "GET /","POST /","HEAD /","OPTIONS /","PUT /","DELETE /","CONNECT /","TRACE /",NULL };
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const char *HttpMethod(const uint8_t *data, size_t len)
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{
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const char **method;
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size_t method_len;
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for (method = http_methods; *method; method++)
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{
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method_len = strlen(*method);
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if (method_len <= len && !memcmp(data, *method, method_len))
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return *method;
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}
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return NULL;
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}
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bool IsHttp(const uint8_t *data, size_t len)
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{
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return !!HttpMethod(data,len);
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}
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static bool IsHostAt(const uint8_t *p)
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{
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return \
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p[0]=='\n' &&
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(p[1]=='H' || p[1]=='h') &&
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(p[2]=='o' || p[2]=='O') &&
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(p[3]=='s' || p[3]=='S') &&
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(p[4]=='t' || p[4]=='T') &&
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p[5]==':';
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}
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static uint8_t *FindHostIn(uint8_t *buf, size_t bs)
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{
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size_t pos;
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if (bs<6) return NULL;
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bs-=6;
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for(pos=0;pos<=bs;pos++)
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if (IsHostAt(buf+pos))
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return buf+pos;
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return NULL;
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}
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static const uint8_t *FindHostInConst(const uint8_t *buf, size_t bs)
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{
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size_t pos;
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if (bs<6) return NULL;
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bs-=6;
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for(pos=0;pos<=bs;pos++)
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if (IsHostAt(buf+pos))
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return buf+pos;
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return NULL;
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}
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// pHost points to "Host: ..."
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bool HttpFindHost(uint8_t **pHost,uint8_t *buf,size_t bs)
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{
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if (!*pHost)
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{
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*pHost = FindHostIn(buf, bs);
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if (*pHost) (*pHost)++;
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}
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return !!*pHost;
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}
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bool HttpFindHostConst(const uint8_t **pHost,const uint8_t *buf,size_t bs)
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{
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if (!*pHost)
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{
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*pHost = FindHostInConst(buf, bs);
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if (*pHost) (*pHost)++;
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}
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return !!*pHost;
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}
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bool IsHttpReply(const uint8_t *data, size_t len)
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{
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// HTTP/1.x 200\r\n
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return len>14 && !memcmp(data,"HTTP/1.",7) && (data[7]=='0' || data[7]=='1') && data[8]==' ' &&
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data[9]>='0' && data[9]<='9' &&
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data[10]>='0' && data[10]<='9' &&
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data[11]>='0' && data[11]<='9';
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}
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int HttpReplyCode(const uint8_t *data, size_t len)
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{
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return (data[9]-'0')*100 + (data[10]-'0')*10 + (data[11]-'0');
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}
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bool HttpExtractHeader(const uint8_t *data, size_t len, const char *header, char *buf, size_t len_buf)
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{
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const uint8_t *p, *s, *e = data + len;
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p = (uint8_t*)strncasestr((char*)data, header, len);
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if (!p) return false;
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p += strlen(header);
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while (p < e && (*p == ' ' || *p == '\t')) p++;
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s = p;
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while (s < e && (*s != '\r' && *s != '\n' && *s != ' ' && *s != '\t')) s++;
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if (s > p)
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{
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size_t slen = s - p;
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if (buf && len_buf)
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{
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if (slen >= len_buf) slen = len_buf - 1;
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for (size_t i = 0; i < slen; i++) buf[i] = tolower(p[i]);
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buf[slen] = 0;
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}
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return true;
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}
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return false;
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}
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bool HttpExtractHost(const uint8_t *data, size_t len, char *host, size_t len_host)
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{
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return HttpExtractHeader(data, len, "\nHost:", host, len_host);
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}
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const char *HttpFind2ndLevelDomain(const char *host)
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{
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const char *p=NULL;
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if (*host)
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{
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for (p = host + strlen(host)-1; p>host && *p!='.'; p--);
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if (*p=='.') for (p--; p>host && *p!='.'; p--);
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if (*p=='.') p++;
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}
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return p;
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}
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// DPI redirects are global redirects to another domain
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bool HttpReplyLooksLikeDPIRedirect(const uint8_t *data, size_t len, const char *host)
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{
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char loc[256],*redirect_host, *p;
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int code;
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if (!host || !*host) return false;
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code = HttpReplyCode(data,len);
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if ((code!=302 && code!=307) || !HttpExtractHeader(data,len,"\nLocation:",loc,sizeof(loc))) return false;
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// something like : https://censor.net/badpage.php?reason=denied&source=RKN
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if (!strncmp(loc,"http://",7))
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redirect_host=loc+7;
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else if (!strncmp(loc,"https://",8))
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redirect_host=loc+8;
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else
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return false;
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// somethinkg like : censor.net/badpage.php?reason=denied&source=RKN
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for(p=redirect_host; *p && *p!='/' ; p++);
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*p=0;
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if (!*redirect_host) return false;
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// somethinkg like : censor.net
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// extract 2nd level domains
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const char *dhost = HttpFind2ndLevelDomain(host);
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const char *drhost = HttpFind2ndLevelDomain(redirect_host);
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return strcasecmp(dhost, drhost)!=0;
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}
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size_t HttpPos(enum httpreqpos tpos_type, size_t hpos_pos, const uint8_t *http, size_t sz)
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{
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const uint8_t *method, *host=NULL;
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int i;
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switch(tpos_type)
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{
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case httpreqpos_method:
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// recognize some tpws pre-applied hacks
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method=http;
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if (sz<10) break;
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if (*method=='\n' || *method=='\r') method++;
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if (*method=='\n' || *method=='\r') method++;
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for (i=0;i<7;i++) if (*method>='A' && *method<='Z') method++;
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if (i<3 || *method!=' ') break;
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return method-http-1;
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case httpreqpos_host:
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if (HttpFindHostConst(&host,http,sz) && (host-http+7)<sz)
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{
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host+=5;
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if (*host==' ') host++;
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return host-http;
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}
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break;
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case httpreqpos_pos:
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break;
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default:
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return 0;
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}
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return hpos_pos<sz ? hpos_pos : 0;
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}
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uint16_t TLSRecordDataLen(const uint8_t *data)
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{
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return pntoh16(data + 3);
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}
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size_t TLSRecordLen(const uint8_t *data)
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{
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return TLSRecordDataLen(data) + 5;
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}
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bool IsTLSRecordFull(const uint8_t *data, size_t len)
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{
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return TLSRecordLen(data)<=len;
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}
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bool IsTLSClientHello(const uint8_t *data, size_t len, bool bPartialIsOK)
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{
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return len >= 6 && data[0] == 0x16 && data[1] == 0x03 && data[2] <= 0x03 && data[5] == 0x01 && (bPartialIsOK || TLSRecordLen(data) <= len);
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}
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// bPartialIsOK=true - accept partial packets not containing the whole TLS message
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bool TLSFindExtInHandshake(const uint8_t *data, size_t len, uint16_t type, const uint8_t **ext, size_t *len_ext, bool bPartialIsOK)
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{
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// +0
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// u8 HandshakeType: ClientHello
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// u24 Length
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// u16 Version
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// c[32] random
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// u8 SessionIDLength
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// <SessionID>
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// u16 CipherSuitesLength
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// <CipherSuites>
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// u8 CompressionMethodsLength
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// <CompressionMethods>
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// u16 ExtensionsLength
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size_t l, ll;
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l = 1 + 3 + 2 + 32;
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// SessionIDLength
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if (len < (l + 1)) return false;
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if (!bPartialIsOK)
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{
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ll = data[1] << 16 | data[2] << 8 | data[3]; // HandshakeProtocol length
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if (len < (ll + 4)) return false;
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}
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l += data[l] + 1;
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// CipherSuitesLength
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if (len < (l + 2)) return false;
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l += pntoh16(data + l) + 2;
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// CompressionMethodsLength
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if (len < (l + 1)) return false;
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l += data[l] + 1;
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// ExtensionsLength
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if (len < (l + 2)) return false;
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data += l; len -= l;
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l = pntoh16(data);
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data += 2; len -= 2;
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if (bPartialIsOK)
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{
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if (len < l) l = len;
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}
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else
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{
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if (len < l) return false;
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}
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while (l >= 4)
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{
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uint16_t etype = pntoh16(data);
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size_t elen = pntoh16(data + 2);
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data += 4; l -= 4;
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if (l < elen) break;
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if (etype == type)
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{
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if (ext && len_ext)
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{
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*ext = data;
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*len_ext = elen;
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}
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return true;
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}
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data += elen; l -= elen;
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}
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return false;
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}
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bool TLSFindExt(const uint8_t *data, size_t len, uint16_t type, const uint8_t **ext, size_t *len_ext, bool bPartialIsOK)
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{
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// +0
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// u8 ContentType: Handshake
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// u16 Version: TLS1.0
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// u16 Length
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size_t reclen;
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if (!IsTLSClientHello(data, len, bPartialIsOK)) return false;
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reclen=TLSRecordLen(data);
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if (reclen<len) len=reclen; // correct len if it has more data than the first tls record has
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return TLSFindExtInHandshake(data + 5, len - 5, type, ext, len_ext, bPartialIsOK);
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}
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static bool TLSExtractHostFromExt(const uint8_t *ext, size_t elen, char *host, size_t len_host)
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{
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// u16 data+0 - name list length
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// u8 data+2 - server name type. 0=host_name
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// u16 data+3 - server name length
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if (elen < 5 || ext[2] != 0) return false;
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size_t slen = pntoh16(ext + 3);
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ext += 5; elen -= 5;
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if (slen < elen) return false;
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if (host && len_host)
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{
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if (slen >= len_host) slen = len_host - 1;
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for (size_t i = 0; i < slen; i++) host[i] = tolower(ext[i]);
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host[slen] = 0;
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}
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return true;
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}
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bool TLSHelloExtractHost(const uint8_t *data, size_t len, char *host, size_t len_host, bool bPartialIsOK)
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{
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const uint8_t *ext;
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size_t elen;
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if (!TLSFindExt(data, len, 0, &ext, &elen, bPartialIsOK)) return false;
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return TLSExtractHostFromExt(ext, elen, host, len_host);
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}
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bool TLSHelloExtractHostFromHandshake(const uint8_t *data, size_t len, char *host, size_t len_host, bool bPartialIsOK)
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{
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const uint8_t *ext;
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size_t elen;
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if (!TLSFindExtInHandshake(data, len, 0, &ext, &elen, bPartialIsOK)) return false;
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return TLSExtractHostFromExt(ext, elen, host, len_host);
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}
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size_t TLSPos(enum tlspos tpos_type, size_t tpos_pos, const uint8_t *tls, size_t sz, uint8_t type)
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{
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size_t elen;
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const uint8_t *ext;
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switch(tpos_type)
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{
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case tlspos_sni:
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case tlspos_sniext:
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if (TLSFindExt(tls,sz,0,&ext,&elen,false))
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return (tpos_type==tlspos_sni) ? ext-tls+6 : ext-tls+1;
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// fall through
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case tlspos_pos:
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return tpos_pos<sz ? tpos_pos : 0;
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default:
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return 0;
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}
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}
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