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作者: 趙氏軟體(http://chiosoft.51.net); h& Q$ T0 y9 P8 n. s
E-mail: chiosoft@163.net) }) ]! @; u: e
※轉貼請注明出處※
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本文以QQ為對像,教你如何寫一個SOCKS5 PROXY
9 J1 N" O6 p; W g4 M. ^本章主要介紹Launch_UDP()的工作原理) E( Q0 q4 G+ B$ @5 P
* F9 I' D7 H0 I$ J1 S+ o! E一、SOCKS5 UDP封包結構
6 T& O7 d2 a( d% Z% Y9 D5 y, y===========================
* y/ M! ]7 S& g# \+ E順序為:
# L3 Y3 y8 {0 N7 ]( l5 p2 Bytes 保留字,一定要為0x0
: }( R: j+ a3 R: }* I! n8 f1 Bytes Current fragment number
2 W- b/ w! l2 m" V" E1 Bytes 地址類型
, E9 `# v2 O/ [! ]2 WX Bytes 目的地地址
0 @% k+ U( i$ O" D2 Bytes 目的地端口號
; @7 `; x" i4 F* c- Y3 U }N Bytes 數據
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二、源代碼
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void Launch_UDP( int udp_proxy_port, const char *udp_proxy_ip, int clt_udp_port )6 G3 P1 w1 e- E# I- ?* _1 G
{
7 Y8 f+ ?0 S9 D4 l; o //port is NOT network orders
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6 j: l& r$ O6 G; C: x$ v- ^ //記錄本機,客戶端,遠端服務器和封包來源地址
- k9 F3 E' B& _& J$ d0 e7 A; ^ struct sockaddr_in servaddr,clientaddr,remoteaddr,inaddr;! S) Q" w6 l0 J4 I
int inlen;
% r- v5 c2 g7 l0 L+ J int listenfd;
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fd_set set;/ p) s2 s; T+ v( p; R) s6 P s) l
//把接收來的數據寫在緩衝區第11個Byte之後,前10 Bytes用來存放Header5 I2 }7 B4 k* u5 \7 J
char *thisbuf = &buf[10];
6 k: I! j/ H5 ^ int thissize = BUFSZ - 10;
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; {: _8 W' S8 z2 {& t- w printf("< UDP Session - START >\n\n");& G! T! Z" E% a5 Q
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//建立一個UDP SOCKET,注意UDP協議不需要listen, accept和conenct
# Q( M" [4 O. A0 _. O5 V k memset(&servaddr, 0, sizeof(servaddr));
5 Y) n6 F# L% O6 G k% G" J9 E servaddr.sin_family = AF_INET;; `( u! Q) k) K# |9 L6 l5 P
servaddr.sin_port = htons( udp_proxy_port );
8 k, M; d9 Y. G% R+ P. n" Q servaddr.sin_addr.s_addr = htonl( INADDR_ANY );
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memset(&remoteaddr, 0, sizeof(remoteaddr));+ H6 L1 o1 M- {/ ~! [1 r b
remoteaddr.sin_family = AF_INET;9 l4 Z4 L4 f$ X1 _
9 Y+ k8 q) a/ k# g* A listenfd = socket(AF_INET, SOCK_DGRAM, 0);+ ?+ Z" u+ P9 a x5 T% ~: B% K t- a
if(listenfd < 0) {, A' } x- a7 _% U' @
p_error("socket error");6 x0 ]- a# _9 A9 r
exit(-1);
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if( bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ) {
: q B2 p! K) F' S2 h; n6 L% m. v; c p_error("bind error");7 X* d3 }- l- f# `) _
exit(-1);
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//使用select來監控Socket是否有資料可讀
! n! Y" P0 {8 H# A1 M% ` FD_ZERO(&set);
- P) e* S( b% d" F" d+ i FD_SET(listenfd, &set);4 g( D' W7 X* Q( x1 v% T" \
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while( 1 ) {
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0 Y% c( Y* L' z. ~; W if( select( listenfd+1, &set, NULL, NULL, NULL) < 0 ) {/ m/ D: O% ~ ]+ k0 l
p_error("select error");
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if( FD_ISSET( listenfd, &set ) ) {
4 }7 \' H- ^3 t7 G8 K' b //UDP協議可使用recvfrom()來接收數據,並獲得來源地地址3 X1 ~% f8 F% r2 M$ c
n = recvfrom( listenfd, thisbuf, thissize, 0, (struct sockaddr *)&inaddr, &inlen );
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if( n >=0 ) {5 Z4 u) i2 R; F0 ~" E
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debug_showip( &inaddr, "Received From", "\n" );
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9 Y, s G3 J, \! C //資料來自客戶端; |+ E* K$ _9 H$ q8 B$ C" B
if( (thisbuf[0]==0x0) && (thisbuf[1]==0x0) && % i* I2 a1 g- I4 O2 A
(htons(inaddr.sin_port)==clt_udp_port) )
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//保存客戶端的地址' |8 v& S/ k0 L" ~; ~. w+ X
memcpy( &clientaddr, &inaddr, sizeof(clientaddr) );' F( L3 N$ _5 b
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if( thisbuf[3] != 0x1 ) {
0 w* E8 @3 [* P //如果目的地地址類型為域名,先進行解析獲得IP再發送
( x$ W/ B' ~. T6 c& l! u struct hostent *h;
) ?2 d; W7 Q9 x char tmp[256];
2 q4 J) w0 Y% G& S$ q int seg;
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6 |: c; a/ b4 U; q strncpy( tmp, &thisbuf[5], thisbuf[4] );3 }# H4 B2 ~6 Z% n( X7 K0 d4 b9 ~
tmp[ thisbuf[4] ] = 0;
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. d. x$ I! ?) z% w- V' [ h = gethostbyname ( tmp ); //<netdb.h>
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2 [+ ~( p, R) y6 R0 b: T' I if( h == NULL )
5 b$ C% w1 M2 y. N7 | p_error("unknown domain name\n");
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{
* {% S' C. a: ~( P" Y v remoteaddr.sin_addr.s_addr = (*(struct in_addr*)h->h_addr).s_addr;
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1 p3 N! C1 S- l seg = thisbuf[4]+1;
x$ _0 i3 }7 |1 o0 |! K memcpy( &remoteaddr.sin_port, &thisbuf[4+seg], 2 );- z# N( q' K( U
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debug_showbin( thisbuf, 4+seg+2, "RECV CLIENT [ Header ]","\n");/ g8 ]2 s" g7 g. p+ j0 L2 P
debug_showbin( &thisbuf[4+seg+2], n-(4+seg+2), "RECV CLIENT [ Data ]","\n");
( G2 m+ H* L ]! g' a d3 y debug_showip( &remoteaddr, "Send to DOMAIN", "\n\n");
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sendto( listenfd, &thisbuf[4+seg+2], n-(4+seg+2), 0, (struct sockaddr*)&remoteaddr,sizeof(remoteaddr));; W0 L6 W6 u d! V' K
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} else {
, r: o5 R+ L+ r: e7 D //目的地地址為IPv4,直接把資料發送過去
% R: X9 ~& x% g* \* g i5 T: @ memcpy( &remoteaddr.sin_port, &thisbuf[8], 2 );
" g6 ^% r3 P5 @' b( V memcpy( &remoteaddr.sin_addr.s_addr, &thisbuf[4], 4 );7 q" S7 ~/ j/ g3 E8 r- F
. b7 H9 X& w) h2 i6 O debug_showbin( thisbuf, 10, "RECV CLIENT [ Header ]","\n");) a! R( s; G @. j, Q
debug_showbin( &thisbuf[10], n-10, "RECV CLIENT [ Data ]","\n");
0 N& N) c$ Q" C/ G6 [: W3 f debug_showip( &remoteaddr, "Send to IP", "\n\n");
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sendto( listenfd, &thisbuf[10], n-10, 0, (struct sockaddr*)&remoteaddr,sizeof(remoteaddr));
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else
" G5 v7 W; Z- G y+ ^" s# r5 J& p. f { //資料來自遠端服務器
* u/ D$ B! m/ k: e& f7 }% X debug_showbin(thisbuf, n, "RECV REMOTE","\n");
) N# S4 E5 K( i/ J y debug_showip(&clientaddr, "Send to CLT","\n\n");
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//編寫Header * r2 g) u: z+ s6 j% z! C$ h
buf[0] = 0x0;, M* P) M7 G, W$ e) L/ R8 y7 s
buf[1] = 0x0;$ v9 \/ t8 k( |4 I
buf[2] = 0x0;
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memcpy( &buf[4], &udp_proxy_ip, 4 );
( X: [. |) X% ? G memcpy( &buf[8], &udp_proxy_port, 2 );
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//發送到客戶端
0 |& a2 k9 m0 B' Y2 x& m3 P sendto( listenfd, buf, n+10, 0, (struct sockaddr*)&clientaddr,sizeof(clientaddr));
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close(listenfd);. p- I$ {$ M2 i: |4 Y; k6 a. |0 ?
7 }5 j( D: W( |/ x1 y3 H2 u% r printf("< UDP Session - END >\n\n");+ m. W6 u/ u* Z% ]
}; `( x* K3 K( g& R' X- \
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三、測試$ ~$ S2 |1 C- R+ A
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到目前為止,整個PROXY已經完成,可以用QQ來測試一下,連接後QQ與遠端服務器之間傳輸的資料都會顯示在屏幕上,我們還可以對數據進行截留,從而把煩人的廣告全去掉 |
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