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作者: 趙氏軟體(http://chiosoft.51.net)
: j) G7 ~- I! `8 n7 `# ^E-mail: chiosoft@163.net
+ M7 I' t1 @2 V* k※轉貼請注明出處※
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; }' g' \- ?7 s4 R0 |本文以QQ為對像,教你如何寫一個SOCKS5 PROXY
. S/ @2 B) {# H; q; |# R9 p本章主要介紹Launch_UDP()的工作原理
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; h; M, r9 W# G+ p1 L4 b O一、SOCKS5 UDP封包結構) v; {7 K! |: p* L& @3 H. O
===========================& w3 n. H1 N# h
順序為:
, {* ?: v0 ?8 k2 Bytes 保留字,一定要為0x0
+ K: k3 t% o- q6 Z- [) A) w+ v1 Bytes Current fragment number
+ h2 R; g1 |: J$ ~7 i; U. f8 w1 Bytes 地址類型
) ]; T; p1 ~3 E2 M; jX Bytes 目的地地址; R! g8 a# P* V' A5 f$ i/ M( I
2 Bytes 目的地端口號7 l0 U' v# V4 ]4 X& X" `
N Bytes 數據& A/ b. p4 X0 r# E( K3 w3 |
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二、源代碼% n6 }' y/ w2 J5 d+ x
===========================
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8 D2 m" _, W2 j0 |( Bvoid Launch_UDP( int udp_proxy_port, const char *udp_proxy_ip, int clt_udp_port ) q: u. e, \) s" k
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//port is NOT network orders
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//記錄本機,客戶端,遠端服務器和封包來源地址8 ^7 J/ y/ N8 Q( d
struct sockaddr_in servaddr,clientaddr,remoteaddr,inaddr;; |# f# o' _) c8 H1 f
int inlen;' k2 `, o9 _5 z! H
int listenfd;
+ z" L# C* B. |8 O. k0 B int n;6 i5 V8 J9 i/ G8 a" o& V
fd_set set;
+ ?8 f& c( B3 ? //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Header% w* ?3 H. {$ q: T6 O v$ R
char *thisbuf = &buf[10];
5 D, u0 u# @5 G* p" k, n5 h int thissize = BUFSZ - 10;( ]" R' H' A- g+ W* \
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printf("< UDP Session - START >\n\n");' C5 F$ A% k4 |- K, j8 L, }
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//建立一個UDP SOCKET,注意UDP協議不需要listen, accept和conenct: C/ [. g. P V& Z$ o8 ?
memset(&servaddr, 0, sizeof(servaddr));
' n' ~6 ^5 O: Q; ~5 Z servaddr.sin_family = AF_INET;
8 B8 b2 x1 D2 i% ?5 t- | servaddr.sin_port = htons( udp_proxy_port );
% o. r* l9 y* P7 ^ servaddr.sin_addr.s_addr = htonl( INADDR_ANY );" g+ p& s7 R+ p5 B/ J
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memset(&remoteaddr, 0, sizeof(remoteaddr));
9 X5 w7 F# ]/ u remoteaddr.sin_family = AF_INET;- A$ ?! N1 T- J2 W. ~* M
2 k8 T0 X) t: |, ]1 g. K$ ~) @- R listenfd = socket(AF_INET, SOCK_DGRAM, 0);
) O! O1 ?$ ^0 \ if(listenfd < 0) {7 l, n, n" {* I3 i& Z& I
p_error("socket error");
& \( X3 D/ }# \' a0 P) G exit(-1);, q( n& m! @2 U$ w( o" ?! n' k% A
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if( bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ) {
. }3 r3 w" b0 h; z. Z; o p_error("bind error");
. E$ s2 |7 p. u, ?7 ^) O. n1 x exit(-1);& [; t: E1 W/ e: _- V7 N7 h
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//使用select來監控Socket是否有資料可讀& @$ l& A6 Z; {: h& z
FD_ZERO(&set);4 p# J: `+ b/ E0 Y- z, i: w
FD_SET(listenfd, &set);5 E/ d6 |7 P+ q$ }
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while( 1 ) {' Z4 H! X9 T- I# C- m- i% t
# V6 g& B* t; W. k6 y, _ if( select( listenfd+1, &set, NULL, NULL, NULL) < 0 ) {
* O9 J$ E! K4 q p_error("select error");
3 J8 c6 ]! M% O+ S exit(-1);* P* A* i. f6 f7 m
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if( FD_ISSET( listenfd, &set ) ) {; l( ~ D/ H! e! M2 |
//UDP協議可使用recvfrom()來接收數據,並獲得來源地地址; _& F3 w7 j- o. @* e; D
n = recvfrom( listenfd, thisbuf, thissize, 0, (struct sockaddr *)&inaddr, &inlen );+ ?" }2 f" }! y. ]4 ]
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if( n >=0 ) {3 @ ]0 Y# Y" a- e
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debug_showip( &inaddr, "Received From", "\n" );$ b' c, }! v3 X* {4 Q
5 L' N6 K; Q6 x+ m: z2 { //資料來自客戶端
9 {9 y1 t! c8 U5 o% F* } if( (thisbuf[0]==0x0) && (thisbuf[1]==0x0) && $ A9 p. y! s5 u
(htons(inaddr.sin_port)==clt_udp_port) )# P% n; H r6 w3 V% M2 I
{
! C$ A, Y% L3 z. [ //保存客戶端的地址) E" z; s9 W: J& ~
memcpy( &clientaddr, &inaddr, sizeof(clientaddr) );
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: ~" ~+ j+ n$ l) h if( thisbuf[3] != 0x1 ) {1 \! f) q* j a
//如果目的地地址類型為域名,先進行解析獲得IP再發送
' s- `2 P9 M- D6 n4 o" Y: C- h( t struct hostent *h;
( q+ {+ h) E6 J char tmp[256];% Z; b9 t7 m2 M' _5 r2 y
int seg;
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7 k6 [2 ]. u5 q: W( ~ strncpy( tmp, &thisbuf[5], thisbuf[4] );
) o( Z! g* J' w tmp[ thisbuf[4] ] = 0;" i) p, ~! s, s! F$ a
2 h# c% x. n6 f% q1 h h = gethostbyname ( tmp ); //<netdb.h>
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if( h == NULL ): f B- i- v* z
p_error("unknown domain name\n");
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remoteaddr.sin_addr.s_addr = (*(struct in_addr*)h->h_addr).s_addr;& r# o% A) c+ L* D
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seg = thisbuf[4]+1;
5 J* d6 t" J+ ~3 G memcpy( &remoteaddr.sin_port, &thisbuf[4+seg], 2 );: n4 j# ?9 H) h9 l8 S
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debug_showbin( thisbuf, 4+seg+2, "RECV CLIENT [ Header ]","\n");
`/ E; e0 v( c1 l debug_showbin( &thisbuf[4+seg+2], n-(4+seg+2), "RECV CLIENT [ Data ]","\n");
. Y8 S2 G- |( T: {. y4 } 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));2 @9 w8 W# d; ^- U7 E1 J, \
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} else {
6 q3 A' A; F3 D. p; e //目的地地址為IPv4,直接把資料發送過去
1 r& X, |: Y+ j/ T; H7 U! q memcpy( &remoteaddr.sin_port, &thisbuf[8], 2 );
8 T! u; H7 p( @. p" H memcpy( &remoteaddr.sin_addr.s_addr, &thisbuf[4], 4 );+ e; I0 v2 X4 ]+ e5 r
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debug_showbin( thisbuf, 10, "RECV CLIENT [ Header ]","\n");& C0 {* J: k( T% n% {; N
debug_showbin( &thisbuf[10], n-10, "RECV CLIENT [ Data ]","\n");# t2 ~/ G4 l- @" {6 a! u
debug_showip( &remoteaddr, "Send to IP", "\n\n");
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sendto( listenfd, &thisbuf[10], n-10, 0, (struct sockaddr*)&remoteaddr,sizeof(remoteaddr));1 |4 ]3 l3 I, K% E. s% \; O
}
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else
8 D' P. i$ G* P" D% j+ Y { //資料來自遠端服務器
/ d+ e* I3 r0 k% j8 i! ^4 d+ q9 W debug_showbin(thisbuf, n, "RECV REMOTE","\n");
: O2 P( a$ C1 G; y debug_showip(&clientaddr, "Send to CLT","\n\n");* c: C0 C' ^5 L2 e
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//編寫Header
0 w; |( F& L8 q0 w% x7 D buf[0] = 0x0;
3 A& O. `7 e l. K buf[1] = 0x0;: t$ g" `! z5 x3 y
buf[2] = 0x0;
9 K8 K- k3 }; Q# A2 f buf[3] = 0x1;
. F9 C. d* x5 L, U- J" l memcpy( &buf[4], &udp_proxy_ip, 4 );
1 B, S3 q/ c4 z; H5 y3 W memcpy( &buf[8], &udp_proxy_port, 2 );
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3 u: {0 C, n! ^; J //發送到客戶端" l0 w; D& S4 ^9 A6 `2 [3 O
sendto( listenfd, buf, n+10, 0, (struct sockaddr*)&clientaddr,sizeof(clientaddr));
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( a6 h, z; N$ [ close(listenfd);
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printf("< UDP Session - END >\n\n");
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三、測試
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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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