dfbb牛写的一个可对base64解码并过滤的补丁
发信人: dfbb (赵无忌☆星心相随), 信区: FreeBSD标 题: Re: 被迫搞邮件过滤，请大家支持
发信站: BBS 水木清华站 (Thu Feb 13 09:17:37 2003), 转信
Post一个我写的给Postfix的补丁,是用来匹配Base64编码过滤的
适用于postfix-1.1.11-20021115,不过最新的postfix自己改一下就
可以.这个补丁不会被Wietse Venema接受,他老人家明确反对这么干.
现在的Content Filter只能明文匹配.
------------------------BEGIN--------------------------------------
diff -urN postfix-1.1.11-20021115/src/cleanup/cleanup.h postfix-1.1.11-20021115.
--- postfix-1.1.11-20021115/src/cleanup/cleanup.h Sat Oct 26 04:26:33 2002
+++ postfix-1.1.11-20021115.new/src/cleanup/cleanup.h Fri Nov 22 02:58:47 2002
@@ -25,6 +25,7 @@
#include <mail_stream.h>
#include <mail_conf.h>
#include <mime_state.h>
+#include <base64_code.h>
/*
* These state variables are accessed by many functions, and there is only
@@ -66,6 +67,8 @@
NVTABLE *attr; /* queue file attribute list */
MIME_STATE *mime_state; /* MIME state engine */
int mime_errs; /* MIME error flags */
+ int text_seen; /* MIME text type SEEN */
+ int base64_seen; /* MIME base64 encoding SEEN */
char *filter; /* from header/body patterns */
} CLEANUP_STATE;
diff -urN postfix-1.1.11-20021115/src/cleanup/cleanup_message.c postfix-1.1.11-2
--- postfix-1.1.11-20021115/src/cleanup/cleanup_message.c Tue Oct 29 06:14:18
+++ postfix-1.1.11-20021115.new/src/cleanup/cleanup_message.c Fri Nov 22 04:22
@@ -85,6 +85,9 @@
#include "cleanup.h"
+#define STR(x) vstring_str(x)
+#define LEN(x) VSTRING_LEN(x)
+
/* cleanup_out_header - output one header as a bunch of records */
static void cleanup_out_header(CLEANUP_STATE *state, VSTRING *header_buf)
@@ -358,10 +361,19 @@
CLEANUP_STATE *state = (CLEANUP_STATE *) context;
const char *myname = "cleanup_header_callback";
char *hdrval;
+ struct type_map {
+ const char *name;
+ const char *type;
+ };
struct code_map {
const char *name;
const char *encoding;
};
+ static struct type_map type_map[] = {
+ "text/html;", MAIL_ATTR_ENC_7BIT,
+ "text/plain;", MAIL_ATTR_ENC_7BIT,
+ 0,
+ };
static struct code_map code_map[] = { /* RFC 2045 */
"7bit", MAIL_ATTR_ENC_7BIT,
"8bit", MAIL_ATTR_ENC_8BIT,
@@ -371,9 +383,16 @@
0,
};
struct code_map *cmp;
+ struct type_map *tmp;
MAPS *checks;
const char *map_class;
+ static VSTRING *src_buf= 0;
+ static VSTRING *base64_buf = 0;
+ src_buf = vstring_alloc(1024);
+ base64_buf = vstring_alloc(1024);
+
+
if (msg_verbose)
msg_info("%s: '%s'", myname, vstring_str(header_buf));
@@ -391,14 +410,28 @@
&& (CHECK(MIME_HDR_PRIMARY, cleanup_header_checks, VAR_HEADER_CHECKS)
││ CHECK(MIME_HDR_MULTIPART, cleanup_mimehdr_checks, VAR_MIMEHDR_CHECKS)
││ CHECK(MIME_HDR_NESTED, cleanup_nesthdr_checks, VAR_NESTHDR_CHECKS))) {
- char *header = vstring_str(header_buf);
+ const char *header = vstring_str(header_buf);
const char *value;
+ char *base64;
+
+ if(extract_base64_header(src_buf,header) !=0 ) {
+ base64_decode(base64_buf,STR(src_buf),LEN(src_buf));
+ base64 = vstring_str(base64_buf);
+ }else{
+ base64 = vstring_str(header_buf);
+ }
+
+
- if ((value = maps_find(checks, header, 0)) != 0) {
- if (cleanup_act(state, "header", header, value, map_class)
+ if ((value = maps_find(checks, base64, 0)) != 0) {
+ if (cleanup_act(state, "header", base64, value, map_class)
== CLEANUP_ACT_DROP)
+ vstring_free(src_buf);
+ vstring_free(base64_buf);
return;
}
+ vstring_free(src_buf);
+ vstring_free(base64_buf);
}
/*
@@ -419,14 +452,31 @@
while (ISSPACE(*hdrval))
hdrval++;
/* trimblanks(hdrval, 0)[0] = 0; */
+ if (hdr_opts->type == HDR_CONTENT_TYPE) {
+ for (tmp = type_map; tmp->name != 0; tmp++) {
+ if (strncasecmp(hdrval, tmp->name, strlen(tmp->name)) == 0) {
+
+ state->text_seen = 1;
+ break;
+ }else{
+ state->text_seen = 0;
+ }
+ }
+ }
+
if (hdr_opts->type == HDR_CONTENT_TRANSFER_ENCODING) {
for (cmp = code_map; cmp->name != 0; cmp++) {
if (strcasecmp(hdrval, cmp->name) == 0) {
+
+ if(strcasecmp(cmp->name,"base64") == 0)
+ state->base64_seen = 1;
+ else
+ state->base64_seen = 0;
if (strcmp(cmp->encoding, MAIL_ATTR_ENC_8BIT) == 0)
nvtable_update(state->attr, MAIL_ATTR_ENCODING,
cmp->encoding);
break;
- }
+ }
}
}
@@ -595,7 +645,10 @@
off_t offset)
{
CLEANUP_STATE *state = (CLEANUP_STATE *) context;
-
+ static VSTRING *src_buf = 0;
+ static VSTRING *base64_buf = 0;
+ src_buf = vstring_alloc(1024);
+ base64_buf = vstring_alloc(1024);
/*
* Crude message body content filter for emergencies. This code has
* several problems: it sees one line at a time; it looks at long lines
@@ -607,12 +660,23 @@
&& (var_body_check_len == 0 ││ offset < var_body_check_len)) {
const char *value;
- if ((value = maps_find(cleanup_body_checks, buf, 0)) != 0) {
- if (cleanup_act(state, "body", buf, value, VAR_BODY_CHECKS)
+ if(state->text_seen == 1 && state->base64_seen == 1){ /* base64 decode */
+ vstring_strcpy(src_buf,buf);
+ base64_decode(base64_buf,STR(src_buf),LEN(src_buf));
+ }else{
+ vstring_strcpy(base64_buf,buf);
+ }
+
+ if ((value = maps_find(cleanup_body_checks, STR(base64_buf), 0)) != 0) {
+ if (cleanup_act(state, "body", STR(base64_buf), value, VAR_BODY_CHECKS)
== CLEANUP_ACT_DROP)
+ vstring_free(src_buf);
+ vstring_free(base64_buf);
return;
}
}
+ vstring_free(src_buf);
+ vstring_free(base64_buf);
cleanup_out(state, type, buf, len);
}
diff -urN postfix-1.1.11-20021115/src/util/base64_code.c postfix-1.1.11-20021115
--- postfix-1.1.11-20021115/src/util/base64_code.c Tue Jan 8 08:55:04 2002
+++ postfix-1.1.11-20021115.new/src/util/base64_code.c Fri Nov 22 04:15:58 2002
@@ -145,6 +145,37 @@
return (result);
}
+VSTRING *extract_base64_header (VSTRING *result, const char *in)
+{
+ const char *o, *p, *q;
+
+ VSTRING_RESET(result);
+ q = in;
+ while ((p = strstr (q, "=?")))
+ {
+ for (q = p + 2;
+ 0x20 < *q && *q < 0x7f && !strchr ("()<>@,;:"/[]?.=", *q);
+ q++)
+ ;
+ if (q[0] != '?' ││ !strchr ("BbQq", q[1]) ││ q[2] != '?')
+ continue;
+ for (q = q + 3; 0x20 < *q && *q < 0x7f && *q != '?'; q++)
+ ;
+ if (q[0] != '?' ││ q[1] != '=')
+ {
+ --q;
+ continue;
+ }
+
+ if((o = strstr (in, "?B?"))) {
+ vstring_strncpy(result,o+3,q-o-3);
+ return result;
+ }
+ }
+
+ return(0);
+}
+
#ifdef TEST
/*
diff -urN postfix-1.1.11-20021115/src/util/base64_code.h postfix-1.1.11-20021115
--- postfix-1.1.11-20021115/src/util/base64_code.h Mon Oct 15 22:45:49 2001
+++ postfix-1.1.11-20021115.new/src/util/base64_code.h Fri Nov 22 03:33:43 2002
@@ -21,6 +21,7 @@
*/
extern VSTRING *base64_encode(VSTRING *, const char *, int);
extern VSTRING *base64_decode(VSTRING *, const char *, int);
+extern VSTRING *extract_base64_header (VSTRING *, const char *);
/* LICENSE
/* .ad
------------------------------END----------------------------------------
【 在 delphij (make universe...) 的大作中提到: 】
: 只是打算做，应该是自己的系统，我可能要写一个反病毒的模块。
: 其实不想做内容过滤，因为这东西在理论上已经证明是不可行的，
: 但如果被要求的话，有点经验也没坏处。
: 初步打算基于postfix的接口。现在正在琢磨方案，有什么建议吗？
: 我计划和入侵检测结合一下。
--
沧海一声笑
滔滔两岸潮
浮沉随浪只记今朝
来!共进一杯
让我们歌〖笑傲江湖〗到通宵!!!
※ 来源:・BBS 水木清华站 smth.edu.cn・[FROM: 210.52.3.200]
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