mirror of
https://github.com/bol-van/zapret.git
synced 2025-04-30 02:42:58 +03:00
408 lines
12 KiB
C
408 lines
12 KiB
C
#define _GNU_SOURCE
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#include "tamper.h"
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#include "params.h"
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#include "hostlist.h"
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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 <stdio.h>
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// segment buffer has at least 5 extra bytes to extend data block
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void tamper_out(t_ctrack *ctrack, uint8_t *segment, size_t segment_buffer_size, size_t *size, size_t *split_pos, uint8_t *split_flags)
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{
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uint8_t *p, *pp, *pHost = NULL;
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size_t method_len = 0, pos;
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const char *method;
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bool bBypass = false, bHaveHost = false, bHostExcluded = false;
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char *pc, Host[256];
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DBGPRINT("tamper_out\n");
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*split_pos = 0;
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*split_flags = 0;
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if ((method = HttpMethod(segment, *size)))
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{
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method_len = strlen(method) - 2;
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VPRINT("Data block looks like HTTP request start : %s\n", method);
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if (!ctrack->l7proto)
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ctrack->l7proto = HTTP;
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// cpu saving : we search host only if and when required. we do not research host every time we need its position
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if ((params.hostlist || params.hostlist_exclude) && HttpFindHost(&pHost, segment, *size))
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{
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p = pHost + 5;
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while (p < (segment + *size) && (*p == ' ' || *p == '\t'))
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p++;
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pp = p;
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while (pp < (segment + *size) && (pp - p) < (sizeof(Host) - 1) && *pp != '\r' && *pp != '\n')
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pp++;
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memcpy(Host, p, pp - p);
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Host[pp - p] = '\0';
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bHaveHost = true;
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VPRINT("Requested Host is : %s\n", Host);
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for (pc = Host; *pc; pc++)
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*pc = tolower(*pc);
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bBypass = !HostlistCheck(Host, &bHostExcluded);
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}
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if (!bBypass)
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{
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if (params.unixeol)
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{
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p = pp = segment;
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while ((p = memmem(p, segment + *size - p, "\r\n", 2)))
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{
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*p = '\n';
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p++;
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memmove(p, p + 1, segment + *size - p - 1);
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(*size)--;
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if (pp == (p - 1))
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{
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// probably end of HTTP headers
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VPRINT("Found double EOL at pos %td. Stop replacing.\n", pp - segment);
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break;
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}
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pp = p;
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}
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pHost = NULL; // invalidate
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}
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if (params.methodeol && (*size + 1 + !params.unixeol) <= segment_buffer_size)
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{
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VPRINT("Adding EOL before method\n");
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if (params.unixeol)
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{
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memmove(segment + 1, segment, *size);
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(*size)++;
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;
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segment[0] = '\n';
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}
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else
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{
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memmove(segment + 2, segment, *size);
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*size += 2;
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segment[0] = '\r';
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segment[1] = '\n';
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}
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pHost = NULL; // invalidate
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}
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if (params.methodspace && *size < segment_buffer_size)
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{
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// we only work with data blocks looking as HTTP query, so method is at the beginning
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VPRINT("Adding extra space after method\n");
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p = segment + method_len + 1;
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pos = method_len + 1;
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memmove(p + 1, p, *size - pos);
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*p = ' '; // insert extra space
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(*size)++; // block will grow by 1 byte
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if (pHost)
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pHost++; // Host: position will move by 1 byte
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}
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if ((params.hostdot || params.hosttab) && *size < segment_buffer_size && HttpFindHost(&pHost, segment, *size))
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{
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p = pHost + 5;
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while (p < (segment + *size) && *p != '\r' && *p != '\n')
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p++;
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if (p < (segment + *size))
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{
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pos = p - segment;
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VPRINT("Adding %s to host name at pos %zu\n", params.hostdot ? "dot" : "tab", pos);
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memmove(p + 1, p, *size - pos);
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*p = params.hostdot ? '.' : '\t'; // insert dot or tab
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(*size)++; // block will grow by 1 byte
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}
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}
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if (params.domcase && HttpFindHost(&pHost, segment, *size))
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{
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p = pHost + 5;
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pos = p - segment;
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VPRINT("Mixing domain case at pos %zu\n", pos);
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for (; p < (segment + *size) && *p != '\r' && *p != '\n'; p++)
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*p = (((size_t)p) & 1) ? tolower(*p) : toupper(*p);
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}
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if (params.hostnospace && HttpFindHost(&pHost, segment, *size) && (pHost + 5) < (segment + *size) && pHost[5] == ' ')
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{
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p = pHost + 6;
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pos = p - segment;
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VPRINT("Removing space before host name at pos %zu\n", pos);
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memmove(p - 1, p, *size - pos);
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(*size)--; // block will shrink by 1 byte
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}
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if (params.hostcase && HttpFindHost(&pHost, segment, *size))
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{
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VPRINT("Changing 'Host:' => '%c%c%c%c:' at pos %td\n", params.hostspell[0], params.hostspell[1], params.hostspell[2], params.hostspell[3], pHost - segment);
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memcpy(pHost, params.hostspell, 4);
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}
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if (params.hostpad && HttpFindHost(&pHost, segment, *size))
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{
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// add : XXXXX: <padding?[\r\n|\n]
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char s[8];
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size_t hsize = params.unixeol ? 8 : 9;
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size_t hostpad = params.hostpad < hsize ? hsize : params.hostpad;
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if ((hsize + *size) > segment_buffer_size)
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VPRINT("could not add host padding : buffer too small\n");
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else
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{
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if ((hostpad + *size) > segment_buffer_size)
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{
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hostpad = segment_buffer_size - *size;
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VPRINT("host padding reduced to %zu bytes : buffer too small\n", hostpad);
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}
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else
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VPRINT("host padding with %zu bytes\n", hostpad);
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p = pHost;
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pos = p - segment;
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memmove(p + hostpad, p, *size - pos);
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(*size) += hostpad;
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while (hostpad)
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{
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#define MAX_HDR_SIZE 2048
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size_t padsize = hostpad > hsize ? hostpad - hsize : 0;
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if (padsize > MAX_HDR_SIZE)
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padsize = MAX_HDR_SIZE;
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// if next header would be too small then add extra padding to the current one
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if ((hostpad - padsize - hsize) < hsize)
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padsize += hostpad - padsize - hsize;
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snprintf(s, sizeof(s), "%c%04x: ", 'a' + rand() % ('z' - 'a' + 1), rand() & 0xFFFF);
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memcpy(p, s, 7);
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p += 7;
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memset(p, 'a' + rand() % ('z' - 'a' + 1), padsize);
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p += padsize;
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if (params.unixeol)
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*p++ = '\n';
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else
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{
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*p++ = '\r';
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*p++ = '\n';
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}
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hostpad -= hsize + padsize;
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}
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pHost = NULL; // invalidate
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}
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}
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*split_pos = HttpPos(params.split_http_req, params.split_pos, segment, *size);
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if (params.disorder_http)
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*split_flags |= SPLIT_FLAG_DISORDER;
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if (params.oob_http)
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*split_flags |= SPLIT_FLAG_OOB;
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}
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else
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{
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VPRINT("Not acting on this request\n");
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}
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}
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else if (IsTLSClientHello(segment, *size, false))
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{
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size_t tpos = 0, spos = 0;
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if (!ctrack->l7proto)
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ctrack->l7proto = TLS;
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VPRINT("packet contains TLS ClientHello\n");
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// we need host only if hostlist is present
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if ((params.hostlist || params.hostlist_exclude) && TLSHelloExtractHost((uint8_t *)segment, *size, Host, sizeof(Host), false))
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{
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VPRINT("hostname: %s\n", Host);
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bHaveHost = true;
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bBypass = !HostlistCheck(Host, &bHostExcluded);
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}
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if (bBypass)
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{
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VPRINT("Not acting on this request\n");
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}
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else
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{
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spos = TLSPos(params.split_tls, params.split_pos, segment, *size, 0);
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if ((5 + *size) <= segment_buffer_size)
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{
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tpos = TLSPos(params.tlsrec, params.tlsrec_pos + 5, segment, *size, 0);
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if (tpos > 5)
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{
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// construct 2 TLS records from one
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uint16_t l = pntoh16(segment + 3); // length
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if (l >= 2)
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{
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// length is checked in IsTLSClientHello and cannot exceed buffer size
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if ((tpos - 5) >= l)
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tpos = 5 + 1;
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VPRINT("making 2 TLS records at pos %zu\n", tpos);
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memmove(segment + tpos + 5, segment + tpos, *size - tpos);
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segment[tpos] = segment[0];
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segment[tpos + 1] = segment[1];
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segment[tpos + 2] = segment[2];
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phton16(segment + tpos + 3, l - (tpos - 5));
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phton16(segment + 3, tpos - 5);
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*size += 5;
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// split pos present and it is not before tlsrec split. increase split pos by tlsrec header size (5 bytes)
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if (spos && spos >= tpos)
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spos += 5;
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}
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}
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}
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if (spos && spos < *size)
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{
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VPRINT("split pos %zu\n", spos);
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*split_pos = spos;
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}
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if (params.disorder_tls)
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*split_flags |= SPLIT_FLAG_DISORDER;
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if (params.oob_tls)
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*split_flags |= SPLIT_FLAG_OOB;
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}
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}
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else if (params.split_any_protocol && params.split_pos < *size)
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*split_pos = params.split_pos;
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if (bHaveHost && bBypass && !bHostExcluded && *params.hostlist_auto_filename)
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{
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DBGPRINT("tamper_out put hostname : %s\n", Host);
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if (ctrack->hostname)
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free(ctrack->hostname);
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ctrack->hostname = strdup(Host);
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}
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if (params.disorder)
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*split_flags |= SPLIT_FLAG_DISORDER;
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if (params.oob)
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*split_flags |= SPLIT_FLAG_OOB;
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}
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static void auto_hostlist_reset_fail_counter(const char *hostname)
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{
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if (hostname)
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{
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hostfail_pool *fail_counter;
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fail_counter = HostFailPoolFind(params.hostlist_auto_fail_counters, hostname);
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if (fail_counter)
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{
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HostFailPoolDel(¶ms.hostlist_auto_fail_counters, fail_counter);
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VPRINT("auto hostlist : %s : fail counter reset. website is working.\n", hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : fail counter reset. website is working.", hostname);
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}
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}
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}
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static void auto_hostlist_failed(const char *hostname)
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{
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hostfail_pool *fail_counter;
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fail_counter = HostFailPoolFind(params.hostlist_auto_fail_counters, hostname);
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if (!fail_counter)
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{
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fail_counter = HostFailPoolAdd(¶ms.hostlist_auto_fail_counters, hostname, params.hostlist_auto_fail_time);
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if (!fail_counter)
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{
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DLOG_ERR("HostFailPoolAdd: out of memory\n");
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return;
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}
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}
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fail_counter->counter++;
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VPRINT("auto hostlist : %s : fail counter %d/%d\n", hostname, fail_counter->counter, params.hostlist_auto_fail_threshold);
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HOSTLIST_DEBUGLOG_APPEND("%s : fail counter %d/%d", hostname, fail_counter->counter, params.hostlist_auto_fail_threshold);
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if (fail_counter->counter >= params.hostlist_auto_fail_threshold)
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{
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VPRINT("auto hostlist : fail threshold reached. adding %s to auto hostlist\n", hostname);
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HostFailPoolDel(¶ms.hostlist_auto_fail_counters, fail_counter);
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VPRINT("auto hostlist : rechecking %s to avoid duplicates\n", hostname);
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bool bExcluded = false;
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if (!HostlistCheck(hostname, &bExcluded) && !bExcluded)
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{
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VPRINT("auto hostlist : adding %s\n", hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : adding", hostname);
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if (!StrPoolAddStr(¶ms.hostlist, hostname))
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{
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DLOG_ERR("StrPoolAddStr out of memory\n");
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return;
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}
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if (!append_to_list_file(params.hostlist_auto_filename, hostname))
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{
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DLOG_PERROR("write to auto hostlist:");
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return;
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}
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params.hostlist_auto_mod_time = file_mod_time(params.hostlist_auto_filename);
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}
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else
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{
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VPRINT("auto hostlist : NOT adding %s\n", hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : NOT adding, duplicate detected", hostname);
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}
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}
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}
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void tamper_in(t_ctrack *ctrack, uint8_t *segment, size_t segment_buffer_size, size_t *size)
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{
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bool bFail = false;
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DBGPRINT("tamper_in hostname=%s\n", ctrack->hostname);
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if (*params.hostlist_auto_filename)
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{
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HostFailPoolPurgeRateLimited(¶ms.hostlist_auto_fail_counters);
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if (ctrack->l7proto == HTTP && ctrack->hostname)
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{
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if (IsHttpReply(segment, *size))
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{
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VPRINT("incoming HTTP reply detected for hostname %s\n", ctrack->hostname);
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bFail = HttpReplyLooksLikeDPIRedirect(segment, *size, ctrack->hostname);
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if (bFail)
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{
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VPRINT("redirect to another domain detected. possibly DPI redirect.\n");
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HOSTLIST_DEBUGLOG_APPEND("%s : redirect to another domain", ctrack->hostname);
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}
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else
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VPRINT("local or in-domain redirect detected. it's not a DPI redirect.\n");
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}
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else
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{
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// received not HTTP reply. do not monitor this connection anymore
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VPRINT("incoming unknown HTTP data detected for hostname %s\n", ctrack->hostname);
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}
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if (bFail)
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auto_hostlist_failed(ctrack->hostname);
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}
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if (!bFail)
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auto_hostlist_reset_fail_counter(ctrack->hostname);
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}
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ctrack->bTamperInCutoff = true;
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}
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void rst_in(t_ctrack *ctrack)
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{
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DBGPRINT("rst_in hostname=%s\n", ctrack->hostname);
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if (!*params.hostlist_auto_filename)
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return;
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HostFailPoolPurgeRateLimited(¶ms.hostlist_auto_fail_counters);
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if (!ctrack->bTamperInCutoff && ctrack->hostname)
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{
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VPRINT("incoming RST detected for hostname %s\n", ctrack->hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : incoming RST", ctrack->hostname);
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auto_hostlist_failed(ctrack->hostname);
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}
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}
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void hup_out(t_ctrack *ctrack)
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{
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DBGPRINT("hup_out hostname=%s\n", ctrack->hostname);
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if (!*params.hostlist_auto_filename)
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return;
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HostFailPoolPurgeRateLimited(¶ms.hostlist_auto_fail_counters);
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if (!ctrack->bTamperInCutoff && ctrack->hostname)
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{
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// local leg dropped connection after first request. probably due to timeout.
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VPRINT("local leg closed connection after first request (timeout ?). hostname: %s\n", ctrack->hostname);
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HOSTLIST_DEBUGLOG_APPEND("%s : client closed connection without server reply", ctrack->hostname);
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auto_hostlist_failed(ctrack->hostname);
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}
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}
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