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ip: some fixes and tweaks

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pull/22/head
cathugger 6 years ago
parent 5169df546c
commit 05e6c31238
3 changed files with 44 additions and 26 deletions
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12
include/llarp/ip.hpp
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@ -117,37 +117,37 @@ namespace llarp
}
};
ip_header*
inline ip_header*
Header()
{
return (ip_header*)&buf[0];
}
const ip_header*
inline const ip_header*
Header() const
{
return (ip_header*)&buf[0];
}
uint32_t
inline uint32_t
src()
{
return ntohl(Header()->saddr);
}
uint32_t
inline uint32_t
dst()
{
return ntohl(Header()->daddr);
}
void
inline void
src(uint32_t ip)
{
Header()->saddr = htonl(ip);
}
void
inline void
dst(uint32_t ip)
{
Header()->daddr = htonl(ip);

1
llarp/handlers/tun.cpp
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@ -1,3 +1,4 @@
#include <algorithm>
// harmless on other platforms
#define __USE_MINGW_ANSI_STDIO 1
#include <llarp/handlers/tun.hpp>

57
llarp/ip.cpp
Unescape Escape View File

@ -8,6 +8,7 @@
#endif
#include <llarp/endian.h>
#include <map>
#include <algorithm>
namespace llarp
{
@ -57,14 +58,9 @@ namespace llarp
}
static uint16_t
deltachksum(uint16_t old_sum, uint32_t old_src_ip_n, uint32_t old_dst_ip_n,
uint32_t new_src_ip_n, uint32_t new_dst_ip_n)
deltachksum(uint16_t old_sum, uint32_t old_src_ip_h, uint32_t old_dst_ip_h,
uint32_t new_src_ip_h, uint32_t new_dst_ip_h)
{
uint32_t old_src_ip_h = htonl(old_src_ip_n);
uint32_t old_dst_ip_h = htonl(old_dst_ip_n);
uint32_t new_src_ip_h = htonl(new_src_ip_n);
uint32_t new_dst_ip_h = htonl(new_dst_ip_n);
#define ADDIPCS(x) ((uint32_t)(x & 0xFFFF) + (uint32_t)(x >> 16))
#define SUBIPCS(x) ((uint32_t)((~x) & 0xFFFF) + (uint32_t)((~x) >> 16))
@ -89,20 +85,26 @@ namespace llarp
{// TCP
6,
[](const ip_header *hdr, byte_t *pkt, size_t sz) {
auto hlen = size_t(hdr->ihl * 4);
auto hlen = size_t(hdr->ihl * 4);
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
*check = deltachksum(*check, 0, 0, hdr->saddr, hdr->daddr);
*check = deltachksum(*check, 0, 0, ntohl(hdr->saddr),
ntohl(hdr->daddr));
}},
{// UDP
17,
[](const ip_header *hdr, byte_t *pkt, size_t sz) {
auto hlen = size_t(hdr->ihl * 4);
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
if(*check != 0xFFff)
{
if(*check == 0x0000)
return; // don't change zero
*check = deltachksum(*check, 0, 0, hdr->saddr, hdr->daddr);
*check = deltachksum(*check, 0, 0, ntohl(hdr->saddr),
ntohl(hdr->daddr));
if(*check == 0x0000)
*check = 0xFFff;
}
@ -110,19 +112,23 @@ namespace llarp
{
// such checksum can mean 2 things: 0x0000 or 0xFFff
// we can only know by looking at data :<
auto hlen = size_t(hdr->ihl * 4);
if(hlen > sz)
return; // malformed, bail out
auto oldcs = *check;
*check = 0; // zero checksum before calculation
auto cs = ipchksum(pkt + hlen, sz - hlen,
ipchksum_pseudoIPv4(0, 0, 17, sz - hlen));
auto mod_cs = deltachksum(cs, 0, 0, hdr->saddr, hdr->daddr);
auto mod_cs = deltachksum(cs, 0, 0, ntohl(hdr->saddr),
ntohl(hdr->daddr));
if(cs != 0x0000 && cs != 0xFFff)
{
// packet was bad - sabotage new checksum
mod_cs += cs - *check;
mod_cs += cs - oldcs;
}
// 0x0000 is reserved for no checksum
if(mod_cs == 0x0000)
@ -139,7 +145,8 @@ namespace llarp
auto hdr = Header();
// IPv4 checksum
hdr->check = deltachksum(hdr->check, 0, 0, hdr->saddr, hdr->daddr);
hdr->check =
deltachksum(hdr->check, 0, 0, ntohl(hdr->saddr), ntohl(hdr->daddr));
// L4 checksum
auto proto = hdr->protocol;
@ -159,18 +166,23 @@ namespace llarp
auto hlen = size_t(hdr->ihl * 4);
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
*check = deltachksum(*check, hdr->saddr, hdr->daddr, 0, 0);
*check = deltachksum(*check, ntohl(hdr->saddr),
ntohl(hdr->daddr), 0, 0);
}},
{// UDP
17,
[](const ip_header *hdr, byte_t *pkt, size_t sz) {
auto hlen = size_t(hdr->ihl * 4);
uint16_t *check = (uint16_t *)(pkt + hlen + 16);
if(*check != 0xFFff)
{
if(*check == 0x0000)
return; // don't change zero
*check = deltachksum(*check, hdr->saddr, hdr->daddr, 0, 0);
*check = deltachksum(*check, ntohl(hdr->saddr),
ntohl(hdr->daddr), 0, 0);
if(*check == 0x0000)
*check = 0xFFff;
}
@ -178,20 +190,24 @@ namespace llarp
{
// such checksum can mean 2 things: 0x0000 or 0xFFff
// we can only know by looking at data :<
auto hlen = size_t(hdr->ihl * 4);
if(hlen > sz)
return; // malformed, bail out
auto oldcs = *check;
*check = 0; // zero checksum before calculation
auto cs = ipchksum(pkt + hlen, sz - hlen,
ipchksum_pseudoIPv4(hdr->saddr, hdr->daddr,
17, sz - hlen));
auto mod_cs = deltachksum(cs, hdr->saddr, hdr->daddr, 0, 0);
auto mod_cs = deltachksum(cs, ntohl(hdr->saddr),
ntohl(hdr->daddr), 0, 0);
if(cs != 0x0000 && cs != 0xFFff)
{
// packet was bad - sabotage new checksum
mod_cs += cs - *check;
mod_cs += cs - oldcs;
}
// 0x0000 is reserved for no checksum
if(mod_cs == 0x0000)
@ -215,7 +231,8 @@ namespace llarp
}
// IPv4
hdr->check = deltachksum(hdr->check, hdr->saddr, hdr->daddr, 0, 0);
hdr->check =
deltachksum(hdr->check, ntohl(hdr->saddr), ntohl(hdr->daddr), 0, 0);
}
} // namespace net
} // namespace llarp

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