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Move ICMP parsing code in src/ip.h

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Signed-off-by: Adrien Gallouët <adrien@gallouet.fr>
This commit is contained in:
Adrien Gallouët
2017-12-17 16:03:00 +00:00
parent 8f35528fde
commit 3b787a2043
2 changed files with 44 additions and 13 deletions
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40
src/ip.h
View File

@@ -19,6 +19,42 @@ ip_get_version(const uint8_t *data, size_t size)
return data[0] >> 4; return data[0] >> 4;
} }
static inline uint32_t
ip_read32(const uint8_t *src)
{
uint32_t ret = src[3];
ret |= ((uint32_t)src[2]) << 8;
ret |= ((uint32_t)src[1]) << 16;
ret |= ((uint32_t)src[0]) << 24;
return ret;
}
static inline uint16_t
ip_read16(const uint8_t *src)
{
uint16_t ret = src[1];
ret |= ((uint16_t)src[0]) << 8;
return ret;
}
static inline int
ip_get_mtu(struct ip_common *ic, const uint8_t *data, size_t size)
{
if (ic->hdr_size <= 0 || ic->hdr_size + 8 > size)
return -1;
const uint8_t *p = &data[ic->hdr_size];
if (ic->version == 4 && ic->proto == 1 && p[0] == 3)
return ip_read16(&p[6]);
// not tested..
// if (ic->version == 6 && ic->proto == 58 && p[0] == 2)
// return ip_read32(&p[4]);
return -1;
}
static inline int static inline int
ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size) ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size)
{ {
@@ -29,7 +65,7 @@ ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size)
ic->tc = data[1]; ic->tc = data[1];
ic->proto = data[9]; ic->proto = data[9];
ic->hdr_size = (data[0] & 0xF) << 2; ic->hdr_size = (data[0] & 0xF) << 2;
ic->size = ((data[2] << 8) | data[3]); ic->size = ip_read16(&data[2]);
if (ic->size >= 20) if (ic->size >= 20)
return 0; return 0;
break; break;
@@ -37,7 +73,7 @@ ip_get_common(struct ip_common *ic, const uint8_t *data, size_t size)
ic->tc = ((data[0] & 0xF) << 4) | (data[1] >> 4); ic->tc = ((data[0] & 0xF) << 4) | (data[1] >> 4);
ic->proto = data[6]; ic->proto = data[6];
ic->hdr_size = 40; ic->hdr_size = 40;
ic->size = ((data[4] << 8) | data[5]) + 40; ic->size = ip_read16(&data[4]) + 40;
return 0; return 0;
} }

17
src/main.c
View File

@@ -411,17 +411,12 @@ main(int argc, char **argv)
socklen_t sl = sizeof(ss); socklen_t sl = sizeof(ss);
ssize_t r = recvfrom(icmp_fd, gt.buf.data, gt.buf.size, 0, ssize_t r = recvfrom(icmp_fd, gt.buf.data, gt.buf.size, 0,
(struct sockaddr *)&ss, &sl); (struct sockaddr *)&ss, &sl);
if (r >= 8) { struct ip_common ic;
struct ip_common ic; if (!ip_get_common(&ic, gt.buf.data, r)) {
if (!ip_get_common(&ic, gt.buf.data, r) && ic.proto == 1) { int mtu = ip_get_mtu(&ic, gt.buf.data, r);
unsigned char *data = &gt.buf.data[ic.hdr_size]; if (mtu > 0) {
if (data[0] == 3) { gt_log("received MTU from ICMP: %i\n", mtu);
int mtu = (data[6] << 8) | data[7]; mud_set_mtu(mud, GT_MTU(mtu));
if (mtu) {
gt_log("received MTU from ICMP: %i\n", mtu);
mud_set_mtu(mud, GT_MTU(mtu));
}
}
} }
} }
} }