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feature: add GRE utils, support overwrite checksum of GTPv0/GTPv1 header

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This commit is contained in:
luwenpeng
2024-07-11 14:26:19 +08:00
parent 6d552acfd0
commit 9e338ffccb
8 changed files with 971 additions and 296 deletions
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222
src/packet/gre1_utils.h Normal file
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#pragma once
#ifdef __cplusplus
extern "C"
{
#endif
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include "eth_utils.h"
/*
* Enhanced GRE header (Version 1)
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |C|R|K|S|s|Recur|A| Flags | Ver | Protocol Type |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Key (HW) Payload Length | Key (LW) Call ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Sequence Number (Optional) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Acknowledgment Number (Optional) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* https://datatracker.ietf.org/doc/html/rfc2637
*/
struct gre1_hdr
{
uint16_t flags;
uint16_t protocol;
uint16_t payload_length;
uint16_t call_id;
};
#define GRE1_FLAG_CHECKSUM 0x8000
#define GRE1_FLAG_ROUTING 0x4000
#define GRE1_FLAG_KEY 0x2000
#define GRE1_FLAG_SEQUENCE 0x1000
#define GRE1_FLAG_STRICT 0x0800
#define GRE1_FLAG_RECURSION 0x0700
#define GRE1_FLAG_ACK 0x0080 /* only in special PPTPized GRE header */
#define GRE1_FLAG_VERSION 0x0007
/******************************************************************************
* get
******************************************************************************/
static inline uint16_t gre1_hdr_get_flags(const struct gre1_hdr *hdr)
{
return ntohs(hdr->flags);
}
static inline uint8_t gre1_hdr_get_seq_flag(const struct gre1_hdr *hdr)
{
return (ntohs(hdr->flags) & GRE1_FLAG_SEQUENCE) >> 12;
}
static inline uint8_t gre1_hdr_get_ack_flag(const struct gre1_hdr *hdr)
{
return (ntohs(hdr->flags) & GRE1_FLAG_ACK) >> 7;
}
static inline uint8_t gre1_hdr_get_version(const struct gre1_hdr *hdr)
{
return ntohs(hdr->flags) & GRE1_FLAG_VERSION;
}
// ethernet protocol type
static inline uint16_t gre1_hdr_get_proto(const struct gre1_hdr *hdr)
{
return ntohs(hdr->protocol);
}
static inline uint16_t gre1_hdr_get_payload_length(const struct gre1_hdr *hdr)
{
return ntohs(hdr->payload_length);
}
static inline uint16_t gre1_hdr_get_call_id(const struct gre1_hdr *hdr)
{
return ntohs(hdr->call_id);
}
static inline uint32_t gre1_hdr_get_seq(const struct gre1_hdr *hdr)
{
if (gre1_hdr_get_seq_flag(hdr))
{
const char *ptr = ((const char *)hdr) + 8;
return ntohl(*((uint32_t *)ptr));
}
else
{
return 0;
}
}
static inline uint32_t gre1_hdr_get_ack(const struct gre1_hdr *hdr)
{
if (gre1_hdr_get_ack_flag(hdr))
{
const char *ptr = ((const char *)hdr) + 8;
if (gre1_hdr_get_seq_flag(hdr))
{
ptr += 4;
}
return ntohl(*((uint32_t *)ptr));
}
else
{
return 0;
}
}
static inline uint16_t calc_gre1_hdr_len(const char *data, uint32_t len)
{
const struct gre1_hdr *hdr = (const struct gre1_hdr *)data;
uint16_t hdr_len = 8;
uint16_t flags = gre1_hdr_get_flags(hdr);
if (flags & GRE1_FLAG_SEQUENCE)
{
hdr_len += 4;
}
if (flags & GRE1_FLAG_ACK)
{
hdr_len += 4;
}
return hdr_len;
}
/******************************************************************************
* set
******************************************************************************/
static inline void gre1_hdr_set_flags(struct gre1_hdr *hdr, uint16_t flags)
{
hdr->flags = htons(flags);
}
static inline void gre1_hdr_set_seq_flag(struct gre1_hdr *hdr, uint8_t seq_flag)
{
hdr->flags = htons((ntohs(hdr->flags) & ~GRE1_FLAG_SEQUENCE) | seq_flag << 12);
}
static inline void gre1_hdr_set_ack_flag(struct gre1_hdr *hdr, uint8_t ack_flag)
{
hdr->flags = htons((ntohs(hdr->flags) & ~GRE1_FLAG_ACK) | ack_flag << 7);
}
static inline void gre1_hdr_set_version(struct gre1_hdr *hdr, uint8_t version)
{
hdr->flags = htons((ntohs(hdr->flags) & ~GRE1_FLAG_VERSION) | version);
}
static inline void gre1_hdr_set_proto(struct gre1_hdr *hdr, uint16_t proto)
{
hdr->protocol = htons(proto);
}
static inline void gre1_hdr_set_payload_length(struct gre1_hdr *hdr, uint16_t payload_length)
{
hdr->payload_length = htons(payload_length);
}
static inline void gre1_hdr_set_call_id(struct gre1_hdr *hdr, uint16_t call_id)
{
hdr->call_id = htons(call_id);
}
static inline void gre1_hdr_set_seq(struct gre1_hdr *hdr, uint32_t seq)
{
if (gre1_hdr_get_seq_flag(hdr))
{
char *ptr = ((char *)hdr) + 8;
*((uint32_t *)ptr) = htonl(seq);
}
}
static inline void gre1_hdr_set_ack(struct gre1_hdr *hdr, uint32_t ack)
{
if (gre1_hdr_get_ack_flag(hdr))
{
char *ptr = ((char *)hdr) + 8;
if (gre1_hdr_get_seq_flag(hdr))
{
ptr += 4;
}
*((uint32_t *)ptr) = htonl(ack);
}
}
/******************************************************************************
* print
******************************************************************************/
static inline int gre1_hdr_to_str(const struct gre1_hdr *hdr, char *buf, size_t size)
{
memset(buf, 0, size);
int used = 0;
uint16_t proto = gre1_hdr_get_proto(hdr);
used += snprintf(buf + used, size - used, "GRE: flags=0x%04x (seq_flag=%u ack_flag=%u version=%u), proto=%s, payload_length=%u, call_id=%u",
gre1_hdr_get_flags(hdr), gre1_hdr_get_seq_flag(hdr), gre1_hdr_get_ack_flag(hdr), gre1_hdr_get_version(hdr),
eth_proto_to_str(proto), gre1_hdr_get_payload_length(hdr), gre1_hdr_get_call_id(hdr));
if (gre1_hdr_get_seq_flag(hdr))
{
used += snprintf(buf + used, size - used, ", seq=%u", gre1_hdr_get_seq(hdr));
}
if (gre1_hdr_get_ack_flag(hdr))
{
used += snprintf(buf + used, size - used, ", ack=%u", gre1_hdr_get_ack(hdr));
}
return used;
}
#ifdef __cplusplus
}
#endif