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const buffer for the pp2_parse_hdr func #25

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Merged
kosmas-valianos merged 1 commit into from
Mar 11, 2026
Merged

const buffer for the pp2_parse_hdr func #25

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55 changes: 35 additions & 20 deletions src/proxy_protocol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -583,14 +583,18 @@ static uint32_t crctable[256] = {
0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
};

static uint32_t crc32c(const uint8_t* buf, uint32_t len)
static uint32_t crc32c_continue(uint32_t crc, const uint8_t* buf, uint32_t len)
{
uint32_t crc = 0xffffffff;
while (len-- > 0)
{
crc = (crc >> 8) ^ crctable[(crc ^ (*buf++)) & 0xFF];
}
return crc ^ 0xffffffff;
return crc;
}

static uint32_t crc32c(const uint8_t* buf, uint32_t len)
{
return crc32c_continue(0xffffffff, buf, len) ^ 0xffffffff;
}

static uint8_t *pp2_create_hdr(const pp_info_t *pp_info, uint16_t *pp2_hdr_len, int32_t *error)
Expand Down Expand Up @@ -844,13 +848,13 @@ uint8_t *pp_create_hdr(uint8_t version, const pp_info_t *pp_info, uint16_t *pp_h
}

/* Verifies and parses a version 2 PROXY protocol header */
static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info)
static int32_t pp2_parse_hdr(const uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info)
{
const uint8_t *pp2_hdr = buffer;
const proxy_hdr_v2_t *proxy_hdr_v2 = (proxy_hdr_v2_t*) buffer;
const proxy_hdr_v2_t *proxy_hdr_v2 = (const proxy_hdr_v2_t*) buffer;
uint8_t cmd, fam;
uint16_t len = 0, tlv_vectors_len = 0;
proxy_addr_t *addr = NULL;
const proxy_addr_t *addr = NULL;

/* The next byte (the 13th one) is the protocol version and command */
/* The highest four bits contains the version. Only \x2 is accepted */
Expand Down Expand Up @@ -924,7 +928,7 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
* - destination layer 4 address if any, in network byte order (port)
*/
buffer += sizeof(proxy_hdr_v2_t);
addr = (proxy_addr_t*) buffer;
addr = (const proxy_addr_t*) buffer;
if (fam == AF_UNSPEC)
{
tlv_vectors_len = len;
Expand Down Expand Up @@ -977,7 +981,7 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
/* Any TLV vector must be at least 3 bytes */
while (tlv_vectors_len > sizeof_pp2_tlv_t)
{
pp2_tlv_t *pp2_tlv = (pp2_tlv_t*) buffer;
const pp2_tlv_t *pp2_tlv = (const pp2_tlv_t*) buffer;
uint16_t pp2_tlv_len = pp2_tlv->length_hi << 8 | pp2_tlv->length_lo;
uint16_t pp2_tlv_offset = sizeof_pp2_tlv_t + pp2_tlv_len;
if (pp2_tlv_offset > tlv_vectors_len)
Expand All @@ -996,7 +1000,9 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
break;
case PP2_TYPE_CRC32C: /* 32-bit number */
{
uint32_t crc32c_chksum, crc32c_calculated;
uint32_t crc32c_chksum, crc32c_calculated, crc;
const uint8_t zeros[4] = {0, 0, 0, 0};
uint32_t total_hdr_len, offset_to_chksum_value, after_chksum_offset;

if (pp2_tlv_len != sizeof(uint32_t))
{
Expand All @@ -1006,11 +1012,20 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
/* Received CRC32c checksum */
memcpy(&crc32c_chksum, pp2_tlv->value, pp2_tlv_len);

/* Calculate the CRC32c checksum value of the whole PROXY header */
memset(pp2_tlv->value, 0, pp2_tlv_len);
crc32c_calculated = crc32c(pp2_hdr, sizeof(proxy_hdr_v2_t) + len);
/* Calculate the CRC32c checksum value of the whole PROXY header.
* The checksum is computed with the checksum field treated as zeros.
* Instead of zeroing the field in the buffer, compute CRC in 3 segments:
* before the checksum value, 4 zero bytes, after the checksum value. */
total_hdr_len = sizeof(proxy_hdr_v2_t) + len;
offset_to_chksum_value = (const uint8_t*)pp2_tlv->value - pp2_hdr;
after_chksum_offset = offset_to_chksum_value + sizeof(uint32_t);

crc = crc32c_continue(0xffffffff, pp2_hdr, offset_to_chksum_value);
crc = crc32c_continue(crc, zeros, sizeof(uint32_t));
crc = crc32c_continue(crc, pp2_hdr + after_chksum_offset, total_hdr_len - after_chksum_offset);
crc32c_calculated = crc ^ 0xffffffff;

/* Verify that the calculated CRC32c checksum is the same as the received CRC32c checksum*/
/* Verify that the calculated CRC32c checksum is the same as the received CRC32c checksum */
if (memcmp(&crc32c_chksum, &crc32c_calculated, 4))
{
return -ERR_PP2_TYPE_CRC32C;
Expand All @@ -1037,7 +1052,7 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
break;
case PP2_TYPE_SSL:
{
pp2_tlv_ssl_t *pp2_tlv_ssl = (pp2_tlv_ssl_t*) pp2_tlv->value;
const pp2_tlv_ssl_t *pp2_tlv_ssl = (const pp2_tlv_ssl_t*) pp2_tlv->value;
uint16_t pp2_tlvs_ssl_len = 0, pp2_sub_tlv_offset = 0;
uint8_t tlv_ssl_version_found = 0;

Expand All @@ -1050,7 +1065,7 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
pp2_tlvs_ssl_len = pp2_tlv_len - sizeof(pp2_tlv_ssl->client) - sizeof(pp2_tlv_ssl->verify);
while (pp2_sub_tlv_offset < pp2_tlvs_ssl_len)
{
pp2_tlv_t *pp2_sub_tlv_ssl = (pp2_tlv_t*) ((uint8_t*) pp2_tlv_ssl->sub_tlv + pp2_sub_tlv_offset);
const pp2_tlv_t *pp2_sub_tlv_ssl = (const pp2_tlv_t*) ((const uint8_t*) pp2_tlv_ssl->sub_tlv + pp2_sub_tlv_offset);
uint16_t pp2_sub_tlv_ssl_len = pp2_sub_tlv_ssl->length_hi << 8 | pp2_sub_tlv_ssl->length_lo;
switch (pp2_sub_tlv_ssl->type)
{
Expand Down Expand Up @@ -1090,12 +1105,12 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
break;
case PP2_TYPE_AWS:
{
pp2_tlv_aws_t *pp2_tlv_aws;
const pp2_tlv_aws_t *pp2_tlv_aws;
if (pp2_tlv_len < sizeof(pp2_tlv_aws_t))
{
return -ERR_PP2_TYPE_AWS;
}
pp2_tlv_aws = (pp2_tlv_aws_t*) pp2_tlv->value;
pp2_tlv_aws = (const pp2_tlv_aws_t*) pp2_tlv->value;
/* Connection is done through Private Link/Interface VPC endpoint */
if (pp2_tlv_aws->type == PP2_SUBTYPE_AWS_VPCE_ID) /* US-ASCII */
{
Expand All @@ -1109,12 +1124,12 @@ static int32_t pp2_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t
}
case PP2_TYPE_AZURE:
{
pp2_tlv_azure_t *pp2_tlv_azure;
const pp2_tlv_azure_t *pp2_tlv_azure;
if (pp2_tlv_len < sizeof(pp2_tlv_azure_t))
{
return -ERR_PP2_TYPE_AZURE;
}
pp2_tlv_azure = (pp2_tlv_azure_t*) pp2_tlv->value;
pp2_tlv_azure = (const pp2_tlv_azure_t*) pp2_tlv->value;
/* Connection is done through Private Link service */
if (pp2_tlv_azure->type == PP2_SUBTYPE_AZURE_PRIVATEENDPOINT_LINKID) /* 32-bit number */
{
Expand Down Expand Up @@ -1309,7 +1324,7 @@ static int32_t pp1_parse_hdr(const uint8_t *buffer, uint32_t buffer_length, pp_i
return pp1_hdr_len;
}

int32_t pp_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info)
int32_t pp_parse_hdr(const uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info)
{
memset(pp_info, 0, sizeof(*pp_info));
if (buffer_length >= 16 && !memcmp(buffer, PP2_SIG, 12))
Expand Down
2 changes: 1 addition & 1 deletion src/proxy_protocol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,6 @@ uint8_t *pp_create_hdr(uint8_t version, const pp_info_t *pp_info, uint16_t *pp_h
* == 0 No PROXY protocol header found
* < 0 Error occurred. Optionally, pp_strerror() with that value can be used to get a descriptive message
*/
int32_t pp_parse_hdr(uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info);
int32_t pp_parse_hdr(const uint8_t *buffer, uint32_t buffer_length, pp_info_t *pp_info);

#endif
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