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ref/c: segwit_decode_addr_details: capture details and return #57

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ref/c: segwit_decode_addr_details: capture details and return #57

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39db24a
ref/c: segwit_decode_addr_details: capture details and return
switck Feb 3, 2021
10d38fb
Restore encoding vs. version checks
switck Feb 5, 2021
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31 changes: 27 additions & 4 deletions ref/c/segwit_addr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -189,21 +189,44 @@ int segwit_addr_encode(char *output, const char *hrp, int witver, const uint8_t
return bech32_encode(output, hrp, data, datalen, enc);
}

int segwit_addr_decode(int* witver, uint8_t* witdata, size_t* witdata_len, const char* hrp, const char* addr) {
int segwit_addr_decode_detailed(int* witver, uint8_t* witdata, size_t* witdata_len,
char *hrp_out, bech32_encoding* enc_out, const char* addr)
{
uint8_t data[84];
char hrp_actual[84];
size_t data_len;

bech32_encoding enc = bech32_decode(hrp_actual, data, &data_len, addr);
if (enc == BECH32_ENCODING_NONE) return 0;
if (data_len == 0 || data_len > 65) return 0;
if (strncmp(hrp, hrp_actual, 84) != 0) return 0;
if (data[0] > 16) return 0;
if (data[0] == 0 && enc != BECH32_ENCODING_BECH32) return 0;
if (data[0] > 0 && enc != BECH32_ENCODING_BECH32M) return 0;

*witdata_len = 0;
if (!convert_bits(witdata, witdata_len, 8, data + 1, data_len - 1, 5, 0)) return 0;
if (*witdata_len < 2 || *witdata_len > 40) return 0;
if (data[0] == 0 && *witdata_len != 20 && *witdata_len != 32) return 0;

*witver = data[0];

if(hrp_out) {
strncpy(hrp_out, hrp_actual, 20);
}
if(enc_out) *enc_out = enc;
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@sipa sipa Feb 3, 2021 •
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I don't like this. I cannot imagine a case where a caller is interested in valid or not, without caring if it's bech32 or bech32m. Validity is defined w.r.t. a specific standard.

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I can make the enc_out argument required


return 1;
}

int segwit_addr_decode(int* witver, uint8_t* witdata, size_t* witdata_len, const char* hrp, const char* addr) {

char hrp_actual[84];
bech32_encoding enc;

int ok = segwit_addr_decode_detailed(witver, witdata, witdata_len, hrp_actual, &enc, addr);
if (!ok) return 0;

if (strncmp(hrp, hrp_actual, 84) != 0) return 0;
if ((*witver) == 0 && enc != BECH32_ENCODING_BECH32) return 0;
if ((*witver) > 0 && enc != BECH32_ENCODING_BECH32M) return 0;

return 1;
}
35 changes: 29 additions & 6 deletions ref/c/segwit_addr.h
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Expand Up @@ -24,6 +24,13 @@

#include <stdint.h>

/** Supported encodings. */
typedef enum {
BECH32_ENCODING_NONE,
BECH32_ENCODING_BECH32,
BECH32_ENCODING_BECH32M
} bech32_encoding;


/** Encode a SegWit address
*
Expand Down Expand Up @@ -65,12 +72,28 @@ int segwit_addr_decode(
const char* addr
);

/** Supported encodings. */
typedef enum {
BECH32_ENCODING_NONE,
BECH32_ENCODING_BECH32,
BECH32_ENCODING_BECH32M
} bech32_encoding;

/** Decode a SegWit address, capturing details.
*
* Out: ver: Pointer to an int that will be updated to contain the witness
* program version (between 0 and 16 inclusive).
* prog: Pointer to a buffer of size 40 that will be updated to
* contain the witness program bytes.
* prog_len: Pointer to a size_t that will be updated to contain the length
* of bytes in prog.
* hrp_out: Pointer to char[10] to hold observed HRP value, or NULL if not wanted.
* encoding: Pointer to return observed bech32 encoding (or NULL, unused)
* addr: Pointer to the null-terminated address.
* Returns 1 if successful.
*/
int segwit_addr_decode_detailed(
int* ver,
uint8_t* prog,
size_t* prog_len,
char *hrp_out,
bech32_encoding* encoding,
const char* addr
);

/** Encode a Bech32 or Bech32m string
*
Expand Down