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Add support for displaying extra data trailing calldata in ERC20 calls #852

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588b4d8
Add support for displaying extra data trailing calldata in ERC20 calls
lcastillo-ledger Aug 29, 2025
3b88556
Apply linter patch
lcastillo-ledger Aug 29, 2025
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19 changes: 19 additions & 0 deletions src/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -47,3 +47,22 @@ bool check_name(const uint8_t *name, uint16_t len) {
}
return true;
}

/**
* @brief Checks if a string contains only displayable ASCII characters.
*
* This function determines if all characters in the provided string are within the
* range of displayable ASCII characters (from 0x20 to 0x7E).
*
* @param str A pointer to the string to be checked.
* @param len The length of the string to be checked.
*/

bool is_displayable_ascii(const char *str, size_t len) {
for (size_t i = 0; i < len; i++) {
if (str[i] < 0x20 || str[i] > 0x7E) {
return false;
}
}
return true;
}
1 change: 1 addition & 0 deletions src/utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,3 +8,4 @@
void buf_shrink_expand(const uint8_t *src, size_t src_size, uint8_t *dst, size_t dst_size);
void str_cpy_explicit_trunc(const char *src, size_t src_size, char *dst, size_t dst_size);
bool check_name(const uint8_t *name, uint16_t len);
bool is_displayable_ascii(const char *str, size_t len);
97 changes: 89 additions & 8 deletions src_plugins/erc20/erc20_plugin.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,13 @@
#include "shared_context.h"
#include "plugin_utils.h"
#include "common_utils.h"
#include "format.h"
#include "utils.h"

typedef enum { ERC20_TRANSFER = 0, ERC20_APPROVE } erc20Selector_t;

#define MAX_CONTRACT_NAME_LEN 15
#define MAX_EXTRA_DATA_SLOTS 2

typedef struct erc20_parameters_t {
uint8_t selectorIndex;
Expand All @@ -16,13 +19,19 @@
char ticker[MAX_TICKER_LEN];
uint8_t decimals;
char contract_name[MAX_CONTRACT_NAME_LEN];
char extra_data[MAX_EXTRA_DATA_SLOTS * 32 + 1];
uint8_t extra_data_len;
} erc20_parameters_t;

void erc20_plugin_call(int message, void *parameters) {
switch (message) {
case ETH_PLUGIN_INIT_CONTRACT: {
ethPluginInitContract_t *msg = (ethPluginInitContract_t *) parameters;
erc20_parameters_t *context = (erc20_parameters_t *) msg->pluginContext;

memset(context->extra_data, 0, sizeof(context->extra_data));
context->extra_data_len = 0;

// enforce that ETH amount should be 0
if (!allzeroes(msg->pluginSharedRO->txContent->value.value, 32)) {
PRINTF("Err: Transaction amount is not 0\n");
Expand Down Expand Up @@ -63,8 +72,18 @@
msg->result = ETH_PLUGIN_RESULT_OK;
break;
default:
PRINTF("Unhandled parameter offset\n");
msg->result = ETH_PLUGIN_RESULT_ERROR;
if (msg->parameterOffset <= 4 + 32 + MAX_EXTRA_DATA_SLOTS * 32) {
// store extra data for possible later use
size_t extra_data_offset = msg->parameterOffset - (4 + 32 + 32);
memmove(context->extra_data + extra_data_offset, msg->parameter, 32);
context->extra_data[extra_data_offset + 32] = '\0';
context->extra_data_len += 32;
msg->result = ETH_PLUGIN_RESULT_OK;
} else {
PRINTF("Extra data too long to buffer\n");
context->extra_data_len = 0;
msg->result = ETH_PLUGIN_RESULT_ERROR;
}
break;
}
} break;
Expand All @@ -73,15 +92,15 @@
ethPluginFinalize_t *msg = (ethPluginFinalize_t *) parameters;
erc20_parameters_t *context = (erc20_parameters_t *) msg->pluginContext;
PRINTF("erc20 plugin finalize\n");
if (context->selectorIndex == ERC20_TRANSFER) {
if (context->selectorIndex == ERC20_TRANSFER & context->extra_data_len == 0) {
msg->tokenLookup1 = msg->pluginSharedRO->txContent->destination;
msg->amount = context->amount;
msg->address = context->destinationAddress;
msg->uiType = ETH_UI_TYPE_AMOUNT_ADDRESS;
msg->result = ETH_PLUGIN_RESULT_OK;
} else if (context->selectorIndex == ERC20_APPROVE) {
} else {
msg->tokenLookup1 = msg->pluginSharedRO->txContent->destination;
msg->numScreens = 2;
msg->numScreens = (context->extra_data_len == 0 ? 2 : 3);
msg->uiType = ETH_UI_TYPE_GENERIC;
msg->result = ETH_PLUGIN_RESULT_OK;
}
Expand All @@ -104,45 +123,107 @@

case ETH_PLUGIN_QUERY_CONTRACT_ID: {
ethQueryContractID_t *msg = (ethQueryContractID_t *) parameters;
erc20_parameters_t *context = (erc20_parameters_t *) msg->pluginContext;

strlcpy(msg->name, "ERC20 token", msg->nameLength);
strlcpy(msg->version, "Approve", msg->versionLength);

if (context->selectorIndex == ERC20_TRANSFER) {
strlcpy(msg->version, "Send", msg->versionLength);
} else {
strlcpy(msg->version, "Approve", msg->versionLength);
}
msg->result = ETH_PLUGIN_RESULT_OK;
} break;

case ETH_PLUGIN_QUERY_CONTRACT_UI: {
ethQueryContractUI_t *msg = (ethQueryContractUI_t *) parameters;
erc20_parameters_t *context = (erc20_parameters_t *) msg->pluginContext;
switch (msg->screenIndex) {
case 0:
strlcpy(msg->title, "Amount", msg->titleLength);
if (context->selectorIndex == ERC20_TRANSFER) {
strlcpy(msg->title, "Send", msg->titleLength);
} else {
strlcpy(msg->title, "Approve", msg->titleLength);
}
if (ismaxint(context->amount, sizeof(context->amount))) {
strlcpy(msg->msg, "Unlimited ", msg->msgLength);
strlcat(msg->msg, context->ticker, msg->msgLength);
} else {
if (!amountToString(context->amount,
sizeof(context->amount),
context->decimals,
context->ticker,
msg->msg,
msg->msgLength)) {
msg->result = ETH_PLUGIN_RESULT_ERROR;
break;
}
}
msg->result = ETH_PLUGIN_RESULT_OK;
break;
case 1:
strlcpy(msg->title, "Approve to", msg->titleLength);
if (context->selectorIndex == ERC20_TRANSFER) {
strlcpy(msg->title, "To", msg->titleLength);
} else {
strlcpy(msg->title, "Approve to", msg->titleLength);
}

if (!getEthDisplayableAddress(context->destinationAddress,
msg->msg,
msg->msgLength,
chainConfig->chainId)) {
msg->result = ETH_PLUGIN_RESULT_ERROR;
}
msg->result = ETH_PLUGIN_RESULT_OK;
break;
case 2: {
uint8_t extra_data_len = strnlen(context->extra_data, context->extra_data_len);

PRINTF("Extra Data Length %d\n", extra_data_len);
PRINTF("Message Length %d\n", msg->msgLength);

if (extra_data_len == 0) {
// should not happen
msg->result = ETH_PLUGIN_RESULT_ERROR;
break;
}

strlcpy(msg->title, "Extra Data", msg->titleLength);

if (is_displayable_ascii(context->extra_data, extra_data_len)) {
// display as string
PRINTF("Display as ASCII string\n");

if (extra_data_len >= msg->msgLength) {
// truncate
extra_data_len = msg->msgLength - 1;
context->extra_data[extra_data_len] = '\0';
}
strlcpy(msg->msg, context->extra_data, msg->msgLength);
} else {
// display as hex
PRINTF("Display as Hex string\n");

if (extra_data_len * 2 + 3 > msg->msgLength) {
// truncate
extra_data_len = (msg->msgLength - 3) / 2;
}
msg->msg[0] = '0';
msg->msg[1] = 'x';
if (format_hex((const uint8_t *) context->extra_data,
extra_data_len,
msg->msg + 2,
msg->msgLength - 2) < 0) {
msg->result = ETH_PLUGIN_RESULT_ERROR;
break;
}
}
msg->result = ETH_PLUGIN_RESULT_OK;
break;
}

default:
break;

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.
}
} break;

Expand Down
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