app-ethereum/src_plugins/erc20/erc20_plugin.c

#include <string.h>
#include "eth_plugin_internal.h"
#include "eth_plugin_handler.h"
#include "shared_context.h"
#include "ethUtils.h"
#include "utils.h"

typedef enum {
	ERC20_TRANSFER = 0,
	ERC20_APPROVE
} erc20Selector_t;

typedef enum {
	TARGET_ADDRESS = 0,
	TARGET_CONTRACT,
	TARGET_COMPOUND
} targetType_t;

typedef struct erc20_parameters_t {
	uint8_t selectorIndex;
	uint8_t destinationAddress[21];
	uint8_t amount[32];
	uint8_t ticker_1[MAX_TICKER_LEN];
	uint8_t ticker_2[MAX_TICKER_LEN];
	uint8_t decimals;
	uint8_t target;
} erc20_parameters_t;

typedef struct ticker_binding_t {
	char ticker1[MAX_TICKER_LEN];
	char ticker2[MAX_TICKER_LEN];
} ticker_binding_t;

#define NUM_COMPOUND_BINDINGS 9
const ticker_binding_t const COMPOUND_BINDINGS[NUM_COMPOUND_BINDINGS] = {
	{"DAI", "CDAI"},
	{"WETH", "CETH"},
	{"USDC", "CUSDC"},
	{"ZRX", "CZRX"},
	{"USDT", "CUSDT"},
	{"WBTC", "CBTC"},
	{"BAT", "CBAT"},
	{"REPv2", "CREP"},
	{"SAI", "CSAI"},
};

bool check_token_binding(char* ticker1, char* ticker2, const ticker_binding_t* bindings, size_t num_bindings){
	for(size_t i = 0; i < num_bindings; i++){
		ticker_binding_t* binding = (ticker_binding_t *)PIC(&bindings[i]);
		if (strncmp(binding->ticker1, ticker1, strnlen(binding->ticker1, MAX_TICKER_LEN)) == 0 &&
			strncmp(binding->ticker2, ticker2, strnlen(binding->ticker2, MAX_TICKER_LEN)) == 0){
			return true;
		}
	}
	return false;
}

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;
			// enforce that ETH amount should be 0
			if (!allzeroes(msg->pluginSharedRO->txContent->value.value, 32)){
				PRINTF("Err: Transaction amount is not 0\n");
				msg->result = ETH_PLUGIN_RESULT_ERROR;
			}
			else {
				size_t i;
				for (i=0; i<NUM_ERC20_SELECTORS; i++) {
					if (memcmp((uint8_t *)PIC(ERC20_SELECTORS[i]), msg->selector, SELECTOR_SIZE) == 0) {
						context->selectorIndex = i;
						break;
					}
				}
				if (i == NUM_ERC20_SELECTORS) {
					PRINTF("Unknown selector %.*H\n", SELECTOR_SIZE, msg->selector);
					msg->result = ETH_PLUGIN_RESULT_ERROR;
					break;
				}
				PRINTF("erc20 plugin init\n");
				msg->result = ETH_PLUGIN_RESULT_OK;
			}
		}
		break;

		case ETH_PLUGIN_PROVIDE_PARAMETER : {
			ethPluginProvideParameter_t *msg = (ethPluginProvideParameter_t*)parameters;
			erc20_parameters_t *context = (erc20_parameters_t*)msg->pluginContext;
			PRINTF("erc20 plugin provide parameter %d %.*H\n", msg->parameterOffset, 32, msg->parameter);
			switch(msg->parameterOffset) {
				case 4:
					memmove(context->destinationAddress, msg->parameter + 12, 20);
					msg->result = ETH_PLUGIN_RESULT_OK;
					break;
				case 4 + 32:
					memmove(context->amount, msg->parameter, 32);
					msg->result = ETH_PLUGIN_RESULT_OK;
					break;
				default:
					PRINTF("Unhandled parameter offset\n");
					msg->result = ETH_PLUGIN_RESULT_ERROR;
					break;
			}
		}
		break;

		case ETH_PLUGIN_FINALIZE: {
			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){
				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){
				msg->tokenLookup1 = msg->pluginSharedRO->txContent->destination;
				msg->tokenLookup2 = context->destinationAddress;
				msg->numScreens = 2;
				msg->uiType = ETH_UI_TYPE_GENERIC;
				msg->result = ETH_PLUGIN_RESULT_OK;
			}
		}
		break;

		case ETH_PLUGIN_PROVIDE_TOKEN: {
			ethPluginProvideToken_t *msg = (ethPluginProvideToken_t*)parameters;
			erc20_parameters_t *context = (erc20_parameters_t*)msg->pluginContext;
			PRINTF("erc20 plugin provide token 1: %d - 2: %d\n", (msg->token1 != NULL), (msg->token2 != NULL));
			if (msg->token1 != NULL) {
				context->target = TARGET_ADDRESS;
				strcpy((char *)context->ticker_1, (char *)msg->token1->ticker);
				context->decimals = msg->token1->decimals;
				if (context->selectorIndex == ERC20_APPROVE){
					if(msg->token2 != NULL){
						context->target = TARGET_CONTRACT;
						strcpy((char *)context->ticker_2, (char *)msg->token2->ticker);
						// test if we're doing a Compound allowance
						if (check_token_binding((char *)msg->token1->ticker, (char *)msg->token2->ticker, COMPOUND_BINDINGS, NUM_COMPOUND_BINDINGS)){
							context->target = TARGET_COMPOUND;
						}
					}
				}
				msg->result = ETH_PLUGIN_RESULT_OK;
			}
			else {
				msg->result = ETH_PLUGIN_RESULT_FALLBACK;
			}
		}
		break;

		case ETH_PLUGIN_QUERY_CONTRACT_ID: {
			ethQueryContractID_t *msg = (ethQueryContractID_t*)parameters;
			strcpy(msg->name, "Type");
			strcpy(msg->version, "Approve");
			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:
					strcpy(msg->title, "Amount");
					if(ismaxint(context->amount, sizeof(context->amount))){
						strcpy(msg->msg, "Unlimited ");
						strcat(msg->msg, (char *)context->ticker_1);
					}
					else{
						amountToString(context->amount, sizeof(context->amount), context->decimals, (char *)context->ticker_1, msg->msg, 100);
					}
					msg->result = ETH_PLUGIN_RESULT_OK;
					break;
				case 1:
					if(context->target >= TARGET_CONTRACT){
						strcpy(msg->title, "Contract");
						if (context->target == TARGET_COMPOUND){
							strcpy(msg->msg, "Compound ");
							strcat(msg->msg, (char *)context->ticker_2 + 1); // remove the 'c' char at beginning of compound ticker
						}
						else {
							strcpy(msg->msg, (char *)context->ticker_2);
						}
					}
					else{
						strcpy(msg->title, "Address");
						msg->msg[0] = '0';
						msg->msg[1] = 'x';
						getEthAddressStringFromBinary(context->destinationAddress, (uint8_t *)msg->msg + 2, msg->pluginSharedRW->sha3, chainConfig);
					}

					msg->result = ETH_PLUGIN_RESULT_OK;
					break;
				default:
					break;
			}
		}
		break;

		default:
			PRINTF("Unhandled message %d\n", message);			
	}
}