Peter M. Groen / libmodbus

Commit 0e2f470a315f19124122d757397145cf3e60c0f8

Authored by Stéphane Raimbault
1 parent 2fb7c2eb

Fix late check of ctx in modbus_reply[|_exception] (closes #269)

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Showing 1 changed file with 16 additions and 7 deletions
src/modbus.c
  View file @0e2f470
... ... @@ -680,10 +680,10 @@ static int response_exception(modbus_t *ctx, sft_t *sft,
680 680 int modbus_reply(modbus_t *ctx, const uint8_t *req,
681 681 int req_length, modbus_mapping_t *mb_mapping)
682 682 {
683   - int offset = ctx->backend->header_length;
684   - int slave = req[offset - 1];
685   - int function = req[offset];
686   - uint16_t address = (req[offset + 1] << 8) + req[offset + 2];
  683 + int offset;
  684 + int slave;
  685 + int function;
  686 + uint16_t address;
687 687 uint8_t rsp[MAX_MESSAGE_LENGTH];
688 688 int rsp_length = 0;
689 689 sft_t sft;
... ... @@ -693,6 +693,11 @@ int modbus_reply(modbus_t *ctx, const uint8_t *req,
693 693 return -1;
694 694 }
695 695  
  696 + offset = ctx->backend->header_length;
  697 + slave = req[offset - 1];
  698 + function = req[offset];
  699 + address = (req[offset + 1] << 8) + req[offset + 2];
  700 +
696 701 sft.slave = slave;
697 702 sft.function = function;
698 703 sft.t_id = ctx->backend->prepare_response_tid(req, &req_length);
... ... @@ -1062,9 +1067,9 @@ int modbus_reply(modbus_t *ctx, const uint8_t *req,
1062 1067 int modbus_reply_exception(modbus_t *ctx, const uint8_t *req,
1063 1068 unsigned int exception_code)
1064 1069 {
1065   - int offset = ctx->backend->header_length;
1066   - int slave = req[offset - 1];
1067   - int function = req[offset];
  1070 + int offset;
  1071 + int slave;
  1072 + int function;
1068 1073 uint8_t rsp[MAX_MESSAGE_LENGTH];
1069 1074 int rsp_length;
1070 1075 int dummy_length = 99;
... ... @@ -1075,6 +1080,10 @@ int modbus_reply_exception(modbus_t *ctx, const uint8_t *req,
1075 1080 return -1;
1076 1081 }
1077 1082  
  1083 + offset = ctx->backend->header_length;
  1084 + slave = req[offset - 1];
  1085 + function = req[offset];
  1086 +
1078 1087 sft.slave = slave;
1079 1088 sft.function = function + 0x80;;
1080 1089 sft.t_id = ctx->backend->prepare_response_tid(req, &dummy_length);
... ...