File: Bridge.sol
119:     function sendMessage(
120:         Message calldata _message
121:     )
122:         external
123:         payable
124:         override
125:         nonReentrant
126:         whenNotPaused
127:         returns (bytes32 msgHash_, Message memory message_)
128:     {
129:         // Ensure the message owner is not null.
130:         if (
131:             _message.srcOwner == address(0) || _message.destOwner == address(0)
132:         ) {
133:             revert B_INVALID_USER();
134:         }
135: 
136:         // Check if the destination chain is enabled.
137:         (bool destChainEnabled, ) = isDestChainEnabled(_message.destChainId);
138: 
139:         // Verify destination chain and to address.
140:         if (!destChainEnabled) revert B_INVALID_CHAINID();
141:         if (_message.destChainId == block.chainid) {
142:             revert B_INVALID_CHAINID();
143:         }
144: 
145:         // Ensure the sent value matches the expected amount.
146:         
148:         uint256 expectedAmount = _message.value + _message.fee;
149:         if (expectedAmount != msg.value) revert B_INVALID_VALUE();
150: 
151:         message_ = _message;
152: 
153:         // Configure message details and send signal to indicate message sending.
154:         message_.id = nextMessageId++;
155:         message_.from = msg.sender; 
156:         message_.srcChainId = uint64(block.chainid);
157: 
158:         msgHash_ = hashMessage(message_);
159: 
160:         ISignalService(resolve("signal_service", false)).sendSignal(msgHash_);
161:         emit MessageSent(msgHash_, message_);
162:     }
