本文分享自华为云社区《华为云短信服务教你用Rust实现Smpp协议》，作者： 张俭。
协议概述
SMPP(Short Message Peer-to-Peer)协议起源于90年代，最初由Aldiscon公司开发，后来由SMPP开发者论坛维护和推广。SMPP常用于在SMSC（Short Message Service Center，短信中心）和短信应用之间传输短消息，支持高效的短信息发送、接收和查询功能，是电信运营商和短信服务提供商之间互通短信的主要协议之一。
SMPP协议基于客户端/服务端模型工作。由客户端（短信应用，如手机，应用程序等）先和SMSC建立起TCP长连接，并使用SMPP命令与SMSC进行交互，实现短信的发送和接收。在SMPP协议中，无需同步等待响应就可以发送下一个指令，实现者可以根据自己的需要，实现同步、异步两种消息传输模式，满足不同场景下的性能要求。
时序图
绑定transmitter模式，发送短信并查询短信发送成功
绑定receiver模式，从SMSC接收到短信
协议帧介绍
![Untitled.png]()
在SMPP协议中，每个PDU都包含两个部分：SMPP Header和SMPP Body。
SMPP Header
Header包含以下字段，大小长度都是4字节：
- Command Length：整个PDU的长度，包括Header和Body。
- Command ID：用于标识PDU的类型（例如，BindReceiver、QuerySM等）。
- Command Status：响应状态码，表示处理的结果。
- Sequence Number：序列号，用来匹配请求和响应。
用Rust实现SMPP协议栈里的BindTransmitter
本文的代码均已上传到smpp-rust
选用Tokio作为基础的异步运行时环境，tokio有非常强大的异步IO支持，也是rust库的事实标准。
代码结构组织如下:
├── lib.rs
├── const.rs
├── protocol.rs
├── smpp_client.rs
└── smpp_server.rs
- lib.rs Rust项目的入口点
- const.rs 包含常量定义，如commandId、状态码等
- protocol.rs 包含PDU定义，编解码处理等
- smpp_client.rs 实现smpp客户端逻辑
- smpp_server.rs 实现
利用rust原子类实现sequence_number
sequence_number是从1到0x7FFFFFFF的值，利用Rust的AtomicI32来生成这个值。
use std::sync::atomic::{AtomicI32, Ordering};
use std::num::TryFromIntError;
struct BoundAtomicInt {
min: i32,
max: i32,
integer: AtomicI32,
}
impl BoundAtomicInt {
pub fn new(min: i32, max: i32) -> Self {
assert!(min <= max, "min must be less than or equal to max");
Self {
min,
max,
integer: AtomicI32::new(min),
}
}
pub fn next_val(&self) -> Result<i32, TryFromIntError> {
let next = self.integer.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| {
Some(if x >= self.max { self.min } else { x + 1 })
})?;
Ok(next)
}
}
在Rust中定义SMPP PDU
pub struct SmppPdu {
pub header: SmppHeader,
pub body: SmppBody,
}
pub struct SmppHeader {
pub command_length: i32,
pub command_id: i32,
pub command_status: i32,
pub sequence_number: i32,
}
pub enum SmppBody {
BindReceiver(BindReceiver),
BindReceiverResp(BindReceiverResp),
BindTransmitter(BindTransmitter),
BindTransmitterResp(BindTransmitterResp),
QuerySm(QuerySm),
QuerySmResp(QuerySmResp),
SubmitSm(SubmitSm),
SubmitSmResp(SubmitSmResp),
DeliverSm(DeliverSm),
DeliverSmResp(DeliverSmResp),
Unbind(Unbind),
UnbindResp(UnbindResp),
ReplaceSm(ReplaceSm),
ReplaceSmResp(ReplaceSmResp),
CancelSm(CancelSm),
CancelSmResp(CancelSmResp),
BindTransceiver(BindTransceiver),
BindTransceiverResp(BindTransceiverResp),
Outbind(Outbind),
EnquireLink(EnquireLink),
EnquireLinkResp(EnquireLinkResp),
SubmitMulti(SubmitMulti),
SubmitMultiResp(SubmitMultiResp),
}
实现编解码方法
impl SmppPdu {
pub fn encode(&self) -> Vec<u8> {
let mut body_buf = match &self.body {
SmppBody::BindTransmitter(bind_transmitter) => bind_transmitter.encode(),
_ => unimplemented!(),
};
let command_length = (body_buf.len() + 16) as i32;
let header = SmppHeader {
command_length,
command_id: self.header.command_id,
command_status: self.header.command_status,
sequence_number: self.header.sequence_number,
};
let mut buf = header.encode();
buf.append(&mut body_buf);
buf
}
pub fn decode(buf: &[u8]) -> io::Result<Self> {
let header = SmppHeader::decode(&buf[0..16])?;
let body = match header.command_id {
constant::BIND_TRANSMITTER_RESP_ID => SmppBody::BindTransmitterResp(BindTransmitterResp::decode(&buf[16..])?),
_ => unimplemented!(),
};
Ok(SmppPdu { header, body })
}
}
impl SmppHeader {
pub(crate) fn encode(&self) -> Vec<u8> {
let mut buf = vec![];
buf.extend_from_slice(&self.command_length.to_be_bytes());
buf.extend_from_slice(&self.command_id.to_be_bytes());
buf.extend_from_slice(&self.command_status.to_be_bytes());
buf.extend_from_slice(&self.sequence_number.to_be_bytes());
buf
}
pub(crate) fn decode(buf: &[u8]) -> io::Result<Self> {
if buf.len() < 16 {
return Err(io::Error::new(io::ErrorKind::InvalidData, "Buffer too short for SmppHeader"));
}
let command_id = u32::from_be_bytes(buf[0..4].try_into().unwrap());
let command_status = i32::from_be_bytes(buf[4..8].try_into().unwrap());
let sequence_number = i32::from_be_bytes(buf[8..12].try_into().unwrap());
Ok(SmppHeader {
command_length: 0,
command_id,
command_status,
sequence_number,
})
}
}
impl BindTransmitter {
pub(crate) fn encode(&self) -> Vec<u8> {
let mut buf = vec![];
write_cstring(&mut buf, &self.system_id);
write_cstring(&mut buf, &self.password);
write_cstring(&mut buf, &self.system_type);
buf.push(self.interface_version);
buf.push(self.addr_ton);
buf.push(self.addr_npi);
write_cstring(&mut buf, &self.address_range);
buf
}
pub(crate) fn decode(buf: &[u8]) -> io::Result<Self> {
let mut offset = 0;
let system_id = read_cstring(buf, &mut offset)?;
let password = read_cstring(buf, &mut offset)?;
let system_type = read_cstring(buf, &mut offset)?;
let interface_version = buf[offset];
offset += 1;
let addr_ton = buf[offset];
offset += 1;
let addr_npi = buf[offset];
offset += 1;
let address_range = read_cstring(buf, &mut offset)?;
Ok(BindTransmitter {
system_id,
password,
system_type,
interface_version,
addr_ton,
addr_npi,
address_range,
})
}
}
实现同步的bind_transmitter方法
pub async fn bind_transmitter(
&mut self,
bind_transmitter: BindTransmitter,
) -> io::Result<BindTransmitterResp> {
if let Some(stream) = &mut self.stream {
let sequence_number = self.sequence_number.next_val();
let pdu = SmppPdu {
header: SmppHeader {
command_length: 0,
command_id: constant::BIND_TRANSMITTER_ID,
command_status: 0,
sequence_number,
},
body: SmppBody::BindTransmitter(bind_transmitter),
};
let encoded_request = pdu.encode();
stream.write_all(&encoded_request).await?;
let mut length_buf = [0u8; 4];
stream.read_exact(&mut length_buf).await?;
let msg_length = u32::from_be_bytes(length_buf) as usize - 4;
let mut msg_buf = vec![0u8; msg_length];
stream.read_exact(&mut msg_buf).await?;
let response = SmppPdu::decode(&msg_buf)?;
if response.header.command_status != 0 {
Err(io::Error::new(
io::ErrorKind::Other,
format!("Error response: {:?}", response.header.command_status),
))
} else {
// Assuming response.body is of type BindTransmitterResp
match response.body {
SmppBody::BindTransmitterResp(resp) => Ok(resp),
_ => Err(io::Error::new(io::ErrorKind::InvalidData, "Unexpected response body")),
}
}
} else {
Err(io::Error::new(io::ErrorKind::NotConnected, "Not connected"))
}
}
运行example，验证连接成功
use smpp_rust::protocol::BindTransmitter;
use smpp_rust::smpp_client::SmppClient;
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let mut client = SmppClient::new("127.0.0.1", 2775);
client.connect().await?;
let bind_transmitter = BindTransmitter{
system_id: "system_id".to_string(),
password: "password".to_string(),
system_type: "system_type".to_string(),
interface_version: 0x34,
addr_ton: 0,
addr_npi: 0,
address_range: "".to_string(),
};
client.bind_transmitter(bind_transmitter).await?;
client.close().await?;
Ok(())
}
![Untitled 1.png]()
相关开源项目
总结
本文简单对SMPP协议进行了介绍，并尝试用rust实现协议栈，但实际商用发送短信往往更加复杂，面临诸如流控、运营商对接、传输层安全等问题，可以选择华为云消息&短信（Message & SMS）服务，华为云短信服务是华为云携手全球多家优质运营商和渠道，为企业用户提供的通信服务。企业调用API或使用群发助手，即可使用验证码、通知短信服务。
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