8 files changed, 236 insertions, 0 deletions
diff --git a/src/encoding/headermap.rs b/src/encoding/headermap.rs
new file mode 100644
index 0000000..313d8b5
--- /dev/null
+++ b/src/encoding/headermap.rs
@@ -0,0 +1,34 @@
+use super::headers::Header;
+use anyhow::Result;
+use std::fmt::Display;
+
+#[derive(Debug)]
+pub struct HeaderMap(pub Vec<(String, String)>);
+
+impl HeaderMap {
+    pub fn new() -> Self {
+        Self(vec![])
+    }
+    pub fn add<H: Header>(mut self, h: H) -> Self {
+        self.0.push((H::NAME.to_string(), format!("{h}")));
+        self
+    }
+    pub fn get<H: Header>(&self) -> Option<Result<H>> {
+        self.0
+            .iter()
+            .find(|(k, _)| k == H::NAME)
+            .map(|(_, v)| H::from_str(v))
+    }
+    pub fn insert_raw(&mut self, key: String, value: String) {
+        self.0.push((key, value))
+    }
+}
+
+impl Display for HeaderMap {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        for (k, v) in &self.0 {
+            write!(f, "{k}: {v}\r\n")?;
+        }
+        Ok(())
+    }
+}
diff --git a/src/encoding/headers.rs b/src/encoding/headers.rs
new file mode 100644
index 0000000..d837ee5
--- /dev/null
+++ b/src/encoding/headers.rs
@@ -0,0 +1,36 @@
+use std::{fmt::Display, str::FromStr};
+
+macro_rules! header {
+    ($hname:literal, struct $name:ident($type:ty)) => {
+        pub struct $name(pub $type);
+        impl Header for $name {
+            const NAME: &'static str = $hname;
+        }
+        impl Display for $name {
+            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+                write!(f, "{}", self.0)
+            }
+        }
+        impl FromStr for $name {
+            type Err = anyhow::Error;
+            fn from_str(s: &str) -> Result<Self, Self::Err> {
+                Ok($name(<$type>::from_str(s)?))
+            }
+        }
+    };
+}
+
+pub trait Header: FromStr<Err = anyhow::Error> + Display {
+    const NAME: &'static str;
+}
+
+header!("Content-Length", struct ContentLength(usize));
+header!("Call-ID", struct CallID(String));
+header!("CSeq", struct CSeq(String));
+header!("Via", struct Via(String));
+header!("Contact", struct Contact(String));
+header!("Max-Forwards", struct MaxForwards(usize));
+header!("From", struct From(String));
+header!("To", struct To(String));
+header!("User-Agent", struct UserAgent(String));
+header!("Allow", struct Allow(String));
diff --git a/src/encoding/method.rs b/src/encoding/method.rs
new file mode 100644
index 0000000..5f8110a
--- /dev/null
+++ b/src/encoding/method.rs
@@ -0,0 +1,23 @@
+use std::fmt::Display;
+
+pub enum Method {
+    Register,
+    Invite,
+    Ack,
+    Option,
+    Cancel,
+    Bye,
+}
+
+impl Display for Method {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(match self {
+            Method::Register => "REGISTER",
+            Method::Invite => "INVITE",
+            Method::Ack => "ACK",
+            Method::Option => "OPTION",
+            Method::Cancel => "CANCEL",
+            Method::Bye => "BYE",
+        })
+    }
+}
diff --git a/src/encoding/mod.rs b/src/encoding/mod.rs
new file mode 100644
index 0000000..a7dd227
--- /dev/null
+++ b/src/encoding/mod.rs
@@ -0,0 +1,7 @@
+pub mod headermap;
+pub mod headers;
+pub mod method;
+pub mod request;
+pub mod response;
+pub mod status;
+pub mod uri;
diff --git a/src/encoding/request.rs b/src/encoding/request.rs
new file mode 100644
index 0000000..03b93c9
--- /dev/null
+++ b/src/encoding/request.rs
@@ -0,0 +1,21 @@
+use super::{headermap::HeaderMap, method::Method, uri::Uri};
+use std::fmt::Display;
+
+pub struct Request {
+    pub method: Method,
+    pub uri: Uri,
+    pub headers: HeaderMap,
+}
+
+impl Display for Request {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self {
+            headers,
+            method,
+            uri,
+        } = self;
+        write!(f, "{method} {uri} SIP/2.0\r\n")?;
+        write!(f, "{headers}\r\n")?;
+        Ok(())
+    }
+}
diff --git a/src/encoding/response.rs b/src/encoding/response.rs
new file mode 100644
index 0000000..3564b34
--- /dev/null
+++ b/src/encoding/response.rs
@@ -0,0 +1,40 @@
+use super::headermap::HeaderMap;
+use anyhow::{anyhow, bail, Context};
+use std::str::FromStr;
+
+#[derive(Debug)]
+pub struct Response {
+    pub code: u16,
+    pub headers: HeaderMap,
+}
+
+impl FromStr for Response {
+    type Err = anyhow::Error;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut lines = s.lines();
+        let statusline = lines.next().ok_or(anyhow!("status line missing"))?;
+        let (sipver, rest) = statusline
+            .split_once(" ")
+            .ok_or(anyhow!("status line malformed"))?;
+        let (code, _status_str) = rest
+            .split_once(" ")
+            .ok_or(anyhow!("status line malformed"))?;
+        let code = u16::from_str(code).context("status code")?;
+
+        let Some(ver) = sipver.strip_prefix("SIP/") else {
+            bail!("sip version malformed");
+        };
+        if ver != "2.0" {
+            bail!("sip version {ver:?} is not supported");
+        }
+
+        let mut headers = HeaderMap::new();
+        for line in lines {
+            // TODO multiline values
+            let (key, value) = line.split_once(":").ok_or(anyhow!("header malformed"))?;
+            headers.insert_raw(key.trim().to_string(), value.trim().to_string())
+        }
+
+        Ok(Self { code, headers })
+    }
+}
diff --git a/src/encoding/status.rs b/src/encoding/status.rs
new file mode 100644
index 0000000..de9ea88
--- /dev/null
+++ b/src/encoding/status.rs
@@ -0,0 +1,63 @@
+
+macro_rules! status_enum {
+    ($v:vis enum $name:ident { $($variant:ident = $value:literal),*, }) => {
+        $v enum $name { $($variant),*, Other(u16) }
+        impl $name { pub fn from_code(c: u16) -> Self { match c { $($value => Self::$variant),*, x => Self::Other(x) } } }
+        impl $name { pub fn to_code(&self) -> u16 { match self { $(Self::$variant => $value),*, Self::Other(x) => *x } } }
+    };
+}
+
+status_enum!(
+    pub enum Status {
+        Trying = 100,
+        Ringing = 180,
+        CallIsBeingForwarded = 181,
+        Queued = 182,
+        SessionProgress = 183,
+        Ok = 200,
+        MultipleChoices = 300,
+        MovedPermanently = 301,
+        MovedTemporarily = 302,
+        UseProxy = 305,
+        AlternativeService = 380,
+        BadRequest = 400,
+        Unauthorized = 401,
+        PaymentRequired = 402,
+        Forbidden = 403,
+        NotFound = 404,
+        MethodNotAllowed = 405,
+        NotAcceptable = 406,
+        ProxyAuthenticationRequired = 407,
+        RequestTimeout = 408,
+        Gone = 410,
+        RequestEntityTooLarge = 413,
+        RequestURITooLarge = 414,
+        UnsupportedMediaType = 415,
+        UnsupportedURIScheme = 416,
+        BadExtension = 420,
+        ExtensionRequired = 421,
+        IntervalTooBrief = 423,
+        TemporarilyNotAvailable = 480,
+        CallLegTransactionDoesNotExist = 481,
+        LoopDetected = 482,
+        TooManyHops = 483,
+        AddressIncomplete = 484,
+        Ambiguous = 485,
+        BusyHere = 486,
+        RequestTerminated = 487,
+        NotAcceptableHere = 488,
+        RequestPending = 491,
+        Undecipherable = 493,
+        InternalServerError = 500,
+        NotImplemented = 501,
+        BadGateway = 502,
+        ServiceUnavailable = 503,
+        ServerTimeout = 504,
+        SIPVersionNotSupported = 505,
+        MessageTooLarge = 513,
+        BusyEverywhere = 600,
+        Decline = 603,
+        DoesNotExistAnywhere = 604,
+        GlobalNotAcceptable = 606,
+    }
+);
diff --git a/src/encoding/uri.rs b/src/encoding/uri.rs
new file mode 100644
index 0000000..2d77df2
--- /dev/null
+++ b/src/encoding/uri.rs
@@ -0,0 +1,12 @@
+use std::fmt::Display;
+
+pub struct Uri {
+    pub content: String,
+}
+
+impl Display for Uri {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.content)?;
+        Ok(())
+    }
+}