feat(rustdns-client): add Rust DNS client binary and TypeScript IPC bridge to enable UDP and DoH resolution, RDATA decoding, and DNSSEC AD/rcode support

rust/crates/rustdns-protocol/src/packet.rs

@@ -1,5 +1,5 @@
 use crate::name::{decode_name, encode_name};
-use crate::types::{QClass, QType, FLAG_QR, FLAG_AA, FLAG_RD, FLAG_RA, EDNS_DO_BIT};
+use crate::types::{QClass, QType, FLAG_QR, FLAG_AA, FLAG_RD, FLAG_RA, FLAG_AD, EDNS_DO_BIT};
 
 /// A parsed DNS question.
 #[derive(Debug, Clone)]
@@ -61,6 +61,16 @@ impl DnsPacket {
         }
     }
 
+    /// Extract the response code (lower 4 bits of flags).
+    pub fn rcode(&self) -> u8 {
+        (self.flags & 0x000F) as u8
+    }
+
+    /// Check if the AD (Authenticated Data) flag is set.
+    pub fn has_ad_flag(&self) -> bool {
+        self.flags & FLAG_AD != 0
+    }
+
     /// Check if DNSSEC (DO bit) is requested in the OPT record.
     pub fn is_dnssec_requested(&self) -> bool {
         for additional in &self.additionals {
@@ -335,6 +345,181 @@ pub fn encode_rrsig(
     buf
 }
 
+// ── RDATA decoding helpers ─────────────────────────────────────────
+
+/// Decode an A record (4 bytes -> IPv4 string).
+pub fn decode_a(rdata: &[u8]) -> Result<String, &'static str> {
+    if rdata.len() < 4 {
+        return Err("A rdata too short");
+    }
+    Ok(format!("{}.{}.{}.{}", rdata[0], rdata[1], rdata[2], rdata[3]))
+}
+
+/// Decode an AAAA record (16 bytes -> IPv6 string).
+pub fn decode_aaaa(rdata: &[u8]) -> Result<String, &'static str> {
+    if rdata.len() < 16 {
+        return Err("AAAA rdata too short");
+    }
+    let groups: Vec<String> = (0..8)
+        .map(|i| {
+            let val = u16::from_be_bytes([rdata[i * 2], rdata[i * 2 + 1]]);
+            format!("{:x}", val)
+        })
+        .collect();
+    // Build full form, then compress :: notation
+    let full = groups.join(":");
+    compress_ipv6(&full)
+}
+
+/// Compress a full IPv6 address to shortest form.
+fn compress_ipv6(full: &str) -> Result<String, &'static str> {
+    let groups: Vec<&str> = full.split(':').collect();
+    if groups.len() != 8 {
+        return Ok(full.to_string());
+    }
+
+    // Find longest run of consecutive "0" groups
+    let mut best_start = None;
+    let mut best_len = 0usize;
+    let mut cur_start = None;
+    let mut cur_len = 0usize;
+
+    for (i, g) in groups.iter().enumerate() {
+        if *g == "0" {
+            if cur_start.is_none() {
+                cur_start = Some(i);
+                cur_len = 1;
+            } else {
+                cur_len += 1;
+            }
+            if cur_len > best_len {
+                best_start = cur_start;
+                best_len = cur_len;
+            }
+        } else {
+            cur_start = None;
+            cur_len = 0;
+        }
+    }
+
+    if best_len >= 2 {
+        let bs = best_start.unwrap();
+        let left: Vec<&str> = groups[..bs].to_vec();
+        let right: Vec<&str> = groups[bs + best_len..].to_vec();
+        let l = left.join(":");
+        let r = right.join(":");
+        if l.is_empty() && r.is_empty() {
+            Ok("::".to_string())
+        } else if l.is_empty() {
+            Ok(format!("::{}", r))
+        } else if r.is_empty() {
+            Ok(format!("{}::", l))
+        } else {
+            Ok(format!("{}::{}", l, r))
+        }
+    } else {
+        Ok(full.to_string())
+    }
+}
+
+/// Decode a TXT record (length-prefixed chunks -> strings).
+pub fn decode_txt(rdata: &[u8]) -> Result<Vec<String>, &'static str> {
+    let mut strings = Vec::new();
+    let mut pos = 0;
+    while pos < rdata.len() {
+        let len = rdata[pos] as usize;
+        pos += 1;
+        if pos + len > rdata.len() {
+            return Err("TXT chunk extends beyond rdata");
+        }
+        let s = std::str::from_utf8(&rdata[pos..pos + len])
+            .map_err(|_| "invalid UTF-8 in TXT")?;
+        strings.push(s.to_string());
+        pos += len;
+    }
+    Ok(strings)
+}
+
+/// Decode an MX record (preference + exchange name with compression).
+pub fn decode_mx(rdata: &[u8], packet: &[u8], rdata_offset: usize) -> Result<(u16, String), String> {
+    if rdata.len() < 3 {
+        return Err("MX rdata too short".into());
+    }
+    let preference = u16::from_be_bytes([rdata[0], rdata[1]]);
+    let (name, _) = decode_name(packet, rdata_offset + 2).map_err(|e| e.to_string())?;
+    Ok((preference, name))
+}
+
+/// Decode a name from RDATA (for NS, CNAME, PTR records with compression).
+pub fn decode_name_rdata(_rdata: &[u8], packet: &[u8], rdata_offset: usize) -> Result<String, String> {
+    let (name, _) = decode_name(packet, rdata_offset).map_err(|e| e.to_string())?;
+    Ok(name)
+}
+
+/// SOA record decoded fields.
+#[derive(Debug, Clone)]
+pub struct SoaData {
+    pub mname: String,
+    pub rname: String,
+    pub serial: u32,
+    pub refresh: u32,
+    pub retry: u32,
+    pub expire: u32,
+    pub minimum: u32,
+}
+
+/// Decode a SOA record RDATA.
+pub fn decode_soa(rdata: &[u8], packet: &[u8], rdata_offset: usize) -> Result<SoaData, String> {
+    let (mname, consumed1) = decode_name(packet, rdata_offset).map_err(|e| e.to_string())?;
+    let (rname, consumed2) = decode_name(packet, rdata_offset + consumed1).map_err(|e| e.to_string())?;
+    let nums_offset = consumed1 + consumed2;
+    if rdata.len() < nums_offset + 20 {
+        return Err("SOA rdata too short for numeric fields".into());
+    }
+    let serial = u32::from_be_bytes([
+        rdata[nums_offset], rdata[nums_offset + 1],
+        rdata[nums_offset + 2], rdata[nums_offset + 3],
+    ]);
+    let refresh = u32::from_be_bytes([
+        rdata[nums_offset + 4], rdata[nums_offset + 5],
+        rdata[nums_offset + 6], rdata[nums_offset + 7],
+    ]);
+    let retry = u32::from_be_bytes([
+        rdata[nums_offset + 8], rdata[nums_offset + 9],
+        rdata[nums_offset + 10], rdata[nums_offset + 11],
+    ]);
+    let expire = u32::from_be_bytes([
+        rdata[nums_offset + 12], rdata[nums_offset + 13],
+        rdata[nums_offset + 14], rdata[nums_offset + 15],
+    ]);
+    let minimum = u32::from_be_bytes([
+        rdata[nums_offset + 16], rdata[nums_offset + 17],
+        rdata[nums_offset + 18], rdata[nums_offset + 19],
+    ]);
+    Ok(SoaData { mname, rname, serial, refresh, retry, expire, minimum })
+}
+
+/// SRV record decoded fields.
+#[derive(Debug, Clone)]
+pub struct SrvData {
+    pub priority: u16,
+    pub weight: u16,
+    pub port: u16,
+    pub target: String,
+}
+
+/// Decode a SRV record RDATA.
+pub fn decode_srv(rdata: &[u8], packet: &[u8], rdata_offset: usize) -> Result<SrvData, String> {
+    if rdata.len() < 7 {
+        return Err("SRV rdata too short".into());
+    }
+    let priority = u16::from_be_bytes([rdata[0], rdata[1]]);
+    let weight = u16::from_be_bytes([rdata[2], rdata[3]]);
+    let port = u16::from_be_bytes([rdata[4], rdata[5]]);
+    let (target, _) = decode_name(packet, rdata_offset + 6).map_err(|e| e.to_string())?;
+    Ok(SrvData { priority, weight, port, target })
+}
+
 /// Build a DnsRecord from high-level data.
 pub fn build_record(name: &str, rtype: QType, ttl: u32, rdata: Vec<u8>) -> DnsRecord {
     DnsRecord {
@@ -416,6 +601,45 @@ mod tests {
         assert_eq!(&data[7..12], b"world");
     }
 
+    #[test]
+    fn test_decode_a() {
+        let rdata = encode_a("192.168.1.1");
+        let decoded = decode_a(&rdata).unwrap();
+        assert_eq!(decoded, "192.168.1.1");
+    }
+
+    #[test]
+    fn test_decode_aaaa() {
+        let rdata = encode_aaaa("::1");
+        let decoded = decode_aaaa(&rdata).unwrap();
+        assert_eq!(decoded, "::1");
+
+        let rdata2 = encode_aaaa("2001:db8::1");
+        let decoded2 = decode_aaaa(&rdata2).unwrap();
+        assert_eq!(decoded2, "2001:db8::1");
+    }
+
+    #[test]
+    fn test_decode_txt() {
+        let strings = vec!["hello".to_string(), "world".to_string()];
+        let rdata = encode_txt(&strings);
+        let decoded = decode_txt(&rdata).unwrap();
+        assert_eq!(decoded, strings);
+    }
+
+    #[test]
+    fn test_rcode_and_ad_flag() {
+        let mut pkt = DnsPacket::new_query(1);
+        assert_eq!(pkt.rcode(), 0);
+        assert!(!pkt.has_ad_flag());
+
+        pkt.flags |= crate::types::FLAG_AD;
+        assert!(pkt.has_ad_flag());
+
+        pkt.flags |= 0x0003; // NXDOMAIN
+        assert_eq!(pkt.rcode(), 3);
+    }
+
     #[test]
     fn test_dnssec_do_bit() {
         let mut query = DnsPacket::new_query(1);

rust/crates/rustdns-protocol/src/types.rs

@@ -127,5 +127,8 @@ pub const FLAG_AA: u16 = 0x0400;
 pub const FLAG_RD: u16 = 0x0100;
 pub const FLAG_RA: u16 = 0x0080;
 
+/// Authenticated Data flag
+pub const FLAG_AD: u16 = 0x0020;
+
 /// OPT record DO bit (DNSSEC OK)
 pub const EDNS_DO_BIT: u16 = 0x8000;