fix: dhcp should not block program from launching

boltconn/src/app.rs

@@ -329,11 +329,8 @@ impl App {
             .map_err(|e| anyhow!("Load intercept rules failed: {}", e))?,
         );
 
-        // this is atomic
-        self.dns.replace_resolvers(&self.outbound_iface, group)?;
-
         // start atomic replacing
-
+        self.dns.replace_resolvers(&self.outbound_iface, group);
         self.dns.replace_ns_policy(ns_policy);
         self.dns.replace_hosts(&config.dns.hosts);
         self.dns_hijack_ctrl.update(
@@ -456,7 +453,7 @@ async fn initialize_dns(
             &config.hosts,
             ns_policy,
             group,
-        )?)
+        ))
     })
 }
 

boltconn/src/network/dns/dns.rs

@@ -4,7 +4,7 @@ use crate::network::dns::hosts::HostsResolver;
 use crate::network::dns::ns_policy::{DispatchedDnsResolver, NameserverPolicies};
 use crate::network::dns::provider::IfaceProvider;
 use crate::network::dns::{default_resolver_opt, AuxiliaryResolver, NameServerConfigEnum};
-use crate::proxy::error::{DnsError, TransportError};
+use crate::proxy::error::TransportError;
 use arc_swap::ArcSwap;
 use hickory_proto::op::{Message, MessageType, ResponseCode};
 use hickory_proto::rr::{DNSClass, RData, Record, RecordType};
@@ -99,17 +99,17 @@ impl Dns {
         hosts: &HashMap<String, IpAddr>,
         ns_policy: NameserverPolicies,
         configs: Vec<NameServerConfigEnum>,
-    ) -> Result<Dns, DnsError> {
-        let resolvers = Self::build_resolvers(iface_name, configs)?;
+    ) -> Dns {
+        let resolvers = Self::build_resolvers(iface_name, configs);
         let host_resolver = HostsResolver::new(hosts);
-        Ok(Dns {
+        Dns {
             name: name.to_string(),
             table: DnsTable::new(),
             preference,
             host_resolver: ArcSwap::new(Arc::new(host_resolver)),
             ns_policy: ArcSwap::new(Arc::new(ns_policy)),
             resolvers: ArcSwap::new(Arc::new(resolvers)),
-        })
+        }
     }
 
     pub fn replace_hosts(&self, hosts: &HashMap<String, IpAddr>) {
@@ -122,21 +122,15 @@ impl Dns {
     }
 
     // This function is atomic
-    pub fn replace_resolvers(
-        &self,
-        iface_name: &str,
-        configs: Vec<NameServerConfigEnum>,
-    ) -> Result<(), DnsError> {
-        let resolvers = Self::build_resolvers(iface_name, configs)?;
+    pub fn replace_resolvers(&self, iface_name: &str, configs: Vec<NameServerConfigEnum>) {
+        let resolvers = Self::build_resolvers(iface_name, configs);
         self.resolvers.store(Arc::new(resolvers));
-        Ok(())
     }
 
     fn build_resolvers(
         iface_name: &str,
         configs: Vec<NameServerConfigEnum>,
-    ) -> Result<Vec<AuxiliaryResolver<AsyncResolver<GenericConnector<IfaceProvider>>>>, DnsError>
-    {
+    ) -> Vec<AuxiliaryResolver<AsyncResolver<GenericConnector<IfaceProvider>>>> {
         let mut resolvers = Vec::new();
         for config in configs.into_iter() {
             let resolver = match config {
@@ -148,11 +142,11 @@ impl Dns {
                         GenericConnector::new(IfaceProvider::new(iface_name)),
                     ))
                 }
-                NameServerConfigEnum::Dhcp(dhcp) => AuxiliaryResolver::new_dhcp(&dhcp)?,
+                NameServerConfigEnum::Dhcp(dhcp) => AuxiliaryResolver::new_dhcp(&dhcp),
             };
             resolvers.push(resolver);
         }
-        Ok(resolvers)
+        resolvers
     }
 }
 

boltconn/src/network/dns/mod.rs

@@ -8,7 +8,7 @@ mod ns_policy;
 mod provider;
 
 use crate::config::DnsConfigError;
-use crate::proxy::error::{DnsError, TransportError};
+use crate::proxy::error::DnsError;
 pub use bootstrap::BootstrapResolver;
 pub use dns::{Dns, GenericDns};
 use hickory_resolver::config::{
@@ -167,32 +167,40 @@ struct DhcpDnsRecord {
 }
 
 impl DhcpDnsRecord {
-    pub fn new(iface: &str) -> Result<Self, DnsError> {
-        let iface_addr = crate::platform::get_iface_address(iface)
-            .map_err(|_| DnsError::DhcpNameServer("failed to get iface address"))?;
-        let ns_addr = crate::platform::dhcp::get_dhcp_dns(iface)?;
-        tracing::debug!(
-            "DHCP DNS: iface={}, iface_addr={}, ns_addr={}",
-            iface,
-            iface_addr,
-            ns_addr
-        );
-        Ok(Self {
+    pub fn new(iface: &str) -> Self {
+        let mut iface_addr = crate::platform::get_iface_address(iface).ok();
+        let ns_addr = match crate::platform::dhcp::get_dhcp_dns(iface) {
+            Ok(addr) => addr,
+            Err(e) => {
+                tracing::warn!(
+                    "DHCP DNS: iface={}, iface_addr={:?}, error={}, use empty address",
+                    iface,
+                    iface_addr,
+                    e
+                );
+                // we don't want the replayable fault stop the program from running
+                // e.g. start offline but soon connect to a network with DHCP
+                iface_addr = None;
+                IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1))
+            }
+        };
+        Self {
             iface: iface.to_string(),
-            iface_addr,
+            iface_addr: iface_addr.unwrap_or(IpAddr::V4(std::net::Ipv4Addr::new(127, 0, 0, 1))),
             ns_addr,
             last_checked: std::time::Instant::now(),
             resolver: Self::create_resolver(ns_addr, iface),
-        })
+        }
     }
 
     // return if the record is updated
-    pub fn refresh(&mut self) -> Result<bool, TransportError> {
+    pub fn refresh(&mut self) -> Result<bool, DnsError> {
         if self.last_checked.elapsed() < Duration::from_secs(30) {
             Ok(false)
         } else {
             // when error occurs, update the record in a best-effort way
-            let addr = crate::platform::get_iface_address(&self.iface)?;
+            let addr = crate::platform::get_iface_address(&self.iface)
+                .map_err(|_| DnsError::DhcpNameServer("failed to get iface address"))?;
             if addr != self.iface_addr {
                 let new_dns = crate::platform::dhcp::get_dhcp_dns(&self.iface)?;
                 self.iface_addr = addr;
@@ -241,8 +249,8 @@ impl<T> AuxiliaryResolver<T> {
         Self::Resolver(resolver)
     }
 
-    pub fn new_dhcp(iface: &str) -> Result<Self, DnsError> {
-        let record = DhcpDnsRecord::new(iface)?;
-        Ok(Self::Dhcp(Mutex::new(record)))
+    pub fn new_dhcp(iface: &str) -> Self {
+        let record = DhcpDnsRecord::new(iface);
+        Self::Dhcp(Mutex::new(record))
     }
 }

boltconn/src/network/dns/ns_policy.rs

@@ -87,7 +87,7 @@ impl NameserverPolicies {
                         }
                     }
                     NameServerConfigEnum::Dhcp(iface) => {
-                        DispatchedDnsResolver::Iface(AuxiliaryResolver::new_dhcp(&iface)?)
+                        DispatchedDnsResolver::Iface(AuxiliaryResolver::new_dhcp(&iface))
                     }
                 };
                 let matcher = m.build();