[common] remove From<Ip*Addr> for IpNet impls (#5711)

Closes #5687.

Author: sunshowers

common/src/api/external/mod.rs

@@ -1234,6 +1234,13 @@ impl DiskState {
 pub struct Ipv4Net(pub ipnetwork::Ipv4Network);
 
 impl Ipv4Net {
+    /// Constructs a new `Ipv4Net` representing a single IP.
+    pub fn single(ip: Ipv4Addr) -> Self {
+        Ipv4Net(
+            ipnetwork::Ipv4Network::new(ip, 32).expect("32 is within range"),
+        )
+    }
+
     /// Return `true` if this IPv4 subnetwork is from an RFC 1918 private
     /// address space.
     pub fn is_private(&self) -> bool {
@@ -1301,6 +1308,13 @@ impl Ipv6Net {
     /// The prefix length for all VPC Sunets
     pub const VPC_SUBNET_IPV6_PREFIX_LENGTH: u8 = 64;
 
+    /// Constructs a new `Ipv6Net` representing a single IPv6 address.
+    pub fn single(ip: Ipv6Addr) -> Self {
+        Ipv6Net(
+            ipnetwork::Ipv6Network::new(ip, 128).expect("128 is within range"),
+        )
+    }
+
     /// Return `true` if this subnetwork is in the IPv6 Unique Local Address
     /// range defined in RFC 4193, e.g., `fd00:/8`
     pub fn is_unique_local(&self) -> bool {
@@ -1436,6 +1450,14 @@ pub enum IpNet {
 }
 
 impl IpNet {
+    /// Constructs a new `IpNet` representing a single IP.
+    pub fn single(ip: IpAddr) -> Self {
+        match ip {
+            IpAddr::V4(ip) => IpNet::V4(Ipv4Net::single(ip)),
+            IpAddr::V6(ip) => IpNet::V6(Ipv6Net::single(ip)),
+        }
+    }
+
     /// Return the underlying address.
     pub fn ip(&self) -> IpAddr {
         match self {
@@ -1508,39 +1530,22 @@ impl From<ipnetwork::IpNetwork> for IpNet {
     }
 }
 
+// NOTE: We deliberately do *NOT* implement `From<Ip{v4,v6,}Addr> for IpNet`.
+// This is because there are many ways to convert an address into a network.
+// See https://github.com/oxidecomputer/omicron/issues/5687.
+
 impl From<Ipv4Net> for IpNet {
     fn from(n: Ipv4Net) -> IpNet {
         IpNet::V4(n)
     }
 }
 
-impl From<Ipv4Addr> for IpNet {
-    fn from(n: Ipv4Addr) -> IpNet {
-        IpNet::V4(Ipv4Net(ipnetwork::Ipv4Network::from(n)))
-    }
-}
-
 impl From<Ipv6Net> for IpNet {
     fn from(n: Ipv6Net) -> IpNet {
         IpNet::V6(n)
     }
 }
 
-impl From<Ipv6Addr> for IpNet {
-    fn from(n: Ipv6Addr) -> IpNet {
-        IpNet::V6(Ipv6Net(ipnetwork::Ipv6Network::from(n)))
-    }
-}
-
-impl From<IpAddr> for IpNet {
-    fn from(n: IpAddr) -> IpNet {
-        match n {
-            IpAddr::V4(v4) => IpNet::from(v4),
-            IpAddr::V6(v6) => IpNet::from(v6),
-        }
-    }
-}
-
 impl std::fmt::Display for IpNet {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {

common/src/api/internal/shared.rs

@@ -608,7 +608,7 @@ mod tests {
         assert_eq!(
             parsed,
             AllowedSourceIps::try_from(vec![
-                IpNet::from(Ipv4Addr::LOCALHOST),
+                IpNet::V4(Ipv4Net::single(Ipv4Addr::LOCALHOST)),
                 IpNet::V4(Ipv4Net(
                     Ipv4Network::new(Ipv4Addr::new(10, 0, 0, 0), 24).unwrap()
                 )),

nexus/networking/src/firewall_rules.rs

@@ -353,7 +353,7 @@ pub async fn resolve_firewall_rules_for_sled_agent(
                                 .unwrap_or(&no_interfaces)
                             {
                                 host_addrs.push(
-                                    HostIdentifier::Ip(IpNet::from(
+                                    HostIdentifier::Ip(IpNet::single(
                                         interface.ip,
                                     ))
                                     .into(),
@@ -373,7 +373,7 @@ pub async fn resolve_firewall_rules_for_sled_agent(
                         }
                         external::VpcFirewallRuleHostFilter::Ip(addr) => {
                             host_addrs.push(
-                                HostIdentifier::Ip(IpNet::from(*addr)).into(),
+                                HostIdentifier::Ip(IpNet::single(*addr)).into(),
                             )
                         }
                         external::VpcFirewallRuleHostFilter::IpNet(net) => {

nexus/tests/integration_tests/allow_list.rs

@@ -9,6 +9,7 @@ use nexus_test_utils::http_testing::{AuthnMode, NexusRequest};
 use nexus_test_utils_macros::nexus_test;
 use nexus_types::external_api::{params, views};
 use omicron_common::api::external::AllowedSourceIps;
+use omicron_common::api::external::IpNet;
 use std::net::IpAddr;
 use std::net::Ipv4Addr;
 
@@ -74,16 +75,18 @@ async fn test_allow_list(cptestctx: &ControlPlaneTestContext) {
     }
 
     // Set the list with exactly one IP, make sure it's the same.
-    let allowed_ips = AllowedSourceIps::try_from(vec![our_addr.into()])
+    let allowed_ips = AllowedSourceIps::try_from(vec![IpNet::single(our_addr)])
         .expect("Expected a valid IP list");
     update_list_and_compare(client, allowed_ips).await;
 
     // Add our IP in the front and end, and still make sure that works.
     //
     // This is a regression for
     // https://github.com/oxidecomputer/omicron/issues/5727.
-    let addrs =
-        vec![our_addr.into(), IpAddr::V4(Ipv4Addr::new(10, 0, 0, 1)).into()];
+    let addrs = vec![
+        IpNet::single(our_addr),
+        IpNet::single(IpAddr::V4(Ipv4Addr::new(10, 0, 0, 1))),
+    ];
     let allowed_ips = AllowedSourceIps::try_from(addrs.clone())
         .expect("Expected a valid IP list");
     update_list_and_compare(client, allowed_ips).await;
@@ -98,7 +101,7 @@ async fn test_allow_list(cptestctx: &ControlPlaneTestContext) {
 
     // Check that we cannot make the request with a list that doesn't include
     // us.
-    let addrs = vec![IpAddr::V4(Ipv4Addr::new(1, 1, 1, 1)).into()];
+    let addrs = vec![IpNet::single(IpAddr::V4(Ipv4Addr::new(1, 1, 1, 1)))];
     let allowed_ips = AllowedSourceIps::try_from(addrs.clone())
         .expect("Expected a valid IP list");
     let new_list = params::AllowListUpdate { allowed_ips };