fix: query host search by email (#15833)

> 📜 Related issue: https://github.com/fleetdm/fleet/issues/15522

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

<!-- Note that API documentation changes are now addressed by the
product design team. -->

- [x] Changes file added for user-visible changes in `changes/` or
`orbit/changes/`.
See [Changes
files](https://fleetdm.com/docs/contributing/committing-changes#changes-files)
for more information.
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [x] Added/updated tests
- [x] Manual QA for all new/changed functionality

changes/15522-query-host-search

@@ -0,0 +1 @@
+- Fixes bug in searching for hosts by email addresses.

server/datastore/mysql/hosts.go

@@ -2369,7 +2369,7 @@ func (ds *Datastore) SearchHosts(ctx context.Context, filter fleet.TeamFilter, m
 	if len(matchQuery) > 0 {
 		// first we'll find the hosts that match the search criteria, to keep thing simple, then we'll query again
 		// to get all the additional data for hosts that match the search criteria by host_id
-		matchingHosts := "SELECT id FROM hosts WHERE TRUE"
+		matchingHosts := "SELECT h.id FROM hosts h WHERE TRUE"
 		var args []interface{}
 		// TODO: should search columns include display_name (requires join to host_display_names)?
 		searchHostsQuery, args, matchesEmail := hostSearchLike(matchingHosts, args, matchQuery, hostSearchColumns...)

server/datastore/mysql/hosts_test.go

@@ -1763,6 +1763,15 @@ func testHostsSearch(t *testing.T, ds *Datastore) {
 	require.NoError(t, err)
 	assert.Len(t, hits, 3)
 	assert.Equal(t, []uint{h3.ID, h2.ID, h1.ID}, []uint{hits[0].ID, hits[1].ID, hits[2].ID})
+
+	// Add email to mapping table
+	_, err = ds.writer(context.Background()).ExecContext(context.Background(), `INSERT INTO host_emails (host_id, email, source) VALUES (?, ?, ?)`,
+		hosts[0].ID, "a@b.c", "src1")
+	require.NoError(t, err)
+	// Verify search works
+	hits, err = ds.SearchHosts(context.Background(), filter, "a@b.c")
+	require.NoError(t, err)
+	assert.Len(t, hits, 1)
 }
 
 func testSearchHostsWildCards(t *testing.T, ds *Datastore) {

server/datastore/mysql/mysql.go

@@ -1118,6 +1118,8 @@ var (
 	nonacsiiReplace = regexp.MustCompile(`[^[:ascii:]]`)
 )
 
+// hostSearchLike searches hosts based on the given columns plus searching in hosts_emails. Note:
+// the host from the `hosts` table must be aliased to `h` in `sql`.
 func hostSearchLike(sql string, params []interface{}, match string, columns ...string) (string, []interface{}, bool) {
 	var matchesEmail bool
 	base, args := searchLike(sql, params, match, columns...)

server/service/integration_core_test.go

@@ -6232,6 +6232,22 @@ func (s *integrationTestSuite) TestSearchHosts() {
 	s.DoJSON("POST", "/api/latest/fleet/hosts/search", searchHostsRequest{MatchQuery: "foo.local0"}, http.StatusOK, &searchResp)
 	require.Len(t, searchResp.Hosts, 1)
 	require.Greater(t, searchResp.Hosts[0].SoftwareUpdatedAt, searchResp.Hosts[0].CreatedAt)
+
+	mysql.ExecAdhocSQL(t, s.ds, func(db sqlx.ExtContext) error {
+		_, err := db.ExecContext(
+			context.Background(),
+			`INSERT INTO host_emails (host_id, email, source) VALUES (?, ?, ?)`,
+			hosts[0].ID, "a@b.c", "src1")
+
+		return err
+	})
+
+	s.DoJSON("POST", "/api/latest/fleet/hosts/search", searchHostsRequest{MatchQuery: "a@b.c"}, http.StatusOK, &searchResp)
+	require.Len(t, searchResp.Hosts, 1)
+
+	// search for non-existent email, shouldn't get anything back
+	s.DoJSON("POST", "/api/latest/fleet/hosts/search", searchHostsRequest{MatchQuery: "not@found.com"}, http.StatusOK, &searchResp)
+	require.Len(t, searchResp.Hosts, 0)
 }
 
 func (s *integrationTestSuite) TestCountTargets() {