fix(NIP-12): only allow single-char tag filters

src/db.rs

@@ -384,11 +384,23 @@ fn query_from_filter(f: &ReqFilter) -> (String, Vec<Box<dyn ToSql>>) {
     // (sqli-safe), or a string that is filtered to only contain
     // hexadecimal characters.  Strings that require escaping (tag
     // names/values) use parameters.
+
+    // if the filter is malformed, don't return anything.
+    if f.force_no_match {
+        let empty_query =
+            "SELECT DISTINCT(e.content), e.created_at FROM event e LEFT JOIN tag t ON e.id=t.event_id WHERE 1=0"
+            .to_owned();
+        // query parameters for SQLite
+        let empty_params: Vec<Box<dyn ToSql>> = vec![];
+        return (empty_query, empty_params);
+    }
+
     let mut query =
         "SELECT DISTINCT(e.content), e.created_at FROM event e LEFT JOIN tag t ON e.id=t.event_id "
             .to_owned();
     // query parameters for SQLite
     let mut params: Vec<Box<dyn ToSql>> = vec![];
+
     // individual filter components (single conditions such as an author or event ID)
     let mut filter_components: Vec<String> = Vec::new();
     // Query for "authors", allowing prefix matches
@@ -471,7 +483,7 @@ fn query_from_filter(f: &ReqFilter) -> (String, Vec<Box<dyn ToSql>>) {
             let blob_clause = format!("value_hex IN ({})", repeat_vars(blob_vals.len()));
             let tag_clause = format!("(name=? AND ({} OR {}))", str_clause, blob_clause);
             // add the tag name as the first parameter
-            params.push(Box::new(key.to_owned()));
+            params.push(Box::new(key.to_string()));
             // add all tag values that are plain strings as params
             params.append(&mut str_vals);
             // add all tag values that are blobs as params

src/event.rs

@@ -39,9 +39,9 @@ pub struct Event {
     pub(crate) tags: Vec<Vec<String>>,
     pub(crate) content: String,
     pub(crate) sig: String,
-    // Optimization for tag search, built on demand
+    // Optimization for tag search, built on demand.
     #[serde(skip)]
-    pub(crate) tagidx: Option<HashMap<String, HashSet<String>>>,
+    pub(crate) tagidx: Option<HashMap<char, HashSet<String>>>,
 }
 
 /// Simple tag type for array of array of strings.
@@ -56,6 +56,25 @@ where
     Ok(opt.unwrap_or_else(Vec::new))
 }
 
+/// Attempt to form a single-char tag name.
+fn single_char_tagname(tagname: &str) -> Option<char> {
+    // We return the tag character if and only if the tagname consists
+    // of a single char.
+    let mut tagnamechars = tagname.chars();
+    let firstchar = tagnamechars.next();
+    return match firstchar {
+        Some(_) => {
+            // check second char
+            if tagnamechars.next().is_none() {
+                firstchar
+            } else {
+                None
+            }
+        }
+        None => None,
+    };
+}
+
 /// Convert network event to parsed/validated event.
 impl From<EventCmd> for Result<Event> {
     fn from(ec: EventCmd) -> Result<Event> {
@@ -99,17 +118,22 @@ impl Event {
             return;
         }
         // otherwise, build an index
-        let mut idx: HashMap<String, HashSet<String>> = HashMap::new();
+        let mut idx: HashMap<char, HashSet<String>> = HashMap::new();
         // iterate over tags that have at least 2 elements
         for t in self.tags.iter().filter(|x| x.len() > 1) {
             let tagname = t.get(0).unwrap();
+            let tagnamechar_opt = single_char_tagname(tagname);
+            if tagnamechar_opt.is_none() {
+                continue;
+            }
+            let tagnamechar = tagnamechar_opt.unwrap();
             let tagval = t.get(1).unwrap();
             // ensure a vector exists for this tag
-            if !idx.contains_key(tagname) {
-                idx.insert(tagname.clone(), HashSet::new());
+            if !idx.contains_key(&tagnamechar) {
+                idx.insert(tagnamechar.clone(), HashSet::new());
             }
             // get the tag vec and insert entry
-            let tidx = idx.get_mut(tagname).expect("could not get tag vector");
+            let tidx = idx.get_mut(&tagnamechar).expect("could not get tag vector");
             tidx.insert(tagval.clone());
         }
         // save the tag structure
@@ -226,9 +250,10 @@ impl Event {
     }
 
     /// Determine if the given tag and value set intersect with tags in this event.
-    pub fn generic_tag_val_intersect(&self, tagname: &str, check: &HashSet<String>) -> bool {
+    pub fn generic_tag_val_intersect(&self, tagname: char, check: &HashSet<String>) -> bool {
         match &self.tagidx {
-            Some(idx) => match idx.get(tagname) {
+            // check if this is indexable tagname
+            Some(idx) => match idx.get(&tagname) {
                 Some(valset) => {
                     let common = valset.intersection(check);
                     common.count() > 0

src/subscription.rs

@@ -1,6 +1,7 @@
 //! Subscription and filter parsing
 use crate::error::Result;
 use crate::event::Event;
+use log::*;
 use serde::de::Unexpected;
 use serde::{Deserialize, Deserializer, Serialize};
 use serde_json::Value;
@@ -35,7 +36,9 @@ pub struct ReqFilter {
     pub limit: Option<u64>,
     /// Set of tags
     #[serde(skip)]
-    pub tags: Option<HashMap<String, HashSet<String>>>,
+    pub tags: Option<HashMap<char, HashSet<String>>>,
+    /// Force no matches due to malformed data
+    pub force_no_match: bool,
 }
 
 impl<'de> Deserialize<'de> for ReqFilter {
@@ -58,6 +61,7 @@ impl<'de> Deserialize<'de> for ReqFilter {
             authors: None,
             limit: None,
             tags: None,
+            force_no_match: false,
         };
         let mut ts = None;
         // iterate through each key, and assign values that exist
@@ -76,8 +80,9 @@ impl<'de> Deserialize<'de> for ReqFilter {
             } else if key == "authors" {
                 rf.authors = Deserialize::deserialize(val).ok();
             } else if key.starts_with('#') && key.len() > 1 && val.is_array() {
-                // remove the prefix
-                let tagname = &key[1..];
+                info!("testing tag search char: {}", key);
+                if let Some(tag_search) = tag_search_char_from_filter(key) {
+                    info!("found a character from the tag search: {}", tag_search);
                     if ts.is_none() {
                         // Initialize the tag if necessary
                         ts = Some(HashMap::new());
@@ -86,9 +91,14 @@ impl<'de> Deserialize<'de> for ReqFilter {
                         let tag_vals: Option<Vec<String>> = Deserialize::deserialize(val).ok();
                         if let Some(v) = tag_vals {
                             let hs = HashSet::from_iter(v.into_iter());
-                        m.insert(tagname.to_owned(), hs);
+                            m.insert(tag_search.to_owned(), hs);
                         }
                     };
+                } else {
+                    // tag search that is multi-character, don't add to subscription
+                    rf.force_no_match = true;
+                    continue;
+                }
             }
         }
         rf.tags = ts;
@@ -96,6 +106,26 @@ impl<'de> Deserialize<'de> for ReqFilter {
     }
 }
 
+/// Attempt to form a single-char identifier from a tag search filter
+fn tag_search_char_from_filter(tagname: &str) -> Option<char> {
+    let tagname_nohash = &tagname[1..];
+    // We return the tag character if and only if the tagname consists
+    // of a single char.
+    let mut tagnamechars = tagname_nohash.chars();
+    let firstchar = tagnamechars.next();
+    return match firstchar {
+        Some(_) => {
+            // check second char
+            if tagnamechars.next().is_none() {
+                firstchar
+            } else {
+                None
+            }
+        }
+        None => None,
+    };
+}
+
 impl<'de> Deserialize<'de> for Subscription {
     /// Custom deserializer for subscriptions, which have a more
     /// complex structure than the other message types.
@@ -194,7 +224,7 @@ impl ReqFilter {
         // get the hashset from the filter.
         if let Some(map) = &self.tags {
             for (key, val) in map.iter() {
-                let tag_match = event.generic_tag_val_intersect(key, val);
+                let tag_match = event.generic_tag_val_intersect(*key, val);
                 // if there is no match for this tag, the match fails.
                 if !tag_match {
                     return false;
@@ -223,6 +253,7 @@ impl ReqFilter {
             && self.kind_match(event.kind)
             && self.authors_match(event)
             && self.tag_match(event)
+            && !self.force_no_match
     }
 }