Add ability to retrieve a list of strings.

This adds the ability to retrieve a list of strings from a SciToken
claim; this is envisioned to be useful for things like lists of
groups from the WLCG.

Author: bbockelm

src/scitokens.cpp

@@ -104,6 +104,68 @@ int scitoken_get_claim_string(const SciToken token, const char *key, char **valu
 }
 
 
+int scitoken_set_claim_string_list(const SciToken token, const char *key,
+    const char **value, char **err_msg)
+{
+    auto real_token = reinterpret_cast<scitokens::SciToken*>(token);
+    if (real_token == nullptr) {
+        if (err_msg) *err_msg = strdup("NULL scitoken passed to scitoken_get_claim_string_list");
+        return -1;
+    }
+    std::vector<std::string> claim_list;
+    int idx = 0;
+    while (value[idx++]) {}
+    claim_list.reserve(idx);
+
+    idx = 0;
+    while (value[idx++]) {
+        claim_list.emplace_back(value[idx-1]);
+    }
+    real_token->set_claim_list(key, claim_list);
+
+    return 0;
+}
+
+
+int scitoken_get_claim_string_list(const SciToken token, const char *key, char ***value, char **err_msg) {
+    auto real_token = reinterpret_cast<scitokens::SciToken*>(token);
+    if (real_token == nullptr) {
+        if (err_msg) *err_msg = strdup("NULL scitoken passed to scitoken_get_claim_string_list");
+        return -1;
+    }
+    std::vector<std::string> claim_list;
+    try {
+        claim_list = real_token->get_claim_list(key);
+    } catch (std::exception &exc) {
+        if (err_msg) {*err_msg = strdup(exc.what());}
+        return -1;
+    }
+    auto claim_list_c = static_cast<char **>(malloc(sizeof(char **) * (claim_list.size() + 1)));
+    claim_list_c[claim_list.size()] = nullptr;
+    int idx = 0;
+    for (const auto &entry : claim_list) {
+        claim_list_c[idx] = strdup(entry.c_str());
+        if (!claim_list_c[idx]) {
+            scitoken_free_string_list(claim_list_c);
+            if (err_msg) {*err_msg = strdup("Failed to create a copy of string entry in list");}
+            return -1;
+        }
+        idx++;
+    }
+    *value = claim_list_c;
+    return 0;
+}
+
+
+void scitoken_free_string_list(char **value) {
+    int idx = 0;
+    do {
+        free(value[idx++]);
+    } while (value[idx]);
+    free(value);
+}
+
+
 int scitoken_get_expiration(const SciToken token, long long *expiry, char **err_msg) {
     scitokens::SciToken *real_token = reinterpret_cast<scitokens::SciToken*>(token);
     if (!real_token->has_claim("exp")) {

src/scitokens.h

@@ -47,6 +47,27 @@ int scitoken_set_claim_string(SciToken token, const char *key, const char *value
 
 int scitoken_get_claim_string(const SciToken token, const char *key, char **value, char **err_msg);
 
+/**
+ * Given a SciToken object, parse a specific claim's value as a list of strings.  If the JSON value
+ * is not actually a list of strings - or the claim is not set - returns an error and sets the
+ * err_msg appropriately.
+ *
+ * The returned value is a list of strings that ends with a nullptr.
+ */
+int scitoken_get_claim_string_list(const SciToken token, const char *key, char ***value, char **err_msg);
+
+/**
+ * Given a list of strings that was returned by scitoken_get_claim_string_list, free all the associated
+ * memory.
+ */
+void scitoken_free_string_list(char **value);
+
+/**
+ * Set the value of a claim to a list of strings.
+ */
+int scitoken_set_claim_string_list(const SciToken token, const char *key,
+    const char **values, char **err_msg);
+
 int scitoken_get_expiration(const SciToken token, long long *value, char **err_msg);
 
 void scitoken_set_lifetime(SciToken token, int lifetime);

src/scitokens_internal.h

@@ -149,6 +149,16 @@ friend class scitokens::Validator;
         return m_claims.find(key) != m_claims.end();
     }
 
+    void
+    set_claim_list(const std::string &claim, std::vector<std::string> &claim_list) {
+        picojson::array array;
+        array.reserve(claim_list.size());
+        for (const auto &entry : claim_list) {
+            array.emplace_back(entry);
+        }
+        m_claims[claim] = jwt::claim(picojson::value(array));
+    }
+
     // Return a claim as a string
     // If the claim is not a string, it can throw
     // a std::bad_cast() exception.
@@ -157,6 +167,21 @@ friend class scitokens::Validator;
         return m_claims[key].as_string();
     }
 
+    const std::vector<std::string>
+    get_claim_list(const std::string &key) {
+        picojson::array array;
+        try {
+            array = m_claims[key].as_array();
+        } catch (std::bad_cast &) {
+            throw JsonException("Claim's value is not a JSON list");
+        }
+       std::vector<std::string> result;
+       for (const auto &value : array) {
+           result.emplace_back(value.get<std::string>());
+       }
+       return result;
+    }
+
     void
     set_lifetime(int lifetime) {
         m_lifetime = lifetime;