Add mg_json_get_hex(), mg_json_get_b64()

docs/README.md

@@ -2846,6 +2846,58 @@ char *str = mg_json_get_str(json, "$.a");        // str = "hi"
 free(str);
 ```
 
+### mg\_json\_get\_hex()
+
+```c
+char *mg_json_get_hex(struct mg_str json, const char *path, int *len);
+```
+
+Fetch hex-encoded buffer from the json string `json` at JSON path
+`path`. If found, a buffer is allocated using `calloc()`, decoded,
+and returned to the caller. It is the caller's responsibility to
+`free()` the returned string. Returned buffer is 0-terminated.
+
+Parameters:
+- `json` - a string containing valid JSON
+- `path` - a JSON path. Must start with `$`
+- `len` - a pointer that receives decoded length. Can be NULL
+
+Return value: non-NULL on success, NULL on error
+
+Usage example:
+
+```c
+struct mg_str json = mg_str("{\"a\": \"6869\"}"); // json = {"a": "6869"}
+char *str = mg_json_get_hex(json, "$.a", NULL);   // str = "hi"
+free(str);
+```
+
+### mg\_json\_get\_b64()
+
+```c
+char *mg_json_get_b4(struct mg_str json, const char *path, int *len);
+```
+
+Fetch base64-encoded buffer from the json string `json` at JSON path
+`path`. If found, a buffer is allocated using `calloc()`, decoded,
+and returned to the caller. It is the caller's responsibility to
+`free()` the returned string. Returned buffer is 0-terminated.
+
+Parameters:
+- `json` - a string containing valid JSON
+- `path` - a JSON path. Must start with `$`
+- `len` - a pointer that receives decoded length. Can be NULL
+
+Return value: non-NULL on success, NULL on error
+
+Usage example:
+
+```c
+struct mg_str json = mg_str("{\"a\": \"YWJj\"}"); // json = {"a": "YWJj"}
+char *str = mg_json_get_b64(json, "$.a", NULL);   // str = "abc"
+free(str);
+```
+
 ## Utility
 
 ### mg\_call()

mongoose.c

@@ -2026,6 +2026,7 @@ void mg_iobuf_free(struct mg_iobuf *io) {
 #endif
 
 
+
 static const char *escapeseq(int esc) {
   return esc ? "\b\f\n\r\t\\\"" : "bfnrt\\\"";
 }
@@ -2246,6 +2247,31 @@ char *mg_json_get_str(struct mg_str json, const char *path) {
   return result;
 }
 
+char *mg_json_get_b64(struct mg_str json, const char *path, int *len) {
+  int n, toklen;
+  char *result = NULL;
+  if ((n = mg_json_get(json.ptr, (int) json.len, path, &toklen)) >= 0 &&
+      json.ptr[n] == '"' && toklen > 1 &&
+      (result = (char *) calloc(1, (size_t) toklen)) != NULL) {
+    int k = mg_base64_decode(json.ptr + n + 1, toklen - 2, result);
+    if (len != NULL) *len = k;
+  }
+  return result;
+}
+
+char *mg_json_get_hex(struct mg_str json, const char *path, int *len) {
+  int n, toklen;
+  char *result = NULL;
+  if ((n = mg_json_get(json.ptr, (int) json.len, path, &toklen)) >= 0 &&
+      json.ptr[n] == '"' && toklen > 1 &&
+      (result = (char *) calloc(1, (size_t) toklen / 2)) != NULL) {
+    mg_unhex(json.ptr + n + 1, (size_t) (toklen - 2), (uint8_t *) result);
+    result[(toklen - 2) / 2] = '\0';
+    if (len != NULL) *len = (toklen - 2) / 2;
+  }
+  return result;
+}
+
 #ifdef MG_ENABLE_LINES
 #line 1 "src/log.c"
 #endif

mongoose.h

@@ -1310,7 +1310,8 @@ int mg_json_get(const char *buf, int len, const char *path, int *toklen);
 bool mg_json_get_num(struct mg_str json, const char *path, double *v);
 bool mg_json_get_bool(struct mg_str json, const char *path, bool *v);
 char *mg_json_get_str(struct mg_str json, const char *path);
-char *mg_json_get_hex(struct mg_str json, const char *path);
+char *mg_json_get_hex(struct mg_str json, const char *path, int *len);
+char *mg_json_get_b64(struct mg_str json, const char *path, int *len);
 
 
 

src/json.c

@@ -1,4 +1,5 @@
 #include "json.h"
+#include "base64.h"
 
 static const char *escapeseq(int esc) {
   return esc ? "\b\f\n\r\t\\\"" : "bfnrt\\\"";
@@ -219,3 +220,28 @@ char *mg_json_get_str(struct mg_str json, const char *path) {
   }
   return result;
 }
+
+char *mg_json_get_b64(struct mg_str json, const char *path, int *len) {
+  int n, toklen;
+  char *result = NULL;
+  if ((n = mg_json_get(json.ptr, (int) json.len, path, &toklen)) >= 0 &&
+      json.ptr[n] == '"' && toklen > 1 &&
+      (result = (char *) calloc(1, (size_t) toklen)) != NULL) {
+    int k = mg_base64_decode(json.ptr + n + 1, toklen - 2, result);
+    if (len != NULL) *len = k;
+  }
+  return result;
+}
+
+char *mg_json_get_hex(struct mg_str json, const char *path, int *len) {
+  int n, toklen;
+  char *result = NULL;
+  if ((n = mg_json_get(json.ptr, (int) json.len, path, &toklen)) >= 0 &&
+      json.ptr[n] == '"' && toklen > 1 &&
+      (result = (char *) calloc(1, (size_t) toklen / 2)) != NULL) {
+    mg_unhex(json.ptr + n + 1, (size_t) (toklen - 2), (uint8_t *) result);
+    result[(toklen - 2) / 2] = '\0';
+    if (len != NULL) *len = (toklen - 2) / 2;
+  }
+  return result;
+}

src/json.h

@@ -14,4 +14,5 @@ int mg_json_get(const char *buf, int len, const char *path, int *toklen);
 bool mg_json_get_num(struct mg_str json, const char *path, double *v);
 bool mg_json_get_bool(struct mg_str json, const char *path, bool *v);
 char *mg_json_get_str(struct mg_str json, const char *path);
-char *mg_json_get_hex(struct mg_str json, const char *path);
+char *mg_json_get_hex(struct mg_str json, const char *path, int *len);
+char *mg_json_get_b64(struct mg_str json, const char *path, int *len);

test/unit_test.c

@@ -2363,6 +2363,7 @@ static void test_json(void) {
   {
     double d = 0;
     bool b = false;
+    int len;
     const char *json = "{\"a\": \"hi\\nthere\",\"b\": [12345, true]}";
     char *str = mg_json_get_str(mg_str(json), "$.a");
 
@@ -2379,6 +2380,14 @@ static void test_json(void) {
     ASSERT(mg_json_get_bool(mg_str(json), "$.b[0]", &b) == false);
     ASSERT(mg_json_get_bool(mg_str(json), "$.b[1]", &b) == true);
     ASSERT(b == true);
+
+    json = "[\"YWJj\", \"0100026869\"]";
+    ASSERT((str = mg_json_get_b64(mg_str(json), "$[0]", &len)) != NULL);
+    ASSERT(len == 3 && memcmp(str, "abc", (size_t) len) == 0);
+    free(str);
+    ASSERT((str = mg_json_get_hex(mg_str(json), "$[1]", &len)) != NULL);
+    ASSERT(len == 5 && memcmp(str, "\x01\x00\x02hi", (size_t) len) == 0);
+    free(str);
   }
 }