feat: add http header param getter

include/lnm/common.h

@@ -97,4 +97,16 @@ uint64_t lnm_digits(uint64_t num);
  */
 bool lnm_is_ascii(const char *s);
 
+/**
+ * Find the first case-insensitive occurence of s2 in s1.
+ *
+ * @param s1 pointer to string to look in
+ * @param s1_len length of s1
+ * @param s2 string to search for in s1
+ * @param s2_len length of s2
+ * @return pointer to start of matched string if found, or NULL otherwise
+ */
+const char *lnm_stristr(const char *s1, size_t s1_len, const char *s2,
+                        size_t s2_len);
+
 #endif

include/lnm/http/req.h

@@ -135,20 +135,6 @@ lnm_err lnm_http_req_header_get_s(lnm_http_req_hdr *out, lnm_http_req *req,
 size_t lnm_http_req_route_segment(const char **out, lnm_http_req *req,
                                   const char *key);
 
-/**
- * Represents a parameter in an HTTP header.
- */
-typedef struct lnm_http_req_hdr_param {
-  struct {
-    const char *s;
-    size_t len;
-  } key;
-  struct {
-    const char *s;
-    size_t len;
-  } value;
-} lnm_http_req_hdr_param;
-
 /**
  * Retrieve a specific key-value parameter from a header.
  *
@@ -159,7 +145,7 @@ typedef struct lnm_http_req_hdr_param {
  * @param header header to look in
  * @param key name of the parameter to return from the header
  */
-lnm_err lnm_http_req_header_param(lnm_http_req_hdr_param *param,
+size_t lnm_http_req_header_param(const char **out,
                                  const lnm_http_req_hdr *header,
                                  const char *key);
 

src/lnm/http/lnm_http_req.c

@@ -129,3 +129,50 @@ size_t lnm_http_req_route_segment(const char **out, lnm_http_req *req,
 
   return segment->len;
 }
+
+size_t lnm_http_req_header_param(const char **out,
+                                 const lnm_http_req_hdr *header,
+                                 const char *key) {
+  size_t key_len = strlen(key);
+  size_t remaining_len = header->value.len;
+
+  // The -1 ensures there's still space for an equals sign after the match
+  const char *s = lnm_stristr(header->value.s, remaining_len - 1, key, key_len);
+
+  // Skip any accidental matches of the key inside another part of the value
+  while (s != NULL && s[key_len] != '=') {
+    remaining_len -= key_len;
+    s = lnm_stristr(s + key_len, remaining_len - 1, key, key_len);
+  };
+
+  // Edge case where empty value is at the end of the string
+  if (s == NULL || s + 2 == header->value.s + header->value.len) {
+    return 0;
+  }
+
+  *out = s + 2;
+  const char *value_end = s + 2;
+
+  // Handle a quoted string
+  if (**out == '"') {
+    value_end++;
+    while (value_end < header->value.s + header->value.len &&
+           (*value_end != '"')) {
+      value_end++;
+    }
+
+    // If we found a matching quote we trim the quotes, otherwise the quote is
+    // part of the value
+    if (value_end < header->value.s + header->value.len) {
+      // We skip the initial quote
+      (*out)++;
+    }
+  } else {
+    while (value_end < header->value.s + header->value.len &&
+           (*value_end != ',') && (*value_end != ';')) {
+      value_end++;
+    }
+  }
+
+  return value_end - *out;
+}

src/lnm/lnm_utils.c

@@ -67,3 +67,17 @@ bool lnm_is_ascii(const char *s) {
 
   return valid;
 }
+
+const char *lnm_stristr(const char *s1, size_t s1_len, const char *s2,
+                        size_t s2_len) {
+  while (s1_len >= s2_len) {
+    if (lnm_strnieq(s1, s1_len, s2, s2_len)) {
+      return s1;
+    }
+
+    s1_len--;
+    s1++;
+  }
+
+  return NULL;
+}