A PoC of http+unix:// support in the Tarantool http client

http_unix_sock.diff

diff --git a/src/httpc.c b/src/httpc.c
index 84ea67aba..cecf30712 100644
--- a/src/httpc.c
+++ b/src/httpc.c
@@ -36,6 +36,33 @@
 
 #include "fiber.h"
 
+int ishex(int x)
+{
+    return	(x >= '0' && x <= '9')	||
+        (x >= 'a' && x <= 'f')	||
+        (x >= 'A' && x <= 'F');
+}
+
+int urldecode(const char *s, char *dec)
+{
+    char *o;
+    const char *end = s + strlen(s);
+    int c;
+
+    for (o = dec; s <= end; o++) {
+        c = *s++;
+        if (c == '+') c = ' ';
+        else if (c == '%' && (	!ishex(*s++)	||
+                    !ishex(*s++)	||
+                    !sscanf(s - 2, "%2x", &c)))
+            return -1;
+
+        if (dec) *o = c;
+    }
+
+    return o - dec;
+}
+
 /**
  * libcurl callback for CURLOPT_WRITEFUNCTION
  * @see https://curl.haxx.se/libcurl/c/CURLOPT_WRITEFUNCTION.html
@@ -134,7 +161,38 @@ httpc_request_new(struct httpc_env *env, const char *method,
         curl_easy_setopt(req->curl_request.easy, CURLOPT_CUSTOMREQUEST, method);
     }
 
+    if (strncmp(url, "http+unix://", 12) == 0) {
+      char http_url[256];
+      char encoded_socket_path[256];
+      char socket_path[256];
+
+
+      const char* beginning_of_socket_path = url + 12;
+
+      const char* slash = strchr(beginning_of_socket_path, '/');
+      const char* rest = 0;
+
+      if (slash != NULL) {
+        rest = slash;
+      }
+      else {
+        rest = url + strlen(url);
+      }
+
+      strncpy(encoded_socket_path,
+              beginning_of_socket_path,
+              rest - (beginning_of_socket_path));
+
+
+      urldecode(encoded_socket_path, socket_path);
+      sprintf(http_url, "http://localhost%s", rest);
+
+      curl_easy_setopt(req->curl_request.easy, CURLOPT_UNIX_SOCKET_PATH, socket_path);
+      curl_easy_setopt(req->curl_request.easy, CURLOPT_URL, http_url);
+    }
+    else {
       curl_easy_setopt(req->curl_request.easy, CURLOPT_URL, url);
+    }
 
     curl_easy_setopt(req->curl_request.easy, CURLOPT_FOLLOWLOCATION, 1);
     curl_easy_setopt(req->curl_request.easy, CURLOPT_SSL_VERIFYPEER, 1);