refactor: put HTTP and XML logic into reusable modules

src/Infobox/Dictionary.c

@@ -1,7 +1,8 @@
 #include "Dictionary.h"
 #include "../Cache/Cache.h"
-#include "../Proxy/Proxy.h"
 #include "../Scraping/Scraping.h"
+#include "../Utility/HttpClient.h"
+#include "../Utility/XmlHelper.h"
 #include <ctype.h>
 #include <curl/curl.h>
 #include <libxml/HTMLparser.h>
@@ -52,44 +53,6 @@ static const char *strcasestr_impl(const char *haystack, const char *needle) {
   return NULL;
 }
 
-struct MemStruct {
-  char *memory;
-  size_t size;
-};
-
-static size_t WriteCallback(void *contents, size_t size, size_t nmemb,
-                            void *userp) {
-  size_t realsize = size * nmemb;
-  struct MemStruct *mem = (struct MemStruct *)userp;
-  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
-  if (!ptr)
-    return 0;
-  mem->memory = ptr;
-  memcpy(&(mem->memory[mem->size]), contents, realsize);
-  mem->size += realsize;
-  mem->memory[mem->size] = 0;
-  return realsize;
-}
-
-static char *xpath_text(xmlDocPtr doc, const char *xpath) {
-  xmlXPathContextPtr ctx = xmlXPathNewContext(doc);
-  if (!ctx)
-    return NULL;
-  xmlXPathObjectPtr obj = xmlXPathEvalExpression((const xmlChar *)xpath, ctx);
-  xmlXPathFreeContext(ctx);
-  if (!obj || !obj->nodesetval || obj->nodesetval->nodeNr == 0) {
-    if (obj)
-      xmlXPathFreeObject(obj);
-    return NULL;
-  }
-  xmlChar *content = xmlNodeGetContent(obj->nodesetval->nodeTab[0]);
-  char *result = content ? strdup((char *)content) : NULL;
-  if (content)
-    xmlFree(content);
-  xmlXPathFreeObject(obj);
-  return result;
-}
-
 static char *build_html(const char *word, const char *pron, const char *pos,
                         const char *def, const char *ex) {
   char html[4096];
@@ -240,13 +203,7 @@ char *construct_dictionary_url(const char *query) {
   if (!word)
     return NULL;
 
-  CURL *curl = curl_easy_init();
-  if (!curl) {
-    free(word);
-    return NULL;
-  }
-
-  char *escaped = curl_easy_escape(curl, word, 0);
+  char *escaped = curl_easy_escape(NULL, word, 0);
   const char *base = "https://dictionary.cambridge.org/dictionary/english/";
   char *url = malloc(strlen(base) + strlen(escaped) + 1);
   if (url) {
@@ -255,7 +212,6 @@ char *construct_dictionary_url(const char *query) {
   }
 
   curl_free(escaped);
-  curl_easy_cleanup(curl);
   free(word);
   return url;
 }
@@ -309,28 +265,15 @@ InfoBox fetch_dictionary_data(const char *query) {
   }
   free(cache_key);
 
-  CURL *curl = curl_easy_init();
-  if (!curl) {
-    free(url);
-    return info;
-  }
-
-  struct MemStruct chunk = {malloc(1), 0};
-  curl_easy_setopt(curl, CURLOPT_URL, url);
-  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
-  curl_easy_setopt(curl, CURLOPT_WRITEDATA, &chunk);
-  curl_easy_setopt(curl, CURLOPT_USERAGENT, "Mozilla/5.0");
-  curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
-  apply_proxy_settings(curl);
-
-  if (curl_easy_perform(curl) == CURLE_OK && chunk.size > 0) {
+  HttpResponse resp = http_get(url, "Mozilla/5.0");
+  if (resp.memory && resp.size > 0) {
     cache_key = cache_compute_key(url, 0, "dictionary");
     if (cache_key && get_cache_ttl_infobox() > 0) {
-      cache_set(cache_key, chunk.memory, chunk.size);
+      cache_set(cache_key, resp.memory, resp.size);
     }
     free(cache_key);
 
-    htmlDocPtr doc = htmlReadMemory(chunk.memory, chunk.size, url, NULL,
+    htmlDocPtr doc = htmlReadMemory(resp.memory, resp.size, url, NULL,
                                     HTML_PARSE_RECOVER | HTML_PARSE_NOERROR |
                                         HTML_PARSE_NOWARNING);
     if (doc) {
@@ -358,8 +301,7 @@ InfoBox fetch_dictionary_data(const char *query) {
     }
   }
 
-  curl_easy_cleanup(curl);
-  free(chunk.memory);
+  http_response_free(&resp);
   free(url);
   return info;
 }

src/Infobox/Wikipedia.c

@@ -1,7 +1,7 @@
 #include "Wikipedia.h"
 #include "../Cache/Cache.h"
-#include "../Proxy/Proxy.h"
 #include "../Scraping/Scraping.h"
+#include "../Utility/HttpClient.h"
 #include <curl/curl.h>
 #include <libxml/parser.h>
 #include <libxml/tree.h>
@@ -9,11 +9,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-struct WikiMemoryStruct {
-  char *memory;
-  size_t size;
-};
-
 static void shorten_summary(char **extract_ptr, int max_chars) {
   if (!extract_ptr || !*extract_ptr)
     return;
@@ -43,25 +38,6 @@ static void shorten_summary(char **extract_ptr, int max_chars) {
   }
 }
 
-static size_t WikiWriteMemoryCallback(void *contents, size_t size, size_t nmemb,
-                                      void *userp) {
-  size_t realsize = size * nmemb;
-  struct WikiMemoryStruct *mem = (struct WikiMemoryStruct *)userp;
-
-  char *ptr = realloc(mem->memory, mem->size + realsize + 1);
-  if (ptr == NULL) {
-    fprintf(stderr, "Not enough memory (realloc returned NULL)\n");
-    return 0;
-  }
-
-  mem->memory = ptr;
-  memcpy(&(mem->memory[mem->size]), contents, realsize);
-  mem->size += realsize;
-  mem->memory[mem->size] = 0;
-
-  return realsize;
-}
-
 static void extract_wiki_info(xmlNode *node, InfoBox *info) {
   xmlNode *cur_node = NULL;
 
@@ -113,9 +89,6 @@ static void extract_wiki_info(xmlNode *node, InfoBox *info) {
 }
 
 InfoBox fetch_wiki_data(char *api_url) {
-  CURL *curl_handle;
-  CURLcode res;
-  struct WikiMemoryStruct chunk;
   InfoBox info = {NULL, NULL, NULL, NULL};
 
   if (!api_url) {
@@ -144,47 +117,31 @@ InfoBox fetch_wiki_data(char *api_url) {
   }
   free(cache_key);
 
-  chunk.memory = malloc(1);
-  chunk.size = 0;
-
-  curl_handle = curl_easy_init();
-
-  if (curl_handle) {
-    curl_easy_setopt(curl_handle, CURLOPT_URL, api_url);
-    curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION,
-                     WikiWriteMemoryCallback);
-    curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
-    curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
-    apply_proxy_settings(curl_handle);
-
-    res = curl_easy_perform(curl_handle);
-
-    if (res == CURLE_OK && chunk.size > 0) {
-      cache_key = cache_compute_key(api_url, 0, "wikipedia");
-      if (cache_key && get_cache_ttl_infobox() > 0) {
-        cache_set(cache_key, chunk.memory, chunk.size);
-      }
-      free(cache_key);
-
-      xmlDocPtr doc =
-          xmlReadMemory(chunk.memory, chunk.size, "noname.xml", NULL, 0);
-      if (doc != NULL) {
-        xmlNode *root_element = xmlDocGetRootElement(doc);
-        extract_wiki_info(root_element, &info);
-        xmlFreeDoc(doc);
-      }
+  HttpResponse resp = http_get(api_url, "libcurl-agent/1.0");
+  if (resp.memory && resp.size > 0) {
+    cache_key = cache_compute_key(api_url, 0, "wikipedia");
+    if (cache_key && get_cache_ttl_infobox() > 0) {
+      cache_set(cache_key, resp.memory, resp.size);
     }
+    free(cache_key);
 
-    curl_easy_cleanup(curl_handle);
-    free(chunk.memory);
+    xmlDocPtr doc =
+        xmlReadMemory(resp.memory, resp.size, "noname.xml", NULL, 0);
+    if (doc != NULL) {
+      xmlNode *root_element = xmlDocGetRootElement(doc);
+      extract_wiki_info(root_element, &info);
+      xmlFreeDoc(doc);
+    }
   }
 
+  http_response_free(&resp);
   return info;
 }
 
 static xmlNode *find_node_recursive(xmlNode *node, const char *target_name) {
   for (xmlNode *cur = node; cur; cur = cur->next) {
-    if (cur->type == XML_ELEMENT_NODE && strcmp((const char *)cur->name, target_name) == 0) {
+    if (cur->type == XML_ELEMENT_NODE &&
+        strcmp((const char *)cur->name, target_name) == 0) {
       return cur;
     }
     xmlNode *found = find_node_recursive(cur->children, target_name);
@@ -195,21 +152,15 @@ static xmlNode *find_node_recursive(xmlNode *node, const char *target_name) {
 }
 
 static char *get_first_search_result(const char *search_term) {
-  CURL *curl = curl_easy_init();
-  if (!curl)
-    return NULL;
-
-  char *escaped_term = curl_easy_escape(curl, search_term, 0);
+  char *escaped_term = curl_easy_escape(NULL, search_term, 0);
   const char *search_base =
       "https://en.wikipedia.org/w/api.php?action=query&list=search&srsearch=";
-  const char *search_suffix =
-      "&format=xml&origin=*&srlimit=1";
+  const char *search_suffix = "&format=xml&origin=*&srlimit=1";
 
   char *search_url = malloc(strlen(search_base) + strlen(escaped_term) +
-                           strlen(search_suffix) + 1);
+                            strlen(search_suffix) + 1);
   if (!search_url) {
     curl_free(escaped_term);
-    curl_easy_cleanup(curl);
     return NULL;
   }
 
@@ -219,22 +170,13 @@ static char *get_first_search_result(const char *search_term) {
 
   curl_free(escaped_term);
 
-  struct WikiMemoryStruct chunk = {malloc(1), 0};
-  if (!chunk.memory) {
-    free(search_url);
-    curl_easy_cleanup(curl);
-    return NULL;
-  }
-
-  curl_easy_setopt(curl, CURLOPT_URL, search_url);
-  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WikiWriteMemoryCallback);
-  curl_easy_setopt(curl, CURLOPT_WRITEDATA, &chunk);
-  curl_easy_setopt(curl, CURLOPT_USERAGENT, "libcurl-agent/1.0");
-  apply_proxy_settings(curl);
+  HttpResponse resp = http_get(search_url, "libcurl-agent/1.0");
+  free(search_url);
 
   char *first_title = NULL;
-  if (curl_easy_perform(curl) == CURLE_OK && chunk.size > 0) {
-    xmlDocPtr doc = xmlReadMemory(chunk.memory, chunk.size, "noname.xml", NULL, 0);
+  if (resp.memory && resp.size > 0) {
+    xmlDocPtr doc =
+        xmlReadMemory(resp.memory, resp.size, "noname.xml", NULL, 0);
     if (doc) {
       xmlNode *root = xmlDocGetRootElement(doc);
       xmlNode *search_node = find_node_recursive(root, "search");
@@ -255,10 +197,7 @@ static char *get_first_search_result(const char *search_term) {
     }
   }
 
-  free(chunk.memory);
-  free(search_url);
-  curl_easy_cleanup(curl);
-
+  http_response_free(&resp);
   return first_title;
 }
 
@@ -267,13 +206,7 @@ char *construct_wiki_url(const char *search_term) {
   if (!first_title)
     return NULL;
 
-  CURL *curl = curl_easy_init();
-  if (!curl) {
-    free(first_title);
-    return NULL;
-  }
-
-  char *escaped_title = curl_easy_escape(curl, first_title, 0);
+  char *escaped_title = curl_easy_escape(NULL, first_title, 0);
   const char *base = "https://en.wikipedia.org/w/"
                      "api.php?action=query&prop=extracts|pageimages&exintro&"
                      "explaintext&pithumbsize=400&format=xml&origin=*&titles=";
@@ -285,7 +218,6 @@ char *construct_wiki_url(const char *search_term) {
   }
 
   curl_free(escaped_title);
-  curl_easy_cleanup(curl);
   free(first_title);
   return full_url;
 }

src/Routes/Images.c

@@ -1,7 +1,8 @@
 #include "Images.h"
-#include "../Proxy/Proxy.h"
 #include "../Scraping/Scraping.h"
+#include "../Utility/HttpClient.h"
 #include "../Utility/Unescape.h"
+#include "../Utility/XmlHelper.h"
 
 #include <curl/curl.h>
 #include <libxml/HTMLparser.h>
@@ -9,61 +10,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
-
-struct MemoryBlock {
-  char *response;
-  size_t size;
-};
-
-static size_t ImageWriteCallback(void *data, size_t size, size_t nmemb,
-                                 void *userp) {
-  size_t realsize = size * nmemb;
-  struct MemoryBlock *mem = (struct MemoryBlock *)userp;
-  char *ptr = (char *)realloc(mem->response, mem->size + realsize + 1);
-  if (ptr == NULL) {
-    return 0;
-  }
-  mem->response = ptr;
-  memcpy(&(mem->response[mem->size]), data, realsize);
-  mem->size += realsize;
-  mem->response[mem->size] = 0;
-  return realsize;
-}
-
-static char *fetch_images_html(const char *url) {
-  CURL *curl_handle;
-  struct MemoryBlock chunk = {.response = malloc(1), .size = 0};
-  if (!chunk.response) {
-    return NULL;
-  }
-
-  curl_handle = curl_easy_init();
-  if (!curl_handle) {
-    free(chunk.response);
-    return NULL;
-  }
-
-  curl_easy_setopt(curl_handle, CURLOPT_URL, url);
-  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, ImageWriteCallback);
-  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
-  curl_easy_setopt(
-      curl_handle, CURLOPT_USERAGENT,
-      "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko");
-  curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1L);
-  curl_easy_setopt(curl_handle, CURLOPT_TIMEOUT, 10L);
-  apply_proxy_settings(curl_handle);
-
-  CURLcode res = curl_easy_perform(curl_handle);
-  if (res != CURLE_OK) {
-    free(chunk.response);
-    curl_easy_cleanup(curl_handle);
-    return NULL;
-  }
-
-  curl_easy_cleanup(curl_handle);
-  return chunk.response;
-}
 
 int images_handler(UrlParams *params) {
   TemplateContext ctx = new_context();
@@ -127,8 +73,10 @@ int images_handler(UrlParams *params) {
   snprintf(url, sizeof(url), "https://www.bing.com/images/search?q=%s&first=%d",
            encoded_query, first);
 
-  char *html = fetch_images_html(url);
-  if (!html) {
+  HttpResponse resp = http_get(
+      url,
+      "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko");
+  if (!resp.memory) {
     send_response("<h1>Error fetching images</h1>");
     free(encoded_query);
     free(display_query);
@@ -136,10 +84,10 @@ int images_handler(UrlParams *params) {
     return -1;
   }
 
-  htmlDocPtr doc = htmlReadMemory(html, (int)strlen(html), NULL, NULL,
+  htmlDocPtr doc = htmlReadMemory(resp.memory, resp.size, NULL, NULL,
                                   HTML_PARSE_RECOVER | HTML_PARSE_NOERROR);
   if (!doc) {
-    free(html);
+    http_response_free(&resp);
     free(encoded_query);
     free(display_query);
     free_context(&ctx);
@@ -150,7 +98,7 @@ int images_handler(UrlParams *params) {
 
   if (!xpathCtx) {
     xmlFreeDoc(doc);
-    free(html);
+    http_response_free(&resp);
     free(encoded_query);
     free(display_query);
     free_context(&ctx);
@@ -325,7 +273,7 @@ int images_handler(UrlParams *params) {
     xmlXPathFreeContext(xpathCtx);
   if (doc)
     xmlFreeDoc(doc);
-  free(html);
+  http_response_free(&resp);
   curl_free(encoded_query);
   free(display_query);
   free_context(&ctx);

src/Scraping/Scraping.c

@@ -2,6 +2,7 @@
 #include "../Cache/Cache.h"
 #include "../Proxy/Proxy.h"
 #include "../Utility/Unescape.h"
+#include "../Utility/XmlHelper.h"
 #include <curl/curl.h>
 #include <libxml/HTMLparser.h>
 #include <libxml/xpath.h>
@@ -57,15 +58,15 @@ static int parse_ddg_lite(const char *engine_name, xmlDocPtr doc,
                           SearchResult **out_results, int max_results) {
   (void)engine_name;
   int found_count = 0;
+
   xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
   if (!xpathCtx) {
     return 0;
   }
 
-  const char *link_xpath = "//tr[not(contains(@class, "
-                           "'result-sponsored'))]//a[@class='result-link']";
-  xmlXPathObjectPtr xpathObj =
-      xmlXPathEvalExpression((xmlChar *)link_xpath, xpathCtx);
+  xmlXPathObjectPtr xpathObj = xml_xpath_eval(
+      xpathCtx, "//tr[not(contains(@class, "
+                "'result-sponsored'))]//a[@class='result-link']");
 
   if (!xpathObj || !xpathObj->nodesetval || xpathObj->nodesetval->nodeNr == 0) {
     if (xpathObj)
@@ -75,9 +76,7 @@ static int parse_ddg_lite(const char *engine_name, xmlDocPtr doc,
   }
 
   int num_links = xpathObj->nodesetval->nodeNr;
-
-  int actual_alloc = (num_links < max_results) ? num_links : max_results;
-  *out_results = (SearchResult *)calloc(actual_alloc, sizeof(SearchResult));
+  *out_results = xml_result_alloc(num_links, max_results);
   if (!*out_results) {
     xmlXPathFreeObject(xpathObj);
     xmlXPathFreeContext(xpathCtx);
@@ -86,7 +85,7 @@ static int parse_ddg_lite(const char *engine_name, xmlDocPtr doc,
 
   for (int i = 0; i < num_links && found_count < max_results; i++) {
     xmlNodePtr linkNode = xpathObj->nodesetval->nodeTab[i];
-    char *title = (char *)xmlNodeGetContent(linkNode);
+    char *title = xml_node_content(linkNode);
     char *url = (char *)xmlGetProp(linkNode, (xmlChar *)"href");
     char *snippet_text = NULL;
 
@@ -100,13 +99,11 @@ static int parse_ddg_lite(const char *engine_name, xmlDocPtr doc,
              xmlStrcasecmp(snippetRow->name, (const xmlChar *)"tr") != 0)
         snippetRow = snippetRow->next;
       if (snippetRow) {
-
         xpathCtx->node = snippetRow;
-        xmlXPathObjectPtr sObj = xmlXPathEvalExpression(
-            (xmlChar *)".//td[@class='result-snippet']", xpathCtx);
+        xmlXPathObjectPtr sObj =
+            xml_xpath_eval(xpathCtx, ".//td[@class='result-snippet']");
         if (sObj && sObj->nodesetval && sObj->nodesetval->nodeNr > 0) {
-          snippet_text =
-              (char *)xmlNodeGetContent(sObj->nodesetval->nodeTab[0]);
+          snippet_text = xml_node_content(sObj->nodesetval->nodeTab[0]);
         }
         if (sObj)
           xmlXPathFreeObject(sObj);
@@ -118,7 +115,6 @@ static int parse_ddg_lite(const char *engine_name, xmlDocPtr doc,
     (*out_results)[found_count].title = strdup(title ? title : "No Title");
     (*out_results)[found_count].snippet =
         strdup(snippet_text ? snippet_text : "");
-
     found_count++;
 
     if (title)
@@ -138,14 +134,14 @@ static int parse_startpage(const char *engine_name, xmlDocPtr doc,
                            SearchResult **out_results, int max_results) {
   (void)engine_name;
   int found_count = 0;
+
   xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
   if (!xpathCtx) {
     return 0;
   }
 
-  const char *container_xpath = "//div[contains(@class, 'result')]";
   xmlXPathObjectPtr xpathObj =
-      xmlXPathEvalExpression((xmlChar *)container_xpath, xpathCtx);
+      xml_xpath_eval(xpathCtx, "//div[contains(@class, 'result')]");
 
   if (!xpathObj || !xpathObj->nodesetval || xpathObj->nodesetval->nodeNr == 0) {
     if (xpathObj)
@@ -155,9 +151,7 @@ static int parse_startpage(const char *engine_name, xmlDocPtr doc,
   }
 
   int num_results = xpathObj->nodesetval->nodeNr;
-
-  int actual_alloc = (num_results < max_results) ? num_results : max_results;
-  *out_results = (SearchResult *)calloc(actual_alloc, sizeof(SearchResult));
+  *out_results = xml_result_alloc(num_results, max_results);
   if (!*out_results) {
     xmlXPathFreeObject(xpathObj);
     xmlXPathFreeContext(xpathCtx);
@@ -168,27 +162,27 @@ static int parse_startpage(const char *engine_name, xmlDocPtr doc,
     xmlNodePtr resultNode = xpathObj->nodesetval->nodeTab[i];
     xpathCtx->node = resultNode;
 
-    xmlXPathObjectPtr linkObj = xmlXPathEvalExpression(
-        (xmlChar *)".//a[contains(@class, 'result-link')]", xpathCtx);
+    xmlXPathObjectPtr linkObj =
+        xml_xpath_eval(xpathCtx, ".//a[contains(@class, 'result-link')]");
     char *url =
         (linkObj && linkObj->nodesetval && linkObj->nodesetval->nodeNr > 0)
             ? (char *)xmlGetProp(linkObj->nodesetval->nodeTab[0],
                                  (xmlChar *)"href")
             : NULL;
 
-    xmlXPathObjectPtr titleObj = xmlXPathEvalExpression(
-        (xmlChar *)".//h2[contains(@class, 'wgl-title')]", xpathCtx);
+    xmlXPathObjectPtr titleObj =
+        xml_xpath_eval(xpathCtx, ".//h2[contains(@class, 'wgl-title')]");
     char *title =
         (titleObj && titleObj->nodesetval && titleObj->nodesetval->nodeNr > 0)
-            ? (char *)xmlNodeGetContent(titleObj->nodesetval->nodeTab[0])
+            ? xml_node_content(titleObj->nodesetval->nodeTab[0])
             : NULL;
 
-    xmlXPathObjectPtr snippetObj = xmlXPathEvalExpression(
-        (xmlChar *)".//p[contains(@class, 'description')]", xpathCtx);
+    xmlXPathObjectPtr snippetObj =
+        xml_xpath_eval(xpathCtx, ".//p[contains(@class, 'description')]");
     char *snippet_text =
         (snippetObj && snippetObj->nodesetval &&
          snippetObj->nodesetval->nodeNr > 0)
-            ? (char *)xmlNodeGetContent(snippetObj->nodesetval->nodeTab[0])
+            ? xml_node_content(snippetObj->nodesetval->nodeTab[0])
             : NULL;
 
     if (url && title) {
@@ -214,7 +208,6 @@ static int parse_startpage(const char *engine_name, xmlDocPtr doc,
   }
 
   xpathCtx->node = NULL;
-
   xmlXPathFreeObject(xpathObj);
   xmlXPathFreeContext(xpathCtx);
   return found_count;
@@ -224,14 +217,14 @@ static int parse_yahoo(const char *engine_name, xmlDocPtr doc,
                        SearchResult **out_results, int max_results) {
   (void)engine_name;
   int found_count = 0;
+
   xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
   if (!xpathCtx) {
     return 0;
   }
 
-  const char *container_xpath = "//div[contains(@class, 'algo-sr')]";
   xmlXPathObjectPtr xpathObj =
-      xmlXPathEvalExpression((xmlChar *)container_xpath, xpathCtx);
+      xml_xpath_eval(xpathCtx, "//div[contains(@class, 'algo-sr')]");
 
   if (!xpathObj || !xpathObj->nodesetval || xpathObj->nodesetval->nodeNr == 0) {
     if (xpathObj)
@@ -241,9 +234,7 @@ static int parse_yahoo(const char *engine_name, xmlDocPtr doc,
   }
 
   int num_results = xpathObj->nodesetval->nodeNr;
-
-  int actual_alloc = (num_results < max_results) ? num_results : max_results;
-  *out_results = (SearchResult *)calloc(actual_alloc, sizeof(SearchResult));
+  *out_results = xml_result_alloc(num_results, max_results);
   if (!*out_results) {
     xmlXPathFreeObject(xpathObj);
     xmlXPathFreeContext(xpathCtx);
@@ -254,28 +245,27 @@ static int parse_yahoo(const char *engine_name, xmlDocPtr doc,
     xmlNodePtr resultNode = xpathObj->nodesetval->nodeTab[i];
     xpathCtx->node = resultNode;
 
-    xmlXPathObjectPtr linkObj = xmlXPathEvalExpression(
-        (xmlChar *)".//div[contains(@class, 'compTitle')]//a[@target='_blank']",
-        xpathCtx);
+    xmlXPathObjectPtr linkObj = xml_xpath_eval(
+        xpathCtx, ".//div[contains(@class, 'compTitle')]//a[@target='_blank']");
     char *url =
         (linkObj && linkObj->nodesetval && linkObj->nodesetval->nodeNr > 0)
             ? (char *)xmlGetProp(linkObj->nodesetval->nodeTab[0],
                                  (xmlChar *)"href")
             : NULL;
 
-    xmlXPathObjectPtr titleObj = xmlXPathEvalExpression(
-        (xmlChar *)".//h3[contains(@class, 'title')]", xpathCtx);
+    xmlXPathObjectPtr titleObj =
+        xml_xpath_eval(xpathCtx, ".//h3[contains(@class, 'title')]");
     char *title =
         (titleObj && titleObj->nodesetval && titleObj->nodesetval->nodeNr > 0)
-            ? (char *)xmlNodeGetContent(titleObj->nodesetval->nodeTab[0])
+            ? xml_node_content(titleObj->nodesetval->nodeTab[0])
             : NULL;
 
-    xmlXPathObjectPtr snippetObj = xmlXPathEvalExpression(
-        (xmlChar *)".//div[contains(@class, 'compText')]//p", xpathCtx);
+    xmlXPathObjectPtr snippetObj =
+        xml_xpath_eval(xpathCtx, ".//div[contains(@class, 'compText')]//p");
     char *snippet_text =
         (snippetObj && snippetObj->nodesetval &&
          snippetObj->nodesetval->nodeNr > 0)
-            ? (char *)xmlNodeGetContent(snippetObj->nodesetval->nodeTab[0])
+            ? xml_node_content(snippetObj->nodesetval->nodeTab[0])
             : NULL;
 
     if (url && title) {
@@ -344,11 +334,8 @@ static void configure_curl_handle(CURL *curl, const char *full_url,
   curl_easy_setopt(curl, CURLOPT_USERAGENT, get_random_user_agent());
 
   curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
-
   curl_easy_setopt(curl, CURLOPT_ACCEPT_ENCODING, "");
-
   curl_easy_setopt(curl, CURLOPT_DNS_CACHE_TIMEOUT, 300L);
-
   curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
   curl_easy_setopt(curl, CURLOPT_TIMEOUT, 15L);
   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
@@ -357,6 +344,102 @@ static void configure_curl_handle(CURL *curl, const char *full_url,
   apply_proxy_settings(curl);
 }
 
+static char *build_search_url(const char *base_url, const char *page_param,
+                              int page_multiplier, int page_base,
+                              const char *encoded_query, int page) {
+  int page_value = (page < 1 ? 1 : page - 1) * page_multiplier + page_base;
+  char *url = malloc(1024);
+  if (!url) {
+    return NULL;
+  }
+  snprintf(url, 1024, "%s%s&%s=%d", base_url, encoded_query, page_param,
+           page_value);
+  return url;
+}
+
+static struct curl_slist *build_request_headers(const char *host_header,
+                                                const char *referer) {
+  struct curl_slist *headers = NULL;
+  char host_buf[256], ref_buf[256];
+
+  snprintf(host_buf, sizeof(host_buf), "Host: %s", host_header);
+  snprintf(ref_buf, sizeof(ref_buf), "Referer: %s", referer);
+
+  headers = curl_slist_append(headers, host_buf);
+  headers = curl_slist_append(headers, ref_buf);
+  headers = curl_slist_append(
+      headers,
+      "Accept: "
+      "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
+  headers = curl_slist_append(headers, "Accept-Language: en-US,en;q=0.5");
+  headers = curl_slist_append(headers, "DNT: 1");
+
+  return headers;
+}
+
+static int check_cache_for_job(ScrapeJob *job) {
+  if (get_cache_ttl_search() <= 0) {
+    return 0;
+  }
+
+  char *key = cache_compute_key(job->query, job->page, job->engine->name);
+  if (!key) {
+    return 0;
+  }
+
+  char *cached_data = NULL;
+  size_t cached_size = 0;
+
+  if (cache_get(key, (time_t)get_cache_ttl_search(), &cached_data,
+                &cached_size) == 0 &&
+      cached_data && cached_size > 0) {
+    xmlDocPtr doc = htmlReadMemory(cached_data, cached_size, NULL, NULL,
+                                   HTML_PARSE_RECOVER | HTML_PARSE_NOERROR |
+                                       HTML_PARSE_NOWARNING);
+    if (doc) {
+      job->results_count = job->engine->parser(
+          job->engine->name, doc, job->out_results, job->max_results);
+      xmlFreeDoc(doc);
+    }
+    free(cached_data);
+    free(key);
+    return 1;
+  }
+
+  free(key);
+  return 0;
+}
+
+static void process_job_response(ScrapeJob *job, CURL *handle, CURLMsg *msg) {
+  if (msg->data.result == CURLE_OK && job->response.size > 0) {
+    char *key = cache_compute_key(job->query, job->page, job->engine->name);
+    if (key && get_cache_ttl_search() > 0) {
+      cache_set(key, job->response.memory, job->response.size);
+      free(key);
+    }
+
+    xmlDocPtr doc = htmlReadMemory(
+        job->response.memory, job->response.size, NULL, NULL,
+        HTML_PARSE_RECOVER | HTML_PARSE_NOERROR | HTML_PARSE_NOWARNING);
+
+    if (doc) {
+      job->results_count = job->engine->parser(
+          job->engine->name, doc, job->out_results, job->max_results);
+      xmlFreeDoc(doc);
+    }
+  } else {
+    job->results_count = 0;
+  }
+
+  struct curl_slist *headers = NULL;
+  curl_easy_getinfo(handle, CURLINFO_PRIVATE, &headers);
+  if (headers)
+    curl_slist_free_all(headers);
+
+  free(job->response.memory);
+  job->response.memory = NULL;
+}
+
 int scrape_engines_parallel(ScrapeJob *jobs, int num_jobs) {
   int retries = 0;
 
@@ -369,10 +452,6 @@ retry:
   for (int i = 0; i < num_jobs; i++) {
     ScrapeJob *job = &jobs[i];
 
-    char cache_key[64];
-    char full_url[1024];
-    char *encoded_query = NULL;
-
     if (job->handle) {
       curl_easy_cleanup(job->handle);
       job->handle = NULL;
@@ -381,57 +460,29 @@ retry:
       free(job->response.memory);
     }
 
-    encoded_query = curl_easy_escape(NULL, job->query, 0);
-    if (!encoded_query) {
+    if (check_cache_for_job(job)) {
+      job->results_count = job->results_count > 0 ? job->results_count : 0;
       continue;
     }
 
-    int page = (job->page < 1) ? 1 : job->page;
-    int page_value =
-        (page - 1) * job->engine->page_multiplier + job->engine->page_base;
-
-    snprintf(full_url, sizeof(full_url), "%s%s&%s=%d", job->engine->base_url,
-             encoded_query, job->engine->page_param, page_value);
-
-    char *key = cache_compute_key(job->query, job->page, job->engine->name);
-    if (key) {
-      strncpy(cache_key, key, sizeof(cache_key) - 1);
-      cache_key[sizeof(cache_key) - 1] = '\0';
-      free(key);
-    } else {
-      snprintf(cache_key, sizeof(cache_key), "uncached_%d_%s", i,
-               job->engine->name);
+    char *encoded_query = curl_easy_escape(NULL, job->query, 0);
+    if (!encoded_query) {
+      continue;
     }
 
-    char *cached_data = NULL;
-    size_t cached_size = 0;
-    int cache_hit = 0;
-
-    if (get_cache_ttl_search() > 0 &&
-        cache_get(cache_key, (time_t)get_cache_ttl_search(), &cached_data,
-                  &cached_size) == 0 &&
-        cached_data && cached_size > 0) {
-      xmlDocPtr doc = htmlReadMemory(cached_data, cached_size, NULL, NULL,
-                                     HTML_PARSE_RECOVER | HTML_PARSE_NOERROR |
-                                         HTML_PARSE_NOWARNING);
-      if (doc) {
-        job->results_count = job->engine->parser(
-            job->engine->name, doc, job->out_results, job->max_results);
-        xmlFreeDoc(doc);
-        cache_hit = 1;
-      }
-      free(cached_data);
-    }
+    char *full_url =
+        build_search_url(job->engine->base_url, job->engine->page_param,
+                         job->engine->page_multiplier, job->engine->page_base,
+                         encoded_query, job->page);
+    free(encoded_query);
 
-    if (cache_hit) {
-      free(encoded_query);
-      job->results_count = job->results_count > 0 ? job->results_count : 0;
+    if (!full_url) {
       continue;
     }
 
     job->handle = curl_easy_init();
     if (!job->handle) {
-      free(encoded_query);
+      free(full_url);
       continue;
     }
 
@@ -439,23 +490,13 @@ retry:
     job->response.size = 0;
     job->response.capacity = 16384;
 
-    struct curl_slist *headers = NULL;
-    char host_buf[256], ref_buf[256];
-    snprintf(host_buf, sizeof(host_buf), "Host: %s", job->engine->host_header);
-    snprintf(ref_buf, sizeof(ref_buf), "Referer: %s", job->engine->referer);
-    headers = curl_slist_append(headers, host_buf);
-    headers = curl_slist_append(headers, ref_buf);
-    headers = curl_slist_append(
-        headers,
-        "Accept: "
-        "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
-    headers = curl_slist_append(headers, "Accept-Language: en-US,en;q=0.5");
-    headers = curl_slist_append(headers, "DNT: 1");
+    struct curl_slist *headers =
+        build_request_headers(job->engine->host_header, job->engine->referer);
 
     configure_curl_handle(job->handle, full_url, &job->response, headers);
-
     curl_easy_setopt(job->handle, CURLOPT_PRIVATE, headers);
 
+    free(full_url);
     curl_multi_add_handle(multi_handle, job->handle);
   }
 
@@ -485,37 +526,8 @@ retry:
         if (jobs[i].handle && jobs[i].handle == handle) {
           ScrapeJob *job = &jobs[i];
 
-          long response_code;
-          curl_easy_getinfo(handle, CURLINFO_RESPONSE_CODE, &response_code);
-
-          if (msg->data.result == CURLE_OK && job->response.size > 0) {
-            char *key =
-                cache_compute_key(job->query, job->page, job->engine->name);
-            if (key && get_cache_ttl_search() > 0) {
-              cache_set(key, job->response.memory, job->response.size);
-              free(key);
-            }
-
-            xmlDocPtr doc = htmlReadMemory(
-                job->response.memory, job->response.size, NULL, NULL,
-                HTML_PARSE_RECOVER | HTML_PARSE_NOERROR | HTML_PARSE_NOWARNING);
-
-            if (doc) {
-              job->results_count = job->engine->parser(
-                  job->engine->name, doc, job->out_results, job->max_results);
-              xmlFreeDoc(doc);
-            }
-          } else {
-            job->results_count = 0;
-          }
-
-          struct curl_slist *headers;
-          curl_easy_getinfo(handle, CURLINFO_PRIVATE, &headers);
-          if (headers)
-            curl_slist_free_all(headers);
-
-          free(job->response.memory);
-          job->response.memory = NULL;
+          process_job_response(job, handle, msg);
+
           curl_multi_remove_handle(multi_handle, handle);
           if (handle)
             curl_easy_cleanup(handle);

src/Utility/HttpClient.c

@@ -0,0 +1,81 @@
+#include "HttpClient.h"
+#include "../Proxy/Proxy.h"
+#include <stdlib.h>
+#include <string.h>
+
+static size_t write_callback(void *contents, size_t size, size_t nmemb,
+                             void *userp) {
+  size_t realsize = size * nmemb;
+  HttpResponse *mem = (HttpResponse *)userp;
+
+  if (mem->size + realsize + 1 > mem->capacity) {
+    size_t new_cap = mem->capacity == 0 ? 16384 : mem->capacity * 2;
+    while (new_cap < mem->size + realsize + 1)
+      new_cap *= 2;
+
+    char *ptr = realloc(mem->memory, new_cap);
+    if (!ptr) {
+      return 0;
+    }
+    mem->memory = ptr;
+    mem->capacity = new_cap;
+  }
+
+  memcpy(&(mem->memory[mem->size]), contents, realsize);
+  mem->size += realsize;
+  mem->memory[mem->size] = 0;
+
+  return realsize;
+}
+
+HttpResponse http_get(const char *url, const char *user_agent) {
+  HttpResponse resp = {.memory = NULL, .size = 0, .capacity = 0};
+
+  if (!url) {
+    return resp;
+  }
+
+  resp.memory = malloc(16384);
+  if (!resp.memory) {
+    return resp;
+  }
+  resp.capacity = 16384;
+
+  CURL *curl = curl_easy_init();
+  if (!curl) {
+    free(resp.memory);
+    resp.memory = NULL;
+    return resp;
+  }
+
+  curl_easy_setopt(curl, CURLOPT_URL, url);
+  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
+  curl_easy_setopt(curl, CURLOPT_WRITEDATA, &resp);
+  curl_easy_setopt(curl, CURLOPT_USERAGENT,
+                   user_agent ? user_agent : "libcurl-agent/1.0");
+  curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+  curl_easy_setopt(curl, CURLOPT_TIMEOUT, 15L);
+  apply_proxy_settings(curl);
+
+  CURLcode res = curl_easy_perform(curl);
+  curl_easy_cleanup(curl);
+
+  if (res != CURLE_OK) {
+    free(resp.memory);
+    resp.memory = NULL;
+    resp.size = 0;
+    resp.capacity = 0;
+  }
+
+  return resp;
+}
+
+void http_response_free(HttpResponse *resp) {
+  if (!resp) {
+    return;
+  }
+  free(resp->memory);
+  resp->memory = NULL;
+  resp->size = 0;
+  resp->capacity = 0;
+}

src/Utility/HttpClient.h

@@ -0,0 +1,16 @@
+#ifndef HTTPCLIENT_H
+#define HTTPCLIENT_H
+
+#include <curl/curl.h>
+#include <stddef.h>
+
+typedef struct {
+  char *memory;
+  size_t size;
+  size_t capacity;
+} HttpResponse;
+
+HttpResponse http_get(const char *url, const char *user_agent);
+void http_response_free(HttpResponse *resp);
+
+#endif

src/Utility/XmlHelper.c

@@ -0,0 +1,65 @@
+#include "XmlHelper.h"
+#include <stdlib.h>
+#include <string.h>
+
+SearchResult *xml_result_alloc(int count, int max_results) {
+  if (count <= 0 || max_results <= 0) {
+    return NULL;
+  }
+  int actual = (count < max_results) ? count : max_results;
+  return (SearchResult *)calloc(actual, sizeof(SearchResult));
+}
+
+void xml_result_free(SearchResult *results, int count) {
+  if (!results) {
+    return;
+  }
+  for (int i = 0; i < count; i++) {
+    free(results[i].url);
+    free(results[i].title);
+    free(results[i].snippet);
+  }
+  free(results);
+}
+
+xmlXPathObjectPtr xml_xpath_eval(xmlXPathContextPtr ctx, const char *xpath) {
+  if (!ctx || !xpath) {
+    return NULL;
+  }
+  return xmlXPathEvalExpression((const xmlChar *)xpath, ctx);
+}
+
+char *xml_node_content(xmlNodePtr node) {
+  if (!node) {
+    return NULL;
+  }
+  char *content = (char *)xmlNodeGetContent(node);
+  return content;
+}
+
+char *xpath_text(xmlDocPtr doc, const char *xpath) {
+  if (!doc || !xpath) {
+    return NULL;
+  }
+
+  xmlXPathContextPtr ctx = xmlXPathNewContext(doc);
+  if (!ctx) {
+    return NULL;
+  }
+
+  xmlXPathObjectPtr obj = xmlXPathEvalExpression((const xmlChar *)xpath, ctx);
+  xmlXPathFreeContext(ctx);
+
+  if (!obj || !obj->nodesetval || obj->nodesetval->nodeNr == 0) {
+    if (obj)
+      xmlXPathFreeObject(obj);
+    return NULL;
+  }
+
+  xmlChar *content = xmlNodeGetContent(obj->nodesetval->nodeTab[0]);
+  char *result = content ? strdup((char *)content) : NULL;
+  if (content)
+    xmlFree(content);
+  xmlXPathFreeObject(obj);
+  return result;
+}

src/Utility/XmlHelper.h

@@ -0,0 +1,14 @@
+#ifndef XMLHELPER_H
+#define XMLHELPER_H
+
+#include "../Scraping/Scraping.h"
+#include <libxml/xpath.h>
+
+SearchResult *xml_result_alloc(int count, int max_results);
+void xml_result_free(SearchResult *results, int count);
+
+xmlXPathObjectPtr xml_xpath_eval(xmlXPathContextPtr ctx, const char *xpath);
+char *xml_node_content(xmlNodePtr node);
+char *xpath_text(xmlDocPtr doc, const char *xpath);
+
+#endif