Very, very basic server responses

CMakeLists.txt

@@ -5,17 +5,19 @@ project(SimpleHttpServer VERSION 1.0
                          LANGUAGES C)
 
 add_library(
-    httpserverlib
-    STATIC
-    src/httpserver.h
-    src/httpserver.c
+        httpserverlib
+        STATIC
+        src/httpserver.h
+        src/httpserver.c
         src/utils/hashmap.c
         src/utils/hashmap.h
+        src/utils/string_builder.c
+        src/utils/string_builder.h
 )
 
 add_executable(
-    httpserver
-    app/main.c
+        httpserver
+        app/main.c
         app/main.h
 )
 

app/main.c

@@ -7,7 +7,27 @@
 
 http_response_t* handle_request(http_request_t* request)
 {
-    http_response_t* http_response = {};
+    http_response_t* http_response = malloc(sizeof *http_response);
+    http_response->http_version.http_name = "HTTP\0";
+    http_response->http_version.http_name_len = 4;
+    http_response->http_version.major = 1;
+    http_response->http_version.minor = 1;
+
+    http_response->http_status_code = 200;
+    http_response->http_status_message = "OK\0";
+    http_response->http_status_message_len = 2;
+
+    char *length_str = malloc(20);
+    sprintf(length_str, "%ld", request->http_path_len);
+
+    http_response->http_headers = new_hash_map();
+    set(http_response->http_headers, "Server", "SimpleHttpServer");
+    set(http_response->http_headers, "Content-Length", length_str);
+    set(http_response->http_headers, "Content-Type", "text/plain");
+
+    http_response->http_content = request->http_path;
+    http_response->http_content_len = request->http_path_len;
+
     return http_response;
 }
 

src/httpserver.c

@@ -60,7 +60,7 @@ void start_http_server(http_server_t* http_server, const char *addr, const short
     close(server_fd);
 }
 
-void process_conn(http_server_t* http_server, const int server_fd, struct sockaddr* address, socklen_t* addr_len)
+void process_conn(const http_server_t* http_server, const int server_fd, struct sockaddr* address, socklen_t* addr_len)
 {
     const int socket_d = accept(server_fd, address, addr_len);
     if (socket_d == -1)
@@ -92,18 +92,18 @@ void process_conn(http_server_t* http_server, const int server_fd, struct sockad
     enum http_request_parsing_stage request_parsing_stage = START_LINE_METHOD;
     http_request_t http_request = {};
 
-    char method_str[8];
+    char *method_str = malloc(8);
     size_t method_str_len = 0;
 
-    char http_path[2048];
+    char *http_path = malloc(2048);
     size_t http_path_len = 0;
 
-    char http_name[16];
+    char *http_name = malloc(16);
     size_t http_name_len = 0;
 
-    char header_key[256];
+    char *header_key = malloc(256);
     size_t header_key_length = 0;
-    char header_val[1024];
+    char *header_val = malloc(1024);
     size_t header_val_length = 0;
 
     http_request.http_content = nullptr;
@@ -203,10 +203,10 @@ void process_conn(http_server_t* http_server, const int server_fd, struct sockad
                 char* val = calloc(header_val_length + 1, sizeof(char));
                 strncpy(val, header_val, header_val_length);
 
-                printf(
-                    "Setting header '%s' (hash %d per cap %d): '%s'\n",
-                    key, hashcode(http_request.http_headers, key),
-                    http_request.http_headers->cap, val);
+                // printf(
+                //     "Setting header '%s' (hash %d per cap %d): '%s'\n",
+                //     key, hashcode(http_request.http_headers, key),
+                //     http_request.http_headers->cap, val);
 
                 set(http_request.http_headers, key, val);
                 header_key[0] = '\0';
@@ -231,8 +231,46 @@ void process_conn(http_server_t* http_server, const int server_fd, struct sockad
 
     http_response_t* http_response = http_server->handle_request(&http_request);
 
-    // TODO: Send response
+    string_builder_t* response_sb = new_string_builder();
 
+    append_fmt(
+        response_sb,
+        "%s/%d.%d %d %s\r\n",
+        http_response->http_version.http_name,
+        http_response->http_version.major,
+        http_response->http_version.minor,
+        http_response->http_status_code,
+        http_response->http_status_message
+    );
+
+    for (int i = 0; i < http_response->http_headers->cap; i++)
+    {
+        const pair_t* iter = http_response->http_headers->list[i];
+        while (iter != nullptr)
+        {
+            append_fmt(response_sb, "%s: %s\r\n", iter->key, iter->val);
+            iter = iter->next;
+        }
+    }
+
+    append_crlf(response_sb, "");
+    append_nstr(response_sb, http_response->http_content, http_response->http_content_len);
+
+    char* response_str = string_builder_to_string(response_sb);
+
+    printf("\nServer response (%ld):\n", response_sb->char_count);
+    for (int i = 0; i < response_sb->char_count; i++)
+    {
+        if (response_str[i] != '\r')
+            putchar(response_str[i]);
+    }
+    putchar('\n');
+    fflush(stdout);
+
+    write(socket_d, response_str, response_sb->char_count);
+
+    free(response_str);
+    free_string_builder(response_sb);
     free_hash_map(http_request.http_headers);
     free(http_response);
 
@@ -251,3 +289,12 @@ enum http_method parse_method_str(const char* str, const size_t len)
 
     return UNKNOWN;
 }
+
+const char* http_method_to_string(const enum http_method m)
+{
+    for (size_t i = 0; i < sizeof(method_map)/sizeof(method_map[0]); i++) {
+        if (method_map[i].method == m)
+            return method_map[i].name;
+    }
+    return "UNKNOWN";
+}

src/httpserver.h

@@ -16,6 +16,7 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include "utils/hashmap.h"
+#include "utils/string_builder.h"
 
 typedef struct http_version
 {
@@ -65,7 +66,7 @@ typedef struct http_request
 typedef struct http_response
 {
     http_version_t http_version;
-    u_short http_status_code;
+    unsigned short http_status_code;
     char* http_status_message;
     size_t http_status_message_len;
     hashmap_t* http_headers;
@@ -79,7 +80,8 @@ typedef struct http_server
 } http_server_t;
 
 void start_http_server(http_server_t* http_server, const char *addr, short port);
-void process_conn(http_server_t* http_server, int server_fd, struct sockaddr* address, socklen_t* addr_len);
+void process_conn(const http_server_t* http_server, int server_fd, struct sockaddr* address, socklen_t* addr_len);
 enum http_method parse_method_str(const char* str, size_t len);
+const char* http_method_to_string(enum http_method m);
 
 #endif //SIMPLEHTTPSERVER_H

src/utils/string_builder.c

@@ -0,0 +1,163 @@
+//
+// Created by nazar on 13.09.2025.
+//
+
+#include "string_builder.h"
+
+#include <stdio.h>
+#include <string.h>
+
+string_builder_t* new_string_builder()
+{
+    string_builder_t* sb = malloc(sizeof *sb);
+    sb->first = nullptr;
+    sb->last = nullptr;
+    sb->char_count = 0;
+    return sb;
+}
+
+char* string_builder_to_string(const string_builder_t* sb)
+{
+    char* str = malloc(sb->char_count + 1);
+    if (!str) return nullptr;
+
+    char* p = str;
+
+    for (const string_builder_part_t* part = sb->first; part; part = part->next) {
+        memcpy(p, part->data, part->len);
+        p += part->len;
+    }
+
+    *p = '\0';
+    return str;
+}
+
+void free_string_builder(string_builder_t* sb)
+{
+    string_builder_part_t* iter = sb->first;
+    while (iter != nullptr)
+    {
+        string_builder_part_t* prev = iter;
+        iter = iter->next;
+        free(prev->data);
+        free(prev);
+    }
+
+    sb->first = nullptr;
+    sb->last = nullptr;
+    free(sb);
+}
+
+void append_part(string_builder_t* sb, string_builder_part_t* part)
+{
+    sb->char_count += part->len;
+    if (sb->last == nullptr)
+    {
+        sb->first = part;
+        sb->last = part;
+        return;
+    }
+
+    sb->last->next = part;
+    sb->last = part;
+}
+
+void append_char(string_builder_t* sb, const char c)
+{
+    char* str = malloc(2);
+    sprintf(str, "%c", c);
+
+    string_builder_part_t* part = malloc(sizeof *part);
+    part->data = str;
+    part->len = 1;
+
+    append_part(sb, part);
+}
+
+void append_int(string_builder_t* sb, const int i)
+{
+    char* str = malloc(20);
+    sprintf(str, "%d", i);
+
+    string_builder_part_t* part = malloc(sizeof *part);
+    part->data = str;
+    part->len = strlen(str);
+
+    append_part(sb, part);
+}
+
+void append_str(string_builder_t* sb, char* str)
+{
+    append_nstr(sb, str, strlen(str));
+}
+
+void append_nstr(string_builder_t* sb, char* str, size_t len)
+{
+    string_builder_part_t* part = malloc(sizeof *part);
+    part->data = str;
+    part->len = len;
+
+    append_part(sb, part);
+}
+
+void append_fmt(string_builder_t* sb, const char* fmt, ...) {
+    va_list args = {};
+    va_start(args, fmt);
+
+    va_list args_copy;
+    va_copy(args_copy, args);
+    const int len = vsnprintf(nullptr, 0, fmt, args_copy);
+    va_end(args_copy);
+
+    if (len < 0) {
+        va_end(args);
+        return;
+    }
+
+    char* buf = malloc(len + 1);
+    if (!buf) {
+        va_end(args);
+        return;
+    }
+
+    vsnprintf(buf, len + 1, fmt, args);
+    va_end(args);
+
+    append_nstr(sb, buf, len);
+}
+
+void append_lf(string_builder_t* sb, char* str)
+{
+    const size_t len = strlen(str);
+    append_nlf(sb, str, len);
+}
+
+void append_nlf(string_builder_t* sb, char* str, size_t len)
+{
+    char* l = malloc(len + 2);
+    sprintf(l, "%s\n", str);
+
+    string_builder_part_t* part = malloc(sizeof *part);
+    part->data = l;
+    part->len = len + 1;
+
+    append_part(sb, part);
+}
+
+void append_crlf(string_builder_t* sb, char* str)
+{
+    const size_t len = strlen(str);
+    append_ncrlf(sb, str, len);
+}
+
+void append_ncrlf(string_builder_t* sb, char* str, size_t len)
+{
+    char* l = malloc(len + 3);
+    sprintf(l, "%s\r\n", str);
+
+    string_builder_part_t* part = malloc(sizeof *part);
+    part->data = l;
+    part->len = len + 2;
+
+    append_part(sb, part);
+}

src/utils/string_builder.h

@@ -0,0 +1,43 @@
+//
+// Created by nazar on 13.09.2025.
+//
+
+#ifndef SIMPLEHTTPSERVER_STRING_BUILDER_H
+#define SIMPLEHTTPSERVER_STRING_BUILDER_H
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+typedef struct string_builder_part string_builder_part_t;
+
+struct string_builder_part
+{
+    char* data;
+    size_t len;
+    string_builder_part_t* next;
+};
+
+typedef struct string_builder
+{
+    string_builder_part_t* first;
+    string_builder_part_t* last;
+    size_t char_count;
+} string_builder_t;
+
+string_builder_t* new_string_builder();
+char* string_builder_to_string(const string_builder_t* sb);
+void free_string_builder(string_builder_t* sb);
+void append_part(string_builder_t* sb, string_builder_part_t* part);
+void append_char(string_builder_t* sb, char c);
+void append_int(string_builder_t* sb, int i);
+void append_str(string_builder_t* sb, char* str);
+void append_nstr(string_builder_t* sb, char* str, size_t len);
+void append_fmt(string_builder_t* sb, const char* fmt, ...);
+void append_lf(string_builder_t* sb, char* str);
+void append_nlf(string_builder_t* sb, char* str, size_t len);
+void append_crlf(string_builder_t* sb, char* str);
+void append_ncrlf(string_builder_t* sb, char* str, size_t len);
+
+#endif //SIMPLEHTTPSERVER_STRING_BUILDER_H