src/server/proxy/httpclient.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2026 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "httpclient.h"

#include <cx/buffer.h>
#include <cx/string.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

static int client_connected(EventHandler *ev, Event *event);
static int client_io(EventHandler *ev, Event *event);
static int client_finished(EventHandler *ev, Event *event);

static int client_send_request(HttpClient *client);

HttpClient* http_client_new(EventHandler *ev) {
    CxMempool *mp = cxMempoolCreate(32, CX_MEMPOOL_TYPE_PURE);
    if(!mp) {
        return NULL;
    }
    
    HttpClient *client = malloc(sizeof(HttpClient));
    HeaderArray *req_headers = header_array_create();
    HeaderArray *resp_headers = header_array_create();
    if(!client || !req_headers || !resp_headers) {
        free(client);
        header_array_free(req_headers);
        header_array_free(resp_headers);
        cxMempoolFree(mp);
        return NULL;
    }
    
    memset(client, 0, sizeof(HttpClient));
    client->ev = ev;
    client->socketfd = -1;
    client->request_headers = req_headers;
    client->response_headers = resp_headers;
    
    client->buffer.maxsize = HTTP_CLIENT_BUFFER_SIZE;
    client->buffer.inbuf = malloc(HTTP_CLIENT_BUFFER_SIZE);
    HttpParser *parser = http_parser_new2(1, &client->buffer, resp_headers);
    if(!parser || !client->buffer.inbuf) {
        http_client_free(client);
        return NULL;
    }
    client->parser = parser;
    
    return client;
}

void http_client_free(HttpClient *client) {
    cxMempoolFree(client->mp);
    header_array_free(client->request_headers);
    http_parser_free(client->parser);
    free(client->buffer.inbuf);
    free(client->addr);
    free(client->method);
    free(client->uri);
    free(client);
}

int http_client_set_addr(HttpClient *client, const struct sockaddr *addr, socklen_t addrlen) {
   free(client->addr);
   client->addr = NULL;
   client->addrlen = 0;
   
   void *newaddr = malloc(addrlen);
   if(!newaddr) {
       return 1;
   }
   memcpy(newaddr, addr, addrlen);
   client->addr = newaddr;
   client->addrlen = addrlen;
   
   return 0;
}

int http_client_set_method(HttpClient *client, const char *method) {
    return http_client_set_method_len(client, method, method ? strlen(method) : 0);
}

int http_client_set_uri(HttpClient *client, const char *uri) {
    return http_client_set_uri_len(client, uri, uri ? strlen(uri) : 0);
}

static int client_set_str(char **ptr, const char *str, size_t len) {
    free(*ptr);
    if(str) {
        char *newvalue = malloc(len+1);
        if(!newvalue) {
            *ptr = NULL;
            return 1;
        }
        memcpy(newvalue, str, len);
        newvalue[len] = 0;
        *ptr = newvalue;
    } else {
        *ptr = NULL;
    }
    return 0;
}

int http_client_set_method_len(HttpClient *client, const char *method, size_t len) {
    return client_set_str(&client->method, method, len);
}

int http_client_set_uri_len(HttpClient *client, const char *uri, size_t len) {
    return client_set_str(&client->uri, uri, len);
}

int http_client_add_request_header(HttpClient *client, cxmutstr name, cxmutstr value) {
    return header_array_add(client->request_headers, name, value);
}

int http_client_add_request_header_copy(HttpClient *client, cxstring name, cxstring value) {
    cxmutstr n = cx_strdup_a(client->mp->allocator, name);
    cxmutstr v = cx_strdup_a(client->mp->allocator, value);
    
    int err = 1;
    if(n.ptr && v.ptr) {
        err = http_client_add_request_header(client, n, v);
    }
    if(err) {
        cxFree(client->mp->allocator, n.ptr);
        cxFree(client->mp->allocator, v.ptr);
    }
    return err;
}

int http_client_start(HttpClient *client) {
    int socketfd = socket(AF_INET, SOCK_STREAM, 0);
    if(socketfd < 0) {
        return 1;
    }
    
    int flags;
    if ((flags = fcntl(socketfd, F_GETFL, 0)) == -1) {
        flags = 0;
    }
    if (fcntl(socketfd, F_SETFL, flags | O_NONBLOCK) != 0) {
        close(socketfd);
        return 1;
    }
    client->socketfd = socketfd;
    
    client->writeev.cookie = client;
    client->writeev.fn = client_connected;
    
    int ret = 1;
    if(connect(socketfd, client->addr, client->addrlen)) {
        int err = errno;
        if(err == EINPROGRESS) {
            ret = ev_pollout(client->ev, socketfd, &client->writeev);
        } else {
            log_ereport(LOG_FAILURE, "http-client-start: connect failed: %s", strerror(err));
        }
    } else {
        // TODO: call client_connected directly
    }
    
    if(ret) {
        close(socketfd);
    }
    return ret;
}

static int create_req_buffer(HttpClient *client) {
    CxBuffer buf;
    if(cxBufferInit(&buf, cxDefaultAllocator, NULL, 1024, CX_BUFFER_AUTO_EXTEND)) {
        return 1;
    }
    
    if(client->method) {
        cxBufferPutString(&buf, "GET ");
    } else {
        cxBufferPutString(&buf, client->method);
    }
    cxBufferPutString(&buf, client->uri ? client->uri : "/");
    cxBufferPutString(&buf, " HTTP/1.1\r\n");
    
    HeaderArray *hdr = client->request_headers;
    while(hdr) {
        for(int i=0;i<hdr->len;i++) {
            cxBufferPutString(&buf, hdr->headers[i].name);
            cxBufferPutString(&buf, ": ");
            cxBufferPutString(&buf, hdr->headers[i].value);
            cxBufferPutString(&buf, "\r\n");
        }
        hdr = hdr->next;
    }
    cxBufferPutString(&buf, "\r\n");
    client->req_buffer = buf.space;
    client->req_buffer_len = buf.size;
    
    return 0;
}

static int client_connected(EventHandler *ev, Event *event) {
    HttpClient *client = event->cookie;
    if(create_req_buffer(client)) {
        // TODO: set error
        return 0; // end
    }
    event->fn = client_io;
    
    return client_io(ev, event);
}

static int client_io(EventHandler *ev, Event *event) {
    HttpClient *client = event->cookie;
    if(client->req_buffer_pos < client->req_buffer_len) {
        if(client_send_request(client)) {
            if(client->error) {
                return 0; // TODO: set error
            }
            return 1;
        } 
    }
    
    // writing complete, switch to read events
    event->events = EVENT_POLLIN;
    
    
    char *buffer;
    size_t nbytes;
    if(client->header_complete) {
        buffer = client->buffer.inbuf;
        nbytes = client->buffer.maxsize;
    } else {
        buffer = client->buffer.inbuf + client->buffer.pos;
        nbytes = client->buffer.maxsize - client->buffer.cursize;
    }
    
    
    ssize_t r;
    while((r = read(client->socketfd, buffer, nbytes)) > 0) {
        client->buffer.cursize += r;
        if(!client->header_complete) {
            switch(http_parser_process(client->parser)) {
                case 0: { // finish
                    if(!http_parser_validate(client->parser)) {
                        client->error = 1;
                        return 0;
                    }
                    client->statuscode = client->parser->status;
                    
                    client->header_complete = 1;
                    if(client->response_start) {
                        cxmutstr msg = client->parser->msg;
                        char t = msg.ptr[msg.length];
                        msg.ptr[msg.length] = 0;
                        int ret = client->response_start(client, client->statuscode, msg.ptr, client->response_start_userdata);
                        msg.ptr[msg.length] = t;
                        
                        // TODO: check ret
                    }
                    break;
                }
                case 1: { // need more data
                    continue;
                }
                case 2: { // error
                    client->error = 1;
                    return 0;
                }
            }
        }
        
        // header complete
        
        char *out = client->buffer.inbuf + client->buffer.pos;
        size_t len = client->buffer.cursize - client->buffer.pos;
        
        if(client->response_body_write) {
            int ret = client->response_body_write(client, out, len, client->response_body_write_userdata);
            // TODO: check ret
        }
        
        client->buffer.pos = 0;
        client->buffer.cursize = 0;
    }
    
    if(r < 0) {
        if(errno == EAGAIN) {
            return 1;
        } else {
            log_ereport(LOG_FAILURE, "http-client: IO error: %s", strerror(errno));
        }
    }
    
    // request finished
    if(client->response_finished) {
        client->response_finished(client, client->response_finished_userdata);
    }
    
    return 0;
}

static int client_finished(EventHandler *ev, Event *event) {
    HttpClient *client = event->cookie;
    
    close(client->socketfd);
    client->socketfd = -1;
    
    // request finished
    if(client->response_finished) {
        client->response_finished(client, client->response_finished_userdata);
    }
    
    return 0;
}

static int client_send_request(HttpClient *client) {
    size_t nbytes = client->req_buffer_len - client->req_buffer_pos;
    ssize_t w = write(client->socketfd, client->req_buffer + client->req_buffer_pos, nbytes);
    if(w <= 0) {
        if(errno != EAGAIN) {
            // TODO: log correct host
            log_ereport(LOG_VERBOSE, "http-client %s - %s: write failed: %s", "localhost", client->uri, strerror(errno));
            client->error = 1;
        }
        return 1;
    }
    
    client->req_buffer_pos += w;
    
    return client->req_buffer_pos < client->req_buffer_len;
}