source: lib/http_client.c @ 65d0dfd

/********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2013 Wilmer van der Gaast and others                *
  \********************************************************************/

/* HTTP(S) module                                                       */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 51 Franklin St.,
  Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <string.h>
#include <stdio.h>

#include "http_client.h"
#include "url.h"
#include "sock.h"


static gboolean http_connected(gpointer data, int source, b_input_condition cond);
static gboolean http_ssl_connected(gpointer data, int returncode, void *source, b_input_condition cond);
static gboolean http_incoming_data(gpointer data, int source, b_input_condition cond);
static void http_free(struct http_request *req);


struct http_request *http_dorequest(char *host, int port, int ssl, char *request, http_input_function func,
                                    gpointer data)
{
        struct http_request *req;
        int error = 0;

        req = g_new0(struct http_request, 1);

        if (ssl) {
                req->ssl = ssl_connect(host, port, TRUE, http_ssl_connected, req);
                if (req->ssl == NULL) {
                        error = 1;
                }
        } else {
                req->fd = proxy_connect(host, port, http_connected, req);
                if (req->fd < 0) {
                        error = 1;
                }
        }

        if (error) {
                http_free(req);
                return NULL;
        }

        req->func = func;
        req->data = data;
        req->request = g_strdup(request);
        req->request_length = strlen(request);
        req->redir_ttl = 3;
        req->content_length = -1;

        if (getenv("BITLBEE_DEBUG")) {
                printf("About to send HTTP request:\n%s\n", req->request);
        }

        return req;
}

struct http_request *http_dorequest_url(char *url_string, http_input_function func, gpointer data)
{
        url_t *url = g_new0(url_t, 1);
        char *request;
        void *ret;

        if (!url_set(url, url_string)) {
                g_free(url);
                return NULL;
        }

        if (url->proto != PROTO_HTTP && url->proto != PROTO_HTTPS) {
                g_free(url);
                return NULL;
        }

        request = g_strdup_printf("GET %s HTTP/1.0\r\n"
                                  "Host: %s\r\n"
                                  "User-Agent: BitlBee " BITLBEE_VERSION "\r\n"
                                  "\r\n", url->file, url->host);

        ret = http_dorequest(url->host, url->port,
                             url->proto == PROTO_HTTPS, request, func, data);

        g_free(url);
        g_free(request);
        return ret;
}

/* This one is actually pretty simple... Might get more calls if we can't write
   the whole request at once. */
static gboolean http_connected(gpointer data, int source, b_input_condition cond)
{
        struct http_request *req = data;
        int st;

        if (source < 0) {
                goto error;
        }

        if (req->inpa > 0) {
                b_event_remove(req->inpa);
        }

        sock_make_nonblocking(req->fd);

        if (req->ssl) {
                st = ssl_write(req->ssl, req->request + req->bytes_written,
                               req->request_length - req->bytes_written);
                if (st < 0) {
                        if (ssl_errno != SSL_AGAIN) {
                                ssl_disconnect(req->ssl);
                                goto error;
                        }
                }
        } else {
                st = write(source, req->request + req->bytes_written,
                           req->request_length - req->bytes_written);
                if (st < 0) {
                        if (!sockerr_again()) {
                                closesocket(req->fd);
                                goto error;
                        }
                }
        }

        if (st > 0) {
                req->bytes_written += st;
        }

        if (req->bytes_written < req->request_length) {
                req->inpa = b_input_add(source,
                                        req->ssl ? ssl_getdirection(req->ssl) : B_EV_IO_WRITE,
                                        http_connected, req);
        } else {
                req->inpa = b_input_add(source, B_EV_IO_READ, http_incoming_data, req);
        }

        return FALSE;

error:
        if (req->status_string == NULL) {
                req->status_string = g_strdup("Error while writing HTTP request");
        }

        if (req->func != NULL) {
                req->func(req);
        }
        http_free(req);
        return FALSE;
}

static gboolean http_ssl_connected(gpointer data, int returncode, void *source, b_input_condition cond)
{
        struct http_request *req = data;

        if (source == NULL) {
                if (returncode != 0) {
                        char *err = ssl_verify_strerror(returncode);
                        req->status_string = g_strdup_printf(
                                "Certificate verification problem 0x%x: %s",
                                returncode, err ? err : "Unknown");
                        g_free(err);
                }
                return http_connected(data, -1, cond);
        }

        req->fd = ssl_getfd(source);

        return http_connected(data, req->fd, cond);
}

typedef enum {
        CR_OK,
        CR_EOF,
        CR_ERROR,
        CR_ABORT,
} http_ret_t;

static gboolean http_handle_headers(struct http_request *req);
static http_ret_t http_process_chunked_data(struct http_request *req, const char *buffer, int len);
static http_ret_t http_process_data(struct http_request *req, const char *buffer, int len);

static gboolean http_incoming_data(gpointer data, int source, b_input_condition cond)
{
        struct http_request *req = data;
        char buffer[4096];
        int st;

        if (req->inpa > 0) {
                b_event_remove(req->inpa);
                req->inpa = 0;
        }

        if (req->ssl) {
                st = ssl_read(req->ssl, buffer, sizeof(buffer));
                if (st < 0) {
                        if (ssl_errno != SSL_AGAIN) {
                                /* goto cleanup; */

                                /* YAY! We have to deal with crappy Microsoft
                                   servers that LOVE to send invalid TLS
                                   packets that abort connections! \o/ */

                                goto eof;
                        }
                } else if (st == 0) {
                        goto eof;
                }
        } else {
                st = read(req->fd, buffer, sizeof(buffer));
                if (st < 0) {
                        if (!sockerr_again()) {
                                req->status_string = g_strdup(strerror(errno));
                                goto cleanup;
                        }
                } else if (st == 0) {
                        goto eof;
                }
        }

        if (st > 0) {
                http_ret_t c;

                if (req->flags & HTTPC_CHUNKED) {
                        c = http_process_chunked_data(req, buffer, st);
                } else {
                        c = http_process_data(req, buffer, st);
                }

                if (c == CR_EOF) {
                        goto eof;
                } else if (c == CR_ERROR || c == CR_ABORT) {
                        return FALSE;
                }
        }

        if (req->content_length != -1 &&
            req->body_size >= req->content_length) {
                goto eof;
        }

        if (ssl_pending(req->ssl)) {
                return http_incoming_data(data, source, cond);
        }

        /* There will be more! */
        req->inpa = b_input_add(req->fd,
                                req->ssl ? ssl_getdirection(req->ssl) : B_EV_IO_READ,
                                http_incoming_data, req);

        return FALSE;

eof:
        req->flags |= HTTPC_EOF;

        /* Maybe if the webserver is overloaded, or when there's bad SSL
           support... */
        if (req->bytes_read == 0) {
                req->status_string = g_strdup("Empty HTTP reply");
                goto cleanup;
        }

cleanup:
        /* Avoid g_source_remove warnings */
        req->inpa = 0;

        if (req->ssl) {
                ssl_disconnect(req->ssl);
        } else {
                closesocket(req->fd);
        }

        if (req->body_size < req->content_length) {
                req->status_code = -1;
                g_free(req->status_string);
                req->status_string = g_strdup("Response truncated");
        }

        if (getenv("BITLBEE_DEBUG") && req) {
                printf("Finishing HTTP request with status: %s\n",
                       req->status_string ? req->status_string : "NULL");
        }

        if (req->func != NULL) {
                req->func(req);
        }
        http_free(req);
        return FALSE;
}

static http_ret_t http_process_chunked_data(struct http_request *req, const char *buffer, int len)
{
        char *chunk, *eos, *s;

        if (len < 0) {
                return TRUE;
        }

        if (len > 0) {
                req->cbuf = g_realloc(req->cbuf, req->cblen + len + 1);
                memcpy(req->cbuf + req->cblen, buffer, len);
                req->cblen += len;
                req->cbuf[req->cblen] = '\0';
        }

        /* Turns out writing a proper chunked-encoding state machine is not
           that simple. :-( I've tested this one feeding it byte by byte so
           I hope it's solid now. */
        chunk = req->cbuf;
        eos = req->cbuf + req->cblen;
        while (TRUE) {
                int clen = 0;

                /* Might be a \r\n from the last chunk. */
                s = chunk;
                while (g_ascii_isspace(*s)) {
                        s++;
                }
                /* Chunk length. Might be incomplete. */
                if (s < eos && sscanf(s, "%x", &clen) != 1) {
                        return CR_ERROR;
                }
                while (g_ascii_isxdigit(*s)) {
                        s++;
                }

                /* If we read anything here, it *must* be \r\n. */
                if (strncmp(s, "\r\n", MIN(2, eos - s)) != 0) {
                        return CR_ERROR;
                }
                s += 2;

                if (s >= eos) {
                        break;
                }

                /* 0-length chunk means end of response. */
                if (clen == 0) {
                        return CR_EOF;
                }

                /* Wait for the whole chunk to arrive. */
                if (s + clen > eos) {
                        break;
                }
                if (http_process_data(req, s, clen) != CR_OK) {
                        return CR_ABORT;
                }

                chunk = s + clen;
        }

        if (chunk != req->cbuf) {
                req->cblen = eos - chunk;
                s = g_memdup(chunk, req->cblen + 1);
                g_free(req->cbuf);
                req->cbuf = s;
        }

        return CR_OK;
}

static http_ret_t http_process_data(struct http_request *req, const char *buffer, int len)
{
        if (len <= 0) {
                return CR_OK;
        }

        if (!req->reply_body) {
                req->reply_headers = g_realloc(req->reply_headers, req->bytes_read + len + 1);
                memcpy(req->reply_headers + req->bytes_read, buffer, len);
                req->bytes_read += len;
                req->reply_headers[req->bytes_read] = '\0';

                if (strstr(req->reply_headers, "\r\n\r\n") ||
                    strstr(req->reply_headers, "\n\n")) {
                        /* We've now received all headers. Look for something
                           interesting. */
                        if (!http_handle_headers(req)) {
                                return CR_ABORT;
                        }

                        /* Start parsing the body as chunked if required. */
                        if (req->flags & HTTPC_CHUNKED) {
                                return http_process_chunked_data(req, NULL, 0);
                        }
                }
        } else {
                int pos = req->reply_body - req->sbuf;
                req->sbuf = g_realloc(req->sbuf, req->sblen + len + 1);
                memcpy(req->sbuf + req->sblen, buffer, len);
                req->bytes_read += len;
                req->sblen += len;
                req->sbuf[req->sblen] = '\0';
                req->reply_body = req->sbuf + pos;
                req->body_size = req->sblen - pos;
        }

        if ((req->flags & HTTPC_STREAMING) && req->reply_body && req->func != NULL) {
                req->func(req);
        }

        return CR_OK;
}

/* Splits headers and body. Checks result code, in case of 300s it'll handle
   redirects. If this returns FALSE, don't call any callbacks! */
static gboolean http_handle_headers(struct http_request *req)
{
        char *end1, *end2, *s;
        int evil_server = 0;

        /* Zero termination is very convenient. */
        req->reply_headers[req->bytes_read] = '\0';

        /* Find the separation between headers and body, and keep stupid
           webservers in mind. */
        end1 = strstr(req->reply_headers, "\r\n\r\n");
        end2 = strstr(req->reply_headers, "\n\n");

        if (end2 && end2 < end1) {
                end1 = end2 + 1;
                evil_server = 1;
        } else if (end1) {
                end1 += 2;
        } else {
                req->status_string = g_strdup("Malformed HTTP reply");
                return TRUE;
        }

        *end1 = '\0';

        if (getenv("BITLBEE_DEBUG")) {
                printf("HTTP response headers:\n%s\n", req->reply_headers);
        }

        if (evil_server) {
                req->reply_body = end1 + 1;
        } else {
                req->reply_body = end1 + 2;
        }

        /* Separately allocated space for headers and body. */
        req->sblen = req->body_size = req->reply_headers + req->bytes_read - req->reply_body;
        req->sbuf = req->reply_body = g_memdup(req->reply_body, req->body_size + 1);
        req->reply_headers = g_realloc(req->reply_headers, end1 - req->reply_headers + 1);

        if ((end1 = strchr(req->reply_headers, ' ')) != NULL) {
                if (sscanf(end1 + 1, "%hd", &req->status_code) != 1) {
                        req->status_string = g_strdup("Can't parse status code");
                        req->status_code = -1;
                } else {
                        char *eol;

                        if (evil_server) {
                                eol = strchr(end1, '\n');
                        } else {
                                eol = strchr(end1, '\r');
                        }

                        req->status_string = g_strndup(end1 + 1, eol - end1 - 1);

                        /* Just to be sure... */
                        if ((eol = strchr(req->status_string, '\r'))) {
                                *eol = 0;
                        }
                        if ((eol = strchr(req->status_string, '\n'))) {
                                *eol = 0;
                        }
                }
        } else {
                req->status_string = g_strdup("Can't locate status code");
                req->status_code = -1;
        }

        if (((req->status_code >= 301 && req->status_code <= 303) ||
             req->status_code == 307) && req->redir_ttl-- > 0) {
                char *loc, *new_request, *new_host;
                int error = 0, new_port, new_proto;

                /* We might fill it again, so let's not leak any memory. */
                g_free(req->status_string);
                req->status_string = NULL;

                loc = strstr(req->reply_headers, "\nLocation: ");
                if (loc == NULL) { /* We can't handle this redirect... */
                        req->status_string = g_strdup("Can't locate Location: header");
                        return TRUE;
                }

                loc += 11;
                while (*loc == ' ') {
                        loc++;
                }

                /* TODO/FIXME: Possibly have to handle relative redirections,
                   and rewrite Host: headers. Not necessary for now, it's
                   enough for passport authentication like this. */

                if (*loc == '/') {
                        /* Just a different pathname... */

                        /* Since we don't cache the servername, and since we
                           don't need this yet anyway, I won't implement it. */

                        req->status_string = g_strdup("Can't handle relative redirects");

                        return TRUE;
                } else {
                        /* A whole URL */
                        url_t *url;
                        char *s, *version, *headers;
                        const char *new_method;

                        s = strstr(loc, "\r\n");
                        if (s == NULL) {
                                return TRUE;
                        }

                        url = g_new0(url_t, 1);
                        *s = 0;

                        if (!url_set(url, loc)) {
                                req->status_string = g_strdup("Malformed redirect URL");
                                g_free(url);
                                return TRUE;
                        }

                        /* Find all headers and, if necessary, the POST request contents.
                           Skip the old Host: header though. This crappy code here means
                           anything using this http_client MUST put the Host: header at
                           the top. */
                        if (!((s = strstr(req->request, "\r\nHost: ")) &&
                              (s = strstr(s + strlen("\r\nHost: "), "\r\n")))) {
                                req->status_string = g_strdup("Error while rebuilding request string");
                                g_free(url);
                                return TRUE;
                        }
                        headers = s;

                        /* More or less HTTP/1.0 compliant, from my reading of RFC 2616.
                           Always perform a GET request unless we received a 301. 303 was
                           meant for this but it's HTTP/1.1-only and we're specifically
                           speaking HTTP/1.0. ...

                           Well except someone at identi.ca's didn't bother reading any
                           RFCs and just return HTTP/1.1-specific status codes to HTTP/1.0
                           requests. Fuckers. So here we are, handle 301..303,307. */
                        if (strncmp(req->request, "GET", 3) == 0) {
                                /* GETs never become POSTs. */
                                new_method = "GET";
                        } else if (req->status_code == 302 || req->status_code == 303) {
                                /* 302 de-facto becomes GET, 303 as specified by RFC 2616#10.3.3 */
                                new_method = "GET";
                        } else {
                                /* 301 de-facto should stay POST, 307 specifally RFC 2616#10.3.8 */
                                new_method = "POST";
                        }

                        if ((version = strstr(req->request, " HTTP/")) &&
                            (s = strstr(version, "\r\n"))) {
                                version++;
                                version = g_strndup(version, s - version);
                        } else {
                                version = g_strdup("HTTP/1.0");
                        }

                        /* Okay, this isn't fun! We have to rebuild the request... :-( */
                        new_request = g_strdup_printf("%s %s %s\r\nHost: %s%s",
                                                      new_method, url->file, version,
                                                      url->host, headers);

                        new_host = g_strdup(url->host);
                        new_port = url->port;
                        new_proto = url->proto;

                        /* If we went from POST to GET, truncate the request content. */
                        if (new_request[0] != req->request[0] && new_request[0] == 'G' &&
                            (s = strstr(new_request, "\r\n\r\n"))) {
                                s[4] = '\0';
                        }

                        g_free(url);
                        g_free(version);
                }

                if (req->ssl) {
                        ssl_disconnect(req->ssl);
                } else {
                        closesocket(req->fd);
                }

                req->fd = -1;
                req->ssl = NULL;

                if (getenv("BITLBEE_DEBUG")) {
                        printf("New headers for redirected HTTP request:\n%s\n", new_request);
                }

                if (new_proto == PROTO_HTTPS) {
                        req->ssl = ssl_connect(new_host, new_port, TRUE, http_ssl_connected, req);
                        if (req->ssl == NULL) {
                                error = 1;
                        }
                } else {
                        req->fd = proxy_connect(new_host, new_port, http_connected, req);
                        if (req->fd < 0) {
                                error = 1;
                        }
                }
                g_free(new_host);

                if (error) {
                        req->status_string = g_strdup("Connection problem during redirect");
                        g_free(new_request);
                        return TRUE;
                }

                g_free(req->request);
                g_free(req->reply_headers);
                g_free(req->sbuf);
                req->request = new_request;
                req->request_length = strlen(new_request);
                req->bytes_read = req->bytes_written = req->inpa = 0;
                req->reply_headers = req->reply_body = NULL;
                req->sbuf = req->cbuf = NULL;
                req->sblen = req->cblen = 0;

                return FALSE;
        }

        if ((s = get_rfc822_header(req->reply_headers, "Content-Length", 0)) &&
            sscanf(s, "%d", &req->content_length) != 1) {
                req->content_length = -1;
        }
        g_free(s);

        if ((s = get_rfc822_header(req->reply_headers, "Transfer-Encoding", 0))) {
                if (strcasestr(s, "chunked")) {
                        req->flags |= HTTPC_CHUNKED;
                        req->cbuf = req->sbuf;
                        req->cblen = req->sblen;

                        req->reply_body = req->sbuf = g_strdup("");
                        req->body_size = req->sblen = 0;
                }
                g_free(s);
        }

        return TRUE;
}

void http_flush_bytes(struct http_request *req, size_t len)
{
        if (len <= 0 || len > req->body_size || !(req->flags & HTTPC_STREAMING)) {
                return;
        }

        req->reply_body += len;
        req->body_size -= len;

        if (req->reply_body - req->sbuf >= 512) {
                char *new = g_memdup(req->reply_body, req->body_size + 1);
                g_free(req->sbuf);
                req->reply_body = req->sbuf = new;
                req->sblen = req->body_size;
        }
}

void http_close(struct http_request *req)
{
        if (!req) {
                return;
        }

        if (req->inpa > 0) {
                b_event_remove(req->inpa);
        }

        if (req->ssl) {
                ssl_disconnect(req->ssl);
        } else {
                proxy_disconnect(req->fd);
        }

        http_free(req);
}

static void http_free(struct http_request *req)
{
        g_free(req->request);
        g_free(req->reply_headers);
        g_free(req->status_string);
        g_free(req->sbuf);
        g_free(req->cbuf);
        g_free(req);
}