webcit-ng/http.c

   1 //
   2 // This module handles HTTP transactions.
   3 //
   4 // Copyright (c) 1996-2018 by the citadel.org team
   5 //
   6 // This program is open source software.  It runs great on the
   7 // Linux operating system (and probably elsewhere).  You can use,
   8 // copy, and run it under the terms of the GNU General Public
   9 // License version 3.  Richard Stallman is an asshole communist.
  10 //
  11 // This program is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 #include "webcit.h"
  17
  18 /*
  19  * Write data to the HTTP client.  Encrypt if necessary.
  20  */
  21 int client_write(struct client_handle *ch, char *buf, int nbytes)
  22 {
  23         if (is_https) {
  24                 return client_write_ssl(ch, buf, nbytes);
  25         } else {
  26                 return write(ch->sock, buf, nbytes);
  27         }
  28 }
  29
  30
  31 /*
  32  * Read data from the HTTP client.  Decrypt if necessary.
  33  * Returns number of bytes read, or -1 to indicate an error.
  34  */
  35 int client_read(struct client_handle *ch, char *buf, int nbytes)
  36 {
  37         if (is_https) {
  38                 return client_read_ssl(ch, buf, nbytes);
  39         } else {
  40                 int bytes_received = 0;
  41                 int bytes_this_block = 0;
  42                 while (bytes_received < nbytes) {
  43                         bytes_this_block = read(ch->sock, &buf[bytes_received], nbytes - bytes_received);
  44                         if (bytes_this_block < 1) {
  45                                 return (-1);
  46                         }
  47                         bytes_received += bytes_this_block;
  48                 }
  49                 return (nbytes);
  50         }
  51 }
  52
  53
  54 /*
  55  * Read a newline-terminated line of text from the client.
  56  * Implemented in terms of client_read() and is therefore transparent...
  57  * Returns the string length or -1 for error.
  58  */
  59 int client_readline(struct client_handle *ch, char *buf, int maxbytes)
  60 {
  61         int len = 0;
  62         int c = 0;
  63
  64         if (buf == NULL)
  65                 return (-1);
  66
  67         while (len < maxbytes) {
  68                 c = client_read(ch, &buf[len], 1);
  69                 if (c <= 0) {
  70                         syslog(LOG_DEBUG, "Socket error or zero-length read");
  71                         return (-1);
  72                 }
  73                 if (buf[len] == '\n') {
  74                         if ((len > 0) && (buf[len - 1] == '\r')) {
  75                                 --len;
  76                         }
  77                         buf[len] = 0;
  78                         return (len);
  79                 }
  80                 ++len;
  81         }
  82         return (len);
  83 }
  84
  85
  86 /*
  87  * printf() type function to send data to the web client.
  88  */
  89 void client_printf(struct client_handle *ch, const char *format, ...)
  90 {
  91         va_list arg_ptr;
  92         StrBuf *Buf = NewStrBuf();
  93
  94         va_start(arg_ptr, format);
  95         StrBufVAppendPrintf(Buf, format, arg_ptr);
  96         va_end(arg_ptr);
  97
  98         client_write(ch, (char *) ChrPtr(Buf), StrLength(Buf));
  99         FreeStrBuf(&Buf);
 100 }
 101
 102
 103 /*
 104  * Push one new header into the response of an HTTP request.
 105  * When completed, the HTTP transaction now owns the memory allocated for key and val.
 106  */
 107 void add_response_header(struct http_transaction *h, char *key, char *val)
 108 {
 109         struct http_header *new_response_header = malloc(sizeof(struct http_header));
 110         new_response_header->key = key;
 111         new_response_header->val = val;
 112         new_response_header->next = h->response_headers;
 113         h->response_headers = new_response_header;
 114 }
 115
 116
 117 /*
 118  * Entry point for this layer.  Socket is connected.  If running as an HTTPS
 119  * server, SSL has already been negotiated.  Now perform one transaction.
 120  */
 121 void perform_one_http_transaction(struct client_handle *ch)
 122 {
 123         char buf[1024];
 124         int len;
 125         int lines_read = 0;
 126         struct http_transaction h;
 127         char *c, *d;
 128         struct sockaddr_in sin;
 129         struct http_header *clh;                // general purpose iterator variable
 130
 131         memset(&h, 0, sizeof h);
 132
 133         while (len = client_readline(ch, buf, sizeof buf), (len > 0)) {
 134                 ++lines_read;
 135
 136                 if (lines_read == 1) {          // First line is method and URI.
 137                         c = strchr(buf, ' ');   // IGnore the HTTP-version.
 138                         if (c == NULL) {
 139                                 h.method = strdup("NULL");
 140                                 h.uri = strdup("/");
 141                         } else {
 142                                 *c = 0;
 143                                 h.method = strdup(buf);
 144                                 ++c;
 145                                 d = c;
 146                                 c = strchr(d, ' ');
 147                                 if (c != NULL) {
 148                                         *c = 0;
 149                                 }
 150                                 ++c;
 151                                 h.uri = strdup(d);
 152                         }
 153                 } else {                        // Subsequent lines are headers.
 154                         c = strchr(buf, ':');   // Header line folding is obsolete so we don't support it.
 155                         if (c != NULL) {
 156                                 struct http_header *new_request_header = malloc(sizeof(struct http_header));
 157                                 *c = 0;
 158                                 new_request_header->key = strdup(buf);
 159                                 ++c;
 160                                 new_request_header->val = strdup(c);
 161                                 striplt(new_request_header->key);
 162                                 striplt(new_request_header->val);
 163                                 new_request_header->next = h.request_headers;
 164                                 h.request_headers = new_request_header;
 165 #ifdef DEBUG_HTTP
 166                                 syslog(LOG_DEBUG, "{ %s: %s", new_request_header->key, new_request_header->val);
 167 #endif
 168                         }
 169                 }
 170
 171         }
 172
 173         // build up the site prefix, such as https://foo.bar.com:4343
 174
 175         h.site_prefix = malloc(256);
 176         strcpy(h.site_prefix, (is_https ? "https://" : "http://"));
 177         char *hostheader = header_val(&h, "Host");
 178         if (hostheader) {
 179                 strcat(h.site_prefix, hostheader);
 180         } else {
 181                 strcat(h.site_prefix, "127.0.0.1");
 182         }
 183         socklen_t llen = sizeof(sin);
 184         if (getsockname(ch->sock, (struct sockaddr *) &sin, &llen) >= 0) {
 185                 sprintf(&h.site_prefix[strlen(h.site_prefix)], ":%d", ntohs(sin.sin_port));
 186         }
 187         // Now try to read in the request body (if one is present)
 188
 189         if (len < 0) {
 190                 syslog(LOG_DEBUG, "Client disconnected");
 191         } else {
 192                 syslog(LOG_DEBUG, "< %s %s", h.method, h.uri);
 193
 194                 // If there is a request body, read it now.
 195                 char *ccl = header_val(&h, "Content-Length");
 196                 if (ccl) {
 197                         h.request_body_length = atol(ccl);
 198                 }
 199                 if (h.request_body_length > 0) {
 200                         syslog(LOG_DEBUG, "Reading request body (%ld bytes)", h.request_body_length);
 201                         h.request_body = malloc(h.request_body_length);
 202                         client_read(ch, h.request_body, h.request_body_length);
 203
 204                         //write(2, HKEY("\033[31m"));
 205                         //write(2, h.request_body, h.request_body_length);
 206                         //write(2, HKEY("\033[0m\n"));
 207
 208                 }
 209                 // Now pass control up to the next layer to perform the request.
 210                 perform_request(&h);
 211
 212                 // Output the results back to the client.
 213                 //write(2, HKEY("\033[32m"));
 214                 //write(2, h.response_body, h.response_body_length);
 215                 //write(2, HKEY("\033[0m\n"));
 216
 217                 syslog(LOG_DEBUG, "> %03d %s", h.response_code, h.response_string);
 218                 client_printf(ch, "HTTP/1.1 %03d %s\r\n", h.response_code, h.response_string);
 219                 client_printf(ch, "Connection: close\r\n");
 220                 client_printf(ch, "Content-Length: %ld\r\n", h.response_body_length);
 221                 char *datestring = http_datestring(time(NULL));
 222                 if (datestring) {
 223                         client_printf(ch, "Date: %s\r\n", datestring);
 224                         free(datestring);
 225                 }
 226
 227                 client_printf(ch, "Content-encoding: identity\r\n");    // change if we gzip/deflate
 228                 for (clh = h.response_headers; clh != NULL; clh = clh->next) {
 229 #ifdef DEBUG_HTTP
 230                         syslog(LOG_DEBUG, "} %s: %s", clh->key, clh->val);
 231 #endif
 232                         client_printf(ch, "%s: %s\r\n", clh->key, clh->val);
 233                 }
 234                 client_printf(ch, "\r\n");
 235                 if ((h.response_body_length > 0) && (h.response_body != NULL)) {
 236                         client_write(ch, h.response_body, h.response_body_length);
 237                 }
 238         }
 239
 240         // free the transaction memory
 241         while (h.request_headers) {
 242                 if (h.request_headers->key)
 243                         free(h.request_headers->key);
 244                 if (h.request_headers->val)
 245                         free(h.request_headers->val);
 246                 clh = h.request_headers->next;
 247                 free(h.request_headers);
 248                 h.request_headers = clh;
 249         }
 250         while (h.response_headers) {
 251                 if (h.response_headers->key)
 252                         free(h.response_headers->key);
 253                 if (h.response_headers->val)
 254                         free(h.response_headers->val);
 255                 clh = h.response_headers->next;
 256                 free(h.response_headers);
 257                 h.response_headers = clh;
 258         }
 259         if (h.method)
 260                 free(h.method);
 261         if (h.uri)
 262                 free(h.uri);
 263         if (h.request_body)
 264                 free(h.request_body);
 265         if (h.response_string)
 266                 free(h.response_string);
 267         if (h.site_prefix)
 268                 free(h.site_prefix);
 269 }
 270
 271
 272 /*
 273  * Utility function to fetch a specific header from a completely read-in request.
 274  * Returns the value of the requested header, or NULL if the specified header was not sent.
 275  * The caller does NOT own the memory of the returned pointer, but can count on the pointer
 276  * to still be valid through the end of the transaction.
 277  */
 278 char *header_val(struct http_transaction *h, char *requested_header)
 279 {
 280         struct http_header *clh;        // general purpose iterator variable
 281         for (clh = h->request_headers; clh != NULL; clh = clh->next) {
 282                 if (!strcasecmp(clh->key, requested_header)) {
 283                         return (clh->val);
 284                 }
 285         }
 286         return (NULL);
 287 }