webcit-ng/server/http.c

   1 // This module handles HTTP transactions.
   2 //
   3 // Copyright (c) 1996-2023 by the citadel.org team
   4 //
   5 // This program is open source software.  Use, duplication, or disclosure is subject to the GNU General Public License v3.
   6
   7 #include "webcit.h"
   8
   9 // Write data to the HTTP client.  Encrypt if necessary.
  10 int client_write(struct client_handle *ch, char *buf, int nbytes) {
  11         if (is_https) {
  12                 return client_write_ssl(ch, buf, nbytes);
  13         }
  14         else {
  15                 return write(ch->sock, buf, nbytes);
  16         }
  17 }
  18
  19
  20 // Read data from the HTTP client.  Decrypt if necessary.
  21 // Returns number of bytes read, or -1 to indicate an error.
  22 int client_read(struct client_handle *ch, char *buf, int nbytes) {
  23         if (is_https) {
  24                 return client_read_ssl(ch, buf, nbytes);
  25         }
  26         else {
  27                 int bytes_received = 0;
  28                 int bytes_this_block = 0;
  29                 while (bytes_received < nbytes) {
  30                         bytes_this_block = read(ch->sock, &buf[bytes_received], nbytes - bytes_received);
  31                         if (bytes_this_block < 1) {
  32                                 return (-1);
  33                         }
  34                         bytes_received += bytes_this_block;
  35                 }
  36                 return (nbytes);
  37         }
  38 }
  39
  40
  41 // Read a newline-terminated line of text from the client.
  42 // Implemented in terms of client_read() and is therefore transparent...
  43 // Returns the string length or -1 for error.
  44 int client_readline(struct client_handle *ch, char *buf, int maxbytes) {
  45         int len = 0;
  46         int c = 0;
  47
  48         if (buf == NULL) {
  49                 return (-1);
  50         }
  51
  52         while (len < maxbytes) {
  53                 c = client_read(ch, &buf[len], 1);
  54                 if (c <= 0) {
  55                         syslog(LOG_DEBUG, "Socket error or zero-length read");
  56                         return (-1);
  57                 }
  58                 if (buf[len] == '\n') {
  59                         if ((len > 0) && (buf[len - 1] == '\r')) {
  60                                 --len;
  61                         }
  62                         buf[len] = 0;
  63                         return (len);
  64                 }
  65                 ++len;
  66         }
  67         return (len);
  68 }
  69
  70
  71 // printf() type function to send data to the web client.
  72 void client_printf(struct client_handle *ch, const char *format, ...) {
  73         va_list arg_ptr;
  74         StrBuf *Buf = NewStrBuf();
  75
  76         va_start(arg_ptr, format);
  77         StrBufVAppendPrintf(Buf, format, arg_ptr);
  78         va_end(arg_ptr);
  79
  80         client_write(ch, (char *) ChrPtr(Buf), StrLength(Buf));
  81         FreeStrBuf(&Buf);
  82 }
  83
  84
  85 // Push one new header into the response of an HTTP request.
  86 // When completed, the HTTP transaction now owns the memory allocated for key and val.
  87 void add_response_header(struct http_transaction *h, char *key, char *val) {
  88         struct keyval new_response_header;
  89         new_response_header.key = key;
  90         new_response_header.val = val;
  91         array_append(h->response_headers, &new_response_header);
  92 }
  93
  94
  95 // Entry point for this layer.  Socket is connected.  If running as an HTTPS
  96 // server, SSL has already been negotiated.  Now perform one transaction.
  97 void perform_one_http_transaction(struct client_handle *ch) {
  98         char buf[1024];
  99         int len;
 100         int lines_read = 0;
 101         struct http_transaction h;
 102         char *c, *d;
 103         struct sockaddr_in sin;
 104         int i;                                  // general purpose iterator variable
 105
 106         memset(&h, 0, sizeof h);
 107         h.request_headers = array_new(sizeof(struct keyval));
 108         h.request_parms = array_new(sizeof(struct keyval));
 109         h.response_headers = array_new(sizeof(struct keyval));
 110
 111         while (len = client_readline(ch, buf, sizeof buf), (len > 0)) {
 112                 ++lines_read;
 113
 114                 if (lines_read == 1) {          // First line is method and URL.
 115                         c = strchr(buf, ' ');   // IGnore the HTTP-version.
 116                         if (c == NULL) {
 117                                 h.method = strdup("NULL");
 118                                 h.url = strdup("/");
 119                         }
 120                         else {
 121                                 *c = 0;
 122                                 h.method = strdup(buf);
 123                                 ++c;
 124                                 d = c;
 125                                 c = strchr(d, ' ');
 126                                 if (c != NULL) {
 127                                         *c = 0;
 128                                 }
 129                                 ++c;
 130                                 h.url = strdup(d);
 131                         }
 132                 }
 133                 else {                          // Subsequent lines are headers.
 134                         c = strchr(buf, ':');   // Header line folding is obsolete so we don't support it.
 135                         if (c != NULL) {
 136
 137                                 struct keyval new_request_header;
 138                                 *c = 0;
 139                                 new_request_header.key = strdup(buf);
 140                                 ++c;
 141                                 new_request_header.val = strdup(c);
 142                                 string_trim(new_request_header.key);
 143                                 string_trim(new_request_header.val);
 144                                 array_append(h.request_headers, &new_request_header);
 145 #ifdef DEBUG_HTTP
 146                                 syslog(LOG_DEBUG, "{ %s: %s", new_request_header.key, new_request_header.val);
 147 #endif
 148                         }
 149                 }
 150
 151         }
 152
 153         // If the URL had any query parameters in it, parse them out now.
 154         char *p = (h.url ? strchr(h.url, '?') : NULL);
 155         if (p) {
 156                 *p++ = 0;                                               // insert a null to remove parameters from the URL
 157                 char *tok, *saveptr = NULL;
 158                 for (tok = strtok_r(p, "&", &saveptr); tok!=NULL; tok = strtok_r(NULL, "&", &saveptr)) {
 159                         char *eq = strchr(tok, '=');
 160                         if (eq) {
 161                                 *eq++ = 0;
 162                                 unescape_input(eq);
 163                                 struct keyval kv;
 164                                 kv.key = strdup(tok);
 165                                 kv.val = strdup(eq);
 166                                 array_append(h.request_parms, &kv);
 167 #ifdef DEBUG_HTTP
 168                                 syslog(LOG_DEBUG, "| %s = %s", kv.key, kv.val);
 169 #endif
 170                         }
 171                 }
 172         }
 173
 174         // build up the site prefix, such as https://foo.bar.com:4343
 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         }
 181         else {
 182                 strcat(h.site_prefix, "127.0.0.1");
 183         }
 184         socklen_t llen = sizeof(sin);
 185         if (getsockname(ch->sock, (struct sockaddr *) &sin, &llen) >= 0) {
 186                 sprintf(&h.site_prefix[strlen(h.site_prefix)], ":%d", ntohs(sin.sin_port));
 187         }
 188
 189         // Now try to read in the request body (if one is present)
 190         if (len < 0) {
 191                 syslog(LOG_DEBUG, "Client disconnected");
 192         }
 193         else {
 194 #ifdef DEBUG_HTTP
 195                 syslog(LOG_DEBUG, "< %s %s", h.method, h.url);
 196 #endif
 197
 198                 // If there is a request body, read it now.
 199                 char *ccl = header_val(&h, "Content-Length");
 200                 if (ccl) {
 201                         h.request_body_length = atol(ccl);
 202                 }
 203                 if (h.request_body_length > 0) {
 204                         syslog(LOG_DEBUG, "Reading request body (%ld bytes)", h.request_body_length);
 205
 206                         // Sometimes we need the request body by itself, sometimes we need it with headers.
 207                         // So we save it with synthetic headers, and also provide a pointer into the place where the body begins.
 208
 209                         char *cct = header_val(&h, "Content-Type");
 210                         if (cct) {
 211                                 h.request_body_with_synth_headers = malloc(h.request_body_length + 1024);
 212                                 memset(h.request_body_with_synth_headers, h.request_body_length + 1024, 0);
 213                                 sprintf(h.request_body_with_synth_headers, "Content-Type: %s\r\n\r\n", cct);
 214                                 h.request_body = h.request_body_with_synth_headers + strlen(h.request_body_with_synth_headers);
 215                         }
 216                         else {  // a request body absent a Content-Type: header is invalid, but handle it anyway.
 217                                 h.request_body_with_synth_headers = malloc(h.request_body_length);
 218                                 memset(h.request_body_with_synth_headers, h.request_body_length, 0);
 219                                 h.request_body = h.request_body_with_synth_headers;
 220                         }
 221
 222                         client_read(ch, h.request_body, h.request_body_length);
 223
 224                         // Write the entire request body to stderr -- not what you want during normal operation.
 225                         #ifdef REQUEST_BODY_TO_STDERR
 226                         write(2, HKEY("--- REQUEST BODY BEGIN ---\n"));
 227                         write(2, h.request_body, h.request_body_length);
 228                         write(2, HKEY("--- REQUEST BODY END ---\n"));
 229                         #endif
 230
 231                 }
 232
 233                 // Now pass control up to the next layer to perform the request.
 234                 perform_request(&h);
 235
 236                 // Write the entire response body to stderr -- not what you want during normal operation.
 237                 #ifdef RESPONSE_BODY_TO_STDERR
 238                 write(2, HKEY("--- RESPONSE BODY BEGIN ---\n"));
 239                 write(2, h.response_body, h.response_body_length);
 240                 write(2, HKEY("--- RESPONSE BODY END ---\n"));
 241                 #endif
 242
 243                 // Output the results back to the client.
 244 #ifdef DEBUG_HTTP
 245                 syslog(LOG_DEBUG, "> %03d %s", h.response_code, h.response_string);
 246 #endif
 247                 client_printf(ch, "HTTP/1.1 %03d %s\r\n", h.response_code, h.response_string);
 248                 client_printf(ch, "Connection: close\r\n");
 249                 client_printf(ch, "Content-Length: %ld\r\n", h.response_body_length);
 250                 char *datestring = http_datestring(time(NULL));
 251                 if (datestring) {
 252                         client_printf(ch, "Date: %s\r\n", datestring);
 253                         free(datestring);
 254                 }
 255
 256                 client_printf(ch, "Content-encoding: identity\r\n");    // change if we gzip/deflate
 257                 int number_of_response_headers = array_len(h.response_headers);
 258                 for (i=0; i<number_of_response_headers; ++i) {
 259                         struct keyval *kv = array_get_element_at(h.response_headers, i);
 260 #ifdef DEBUG_HTTP
 261                         syslog(LOG_DEBUG, "} %s: %s", kv->key, kv->val);
 262 #endif
 263                         client_printf(ch, "%s: %s\r\n", kv->key, kv->val);
 264                 }
 265                 client_printf(ch, "\r\n");
 266                 if ((h.response_body_length > 0) && (h.response_body != NULL)) {
 267                         client_write(ch, h.response_body, h.response_body_length);
 268                 }
 269         }
 270
 271         // free the transaction memory
 272         while (array_len(h.request_headers) > 0) {
 273                 struct keyval *kv = array_get_element_at(h.request_headers, 0);
 274                 if (kv->key) free(kv->key);
 275                 if (kv->val) free(kv->val);
 276                 array_delete_element_at(h.request_headers, 0);
 277         }
 278         array_free(h.request_headers);
 279         while (array_len(h.request_parms) > 0) {
 280                 struct keyval *kv = array_get_element_at(h.request_parms, 0);
 281                 if (kv->key) free(kv->key);
 282                 if (kv->val) free(kv->val);
 283                 array_delete_element_at(h.request_parms, 0);
 284         }
 285         array_free(h.request_parms);
 286         while (array_len(h.response_headers) > 0) {
 287                 struct keyval *kv = array_get_element_at(h.response_headers, 0);
 288                 if (kv->key) free(kv->key);
 289                 if (kv->val) free(kv->val);
 290                 array_delete_element_at(h.response_headers, 0);
 291         }
 292         array_free(h.response_headers);
 293         if (h.method) {
 294                 free(h.method);
 295         }
 296         if (h.url) {
 297                 free(h.url);
 298         }
 299         if (h.request_body_with_synth_headers) {
 300                 free(h.request_body_with_synth_headers);
 301         }
 302         if (h.response_string) {
 303                 free(h.response_string);
 304         }
 305         if (h.site_prefix) {
 306                 free(h.site_prefix);
 307         }
 308 }
 309
 310
 311 // Utility function to fetch a specific header from a completely read-in request.
 312 // Returns the value of the requested header, or NULL if the specified header was not sent.
 313 // The caller does NOT own the memory of the returned pointer, but can count on the pointer
 314 // to still be valid through the end of the transaction.
 315 char *header_val(struct http_transaction *h, char *requested_header) {
 316         struct keyval *kv;
 317         int i;
 318         for (i=0; i<array_len(h->request_headers); ++i) {
 319                 kv = array_get_element_at(h->request_headers, i);
 320                 if (!strcasecmp(kv->key, requested_header)) {
 321                         return (kv->val);
 322                 }
 323         }
 324         return (NULL);
 325 }
 326
 327
 328 // Utility function to fetch a specific URL parameter from a completely read-in request.
 329 // Returns the value of the requested parameter, or NULL if the specified parameter was not sent.
 330 // The caller does NOT own the memory of the returned pointer, but can count on the pointer
 331 // to still be valid through the end of the transaction.
 332 char *get_url_param(struct http_transaction *h, char *requested_param) {
 333         struct keyval *kv;
 334         int i;
 335         for (i=0; i<array_len(h->request_parms); ++i) {
 336                 kv = array_get_element_at(h->request_parms, i);
 337                 if (!strcasecmp(kv->key, requested_param)) {
 338                         return (kv->val);
 339                 }
 340         }
 341         return (NULL);
 342 }