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	pubsub_cgi.c - pubsubhubbubblub - pubsubhubbub client implementation
	git clone git://git.codemadness.org/pubsubhubbubblub
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	---
	pubsub_cgi.c (11386B)
	---
	1 #include <sys/stat.h>
	2
	3 #include <ctype.h>
	4 #include <err.h>
	5 #include <errno.h>
	6 #include <limits.h>
	7 #include <stdio.h>
	8 #include <stdlib.h>
	9 #include <string.h>
	10 #include <time.h>
	11 #include <unistd.h>
	12
	13 #ifdef __OpenBSD__
	14 #include <unistd.h>
	15 #else
	16 #define pledge(p1,p2) 0
	17 #define unveil(p1,p2) 0
	18 #endif
	19
	20 #include "hmac_sha1.h"
	21
	22 static const char *relpath = "/pubsub/";
	23
	24 #define DATADIR "/pubsub-data"
	25
	26 static const char *configdir = DATADIR "/config";
	27 static const char *datadir = DATADIR "/feeds";
	28 static const char *tmpdir = DATADIR "/tmp";
	29 static const char *logfile = DATADIR "/log";
	30 static time_t now;
	31
	32 char *
	33 readfile(const char *path)
	34 {
	35 static char buf[256];
	36 FILE *fp;
	37
	38 if (!(fp = fopen(path, "rb")))
	39 goto err;
	40 if (!fgets(buf, sizeof(buf), fp))
	41 goto err;
	42 fclose(fp);
	43 buf[strcspn(buf, "\n")] = '\0';
	44 return buf;
	45
	46 err:
	47 if (fp)
	48 fclose(fp);
	49 return NULL;
	50 }
	51
	52 int
	53 hexdigit(int c)
	54 {
	55 if (c >= '0' && c <= '9')
	56 return c - '0';
	57 else if (c >= 'A' && c <= 'F')
	58 return c - 'A' + 10;
	59 else if (c >= 'a' && c <= 'f')
	60 return c - 'a' + 10;
	61
	62 return 0;
	63 }
	64
	65 /* decode until NUL separator or end of "key". */
	66 int
	67 decodeparamuntilend(char buf, size_t bufsiz, const char s, int end)
	68 {
	69 size_t i;
	70
	71 if (!bufsiz)
	72 return -1;
	73
	74 for (i = 0; s && s != end; s++) {
	75 switch (*s) {
	76 case '%':
	77 if (i + 3 >= bufsiz)
	78 return -1;
	79 if (!isxdigit((unsigned char)*(s+1)) \|\|
	80 !isxdigit((unsigned char)*(s+2)))
	81 return -1;
	82 buf[i++] = hexdigit((s+1)) 16 + hexdigit(*(s+…
	83 s += 2;
	84 break;
	85 case '+':
	86 if (i + 1 >= bufsiz)
	87 return -1;
	88 buf[i++] = ' ';
	89 break;
	90 default:
	91 if (i + 1 >= bufsiz)
	92 return -1;
	93 buf[i++] = *s;
	94 break;
	95 }
	96 }
	97 buf[i] = '\0';
	98
	99 return i;
	100 }
	101
	102 /* decode until NUL separator or end of "key". */
	103 int
	104 decodeparam(char buf, size_t bufsiz, const char s)
	105 {
	106 return decodeparamuntilend(buf, bufsiz, s, '&');
	107 }
	108
	109 char *
	110 getparam(const char query, const char s)
	111 {
	112 const char p, last = NULL;
	113 size_t len;
	114
	115 len = strlen(s);
	116 for (p = query; (p = strstr(p, s)); p += len) {
	117 if (p[len] == '=' && (p == query \|\| p[-1] == '&' \|\| p[-1…
	118 last = p + len + 1;
	119 }
	120
	121 return (char *)last;
	122 }
	123
	124 const char *
	125 httpstatusmsg(int code)
	126 {
	127 switch (code) {
	128 case 200: return "200 OK";
	129 case 202: return "202 Accepted";
	130 case 400: return "400 Bad Request";
	131 case 403: return "403 Forbidden";
	132 case 404: return "404 Not Found";
	133 case 500: return "500 Internal Server Error";
	134 }
	135 return NULL;
	136 }
	137
	138 void
	139 httpstatus(int code)
	140 {
	141 const char *msg;
	142
	143 if ((msg = httpstatusmsg(code)))
	144 printf("Status: %s\r\n", msg);
	145 }
	146
	147 void
	148 httperror(int code, const char *s)
	149 {
	150 httpstatus(code);
	151 fputs("Content-Type: text/plain; charset=utf-8\r\n", stdout);
	152 fputs("\r\n", stdout);
	153 if (s)
	154 printf("%s: %s\r\n", httpstatusmsg(code), s);
	155 else
	156 printf("%s\r\n", httpstatusmsg(code));
	157 exit(0);
	158 }
	159
	160 void
	161 badrequest(const char *s)
	162 {
	163 httperror(400, s);
	164 }
	165
	166 void
	167 forbidden(const char *s)
	168 {
	169 httperror(403, s);
	170 }
	171
	172 void
	173 notfound(const char *s)
	174 {
	175 httperror(404, s);
	176 }
	177
	178 void
	179 servererror(const char *s)
	180 {
	181 httperror(500, s);
	182 }
	183
	184 void
	185 logrequest(const char feedname, const char filename, const char *signa…
	186 {
	187 FILE *fp;
	188
	189 /* file format: timestamp TAB feedname TAB data-filename */
	190 if (!(fp = fopen(logfile, "a")))
	191 servererror("cannot write data");
	192 fprintf(fp, "%lld\t", (long long)now);
	193 fputs(feedname, fp);
	194 fputs("\t", fp);
	195 fputs(filename, fp);
	196 fputs("\t", fp);
	197 fputs(signature, fp);
	198 fputs("\n", fp);
	199 fclose(fp);
	200 }
	201
	202 char *
	203 contenttypetoext(const char *s)
	204 {
	205 return "xml"; /* for now just support XML, for RSS and Atom */
	206 }
	207
	208 int
	209 main(void)
	210 {
	211 FILE *fpdata;
	212 char challenge[256], mode[32] = "", signature[128] = "";
	213 char requesturi[4096], requesturidecoded[4096];
	214 char feedname[256], token[256] = "";
	215 char filename[PATH_MAX], tmpfilename[PATH_MAX];
	216 char configpath[PATH_MAX], feedpath[PATH_MAX], secretpath[PATH_M…
	217 char tokenpath[PATH_MAX];
	218 char contentlength = "", contenttype = "", method = "GET", q…
	219 char p, fileext, *tmp;
	220 char buf[4096];
	221 size_t n, total;
	222 long long ll;
	223 int i, j, fd, r;
	224 /* HMAC */
	225 SHA_CTX ctx;
	226 unsigned char key_opad[65]; /* outer padding - key XORd with opa…
	227 unsigned char *key;
	228 size_t key_len;
	229 unsigned char digest[SHA_DIGEST_LENGTH];
	230 unsigned char inputdigest[SHA_DIGEST_LENGTH];
	231
	232 if (unveil(DATADIR, "rwc") == -1)
	233 err(1, "unveil");
	234 if (pledge("stdio rpath wpath cpath fattr", NULL) == -1)
	235 err(1, "pledge");
	236
	237 if ((tmp = getenv("CONTENT_TYPE")))
	238 contenttype = tmp;
	239 if ((tmp = getenv("CONTENT_LENGTH")))
	240 contentlength = tmp;
	241 if ((tmp = getenv("REQUEST_METHOD")))
	242 method = tmp;
	243 if ((tmp = getenv("QUERY_STRING")))
	244 query = tmp;
	245
	246 /* "8. Authenticated Content Distribution" */
	247 if ((p = getenv("HTTP_X_HUB_SIGNATURE"))) {
	248 r = snprintf(signature, sizeof(signature), "%s", p);
	249 if (r < 0 \|\| (size_t)r >= sizeof(signature))
	250 badrequest("invalid signature (truncated)");
	251
	252 /* accept sha1=digest or sha=digest */
	253 if ((tmp = strstr(signature, "sha1=")))
	254 tmp += sizeof("sha1=") - 1;
	255 else if ((tmp = strstr(signature, "sha=")))
	256 tmp += sizeof("sha=") - 1;
	257 if (tmp) {
	258 for (p = tmp, i = 0; *p; p++, i++) {
	259 if (!isxdigit((unsigned char)*p))
	260 break;
	261 }
	262 }
	263 if (tmp && !p && i == (SHA_DIGEST_LENGTH 2)) {
	264 for (i = 0, j = 0, p = tmp; i < SHA_DIGEST_LENGT…
	265 inputdigest[i] = (hexdigit(p[j]) << 4) \|
	266 hexdigit(p[j + 1]);
	267 }
	268 } else {
	269 badrequest("invalid hash format");
	270 }
	271 }
	272
	273 if (!(p = getenv("REQUEST_URI")))
	274 p = "";
	275 snprintf(requesturi, sizeof(requesturi), "%s", p);
	276 if ((p = strchr(requesturi, '?')))
	277 p = '\0'; / remove query string */
	278
	279 if (decodeparamuntilend(requesturidecoded, sizeof(requesturideco…
	280 badrequest("request URI");
	281
	282 p = requesturidecoded;
	283 if (strncmp(p, relpath, strlen(relpath)))
	284 forbidden("invalid relative path");
	285 p += strlen(relpath);
	286
	287 /* first part of path of request URI is the feedname, last part …
	288 if ((tmp = strchr(p, '/'))) {
	289 tmp = '\0'; / temporary NUL terminate */
	290
	291 r = snprintf(feedname, sizeof(feedname), "%s", p);
	292 if (r < 0 \|\| (size_t)r >= sizeof(feedname))
	293 servererror("path truncated");
	294
	295 r = snprintf(token, sizeof(token), "%s", tmp + 1);
	296 if (r < 0 \|\| (size_t)r >= sizeof(token))
	297 servererror("path truncated");
	298
	299 tmp = '/'; / restore NUL byte to '/' */
	300 } else {
	301 r = snprintf(feedname, sizeof(feedname), "%s", p);
	302 if (r < 0 \|\| (size_t)r >= sizeof(feedname))
	303 servererror("path truncated");
	304 }
	305 if (strstr(feedname, ".."))
	306 badrequest("invalid feed name");
	307
	308 /* check if configdir of feedname exists, else skip request and …
	309 r = snprintf(configpath, sizeof(configpath), "%s/%s", configdir,…
	310 if (r < 0 \|\| (size_t)r >= sizeof(configpath))
	311 servererror("path truncated");
	312 if (access(configpath, X_OK) == -1)
	313 notfound("feed entrypoint does not exist");
	314
	315 r = snprintf(tokenpath, sizeof(tokenpath), "%s/%s/token", config…
	316 if (r < 0 \|\| (size_t)r >= sizeof(tokenpath))
	317 servererror("path truncated");
	318 if ((tmp = readfile(tokenpath))) {
	319 if (strcmp(tmp, token))
	320 forbidden("missing or incorrect token in path");
	321 }
	322
	323 if (!strcasecmp(method, "POST")) {
	324 if (!feedname[0])
	325 badrequest("feed name part of path is missing");
	326
	327 /* read secret, initialize for HMAC and data signature v…
	328 r = snprintf(secretpath, sizeof(secretpath), "%s/%s/secr…
	329 if (r < 0 \|\| (size_t)r >= sizeof(secretpath))
	330 servererror("path truncated");
	331 key = readfile(secretpath);
	332 if (key && !signature[0])
	333 forbidden("requires signature header X-Hub-Signa…
	334
	335 if (key) {
	336 key_len = strlen(key);
	337 hmac_sha1_init(&ctx, key, key_len, key_opad, siz…
	338 }
	339
	340 /* temporary file with random characters */
	341 if ((now = time(NULL)) == (time_t)-1)
	342 servererror("cannot get current time");
	343 r = snprintf(tmpfilename, sizeof(tmpfilename), "%s/%s/%l…
	344 if (r < 0 \|\| (size_t)r >= sizeof(tmpfilename))
	345 servererror("path truncated");
	346
	347 if ((fd = mkstemp(tmpfilename)) == -1)
	348 servererror("cannot create tmpfilename");
	349 if (!(fpdata = fdopen(fd, "wb")))
	350 servererror(tmpfilename);
	351
	352 total = 0;
	353 while ((n = fread(buf, 1, sizeof(buf), stdin)) == sizeof…
	354 if (fwrite(buf, 1, n, fpdata) != n)
	355 break;
	356 if (key)
	357 SHA1_Update(&ctx, buf, n); /* hash data …
	358 total += n;
	359 }
	360 if (n) {
	361 fwrite(buf, 1, n, fpdata);
	362 if (key)
	363 SHA1_Update(&ctx, buf, n);
	364 total += n;
	365 }
	366 if (ferror(stdin)) {
	367 fclose(fpdata);
	368 unlink(tmpfilename);
	369 servererror("cannot process POST message: read e…
	370 }
	371 if (fflush(fpdata) \|\| ferror(fpdata)) {
	372 fclose(fpdata);
	373 unlink(tmpfilename);
	374 servererror("cannot process POST message: write …
	375 }
	376 fclose(fpdata);
	377 chmod(tmpfilename, 0644);
	378
	379 /* if Content-Length is set then check if it matches */
	380 if (contentlength[0]) {
	381 ll = strtoll(contentlength, NULL, 10);
	382 if (ll < 0 \|\| (size_t)ll != total) {
	383 unlink(tmpfilename);
	384 badrequest("Content-Length does not matc…
	385 }
	386 }
	387
	388 if (key) {
	389 /* finalize signature digest */
	390 hmac_sha1_final(&ctx, key_opad, digest);
	391
	392 /* compare digest */
	393 if (memcmp(inputdigest, digest, sizeof(digest)))…
	394 unlink(tmpfilename);
	395 forbidden("invalid digest for data");
	396 }
	397 }
	398
	399 /* use part of basename of the random temp file as the f…
	400 if (!(tmp = strrchr(tmpfilename, '/')))
	401 servererror("invalid path"); /* cannot happen */
	402 r = snprintf(feedpath, sizeof(feedpath), "%s/%s", datadi…
	403 if (r < 0 \|\| (size_t)r >= sizeof(feedpath))
	404 servererror("path truncated");
	405 fileext = contenttypetoext(contenttype);
	406 r = snprintf(filename, sizeof(filename), "%s/%s%s%s", fe…
	407 fileext[0] ? "." : "", fileext);
	408 if (r < 0 \|\| (size_t)r >= sizeof(filename))
	409 servererror("path truncated");
	410
	411 if ((r = rename(tmpfilename, filename)) != 0) {
	412 unlink(filename);
	413 unlink(tmpfilename);
	414 servererror("cannot process POST message: failed…
	415 }
	416 chmod(filename, 0644);
	417
	418 httpstatus(200);
	419 fputs("Content-Type: text/plain; charset=utf-8\r\n", std…
	420 fputs("\r\n", stdout);
	421
	422 /* output stored file: feedname, basename of the file */
	423 if ((tmp = strrchr(filename, '/')))
	424 tmp++;
	425 else
	426 tmp = "";
	427 printf("%s/%s\n", feedname, tmp);
	428
	429 /* write to a log file, this could be a pipe or used wit…
	430 logrequest(feedname, tmp, signature);
	431
	432 return 0;
	433 }
	434
	435 if ((p = getparam(query, "hub.mode"))) {
	436 if (decodeparam(mode, sizeof(mode), p) == -1)
	437 badrequest("hub.mode");
	438 }
	439
	440 if (!strcmp(mode, "subscribe") \|\| !strcmp(mode, "unsubscribe")) {
	441 if ((p = getparam(query, "hub.challenge"))) {
	442 if (decodeparam(challenge, sizeof(challenge), p)…
	443 badrequest("hub.challenge");
	444 }
	445 if (!challenge[0])
	446 badrequest("hub.challenge is required, but is mi…
	447
	448 httpstatus(202);
	449 fputs("Content-Type: text/plain; charset=utf-8\r\n", std…
	450 fputs("\r\n", stdout);
	451 printf("%s\r\n", challenge);
	452 return 0;
	453 } else if (mode[0]) {
	454 badrequest("hub.mode: only subscribe or unsubscribe is s…
	455 }
	456
	457 httpstatus(200);
	458 fputs("Content-Type: text/plain; charset=utf-8\r\n", stdout);
	459 fputs("\r\n", stdout);
	460 printf("pubsubhubbubblub running perfectly and flapping gracious…
	461
	462 return 0;
	463 }