added .lastudate support for HTTP protocol

known limitation: do not work when connected to some web servers (lighttpd)

lib/libftp/ftplib.c

@@ -32,6 +32,7 @@
 #include <string.h>
 #include <errno.h>
 #include <ctype.h>
+#include <time.h>
 #if defined(__unix__)
 #include <sys/time.h>
 #include <sys/types.h>
@@ -1512,18 +1513,35 @@ static int HttpXfer(const char *localfile, const char *path, int *size,
  * return 1 if successful, 0 otherwise
  */
 GLOBALREF int HttpGet(const char *host, const char *outputfile, const char *path,
-		int *size, netbuf *nControl, unsigned int offset)
+		int *size, netbuf *nControl, unsigned int offset,
+		const struct tm *mtime1, struct tm *mtime2)
 {
-	char buf[256];
+	char buf[512];
 
+	sprintf(buf, "GET %s HTTP/1.1\r\nHost: %s\r\n", path, host);
 	if (offset > 0)
-		sprintf(buf, "GET %s HTTP/1.1\r\nHost: %s\r\nRange: bytes=%d-\r\n\r\n", path, host, offset);
-	else
-		sprintf(buf, "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", path, host);
+		sprintf(buf, "%sRange: bytes=%d-\r\n", buf, offset);
+	if (mtime1 && mtime1->tm_year)
+	{
+		char mtime[30];
+		/* Format:
+		 * "If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT\r\n" */
+		strftime(mtime, sizeof(mtime), "%a, %d %b %Y %H:%M:%S GMT", mtime1);
+		sprintf(buf, "%sIf-Modified-Since: %s\r\n", buf, mtime);
+	}
+	sprintf(buf, "%s\r\n", buf);
+
 	if (!HttpSendCmd(buf,'2',nControl))
 	{
 		if (nControl->response[9] == '3')
+		{
+			/* If the answer from the server is 304, the requested file
+			 * hasn't been modified: no need to retrieve it */
+			if (mtime1 && mtime1->tm_year && nControl->response[11] == '4')
+				return 0;
+			/* otherwise, it is a redirection */
 			printf("redirection not supported\n");
+		}
 		return 0;
 	}
 
@@ -1548,6 +1566,43 @@ GLOBALREF int HttpGet(const char *host, const char *outputfile, const char *path
 			if (offset > 0)
 				*size += offset;
 		}
+		else if (mtime2 && strstr(nControl->response,"Last-Modified"))
+		{
+			/* Format:
+			 * "Last-Modified: Sat, 29 Oct 1994 19:43:31 GMT\r\n" */
+			char *c = nControl->response+20;
+			int mint, j;
+			static const int months[12] = {
+				('J'<<16)|('a'<<8)|'n',
+				('F'<<16)|('e'<<8)|'b',
+				('M'<<16)|('a'<<8)|'r',
+				('A'<<16)|('p'<<8)|'r',
+				('M'<<16)|('a'<<8)|'y',
+				('J'<<16)|('u'<<8)|'n',
+				('J'<<16)|('u'<<8)|'l',
+				('A'<<16)|('u'<<8)|'g',
+				('S'<<16)|('e'<<8)|'p',
+				('O'<<16)|('c'<<8)|'t',
+				('N'<<16)|('o'<<8)|'v',
+				('D'<<16)|('e'<<8)|'c'
+			};
+			mtime2->tm_mday = (c[0]-'0')*10+c[1]-'0';
+			mint = (c[3]<<16)|(c[4]<<8)|c[5];
+			mtime2->tm_mon = 0;
+			for(j = 0; j < 12; j++)
+			{
+				if (mint == months[j]) 
+				{
+					mtime2->tm_mon = j;
+					break;
+				}
+			}
+			mtime2->tm_year = ((c[7]-'0')*10+(c[8]-'0')-19)*100;
+			mtime2->tm_year += (c[9]-'0')*10+c[10]-'0';
+			mtime2->tm_hour = (c[12]-'0')*10+c[13]-'0';
+			mtime2->tm_min = (c[15]-'0')*10+c[16]-'0';
+			mtime2->tm_sec = (c[18]-'0')*10+c[19]-'0';
+		}
 		if (strlen(nControl->response) == 0)
 			break;
 	}

lib/libftp/ftplib.h

@@ -121,7 +121,8 @@ GLOBALREF void FtpQuit(netbuf *nControl);
 
 GLOBALREF int HttpConnect(const char *host, unsigned short port, netbuf **nControl);
 GLOBALREF int HttpGet(const char *host, const char *output, const char *path,
-	int *size, netbuf *nControl, unsigned int offset);
+	int *size, netbuf *nControl, unsigned int offset,
+	const struct tm *mtime1, struct tm *mtime2);
 GLOBALREF void HttpQuit(netbuf *nControl);
 
 #ifdef __cplusplus

src/pacman/download.c

@@ -26,6 +26,7 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <time.h>
 #include <sys/time.h>
 #include <ftplib.h>
 
@@ -366,13 +367,14 @@ int downloadfiles_forreal(list_t *servers, const char *localpath,
 								vprint("mtimes are identical, skipping %s\n", fn);
 								filedone = -1;
 								complete = list_add(complete, fn);
-							}
+							} else {
 								if(mtime2) {								
 									strncpy(mtime2, fmtime, 15); /* YYYYMMDDHHMMSS (=14b) */
 									mtime2[14] = '\0';
 								}
 							}
 						}
+					}
 					if(!filedone) {
 						if(!stat(output, &st)) {
 							offset = (int)st.st_size;
@@ -395,6 +397,10 @@ int downloadfiles_forreal(list_t *servers, const char *localpath,
 					char src[PATH_MAX];
 					char *host;
 					unsigned port;
+					struct tm fmtime1;
+					struct tm fmtime2;
+					memset(&fmtime1, 0, sizeof(struct tm));
+					memset(&fmtime2, 0, sizeof(struct tm));
 					if(!strcmp(server->protocol, "http") && !config->proxyhost) {
 						/* HTTP servers hang up after each request (but not proxies), so
 						 * we have to re-connect for each file.
@@ -402,9 +408,9 @@ int downloadfiles_forreal(list_t *servers, const char *localpath,
 						host = (config->proxyhost) ? config->proxyhost : server->server;
 						port = (config->proxyhost) ? config->proxyport : 80;
 						if(strchr(host, ':')) {
-							vprint("Connecting to %s\n", host);
+							vprint("connecting to %s\n", host);
 						} else {
-							vprint("Connecting to %s:%u\n", host, port);
+							vprint("connecting to %s:%u\n", host, port);
 						}
 						if(!HttpConnect(host, port, &control)) {
 							fprintf(stderr, "error: cannot connect to %s\n", host);
@@ -427,13 +433,38 @@ int downloadfiles_forreal(list_t *servers, const char *localpath,
 					} else {
 						snprintf(src, PATH_MAX, "%s://%s%s%s", server->protocol, server->server, server->path, fn);
 					}
-					if(!HttpGet(server->server, output, src, &fsz, control, offset)) {
-						fprintf(stderr, "\nfailed downloading %s from %s: %s\n",
-								src, server->server, FtpLastResponse(control));
+					if(mtime1) {
+						/* date conversion from YYYYMMDDHHMMSS to "rfc1123-date" */
+						sscanf(mtime1, "%4d%2d%2d%2d%2d%2d",
+						       &fmtime1.tm_year, &fmtime1.tm_mon, &fmtime1.tm_mday,
+						       &fmtime1.tm_hour, &fmtime1.tm_min, &fmtime1.tm_sec);
+						fmtime1.tm_year -= 1900;
+						fmtime1.tm_mon--;
+						/* ORE - really compute the week day because some web servers (like lighttpd)
+						 * need them.
+						 * Fortunately, Apache does not use it: so our loosy implementation with a
+						 * hardcoded week day will work in almost all cases. */
+						fmtime1.tm_wday = 0;
+					}
+					fmtime2.tm_year = 0;
+					if(!HttpGet(server->server, output, src, &fsz, control, offset, &fmtime1, &fmtime2)) {
+						if(strstr(FtpLastResponse(control), "304")) {
+							vprint("mtimes are identical, skipping %s\n", fn);
+							filedone = -1;
+							complete = list_add(complete, fn);
+						} else {
+							fprintf(stderr, "\nfailed downloading %s from %s: %s\n", src, server->server, FtpLastResponse(control));
 							/* we leave the partially downloaded file in place so it can be resumed later */
+						}
 					} else {
 						filedone = 1;
 					}
+					if(mtime2 && fmtime2.tm_year) {
+						/* date conversion from "rfc1123-date" to YYYYMMDDHHMMSS */
+						sprintf(mtime2, "%4d%02d%02d%02d%02d%02d",
+						        fmtime2.tm_year+1900, fmtime2.tm_mon+1, fmtime2.tm_mday,
+						        fmtime2.tm_hour, fmtime2.tm_min, fmtime2.tm_sec);
+					}
 				} else if(!strcmp(server->protocol, "file")) {
 					char src[PATH_MAX];
 					snprintf(src, PATH_MAX, "%s%s", server->path, fn);

src/pacman/sync.c

@@ -177,7 +177,9 @@ static int sync_synctree(list_t *syncs)
 		snprintf(path, PATH_MAX, "%s%s", root, dbpath);
 
 		ret = downloadfiles_forreal(sync->servers, path, files, lastupdate, newmtime);
+		if(strlen(newmtime)) {
 			vprint("sync: new mtime for %s: %s\n", sync->treename, newmtime);
+		}
 		FREELIST(files);
 		if(ret > 0) {
 			ERR(NL, "failed to synchronize %s\n", sync->treename);
@@ -190,7 +192,7 @@ static int sync_synctree(list_t *syncs)
 				if(pm_errno != PM_ERR_DB_UPTODATE) {
 					ERR(NL, "failed to synchronize %s (%s)\n", sync->treename, alpm_strerror(pm_errno));
 					success--;
-				} else {
+				} else if(!strlen(newmtime)){
 					MSG(NL, ":: %s is up to date\n", sync->treename);
 				}
 			}