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[rsync.git] / checksum.c
index ec7ec13ce73691a2437c05f4f9a8cb32c3cb84df..1ed7682817ac1087bbf7f483df9d65487dee0ea6 100644 (file)
 /*
-   Copyright (C) Andrew Tridgell 1996
-   Copyright (C) Paul Mackerras 1996
-
-   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
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-*/
+ * Routines to support checksumming of bytes.
+ *
+ * Copyright (C) 1996 Andrew Tridgell
+ * Copyright (C) 1996 Paul Mackerras
+ * Copyright (C) 2004-2020 Wayne Davison
+ *
+ * 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to dynamically link rsync with the OpenSSL and xxhash
+ * libraries when those libraries are being distributed in compliance
+ * with their license terms, and to distribute a dynamically linked
+ * combination of rsync and these libraries.  This is also considered
+ * to be covered under the GPL's System Libraries exception.
+ *
+ * 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 along
+ * with this program; if not, visit the http://fsf.org website.
+ */
 
 #include "rsync.h"
 
-int csum_length=2; /* initial value */
-
-#define CSUM_CHUNK 64
+#ifdef SUPPORT_XXHASH
+#include <xxhash.h>
+# if XXH_VERSION_NUMBER >= 800
+#  define SUPPORT_XXH3 1
+# endif
+#endif
 
+extern int am_server;
+extern int whole_file;
 extern int checksum_seed;
 extern int protocol_version;
+extern int proper_seed_order;
+extern const char *checksum_choice;
+
+struct name_num_obj valid_checksums = {
+       "checksum", NULL, NULL, 0, 0, {
+#ifdef SUPPORT_XXH3
+               { CSUM_XXH3_128, "xxh128", NULL },
+               { CSUM_XXH3_64, "xxh3", NULL },
+#endif
+#ifdef SUPPORT_XXHASH
+               { CSUM_XXH64, "xxh64", NULL },
+               { CSUM_XXH64, "xxhash", NULL },
+#endif
+               { CSUM_MD5, "md5", NULL },
+               { CSUM_MD4, "md4", NULL },
+               { CSUM_NONE, "none", NULL },
+               { 0, NULL, NULL }
+       }
+};
 
-/*
-  a simple 32 bit checksum that can be upadted from either end
-  (inspired by Mark Adler's Adler-32 checksum)
-  */
-uint32 get_checksum1(char *buf1, int32 len)
+int xfersum_type = 0; /* used for the file transfer checksums */
+int checksum_type = 0; /* used for the pre-transfer (--checksum) checksums */
+
+int parse_csum_name(const char *name, int len)
 {
-    int32 i;
-    uint32 s1, s2;
-    schar *buf = (schar *)buf1;
-
-    s1 = s2 = 0;
-    for (i = 0; i < (len-4); i+=4) {
-       s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] +
-         10*CHAR_OFFSET;
-       s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
-    }
-    for (; i < len; i++) {
-       s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
-    }
-    return (s1 & 0xffff) + (s2 << 16);
+       struct name_num_item *nni;
+
+       if (len < 0 && name)
+               len = strlen(name);
+
+       if (!name || (len == 4 && strncasecmp(name, "auto", 4) == 0)) {
+               if (protocol_version >= 30)
+                       return CSUM_MD5;
+               if (protocol_version >= 27)
+                       return CSUM_MD4_OLD;
+               if (protocol_version >= 21)
+                       return CSUM_MD4_BUSTED;
+               return CSUM_MD4_ARCHAIC;
+       }
+
+       nni = get_nni_by_name(&valid_checksums, name, len);
+
+       if (!nni) {
+               rprintf(FERROR, "unknown checksum name: %s\n", name);
+               exit_cleanup(RERR_UNSUPPORTED);
+       }
+
+       return nni->num;
 }
 
+static const char *checksum_name(int num)
+{
+       struct name_num_item *nni = get_nni_by_num(&valid_checksums, num);
 
-void get_checksum2(char *buf, int32 len, char *sum)
+       return nni ? nni->name : num < CSUM_MD4 ? "md4" : "UNKNOWN";
+}
+
+void parse_checksum_choice(int final_call)
 {
-       int32 i;
-       static char *buf1;
-       static int32 len1;
-       struct mdfour m;
-
-       if (len > len1) {
-               if (buf1)
-                       free(buf1);
-               buf1 = new_array(char, len+4);
-               len1 = len;
-               if (!buf1)
-                       out_of_memory("get_checksum2");
+       if (valid_checksums.negotiated_name)
+               xfersum_type = checksum_type = valid_checksums.negotiated_num;
+       else {
+               char *cp = checksum_choice ? strchr(checksum_choice, ',') : NULL;
+               if (cp) {
+                       xfersum_type = parse_csum_name(checksum_choice, cp - checksum_choice);
+                       checksum_type = parse_csum_name(cp+1, -1);
+               } else
+                       xfersum_type = checksum_type = parse_csum_name(checksum_choice, -1);
+               if (am_server && checksum_choice)
+                       validate_choice_vs_env(NSTR_CHECKSUM, xfersum_type, checksum_type);
        }
 
-       mdfour_begin(&m);
+       if (xfersum_type == CSUM_NONE)
+               whole_file = 1;
 
-       memcpy(buf1,buf,len);
-       if (checksum_seed) {
-               SIVAL(buf1,len,checksum_seed);
-               len += 4;
+       /* Snag the checksum name for both write_batch's option output & the following debug output. */
+       if (valid_checksums.negotiated_name)
+               checksum_choice = valid_checksums.negotiated_name;
+       else if (checksum_choice == NULL)
+               checksum_choice = checksum_name(xfersum_type);
+
+       if (final_call && DEBUG_GTE(NSTR, am_server ? 3 : 1)) {
+               rprintf(FINFO, "%s%s checksum: %s\n",
+                       am_server ? "Server" : "Client",
+                       valid_checksums.negotiated_name ? " negotiated" : "",
+                       checksum_choice);
        }
+}
 
-       for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
-               mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
+int csum_len_for_type(int cst, BOOL flist_csum)
+{
+       switch (cst) {
+         case CSUM_NONE:
+               return 1;
+         case CSUM_MD4_ARCHAIC:
+               /* The oldest checksum code is rather weird: the file-list code only sent
+                * 2-byte checksums, but all other checksums were full MD4 length. */
+               return flist_csum ? 2 : MD4_DIGEST_LEN;
+         case CSUM_MD4:
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+               return MD4_DIGEST_LEN;
+         case CSUM_MD5:
+               return MD5_DIGEST_LEN;
+         case CSUM_XXH64:
+         case CSUM_XXH3_64:
+               return 64/8;
+         case CSUM_XXH3_128:
+               return 128/8;
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
        }
-       /*
-        * Prior to version 27 an incorrect MD4 checksum was computed
-        * by failing to call mdfour_tail() for block sizes that
-        * are multiples of 64.  This is fixed by calling mdfour_update()
-        * even when there are no more bytes.
-        */
-       if (len - i > 0 || protocol_version >= 27) {
-               mdfour_update(&m, (uchar *)(buf1+i), (len-i));
+       return 0;
+}
+
+/* Returns 0 if the checksum is not canonical (i.e. it includes a seed value).
+ * Returns 1 if the public sum order matches our internal sum order.
+ * Returns -1 if the public sum order is the reverse of our internal sum order.
+ */
+int canonical_checksum(int csum_type)
+{
+       switch (csum_type) {
+         case CSUM_NONE:
+         case CSUM_MD4_ARCHAIC:
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+               break;
+         case CSUM_MD4:
+         case CSUM_MD5:
+               return -1;
+         case CSUM_XXH64:
+         case CSUM_XXH3_64:
+         case CSUM_XXH3_128:
+               return 1;
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
        }
+       return 0;
+}
 
-       mdfour_result(&m, (uchar *)sum);
+#ifndef HAVE_SIMD /* See simd-checksum-*.cpp. */
+/*
+  a simple 32 bit checksum that can be updated from either end
+  (inspired by Mark Adler's Adler-32 checksum)
+  */
+uint32 get_checksum1(char *buf1, int32 len)
+{
+       int32 i;
+       uint32 s1, s2;
+       schar *buf = (schar *)buf1;
+
+       s1 = s2 = 0;
+       for (i = 0; i < (len-4); i+=4) {
+               s2 += 4*(s1 + buf[i]) + 3*buf[i+1] + 2*buf[i+2] + buf[i+3] + 10*CHAR_OFFSET;
+               s1 += (buf[i+0] + buf[i+1] + buf[i+2] + buf[i+3] + 4*CHAR_OFFSET);
+       }
+       for (; i < len; i++) {
+               s1 += (buf[i]+CHAR_OFFSET); s2 += s1;
+       }
+       return (s1 & 0xffff) + (s2 << 16);
 }
+#endif
 
+void get_checksum2(char *buf, int32 len, char *sum)
+{
+       switch (xfersum_type) {
+#ifdef SUPPORT_XXHASH
+         case CSUM_XXH64:
+               SIVAL64(sum, 0, XXH64(buf, len, checksum_seed));
+               break;
+#endif
+#ifdef SUPPORT_XXH3
+         case CSUM_XXH3_64:
+               SIVAL64(sum, 0, XXH3_64bits_withSeed(buf, len, checksum_seed));
+               break;
+         case CSUM_XXH3_128: {
+               XXH128_hash_t digest = XXH3_128bits_withSeed(buf, len, checksum_seed);
+               SIVAL64(sum, 0, digest.low64);
+               SIVAL64(sum, 8, digest.high64);
+               break;
+         }
+#endif
+         case CSUM_MD5: {
+               MD5_CTX m5;
+               uchar seedbuf[4];
+               MD5_Init(&m5);
+               if (proper_seed_order) {
+                       if (checksum_seed) {
+                               SIVALu(seedbuf, 0, checksum_seed);
+                               MD5_Update(&m5, seedbuf, 4);
+                       }
+                       MD5_Update(&m5, (uchar *)buf, len);
+               } else {
+                       MD5_Update(&m5, (uchar *)buf, len);
+                       if (checksum_seed) {
+                               SIVALu(seedbuf, 0, checksum_seed);
+                               MD5_Update(&m5, seedbuf, 4);
+                       }
+               }
+               MD5_Final((uchar *)sum, &m5);
+               break;
+         }
+         case CSUM_MD4:
+#ifdef USE_OPENSSL
+         {
+               MD4_CTX m4;
+               MD4_Init(&m4);
+               MD4_Update(&m4, (uchar *)buf, len);
+               if (checksum_seed) {
+                       uchar seedbuf[4];
+                       SIVALu(seedbuf, 0, checksum_seed);
+                       MD4_Update(&m4, seedbuf, 4);
+               }
+               MD4_Final((uchar *)sum, &m4);
+               break;
+         }
+#endif
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+         case CSUM_MD4_ARCHAIC: {
+               md_context m;
+               int32 i;
+               static char *buf1;
+               static int32 len1;
+
+               mdfour_begin(&m);
+
+               if (len > len1) {
+                       if (buf1)
+                               free(buf1);
+                       buf1 = new_array(char, len+4);
+                       len1 = len;
+               }
+
+               memcpy(buf1, buf, len);
+               if (checksum_seed) {
+                       SIVAL(buf1,len,checksum_seed);
+                       len += 4;
+               }
+
+               for (i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK)
+                       mdfour_update(&m, (uchar *)(buf1+i), CSUM_CHUNK);
+
+               /*
+                * Prior to version 27 an incorrect MD4 checksum was computed
+                * by failing to call mdfour_tail() for block sizes that
+                * are multiples of 64.  This is fixed by calling mdfour_update()
+                * even when there are no more bytes.
+                */
+               if (len - i > 0 || xfersum_type > CSUM_MD4_BUSTED)
+                       mdfour_update(&m, (uchar *)(buf1+i), len-i);
+
+               mdfour_result(&m, (uchar *)sum);
+               break;
+         }
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
+       }
+}
 
-void file_checksum(char *fname,char *sum,OFF_T size)
+void file_checksum(const char *fname, const STRUCT_STAT *st_p, char *sum)
 {
-       OFF_T i;
        struct map_struct *buf;
+       OFF_T i, len = st_p->st_size;
+       int32 remainder;
        int fd;
-       OFF_T len = size;
-       struct mdfour m;
 
-       memset(sum,0,MD4_SUM_LENGTH);
+       memset(sum, 0, MAX_DIGEST_LEN);
 
        fd = do_open(fname, O_RDONLY, 0);
        if (fd == -1)
                return;
 
-       buf = map_file(fd, size, MAX_MAP_SIZE, CSUM_CHUNK);
-
-       mdfour_begin(&m);
-
-       for(i = 0; i + CSUM_CHUNK <= len; i += CSUM_CHUNK) {
-               mdfour_update(&m, (uchar *)map_ptr(buf, i, CSUM_CHUNK),
-                             CSUM_CHUNK);
+       buf = map_file(fd, len, MAX_MAP_SIZE, CHUNK_SIZE);
+
+       switch (checksum_type) {
+#ifdef SUPPORT_XXHASH
+         case CSUM_XXH64: {
+               static XXH64_state_t* state = NULL;
+               if (!state && !(state = XXH64_createState()))
+                       out_of_memory("file_checksum");
+
+               XXH64_reset(state, 0);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       XXH64_update(state, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               remainder = (int32)(len - i);
+               if (remainder > 0)
+                       XXH64_update(state, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               SIVAL64(sum, 0, XXH64_digest(state));
+               break;
+         }
+#endif
+#ifdef SUPPORT_XXH3
+         case CSUM_XXH3_64: {
+               static XXH3_state_t* state = NULL;
+               if (!state && !(state = XXH3_createState()))
+                       out_of_memory("file_checksum");
+
+               XXH3_64bits_reset(state);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       XXH3_64bits_update(state, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               remainder = (int32)(len - i);
+               if (remainder > 0)
+                       XXH3_64bits_update(state, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               SIVAL64(sum, 0, XXH3_64bits_digest(state));
+               break;
+         }
+         case CSUM_XXH3_128: {
+               XXH128_hash_t digest;
+               static XXH3_state_t* state = NULL;
+               if (!state && !(state = XXH3_createState()))
+                       out_of_memory("file_checksum");
+
+               XXH3_128bits_reset(state);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       XXH3_128bits_update(state, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               remainder = (int32)(len - i);
+               if (remainder > 0)
+                       XXH3_128bits_update(state, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               digest = XXH3_128bits_digest(state);
+               SIVAL64(sum, 0, digest.low64);
+               SIVAL64(sum, 8, digest.high64);
+               break;
+         }
+#endif
+         case CSUM_MD5: {
+               MD5_CTX m5;
+
+               MD5_Init(&m5);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       MD5_Update(&m5, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               remainder = (int32)(len - i);
+               if (remainder > 0)
+                       MD5_Update(&m5, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               MD5_Final((uchar *)sum, &m5);
+               break;
+         }
+         case CSUM_MD4:
+#ifdef USE_OPENSSL
+         {
+               MD4_CTX m4;
+
+               MD4_Init(&m4);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       MD4_Update(&m4, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               remainder = (int32)(len - i);
+               if (remainder > 0)
+                       MD4_Update(&m4, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               MD4_Final((uchar *)sum, &m4);
+               break;
+         }
+#endif
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+         case CSUM_MD4_ARCHAIC: {
+               md_context m;
+
+               mdfour_begin(&m);
+
+               for (i = 0; i + CHUNK_SIZE <= len; i += CHUNK_SIZE)
+                       mdfour_update(&m, (uchar *)map_ptr(buf, i, CHUNK_SIZE), CHUNK_SIZE);
+
+               /* Prior to version 27 an incorrect MD4 checksum was computed
+                * by failing to call mdfour_tail() for block sizes that
+                * are multiples of 64.  This is fixed by calling mdfour_update()
+                * even when there are no more bytes. */
+               remainder = (int32)(len - i);
+               if (remainder > 0 || checksum_type > CSUM_MD4_BUSTED)
+                       mdfour_update(&m, (uchar *)map_ptr(buf, i, remainder), remainder);
+
+               mdfour_result(&m, (uchar *)sum);
+               break;
+         }
+         default:
+               rprintf(FERROR, "Invalid checksum-choice for --checksum: %s (%d)\n",
+                       checksum_name(checksum_type), checksum_type);
+               exit_cleanup(RERR_UNSUPPORTED);
        }
 
-       /* Prior to version 27 an incorrect MD4 checksum was computed
-        * by failing to call mdfour_tail() for block sizes that
-        * are multiples of 64.  This is fixed by calling mdfour_update()
-        * even when there are no more bytes. */
-       if (len - i > 0 || protocol_version >= 27)
-               mdfour_update(&m, (uchar *)map_ptr(buf, i, len-i), len-i);
-
-       mdfour_result(&m, (uchar *)sum);
-
        close(fd);
        unmap_file(buf);
 }
 
-
 static int32 sumresidue;
-static char sumrbuf[CSUM_CHUNK];
-static struct mdfour md;
-
-void sum_init(int seed)
+static union {
+       md_context md;
+#ifdef USE_OPENSSL
+       MD4_CTX m4;
+#endif
+       MD5_CTX m5;
+} ctx;
+#ifdef SUPPORT_XXHASH
+static XXH64_state_t* xxh64_state;
+#endif
+#ifdef SUPPORT_XXH3
+static XXH3_state_t* xxh3_state;
+#endif
+static int cursum_type;
+
+void sum_init(int csum_type, int seed)
 {
        char s[4];
-       mdfour_begin(&md);
-       sumresidue = 0;
-       SIVAL(s, 0, seed);
-       sum_update(s, 4);
+
+       if (csum_type < 0)
+               csum_type = parse_csum_name(NULL, 0);
+       cursum_type = csum_type;
+
+       switch (csum_type) {
+#ifdef SUPPORT_XXHASH
+         case CSUM_XXH64:
+               if (!xxh64_state && !(xxh64_state = XXH64_createState()))
+                       out_of_memory("sum_init");
+               XXH64_reset(xxh64_state, 0);
+               break;
+#endif
+#ifdef SUPPORT_XXH3
+         case CSUM_XXH3_64:
+               if (!xxh3_state && !(xxh3_state = XXH3_createState()))
+                       out_of_memory("sum_init");
+               XXH3_64bits_reset(xxh3_state);
+               break;
+         case CSUM_XXH3_128:
+               if (!xxh3_state && !(xxh3_state = XXH3_createState()))
+                       out_of_memory("sum_init");
+               XXH3_128bits_reset(xxh3_state);
+               break;
+#endif
+         case CSUM_MD5:
+               MD5_Init(&ctx.m5);
+               break;
+         case CSUM_MD4:
+#ifdef USE_OPENSSL
+               MD4_Init(&ctx.m4);
+#else
+               mdfour_begin(&ctx.md);
+               sumresidue = 0;
+#endif
+               break;
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+         case CSUM_MD4_ARCHAIC:
+               mdfour_begin(&ctx.md);
+               sumresidue = 0;
+               SIVAL(s, 0, seed);
+               sum_update(s, 4);
+               break;
+         case CSUM_NONE:
+               break;
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
+       }
 }
 
 /**
@@ -148,37 +515,111 @@ void sum_init(int seed)
  * @todo Perhaps get rid of md and just pass in the address each time.
  * Very slightly clearer and slower.
  **/
-void sum_update(char *p, int32 len)
+void sum_update(const char *p, int32 len)
 {
-       if (len + sumresidue < CSUM_CHUNK) {
-               memcpy(sumrbuf + sumresidue, p, len);
-               sumresidue += len;
-               return;
-       }
-
-       if (sumresidue) {
-               int32 i = CSUM_CHUNK - sumresidue;
-               memcpy(sumrbuf + sumresidue, p, i);
-               mdfour_update(&md, (uchar *)sumrbuf, CSUM_CHUNK);
-               len -= i;
-               p += i;
+       switch (cursum_type) {
+#ifdef SUPPORT_XXHASH
+         case CSUM_XXH64:
+               XXH64_update(xxh64_state, p, len);
+               break;
+#endif
+#ifdef SUPPORT_XXH3
+         case CSUM_XXH3_64:
+               XXH3_64bits_update(xxh3_state, p, len);
+               break;
+         case CSUM_XXH3_128:
+               XXH3_128bits_update(xxh3_state, p, len);
+               break;
+#endif
+         case CSUM_MD5:
+               MD5_Update(&ctx.m5, (uchar *)p, len);
+               break;
+         case CSUM_MD4:
+#ifdef USE_OPENSSL
+               MD4_Update(&ctx.m4, (uchar *)p, len);
+               break;
+#endif
+         case CSUM_MD4_OLD:
+         case CSUM_MD4_BUSTED:
+         case CSUM_MD4_ARCHAIC:
+               if (len + sumresidue < CSUM_CHUNK) {
+                       memcpy(ctx.md.buffer + sumresidue, p, len);
+                       sumresidue += len;
+                       break;
+               }
+
+               if (sumresidue) {
+                       int32 i = CSUM_CHUNK - sumresidue;
+                       memcpy(ctx.md.buffer + sumresidue, p, i);
+                       mdfour_update(&ctx.md, (uchar *)ctx.md.buffer, CSUM_CHUNK);
+                       len -= i;
+                       p += i;
+               }
+
+               while (len >= CSUM_CHUNK) {
+                       mdfour_update(&ctx.md, (uchar *)p, CSUM_CHUNK);
+                       len -= CSUM_CHUNK;
+                       p += CSUM_CHUNK;
+               }
+
+               sumresidue = len;
+               if (sumresidue)
+                       memcpy(ctx.md.buffer, p, sumresidue);
+               break;
+         case CSUM_NONE:
+               break;
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
        }
-
-       while (len >= CSUM_CHUNK) {
-               mdfour_update(&md, (uchar *)p, CSUM_CHUNK);
-               len -= CSUM_CHUNK;
-               p += CSUM_CHUNK;
-       }
-
-       sumresidue = len;
-       if (sumresidue)
-               memcpy(sumrbuf, p, sumresidue);
 }
 
-void sum_end(char *sum)
+/* NOTE: all the callers of sum_end() pass in a pointer to a buffer that is
+ * MAX_DIGEST_LEN in size, so even if the csum-len is shorter that that (i.e.
+ * CSUM_MD4_ARCHAIC), we don't have to worry about limiting the data we write
+ * into the "sum" buffer. */
+int sum_end(char *sum)
 {
-       if (sumresidue || protocol_version >= 27)
-               mdfour_update(&md, (uchar *)sumrbuf, sumresidue);
+       switch (cursum_type) {
+#ifdef SUPPORT_XXHASH
+         case CSUM_XXH64:
+               SIVAL64(sum, 0, XXH64_digest(xxh64_state));
+               break;
+#endif
+#ifdef SUPPORT_XXH3
+         case CSUM_XXH3_64:
+               SIVAL64(sum, 0, XXH3_64bits_digest(xxh3_state));
+               break;
+         case CSUM_XXH3_128: {
+               XXH128_hash_t digest = XXH3_128bits_digest(xxh3_state);
+               SIVAL64(sum, 0, digest.low64);
+               SIVAL64(sum, 8, digest.high64);
+               break;
+         }
+#endif
+         case CSUM_MD5:
+               MD5_Final((uchar *)sum, &ctx.m5);
+               break;
+         case CSUM_MD4:
+#ifdef USE_OPENSSL
+               MD4_Final((uchar *)sum, &ctx.m4);
+               break;
+#endif
+         case CSUM_MD4_OLD:
+               mdfour_update(&ctx.md, (uchar *)ctx.md.buffer, sumresidue);
+               mdfour_result(&ctx.md, (uchar *)sum);
+               break;
+         case CSUM_MD4_BUSTED:
+         case CSUM_MD4_ARCHAIC:
+               if (sumresidue)
+                       mdfour_update(&ctx.md, (uchar *)ctx.md.buffer, sumresidue);
+               mdfour_result(&ctx.md, (uchar *)sum);
+               break;
+         case CSUM_NONE:
+               *sum = '\0';
+               break;
+         default: /* paranoia to prevent missing case values */
+               exit_cleanup(RERR_UNSUPPORTED);
+       }
 
-       mdfour_result(&md, (uchar *)sum);
+       return csum_len_for_type(cursum_type, 0);
 }