From e07472a3370edf59e7293f7bd5b273187b3f84d5 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 9 Apr 2024 15:24:57 +0200
Subject: [PATCH 2/3] login: do not try to "emulate" the libgcrypt API
Content-Type: text/plain; charset=UTF-8

Implement a more generic wrapper API for message digests, so
that it is easier to also include gnutls as an option.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 lib/login.c | 64 +++++++++++++++++++++++++++++------------------------
 1 file changed, 35 insertions(+), 29 deletions(-)

diff --git a/lib/login.c b/lib/login.c
index 8251d16..03c4a7d 100644
--- a/lib/login.c
+++ b/lib/login.c
@@ -681,41 +681,48 @@ i2h(int i)
 	return i + '0';
 }
 
-#ifndef HAVE_LIBGCRYPT
-typedef struct MD5Context *gcry_md_hd_t;
-#define gcry_md_write MD5Update
-#define GCRY_MD_MD5 1
+#ifdef HAVE_LIBGCRYPT
+typedef gcry_md_hd_t md5_context_t;
+#define md5_open(hd) gcry_md_open(hd, GCRY_MD_MD5, 0)
+#define md5_write gcry_md_write
+#define md5_close gcry_md_close
 
-static void gcry_md_open(gcry_md_hd_t *hd, int algo, unsigned int flags)
+static void md5_read(md5_context_t h, uint8_t *result)
+{
+	memcpy(result, gcry_md_read(h, 0), 16);
+}
+#else
+typedef struct MD5Context *md5_context_t;
+#define md5_write MD5Update
+
+static void md5_open(md5_context_t *hd)
 {
-	assert(algo == GCRY_MD_MD5 && flags == 0);
 	*hd = malloc(sizeof(struct MD5Context));
 	if (*hd) {
 		MD5Init(*hd);
 	}
 }
 
-static void gcry_md_putc(gcry_md_hd_t h, unsigned char c)
-{
-	MD5Update(h, &c, 1);
-}
-
-static char *gcry_md_read(gcry_md_hd_t h, int algo)
+static void md5_read(md5_context_t h, uint8_t *result)
 {
 	unsigned char digest[16];
-	assert(algo == 0 || algo == GCRY_MD_MD5);
 
 	MD5Final(digest, h);
-	return memcpy(h->buf, digest, sizeof(digest));
+	memcpy(result, digest, sizeof(digest));
 }
 
-static void gcry_md_close(gcry_md_hd_t h)
+static void md5_close(md5_context_t h)
 {
 	memset(h, 0, sizeof(*h));
 	free(h);
 }
 #endif
 
+static inline void md5_putc(md5_context_t h, unsigned char c)
+{
+	md5_write(h, &c, 1);
+}
+
 /* size of the challenge used for bidirectional chap */
 #define TARGET_CHAP_C_SIZE 32
 
@@ -726,7 +733,7 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 	char * strp;
 	unsigned char c, cc[2];
 	unsigned char digest[CHAP_R_SIZE];
-	gcry_md_hd_t ctx;
+	md5_context_t ctx;
 	int i;
 
 	if (iscsi->current_phase != ISCSI_PDU_LOGIN_CSG_SECNEG
@@ -739,22 +746,22 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 		return -1;
 	}
 
-	gcry_md_open(&ctx, GCRY_MD_MD5, 0);
+	md5_open(&ctx);
 	if (ctx == NULL) {
 		iscsi_set_error(iscsi, "Cannot create MD5 algorithm");
 		return -1;
 	}
-	gcry_md_putc(ctx, iscsi->chap_i);
-	gcry_md_write(ctx, (unsigned char *)iscsi->passwd, strlen(iscsi->passwd));
+	md5_putc(ctx, iscsi->chap_i);
+	md5_write(ctx, (unsigned char *)iscsi->passwd, strlen(iscsi->passwd));
 
 	strp = iscsi->chap_c;
 	while (*strp != 0) {
 		c = (h2i(strp[0]) << 4) | h2i(strp[1]);
 		strp += 2;
-		gcry_md_putc(ctx, c);
+		md5_putc(ctx, c);
 	}
-	memcpy(digest, gcry_md_read(ctx, 0), sizeof(digest));
-	gcry_md_close(ctx);
+	md5_read(ctx, digest);
+	md5_close(ctx);
 
 	strncpy(str,"CHAP_R=0x",MAX_STRING_SIZE);
 	if (iscsi_pdu_add_data(iscsi, pdu, (unsigned char *)str, strlen(str))
@@ -822,20 +829,19 @@ iscsi_login_add_chap_response(struct iscsi_context *iscsi, struct iscsi_pdu *pdu
 			return -1;
 		}
 
-		gcry_md_open(&ctx, GCRY_MD_MD5, 0);
+		md5_open(&ctx);
 		if (ctx == NULL) {
 			iscsi_set_error(iscsi, "Cannot create MD5 algorithm");
 			return -1;
 		}
-		gcry_md_putc(ctx, iscsi->target_chap_i);
-		gcry_md_write(ctx, (unsigned char *)iscsi->target_passwd,
+		md5_putc(ctx, iscsi->target_chap_i);
+		md5_write(ctx, (unsigned char *)iscsi->target_passwd,
 			      strlen(iscsi->target_passwd));
-		gcry_md_write(ctx, (unsigned char *)target_chap_c,
+		md5_write(ctx, (unsigned char *)target_chap_c,
 			      TARGET_CHAP_C_SIZE);
 
-		memcpy(iscsi->target_chap_r, gcry_md_read(ctx, 0),
-		       sizeof(iscsi->target_chap_r));
-		gcry_md_close(ctx);
+		md5_read(ctx, iscsi->target_chap_r);
+		md5_close(ctx);
 	}
 
 	return 0;
-- 
2.44.0